Adenosine diphosphate strongly potentiates the ability of the chemokines MDC, TARC, and SDF-1 to stimulate platelet function

Blood ◽  
2001 ◽  
Vol 97 (4) ◽  
pp. 937-945 ◽  
Author(s):  
Adrian R. L. Gear ◽  
Sudawadee Suttitanamongkol ◽  
Delia Viisoreanu ◽  
Renata K. Polanowska-Grabowska ◽  
Sanghamitra Raha ◽  
...  
Keyword(s):  
Platelet Activation ◽  
Platelet Function ◽  
Stromal Cell ◽  
Inflammatory Responses ◽  
Shape Change ◽  
Adenosine Diphosphate ◽  
Flow Conditions ◽  
Low Levels ◽  
Stromal Cell Derived Factor ◽  
Platelet Shape

Abstract Platelet activation is normally induced by primary agonists such as adenosine diphosphate (ADP), thrombin, and collagen, whereas other agonists, such as epinephrine, can play important accessory roles. It is now reported that the macrophage-derived chemokine (MDC), thymus activation–regulated chemokine (TARC), and stromal cell–derived factor one (SDF-1) are highly effective activators of platelet function under a variety of conditions, stimulating platelet shape change, aggregation, and adhesion to collagen or fibrinogen. Chemokine-mediated platelet activation was rapid and maximal (less than 5 seconds) under arterial flow conditions and depended strongly on the presence of low levels of primary agonists such as ADP or thrombin. Concentrations of ADP (0.05-0.25 μM) or thrombin (0.005-0.02 U/mL) that induced minimal aggregation caused major aggregation acting in combination with the chemokines. The ability of apyrase to block chemokine-dependent aggregation or adhesion was consistent with an important role for ADP. Chemokine-stimulated aggregation was also insensitive to indomethacin, suggesting that the activation of cyclo-oxygenase is not involved. TARC, MDC, and SDF-1 increased intracellular calcium concentrations [Ca2+]iwhen combined with low levels of ADP. The MDC and TARC receptor CCR4 was expressed on platelets, and an anti-CCR4 antibody blocked aggregation induced by TARC or MDC. Treatment of platelets with SDF-1 and MDC rapidly exposed P-selectin (CD62P) on the cell surface but did not induce the secretion of serotonin. These findings suggest that the chemokines MDC, TARC, and SDF-1, which may be produced during inflammatory responses, coupled with low levels of ADP or thrombin, can serve as strong stimuli for activating platelet function.

PAR1-Induced Human Platelet Shape Change, Aggregation and Secretion Requires Gα13 Switch Region I Signaling.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1522-1522
Author(s):  
Jin-Sheng Huang ◽  
Lanlan Dong ◽  
Guy C. Le Breton
Keyword(s):  
G Protein ◽  
Platelet Activation ◽  
Platelet Function ◽  
Human Platelet ◽  
Shape Change ◽  
Human Platelets ◽  
G Protein Signaling ◽  
Protein Signaling ◽  
Rhoa Activation ◽  
Platelet Shape

Abstract While it is known that platelets possess multiple G protein signaling pathways that contribute to the different platelet functional responses, the relative participation of these individual pathways in platelet shape change, aggregation and secretion is not well characterized. To a large extent this is due to the lack of suitable reagents which selectively interfere with specific G protein signaling events, and which can be applied to the study of intact human platelets. With the exception of pepducins, which modulate receptor-G protein coupling (Kuliopulos, A. and Covic, L. Life Sciences 74, 255–262, 2003), the field has for the most part been limited to agents which interfere with different downstream kinases or other downstream effectors. However, the G protein pathways share many of these downstream targets, and consequently, it has been difficult to assign a specific platelet function to a certain G protein. In order to address this issue, it was reasoned that more direct information about specific G protein involvement in human platelet activation might be obtained by interfering with the initial G protein signal transduction events, rather than by interfering with the secondary downstream consequences of this transduction process. Based on this consideration, the present study used a specific Gα13 switch region I (SRI) peptide to investigate the involvement of Gα13 signaling in protease-activated receptor 1 (PAR1)-mediated human platelet function. Specifically, a myristoylated peptide representing the Gα13 SRI (Myr-G13SRIpep) was synthesized and evaluated for its effects on PAR1 activation. Initial studies using dot blot and mass spectrum analysis demonstrated that Myr-G13SRIpep, and its random sequence control (Myr-G13SRIRandom-pep), were equally taken up by intact human platelets. Radioligand binding experiments revealed that Myr-G13SRIpep did not interfere with PAR1-ligand interaction. Subsequent experiments demonstrated that G13SRIpep specifically bound to platelet p115Rho guanine nucleotide exchange factor (p115RhoGEF) and blocked PAR1-mediated RhoA activation. These results suggest a direct interaction of Gα13 SRI with p115RhoGEF, and indicate a possible mechanism for Myr-G13SRIpep inhibition of RhoA activation. Platelet function studies revealed that Myr-G13SRIpep inhibited PAR1-stimulated platelet shape change, aggregation and dense granule secretion in a dose-dependent manner. On the other hand, Myr-G13SRIpep did not inhibit platelet activation induced by ADP, A23187 or PAR4 activating peptide (AYPGKF). Taken together, these findings demonstrate that the inhibitory effects of Myr-G13SRIpep are limited to PAR1 signaling mechanisms and are not due to nonspecific effects on platelet function. These results also suggest a significant role for Gα13 SRI signaling in the process of PAR1-mediated human platelet activation. In additional studies it was found that Myr-G13SRIpep also inhibited low-dose thrombin-induced aggregation and PAR1-induced intraplatelet calcium mobilization. Collectively, these results provide evidence that: 1. interaction of Gα13 SRI with p115RhoGEF is required for G13-mediated RhoA activation in platelets; 2. signaling through the G13 pathway is critical for PAR1-mediated human platelet functional changes; 3. Gα13 SRI signaling is involved in low-dose thrombin-induced platelet aggregation as well as PAR1-mediated calcium mobilization; and 4. permeable peptides representing SRI of Gα-subunits should be a useful approach for studying individual G protein signaling pathways in intact cells.

scholarly journals The Effect of Tirofiban on Fibrinogen/Agonist-Induced Platelet Shape Change and Aggregation

2008 ◽  
Vol 14 (3) ◽  
pp. 295-302 ◽  
Author(s):  
I. Anita Jagroop ◽  
Dimitri P. Mikhailidis
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activation ◽  
Whole Blood ◽  
Platelet Rich Plasma ◽  
Shape Change ◽  
Adenosine Diphosphate ◽  
Vascular Events ◽  
Spontaneous Platelet Aggregation ◽  
Induced Aggregation ◽  
Platelet Shape

There is evidence linking raised plasma fibrinogen (fib) and platelet hyperactivity with vascular events. One way to inhibit platelets is to block the platelet membrane glycoprotein (GP) IIb/IIIa receptor, which binds circulating fib or von Willebrand factor and cross-links platelets at the final common pathway to platelet aggregation. Tirofiban is a potent and specific fib receptor antagonist, used in the treatment of unstable angina. The authors assessed the effect of tirofiban on spontaneous platelet aggregation (SPA), fib-induced, serotonin (5HT)-induced, and adenosine diphosphate (ADP)-induced aggregation in whole blood by calculating the percentage free platelet count. These various agonists were used alone and in combination. The authors also measured the effect of tirofiban on agonists-induced (ADP, 5HT) platelet shape change (PSC). The effect of fib on PSC was also evaluated in platelet-rich plasma using a high-resolution (0.07 fL) channelyzer. Tirofiban significantly inhibited SPA, fib (2, 4, 8 g/L), ADP, ADP + fib combination, and 5HT-induced aggregation. Tirofiban had no effect on agonist-induced PSC. There was no apparent change in platelet volume with fib. In conclusion, tirofiban does not appear to have an effect on PSC, an early phase of platelet activation. Tirofiban seems to be a nonspecific and an effective inhibitor of platelet aggregation (a later phase of platelet activation) in whole blood. The clinical significance of these findings remains to be established.

Apolipoprotein B100 danger-associated signal 1 (ApoBDS-1) triggers platelet activation and boosts platelet-leukocyte proinflammatory responses

2014 ◽  
Vol 112 (08) ◽  
pp. 332-341 ◽  
Author(s):  
Yajuan Wang ◽  
Lynn M. Butler ◽  
Göran K. Hansson ◽  
Zhong-qun Yan ◽  
Cecilia Söderberg-Nauclér ◽  
...  
Keyword(s):  
Platelet Activation ◽  
Platelet Function ◽  
Inflammatory Responses ◽  
Innate Immune ◽  
Innate Immune Responses ◽  
Flow Conditions ◽  
Intracellular Signalling Pathways ◽  
Proinflammatory Responses

SummaryLow-density lipoproteins (LDL), occurring in vivo in both their native and oxidative form, modulate platelet function and thereby contribute to atherothrombosis. We recently identified and demonstrated that ‘ApoB100 danger-associated signal 1’ (ApoBDS-1), a native peptide derived from Apolipoprotein B-100 (ApoB100) of LDL, induces inflammatory responses in innate immune cells. Platelets are critically involved in the development as well as in the lethal consequences of atherothrombotic diseases, but whether ApoBDS-1 has also an impact on platelet function is unknown. In this study we examined the effect of ApoBDS-1 on human platelet function and platelet-leukocyte interactions in vitro. Stimulation with ApoBDS-1 induced platelet activation, degranulation, adhesion and release of proinflammatory cytokines. ApoBDS-1-stimulated platelets triggered innate immune responses by augmenting leukocyte activation, adhesion and transmigration to/through activated HUVEC monolayers, under flow conditions. These platelet-activating effects were sequence-specific, and stimulation of platelets with ApoBDS-1 activated intracellular signalling pathways, including Ca2+, PI3K/Akt, PLC, and p38– and ERKMAPK. Moreover, our data indicates that ApoBDS-1-induced platelet activation is partially dependent of positive feedback from ADP on P2Y1 and P2Y12, and TxA2. In conclusion, we demonstrate that ApoBDS-1 is an effective platelet agonist, boosting platelet-leukocyte’s proinflammatory responses, and potentially contributing to the multifaceted inflammatory-promoting effects of LDL in the pathogenesis of atherothrombosis.

Adenosine Diphosphate (ADP)-Induced ⍺-Granules Release from Platelets of Native Whole Blood Is Reduced by Ticlopidine but Not by Aspirin or Dipyridamole

1986 ◽  
Vol 56 (02) ◽  
pp. 147-150 ◽  
Author(s):  
V Pengo ◽  
M Boschello ◽  
A Marzari ◽  
M Baca ◽  
L Schivazappa ◽  
...  
Keyword(s):  
Whole Blood ◽  
Light Transmission ◽  
Ex Vivo ◽  
Early Stage ◽  
Shape Change ◽  
Adenosine Diphosphate ◽  
Dose Dependent ◽  
Plateletderived Growth Factor ◽  
Platelet Shape

SummaryA brief contact between native whole blood and ADP promotes a dose-dependent release of platelet a-granules without a fall in the platelet number. We assessed the “ex vivo” effect of three widely used antiplatelet drugs, aspirin dipyridamole and ticlopidine, on this system. Aspirin (a single 800 mg dose) and dipyridamole (300 mg/die for four days) had no effect, while ticlopidine (500 mg/die for four days) significantly reduced the a-granules release for an ADP stimulation of 0.4 (p <0.02), 1.2 (p <0.01) and 2 pM (p <0.01). No drug, however, completeley inhibits this early stage of platelet activation. The platelet release of α-granules may be related to platelet shape change of the light transmission aggregometer and may be important “in vivo” by enhancing platelet adhesiveness and by liberating the plateletderived growth factor.

scholarly journals Effect of aspirin on platelet-von Willebrand factor surface expression on thrombin and ADP-stimulated platelets

Blood ◽  
1989 ◽  
Vol 74 (6) ◽  
pp. 2016-2021 ◽  
Author(s):  
RI Parker ◽  
HR Gralnick
Keyword(s):  
Von Willebrand Factor ◽  
Shape Change ◽  
Adenosine Diphosphate ◽  
Surface Expression ◽  
Platelet Surface ◽  
Granule Secretion ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Platelet Shape ◽  
Stimulation Of

Abstract Platelets contain a pool of endogenous platelet-von Willebrand factor (vWF) that becomes expressed on the platelet surface when platelets are stimulated by a variety of agonists. Maximal platelet-vWF expression occurs in concert with platelet alpha-granule secretion. Aspirin (ASA) is known to impair platelet activation and alpha-granule secretion by irreversible inhibition of platelet cyclo-oxygenase. We studied native and ASA-treated platelets for their ability to mobilize and to express platelet-vWF in response to adenosine diphosphate (ADP) or thrombin. We found that each agonist was effective in promoting increased platelet- vWF surface expression on native and ASA-treated platelets. ASA-treated platelets responded identically to native platelets to low (0.01 U/mL) and high (1.0 U/mL) concentrations of thrombin, while the ADP-induced increase in ASA-treated platelets was only 50% to 60% of that for control platelets. Measurement of secreted platelet-vWF and beta- thromboglobulin indicated that the increase seen with ADP was largely independent of alpha-granule secretion. Using monoclonal antibodies (MoAbs) against the platelet glycoproteins (GP) IIb/IIIa and Ib (MoAbs 10E5 and 6D1, respectively), we demonstrated that the ADP-induced increase in platelet-vWF expression on control platelets primarily involved the binding of secreted platelet-vWF to the platelet GPIIb/IIIa. In contrast, the increase in platelet-vWF that occurred following ADP stimulation of ASA-treated platelets was largely insensitive to GPIIb/IIIa blockade. No effect of GPIb blockade in platelet-vWf expression was noted for either control or ASA-treated platelets. When platelet shape change was prevented by the addition of cytochalasin D, ADP-induced platelet-vWf surface expression on ASA- treated platelets was reduced by more than 80%. Our data indicate that platelets in which the cyclooxygenase pathway is blocked by the action of aspirin can increase surface expression of platelet-vWf as a consequence of platelet shape change. We speculate that this process exposes platelet-vWf bound to GPIIb/IIIa, or possibly GPIb, within the surface connected canalicular system.

scholarly journals Inhibition of collagen-induced platelet activation by 5'-p- fluorosulfonylbenzoyl adenosine: evidence for an adenosine diphosphate requirement and synergistic influence of prostaglandin endoperoxides

Blood ◽  
1986 ◽  
Vol 68 (2) ◽  
pp. 565-570 ◽  
Author(s):  
RW Colman ◽  
WR Figures ◽  
LM Scearce ◽  
AM Strimpler ◽  
FX Zhou ◽  
...  
Keyword(s):  
Platelet Activation ◽  
Shape Change ◽  
Thromboxane A2 ◽  
Adenosine Diphosphate ◽  
Platelet Surface ◽  
Prostaglandin Endoperoxide ◽  
Fibrinogen Binding ◽  
Low Concentrations ◽  
Absolute Requirement

Abstract The relative roles of platelet autacoids such as adenosine diphosphate (ADP), prostaglandin endoperoxides, and thromboxane A2 (TXA2) in collagen-induced platelet activation are not fully understood. We reexamined this relationship using the ADP affinity analogue, 5'-p- fluorosulfonylbenzoyl adenosine (FSBA), which covalently modifies a receptor for ADP on the platelet surface, thereby inhibiting ADP- induced platelet activation. Collagen-induced shape change, aggregation, and fibrinogen binding were each fully inhibited under conditions in which FSBA is covalently incorporated and could not be overcome by raising the collagen used to supramaximal concentrations. In contrast, TXA2 synthesis stimulated by collagen under conditions that produced maximum aggregation was only minimally inhibited by FSBA. Since covalent incorporation of FSBA has been previously shown to specifically inhibit ADP-induced activation of platelets, the present study supports the contention that ADP is required for collagen-induced platelet activation. Under similar conditions, indomethacin, an inhibitor of cyclooxygenase, inhibited collagen-induced shape change, indicating that endoperoxides and/or TXA2 also play a role in this response. Shape change induced by low concentrations (10 nmol/L) of the stable prostaglandin endoperoxide, azo-PGH2, was also inhibited by FSBA. These observations indicate a role for ADP in responses elicited by low concentrations of endoperoxides. However, at higher concentrations of azo-PGH2 (100 nmol/L), inhibition by FSBA could be overcome. Thus, the effect of collagen apparently has an absolute requirement for ADP for aggregation and fibrinogen binding and for both ADP and prostaglandins for shape change. Aggregation and fibrinogen binding induced by prostaglandin endoperoxides also required ADP as a mediator, but ADP is not absolutely required at high endoperoxide concentration to induce shape change.

Measuring platelet function with platelet shape change, an early event in aggregation

1989 ◽  
Vol 53 (2) ◽  
pp. 109-127 ◽  
Author(s):  
Duane O. Beaumont ◽  
Keith W. Whitten ◽  
Rhonda G. Mock ◽  
Charles W. Slattery
Keyword(s):  
Platelet Function ◽  
Shape Change ◽  
Early Event ◽  
Platelet Shape

scholarly journals Effect of alteplase on platelet function and receptor expression

2019 ◽  
Vol 47 (4) ◽  
pp. 1731-1739 ◽  
Author(s):  
Jun Lu ◽  
Peng Hu ◽  
Guangyu Wei ◽  
Qi Luo ◽  
Jianlin Qiao ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Platelet Activation ◽  
Platelet Function ◽  
Adenosine Diphosphate ◽  
Receptor Expression ◽  
Light Transmittance ◽  
Dependent Manner ◽  
Clot Retraction ◽  
Platelet Receptors

Objective To investigate the role of alteplase, a widely-used thrombolytic drug, in platelet function. Methods Human platelets were incubated with different concentrations of alteplase followed by analysis of platelet aggregation in response to adenosine diphosphate (ADP), collagen, ristocetin, arachidonic acid or epinephrine using light transmittance aggregometry. Platelet activation and surface levels of platelet receptors GPIbα, GPVI and αIIbβ3 were analysed using flow cytometry. The effect of alteplase on clot retraction was also examined. Results This study demonstrated that alteplase significantly inhibited platelet aggregation in response to ADP, collagen and epinephrine in a dose-dependent manner, but it did not affect ristocetin- or arachidonic acid-induced platelet aggregation. Alteplase did not affect platelet activation as demonstrated by no differences in P-selectin levels and PAC-1 binding being observed in collagen-stimulated platelets after alteplase treatment compared with vehicle. There were no changes in the surface levels of the platelet receptors GPIbα, GPVI and αIIbβ3 in alteplase-treated platelets. Alteplase treatment reduced thrombin-mediated clot retraction. Conclusions Alteplase inhibits platelet aggregation and clot retraction without affecting platelet activation and surface receptor levels.

Roles of SLP-76, phosphoinositide 3-kinase, and gelsolin in the platelet shape changes initiated by the collagen receptor GPVI/FcRγ-chain complex

Blood ◽  
2000 ◽  
Vol 96 (12) ◽  
pp. 3786-3792 ◽  
Author(s):  
Hervé Falet ◽  
Kurt L. Barkalow ◽  
Vadim I. Pivniouk ◽  
Michael J. Barnes ◽  
Raif S. Geha ◽  
...  
Keyword(s):  
Platelet Activation ◽  
Shape Change ◽  
Chain Complex ◽  
Actin Assembly ◽  
Coated Surface ◽  
Phosphoinositide 3 Kinase ◽  
Collagen Receptor ◽  
Shape Changes ◽  
Platelet Shape

Abstract How platelet shape change initiated by a collagen-related peptide (CRP) specific for the GPVI/FcRγ-chain complex (GPVI/FcRγ-chain) is coupled to SLP-76, phosphoinositide (PI) 3-kinase, and gelsolin is reported. As shown by video microscopy, platelets rapidly round and grow dynamic filopodial projections that rotate around the periphery of the cell after they contact a CRP-coated surface. Lamellae subsequently spread between the projections. All the actin-driven shape changes require SLP-76 expression. SLP-76 is essential for the Ca++mobilization induced by CRP, whereas PI 3-kinase only modulates it. The extension of lamellae requires net actin assembly and an exposure of actin filament barbed ends downstream of PI 3-kinase. Gelsolin expression is also required for the extension of lamellae, but not for the formation of filopodia. Altogether, the data describe the role of SLP-76 in the platelet activation initiated by GPVI/FcRγ-chain and the roles of PI 3-kinase and gelsolin in lamellae spreading.

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