Platelet activation by polymorphonuclear leukocytes exposed to chemotactic agents

1990 ◽  
Vol 258 (3) ◽  
pp. H870-H879 ◽  
Author(s):  
A. Del Maschio ◽  
V. Evangelista ◽  
G. Rajtar ◽  
Z. M. Chen ◽  
C. Cerletti ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Polymorphonuclear Leukocytes ◽  
Platelet Activating Factor ◽  
Cell Interaction ◽  
Leukotriene B4 ◽  
Simultaneous Recording ◽  
Human Platelets ◽  
Thromboxane B2 ◽  
Induce Platelet Aggregation ◽  
Platelet Thromboxane

Human platelets were loaded with aequorin, a Ca2(+)-sensitive photoprotein, and tested in the platelet-ionized calcium aggregometer for simultaneous recording of platelet aggregation and intraplatelet Ca2+ levels both in the presence and in the absence of autologous polymorphonuclear leukocytes. Cells were exposed to one of three chemotactic stimuli: platelet-activating factor (PAF), N-formyl-methionyl-leucyl-phenylalanine (FMLP), or leukotriene B4 (LTB4). Platelets alone aggregated and showed intracellular Ca2+ movement only when exposed to PAF. Amplification of both platelet aggregation and intraplatelet Ca2+ movement was induced by PAF in the presence of leukocytes. Aggregation and intraplatelet Ca2+ mobilization were also observed in the presence of leukocytes activated by either FMLP or LTB4. Both parameters increased with the concentration of the stimuli and/or the number of leukocytes. Platelet thromboxane B2 production was also significantly increased in the presence of leukocytes. Addition of platelets at different times after leukocyte activation resulted in progressively reduced cytoplasmic Ca2+ increase. Cell-free supernatants prepared from FMLP-stimulated leukocytes were able to induce platelet aggregation, thromboxane B2 generation, and Ca2+ mobilization, although at a reduced degree as compared with intact leukocyte addition. The activity of leukocyte supernatants was stable at 37 degrees C for up to 30 min and was suppressed by trypsin inhibitor. Our study indicates that stimulated leukocytes release a soluble enzymatic activity able to activate platelets; cell-to-cell interaction may also play a role in this phenomenon. Platelet-leukocyte interaction could have physiopathological relevance and constitutes a new model for studying old and new platelet inhibitory drugs.

Trimucytin: A Collagen-Like Aggregating Inducer Isolated from Trimeresurus mucrosquamatus Snake Venom

1993 ◽  
Vol 69 (03) ◽  
pp. 286-292 ◽  
Author(s):  
Che-Ming Teng ◽  
Feng-Nien Ko ◽  
Inn-Ho Tsai ◽  
Man-Ling Hung ◽  
Tur-Fu Huang
Keyword(s):  
Platelet Aggregation ◽  
Snake Venom ◽  
Inositol Phosphate ◽  
Shape Change ◽  
Platelet Activating Factor ◽  
Atp Release ◽  
Platelet Membrane ◽  
Thromboxane B2 ◽  
Dependent Manner ◽  
Concentration Dependent Manner

SummaryTrimucytin is a potent platelet aggregation inducer isolated from Trimeresurus mucrosquamatus snake venom. Similar to collagen, trimucytin has a run of (Gly-Pro-X) repeats at the N-terminal amino acids sequence. It induced platelet aggregation, ATP release and thromboxane formation in rabbit platelets in a concentration-dependent manner. The aggregation was not due to released ADP since it was not suppressed by creatine phosphate/creatine phosphokinase. It was not either due to thromboxane A2 formation because indomethacin and BW755C did not have any effect on the aggregation even thromboxane B2 formation was completely abolished by indomethacin. Platelet-activating factor (PAF) was not involved in the aggregation since a PAF antagonist, kadsurenone, did not affect. However, RGD-containing peptide triflavin inhibited the aggregation, but not the release of ATP, of platelets induced by trimucytin. Indomethacin, mepacrine, prostaglandin E1 and tetracaine inhibited the thromboxane B2 formation of platelets caused by collagen and trimucytin. Forskolin and sodium nitroprusside inhibited both platelet aggregation and ATP release, but not the shape change induced by trimucytin. In quin-2 loaded platelets, the rise of intracellular calcium concentration caused by trimucytin was decreased by 12-O-tetradecanoyl phorbol-13 acetate, imipramine, TMB-8 and indomethacin. In the absence of extracellular calcium, both collagen and trimucytin caused no thromboxane B2 formation, but still induced ATP release which was completely blocked by R 59022. Inositol phosphate formation in platelets was markedly enhanced by trimucytin and collagen. MAB1988, an antibody against platelet membrane glycoprotein Ia, inhibited trimucytinand collagen-induced platelet aggregation and ATP release. However, trimucytin did not replace the binding of 125I-labeled MAB1988 to platelets. Platelets pre-exposed to trimucytin were resistant to the second challenge with trimucytin itself or collagen. It is concluded that trimucytin may activate collagen receptors on platelet membrane, and cause aggregation and release mainly through phospholipase C-phosphoinositide pathway.

scholarly journals Activation of human platelets by immune complexes prepared with cationized human IgG

Blood ◽  
1993 ◽  
Vol 82 (10) ◽  
pp. 3045-3051
Author(s):  
M Schattner ◽  
M Lazzari ◽  
AS Trevani ◽  
E Malchiodi ◽  
AC Kempfer ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activation ◽  
Immune Complexes ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Human Igg ◽  
Experimental Conditions ◽  
Induce Platelet Aggregation ◽  
Soluble Immune Complexes ◽  
High Concentrations

The present study shows that the ability of soluble immune complexes (IC), prepared with human IgG and rabbit IgG antibodies against human IgG, to trigger platelet activation was markedly higher for IC prepared with cationized human IgG (catIC) compared with those prepared with untreated human IgG (cIC). CatIC induced platelet aggregation and adenosine triphosphate release in washed platelets (WP), gel-filtered platelets (GFP), or platelet-rich plasma (PRP) at physiologic concentrations of platelets (3 x 10(8)/mL) and at low concentrations of catIC (1 to 30 micrograms/mL). On the contrary, under similar experimental conditions, cIC did not induce aggregation in PRP, WP, or GFP. Low aggregation responses were only observed using high concentrations of both WP (9 x 10(8)/mL) and cIC (500 micrograms/mL). Interestingly, catIC were also able to induce platelet activation under nonaggregating conditions, as evidenced by P-selectin expression. Cationized human IgG alone did not induce platelet aggregation in PRP but triggered either WP or GFP aggregation. However, the concentration needed to induce these responses, was about eightfold higher than those required for catIC. The responses induced either by catIC or cationized human IgG were completely inhibited by treatment with heparin, dextran sulphate, EDTA, prostaglandin E1, or IV3, a monoclonal antibody against the receptor II for the Fc portion of IgG (Fc gamma RII). The data presented in this study suggest that IgG charge constitutes a critical property that conditions the ability of IC to trigger platelet activation.

Role of phosphoinositide 3-kinase β in platelet aggregation and thromboxane A2 generation mediated by Gi signalling pathways

2010 ◽  
Vol 429 (2) ◽  
pp. 369-377 ◽  
Author(s):  
Analia Garcia ◽  
Soochong Kim ◽  
Kamala Bhavaraju ◽  
Simone M. Schoenwaelder ◽  
Satya P. Kunapuli
Keyword(s):  
Platelet Aggregation ◽  
Critical Role ◽  
Thromboxane A2 ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
P2y12 Receptor ◽  
Functional Responses ◽  
Induce Platelet Aggregation ◽  
Erk Phosphorylation

PI3Ks (phosphoinositide 3-kinases) play a critical role in platelet functional responses. PI3Ks are activated upon P2Y12 receptor stimulation and generate pro-aggregatory signals. P2Y12 receptor has been shown to play a key role in the platelet aggregation and thromboxane A2 generation caused by co-stimulation with Gq or Gz, or super-stimulation of Gi pathways. In the present study, we evaluated the role of specific PI3K isoforms α, β, γ and δ in platelet aggregation, thromboxane A2 generation and ERK (extracellular-signal-regulated kinase) activation. Our results show that loss of the PI3K signal impaired the ability of ADP to induce platelet aggregation, ERK phosphorylation and thromboxane A2 generation. We also show that Gq plus Gi- or Gi plus Gz-mediated platelet aggregation, ERK phosphorylation and thromboxane A2 generation in human platelets was inhibited by TGX-221, a PI3Kβ-selective inhibitor, but not by PIK75 (a PI3Kα inhibitor), AS252424 (a PI3Kγ inhibitor) or IC87114 (a PI3Kδ inhibitor). TGX-221 also showed a similar inhibitory effect on the Gi plus Gz-mediated platelet responses in platelets from P2Y1−/− mice. Finally, 2MeSADP (2-methyl-thio-ADP)-induced Akt phosphorylation was significantly inhibited in the presence of TGX-221, suggesting a critical role for PI3Kβ in Gi-mediated signalling. Taken together, our results demonstrate that PI3Kβ plays an important role in ADP-induced platelet aggregation. Moreover, PI3Kβ mediates ADP-induced thromboxane A2 generation by regulating ERK phosphorylation.

scholarly journals Fibrinogen-independent aggregation and deaggregation of human platelets: studies in two afibrinogenemic patients

Blood ◽  
1987 ◽  
Vol 70 (1) ◽  
pp. 221-226 ◽  
Author(s):  
M Cattaneo ◽  
RL Kinlough-Rathbone ◽  
A Lecchi ◽  
C Bevilacqua ◽  
MA Packham ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Plasma Proteins ◽  
Platelet Rich Plasma ◽  
Platelet Activating Factor ◽  
Adenosine Diphosphate ◽  
Human Platelets ◽  
Human Fibrinogen ◽  
Control Subjects ◽  
Platelet Aggregates ◽  
And Control

Abstract Platelets from two afibrinogenemic patients were used to determine whether fibrinogen is essential for platelet aggregation and to examine whether released fibrinogen contributes to the stabilization of platelet aggregates when platelets have been induced to aggregate and release their granule contents by stimulation with thrombin. The addition of adenosine diphosphate (ADP) to platelet-rich plasma (PRP) or to suspensions of washed platelets from the afibrinogenemic patients caused the formation of small aggregates, which was either not inhibited or only slightly inhibited by the F(ab')2 fragments of an antibody to fibrinogen but was inhibited by an antibody (10E5) to glycoprotein IIb/IIIa. Thus there is a component of ADP-induced platelet aggregation that is not dependent on fibrinogen or other plasma proteins but is dependent on glycoprotein IIb/IIIa. There was little difference in the extent of aggregation and the release of granule contents of normal and afibrinogenemic platelets in response to the release-inducing agents collagen, platelet-activating factor (PAF), sodium arachidonate, or thrombin. With normal or afibrinogenemic platelets, aggregation by thrombin (0.2 U/mL or higher) was not inhibited by the F(ab')2 fragments of an antibody to human fibrinogen. Deaggregation by combinations of inhibitors of platelets aggregated by 1 U/mL thrombin showed no difference between platelets from afibrinogenemic and control subjects, indicating that released fibrinogen does not make a major contribution to the stabilization of platelet aggregates formed by thrombin stimulation.

scholarly journals In Vitro Antithrombotic Properties of Salmon (Salmo salar) Phospholipids in a Novel Food-Grade Extract

Marine Drugs ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 62 ◽  
Author(s):  
Alexandros Tsoupras ◽  
Ronan Lordan ◽  
Katie Shiels ◽  
Sushanta Saha ◽  
Constantina Nasopoulou ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Salmo Salar ◽  
Platelet Activating Factor ◽  
Human Platelets ◽  
Food Grade ◽  
Farmed Salmon ◽  
Lipid Fractions ◽  
Antithrombotic Effects ◽  
Layer Chromatography

Marine and salmon polar lipids (PLs) extracted by conventional extractions with non-food-grade solvents (CE-salmon-PLs) possess antithrombotic bioactivities against platelet-activating factor (PAF) and thrombin. Similar effects of food-grade-extracted (FGE) marine PLs have not yet been reported. In this study, food-grade solvents were used to extract PLs from Irish organic farmed salmon (Salmo salar) fillets (FGE-salmon-PLs), while their antithrombotic bioactivities were assessed in human platelets induced by platelet aggregation agonists (PAF/thrombin). FGE-salmon-PLs were further separated by thin layer chromatography (TLC) into lipid subclasses, and the antithrombotic bioactivities of each subclass were also assessed. LC-MS was utilized to elucidate the structure-activity relationships. FGE-salmon-PLs strongly inhibited PAF-induced platelet aggregation, while their relevant anti-thrombin effects were at least three times more potent than the previously reported activities of CE-salmon-PLs. TLC-derived lipid fractions corresponding to phosphatidylcholines (PC) and phosphatidylethanolamines (PE) were the most bioactive lipid subclasses obtained, especially against thrombin. Their LC-MS analysis elucidated that they are diacyl- or alkyl-acyl- PC and PE moieties baring ω3 polyunsaturated fatty acids (PUFA) at their sn-2 position, such as eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA). Our results concerning the potent antithrombotic effects of FGE-salmon-PLs against both PAF and thrombin pathways strongly suggest that such food-grade extracts are putative candidates for the development of novel cardioprotective supplements and nutraceuticals.

scholarly journals Expression of Phosphorylcholine by Histophilus somni Induces BovinePlatelet Aggregation

2006 ◽  
Vol 75 (2) ◽  
pp. 1045-1049 ◽  
Author(s):  
Christopher J. Kuckleburg ◽  
Shaadi F. Elswaifi ◽  
Thomas J. Inzana ◽  
Charles J. Czuprynski
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activating Factor ◽  
Induce Platelet Aggregation ◽  
Histophilus Somni ◽  
Paf Receptor ◽  
Induced Aggregation

ABSTRACT Histophilus somni-induced platelet aggregation was inhibited by antagonists of the platelet-activating factor (PAF) receptor but not inhibitors of PAF synthesis. In addition, H. somni cells expressing phosphorylcholine (ChoP) induced aggregation, while ChoP− H. somni cells did not. This suggests that H. somni ChoP may induce platelet aggregation via interactions with the PAF receptor.

Non-Genomic Effects of Estradiol on Human Platelets: Regulation of Mitogen Activated Protein Kinase Activation and Enhanced Spreading and Aggregation.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2620-2620
Author(s):  
Kadekuzhi V. Vijayan ◽  
Yan Liu ◽  
Tong-Tong Li ◽  
Paul F. Bray
Keyword(s):  
Bone Marrow ◽  
Platelet Aggregation ◽  
Protein Kinase ◽  
Randomized Clinical Trials ◽  
Hormone Replacement ◽  
Cell Types ◽  
Human Platelets ◽  
Mitogen Activated Protein Kinase ◽  
Induce Platelet Aggregation ◽  
Mitogen Activated Protein

Abstract 17β-estradiol or estrogen (E2) is a sex hormone that modulates platelet function and is widely used in hormone replacement therapy (HRT). We and others have previously demonstrated that human megakaryocytes and platelets posses estrogen receptors ERα and ERβ. HRT treatment augmented the bone marrow megakaryocytes without increasing other bone marrow cells, suggesting that E2 can modulate proliferation of megakaryocytes. Since mitogen activated protein kinases (MAPKs) are critical for 1) cell proliferation, 2) megakarytocyte differentiation and proplatelet formation and estrogen activates MAPK in other cell types, we hypothesized that estrogen regulates the activation of MAPK in human platelets. Signaling was studied using washed platelets from male and female subjects in response to varying concentrations of estrogen. Compared to the ethanol (vehicle) treated platelets, 1 nM E2 treated platelets for 60 seconds resulted in an enhanced activation of extracellular signal-regulated kinase 2 (ERK 2) and P38 but not Jun N-kinase (JNK). These results suggest that E2 can cause a non-genomic signaling in human platelets. The MEK inhibitors PD98059 and U0216 blocked the E2 effect, suggesting that the activation of ERK 2 was mediated through the upstream mitogen activated protein kinase kinase (MAPKK). Because E2 can modulate actin reorganization in other cell types and cell spreading is promoted by ERK 2 activation, we examined the effect of E2 on platelet spreading - a process not dependent on agonist stimulation. Compared to ethanol treated platelets, platelets preincubated with 100 nM E2 for 60 seconds and stained with rhodamine phallodine exhibited a ~60 % greater spreading at 5 and 15 minutes. This observation suggests that that E2 can cause rapid actin cytoskeletal reorganization in platelets. Since inhibition of ERK 2 activation blocks aggregation to low doses of thrombin and collagen, we examined a role for E2 in platelet aggregation. E2 alone did not induce platelet aggregation. However, E2 potentiated aggregation with low but not high doses of thrombin and collagen related peptide (CRP) (P=0.05 for 0.02 μg/ml thrombin and P<0.001 for 0.2 μg/ml CRP). Our data demonstrates that E2 can activate MAPK through a non-genomic mechanism and this activation correlates with greater platelet functions like spreading and aggregation. Our findings support a mechanism whereby a consistent non-genomic enhancement of platelet signaling and reactivity by E2 may underlie the increased cardiovascular events observed in recent randomized clinical trials with HRT.

scholarly journals Platelet-melanoma cell interaction is mediated by the glycoprotein IIb- IIIa complex

Blood ◽  
1989 ◽  
Vol 74 (2) ◽  
pp. 658-663
Author(s):  
H Boukerche ◽  
O Berthier-Vergnes ◽  
E Tabone ◽  
JF Dore ◽  
LL Leung ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Monoclonal Antibody ◽  
Platelet Aggregation ◽  
Melanoma Cell ◽  
Melanoma Cell Line ◽  
Cell Interaction ◽  
Melanoma Cells ◽  
Human Platelets ◽  
Platelet Glycoprotein ◽  
Human Malignant Melanoma

A human malignant melanoma cell line (M3Dau) was observed by electron microscopy to interact directly with human platelets and induced platelet aggregation. Fab fragments of a monoclonal antibody MoAb (LYP18), directed against the platelet glycoprotein (GP) IIb-IIIa complex, inhibited platelet-melanoma interactions and platelet-platelet aggregation. M3Dau melanoma cells bind LYP 18 and synthesize IIb-IIIa- like GPs. When the melanoma cells were preincubated with LYP 18, tumor- platelet interaction did not occur, suggesting that the interaction may be mediated by the IIb-IIIa-like GPs present on the melanoma cell surface. Glanzmann's thrombasthenic platelets, lacking GPIIb and IIIa, did not interact with melanoma cells, indicating that the platelet GPIIb-IIIa complex is also necessary for the platelet-melanoma cell interaction. This work demonstrates the importance of the IIb-IIIa-like GPs, present on M3Dau melanoma cells, in mediating tumor-platelet interactions.

Human Anti-Streptokinase Antibodies Induce Platelet Aggregation in an Fc Receptor (CD32) Dependent Manner

1995 ◽  
Vol 74 (03) ◽  
pp. 938-942 ◽  
Author(s):  
Jamal Lebrazi ◽  
Gérard Helft ◽  
Mustapha Abdelouahed ◽  
Ismaïl Elalamy ◽  
Massoud Mirshahi ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Response Curve ◽  
Human Platelets ◽  
Antibody Concentration ◽  
Dependent Manner ◽  
Platelet Response ◽  
Induce Platelet Aggregation ◽  
Fibrinogen Binding ◽  
Two Factors ◽  
Unimodal Response

SummaryExposure to streptokinase (SK) elicits anti-SK antibodies (Abs), which inhibit fibrinolysis and induce platelet aggregation. The mechanism of the latter is not fully understood, although it seems to involve platelet binding by a plasminogen streptokinase and anti-SK ternary complex. Anti-SK Abs were purified by affinity chromatography from serum of patients having received SK for acute myocardial infarction (AMI), and were shown to be of the IgG type. Their effects were studied with (i) human platelets in citrated plasma in the presence of SK or acetylated plasminogen-SK activator complex (APSAC), and (ii) in washed platelets, resuspended in Tyrode buffer after lowering the ionic strength, in the presence of APSAC (which provides both SK and plasminogen). An antibody concentration-response curve was obtained, showing a plateau in the presence of 0.1 mg/ml IgG. By increasing the concentration of APSAC, we obtained a unimodal response curve, the optimal concentration of APSAC being 0.05 U/ml. Aggregation was suppressed by chelating calcium with EDTA, blocking fibrinogen binding by the synthetic peptide Arg-Gly-Asp-Ser (RGDS), and raising intraplatelet cAMP with Iloprost (a prostacyclin analogue). Aggregation required the interaction of the anti-SK Ab Fc domain with the platelet Fc-gamma receptor type II, also known as CD32, since: (i) it was blocked by the monoclonal antibody IV-3 directed against CD32, (ii) it did not occur with F(ab)’2 fragments, which block the response to the intact IgG. The clinical relevance of these platelet-activating anti-SK antibodies remains to be determined. Two factors might influence clinical outcome: (i) the amount and type of pre-existing anti-SK Abs; (ii) the known interindividual variability of the platelet response to binding and activation by IgG involving the CD32 molecule.

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