Specific Marker Of Platelet Activation Research Articles

Association between platelet distribution width and prognosis in patients with heart failure

The prognostic impact of platelet distribution width (PDW), which is a specific marker of platelet activation, has been unclear in patients with heart failure (HF). We conducted a prospective observational study enrolling 1,746 hospitalized patients with HF. Patients were divided into tertiles based on levels of PDW: 1st (PDW < 15.9 fL, n = 586), 2nd (PDW 15.9-16.8 fL, n = 617), and 3rd (PDW ≥ 16.9, n = 543) tertiles. We compared baseline patients' characteristics and post-discharge prognosis: all-cause death; cardiac death; and cardiac events. The 3rd tertile showed the highest age and levels of B-type natriuretic peptide compared to other tertiles (1st, 2nd, and 3rd tertiles; age, 69.0, 68.0, and 70.0 years old, P = 0.038; B-type natriuretic peptide, 235.2, 171.9, and 241.0 pg/mL, P < 0.001). Left ventricular ejection fraction was equivalent among the tertiles. In the Kaplan-Meier analysis, rates of all endpoints were the highest in the 3rd tertile (log-rank P < 0.001, respectively). The Cox proportional hazard analysis revealed that the 3rd tertile was associated with adverse prognosis (all-cause death, hazard ratio [HR] 1.716, P < 0.001; cardiac death, HR 1.919, P < 0.001; cardiac event, HR 1.401, P = 0.002). High PDW is a novel predictor of adverse prognosis in patients with HF.

Soluble glycoprotein VI, a specific marker of platelet activation is increased in the plasma of subjects with seropositive rheumatoid arthritis.

ObjectivesAnti-citrullinated protein antibodies (ACPA) have been shown to cause platelet activation in vitro, through the low-affinity immunoglobulin G (IgG) receptor (FcγRIIa) on platelets. Platelet activation via engagement of FcγRIIa results in proteolytic cleavage and shedding of platelet specific glycoprotein VI (GPVI) which can be detected in the plasma as soluble GPVI (sGPVI). We hypothesized that plasma levels of sGPVI would be increased among patients with seropositive RA as a consequence of antibody-induced platelet activation and GPVI shedding.MethodsSamples from 84 patients with RA (65 seropositive and 19 seronegative) and 67 healthy controls were collected prospectively and analysed for sGPVI using a standardised ELISA.ResultsPatients with seropositive RA had significantly higher levels of sGPVI compared to seronegative RA and controls. Median (IQR) sGPVI levels were 4.2 ng/ml (3.2, 8.0) in seropositve RA, 2.2 ng/ml (1.5, 3.5) in seronegative RA and 2.2 ng/ml (1.6, 3.4) in controls (p<0.0001). sGPVI levels correlated with ACPA titres (r = 0.32, p = 0.0026) and with RF titres (r = 0.48, p<0.0001).ConclusionPlasma sGPVI, a specific marker of platelet activation is increased among patients with seropositive RA.

The Comparative and Usefulness of Platelet Distribution Width in Acute Coronary Syndrome

BACKGROUND: Identifying risk factors for acute coronary syndrome (ACS) is important for both diagnostic and prognostic purposes. Abnormal platelet parameters, mainly platelet count (PC), mean platelet volume (MPV) and platelet distribution width (PDW) are thought to be among these risk factors because platelet activation plays a pivotal role in ACS. PDW is a more specific marker of platelet activation, since it does not increase during simple platelet swelling. In this study, the comparison of risk factors along with the PDW between Non ST-Elevation ACS (NSTEACS) and ST-Elevation ACS (STEACS) were investigated.METHODS: This is a cross-sectional study, patients with ACS that admitted at dr.Wahidin Sudirohusodo General Hospital Makassar since December 2014 to March 2015 who undergo coronary angiography were enrolled. All data variables were taken according to the medical record. PDW was taken on first blood examination at hospital admission. Data was significant if p-value &lt;0.05 and was processed with SPSS version 16.RESULTS: A total of 63 patients were enrolled. There were significantly higher PDW (p=0.047) in STEACS group (13.7±2.0 fL) than in NSTEACS group (12.6±2.3 fL). There were a significant positive correlation between PDW value and SYNTAX scores (Pearson, r=0.552, p=0.000). Cardiovascular risk factors such as history of ACS before (p=0.049 &amp; OR=10.216) and dyslipidemia (p=0.049 &amp; OR=3.915) along with PDW (p=0.003 &amp; OR=1.733) were significant predictor of the incidence of multivessel disease in patient with ACS.CONCLUSION: An increased PDW may predicting more severe disease in ACS based on incidence of STEACS and multivessel disease more often and higher SYNTAX score.KEYWORDS: platelet distribution width, PDW, acute coronary syndrome, ACS, multivessel disease, SYNTAX

GPVI modulation during platelet activation and storage: its expression levels and ectodomain shedding compared to markers of platelet storage lesion

ABSTRACTPlatelet storage is associated with deleterious changes leading to the loss of platelet reactivity and response. During storage, platelets experience increased expression and shedding of P-selectin and CD40L as specific markers of platelet activation, whereas GPIbα decreases due to ectodomain shedding. As an important adhesive receptor, GPVI contributes significantly to thrombus formation while its expression and shedding levels during storage of platelet products have not been well characterized yet. This study investigated the modulation of GPVI during platelet storage.For this study, samples obtained from 10 PRP-platelet concentrates (PCs) were subjected to flow-cytometry analysis to examine the expression of platelet activation markers and GPVI on days 1, 3, and 5 post-storage. To examine the levels of etcodomain shedding of these molecules, microparticle (MP)-free supernatants were also analyzed by either ELISA or Western blot methods.According to results, the expression levels of P-selectin and CD40L as well as the amounts of their soluble forms significantly increased during storage. The expression of GPIbα and GPVI decreased whereas their shedding significantly increased post-storage. The expression and shedding levels of these two receptors were significantly correlated. Negative correlations between the expressions of GPIbα or GPVI and P-selectin have been observed whereas their shedding levels were significantly relevant together. In a control study, the use of biotinylated platelet resuspended in Tyrode’s buffer in the presence of ionophore with/without EDTA, confirmed the role of calcium in receptors shedding. In citrated PRP-PCs, recalcification of platelets also enhanced shedding levels of both GPIbα and GPVI. Intriguingly, the shedding levels of GPVI in stored PRP-PCs were much higher than those of ionophore-treated controls obtained from washed platelets. The ratios of sGPVI in stored platelet to ionophore-treated controls were also at least six times higher than those of GPIbα during storage. In conclusion, here we showed significant decreases of GPVI expression associated with its increasing levels of shedding during storage, suggesting GPVI as a valid marker of platelet storage lesion. Importantly, we found higher levels of GPVI shedding in stored platelets than those of ionophore-treated non-stored control samples. This suggests whereas platelet receptor shedding is mainly modulated by calcium-dependent signals, either platelet–surface interactions with the container walls during storage or induced shear stress under long-term agitation, might be also involved in the excessive shedding of GPVI during the storage of PCs.

Effects of xinfeng capsules on expression of platelet granule membrane protein 140 and platelet cluster of differentiation 40 ligand in peripheral blood of adjuvant arthritis rats.

Platelet GMP-140 and CD40L as specific markers of platelet activation play an important role in the morbidity and development of rheumatoid arthritis. The expression of GMP-140, CD40L increases in peripheral blood of AA rats. And they have correlation with voix pedis' swelling, AI. XFC could inhibit the inflammatory response through inhibiting platelet activation of AA rats, which means decreasing the expression of GMP-140, CD40L in peripheral blood. So, the voix pedis' swelling and AI were decreased as the result.

Increased platelet activity in patients with isolated coronary artery ectasia

The common coexistence with coronary artery disease has led to the suggestion that coronary artery ectasia (CAE) is a variant of coronary artery disease. The mechanisms, however, responsible for CAE formation during the atherosclerotic process and the exact clinical significance are not well known. In this study, we aimed to investigate platelet activity in patients with isolated CAE by using specific markers of platelet activation as P-selectin, beta-thromboglobulin (beta-TG) and platelet factor 4 (PF4). Thirty-two patients with isolated CAE without significant stenosis and 30 control participants with angiographically normal coronary arteries were included in this study. According to the angiographic definition used in the Coronary Artery Surgery Study, a vessel is considered to be ectasic when its diameter is > or = 1.5 times that of the adjacent normal segment in segmental ectasia. Plasma P-selectin, beta-TG and PF4 levels were measured in all patients and control participants using enzyme-linked immunosorbent assay method. Patients with isolated CAE were detected to have significantly higher levels of plasma P-selectin, beta-TG and PF4 in comparison with control participants with angiographically normal coronary arteries (P-selectin: 248+/-46 vs. 154+/-32 ng/ml, respectively, P<0.001; beta-TG: 51+/-19 vs. 21+/-9 ng/ml, respectively, P<0.001; PF4: 58+/-23 vs. 33+/-11 ng/ml, respectively, P<0.001). In conclusion, we have shown for the first time that patients with isolated CAE have raised levels of plasma P-selectin, beta-TG and PF4 compared with control participants with angiographically normal coronary arteries, suggesting increased platelet activation in patients with CAE.

Detection of activated platelets in canine blood by use of flow cytometry

To evaluate whether markers of platelet activation, including P-selectin expression, phosphatidylserine exposure, platelet-leukocyte aggregates, and microparticle formation, could be measured in nonstimulated and stimulated canine blood samples and develop a standardized protocol for detection of activated platelet markers in canine blood. Blood samples from 10 dogs. Platelet activation was determined by flow cytometric measurement of platelets with P-selectin expression, platelet-leukocyte aggregates, platelet microparticles, and platelets with phosphatidylserine exposure. Changes in specific markers of platelet activation in nonstimulated versus stimulated samples were assessed by use of varying concentrations of 2 platelet agonists, platelet-activating factor (PAF) and adenosine diphosphate. Flow cytometry was used to detect platelet CD61 (glycoprotein IIIa), CD62P (P-selectin), and the leukocyte marker CD45. Annexin V was used to identify exposed phosphatidylserine. A significant difference was detected in the percentages of platelets with P-selectin, plateletleukocyte aggregates, microparticles, and platelets with annexin V exposure (phosphatidylserine) in samples stimulated with 10nM PAF versus the nonstimulated samples, with platelet-leukocyte aggregates having the greatest difference. Platelet activation is essential for thrombus formation and hemostasis and may be potentially useful for evaluation of dogs with suspected thromboembolic disease. Prior to development of a thrombotic state, a prothrombotic state may exist in which only a small number of platelets is activated. Identification of a prothrombotic state by use of activated platelets may help direct medical intervention to prevent a thromboembolic episode.

Platelet Activation Markers in Patients With Heart Assist Device

Clinical use of heart assist devices is often associated with thromboembolic complications. We hypothesized that platelets may be activated in patients receiving assist devices and examined expression of the platelet activation markers CD62, CD63, and thrombospondin using flow cytometry in eight patients with Novacor left ventricular assist system (LVAS) or Berlin Heart. Patients with end-stage heart failure had elevated expression of platelet activation markers before insertion of the assist device. While CD62 (P < 0.05) and thrombospondin expression (n.s.) decreased by the 14th postoperative day, the CD63 expression remained elevated (n.s.). A good correlation was found between CD62 and thrombospondin expression (r = 0.72). Bleeding time ex vivo indicated platelet dysfunction during the first 4 weeks after implantation. No relation between expression of platelet activation markers and bleeding time ex vivo were found. In conclusion, expression of the platelet activation markers CD62, CD63, and thrombospondin is increased in patients with end-stage heart failure before device placement and shows prolonged elevation during the assist period. Future studies in larger patient populations are necessary to identify new and specific markers of platelet activation in this clinical setting.

Pulmonary Hypertension in Thalassemia: Association with Platelet Activation and Hypercoagulable State.

Pulmonary hypertension (PHT) is a serious, under diagnosed, potentially fatal complication, reported mostly in non-transfused adult thalassemia intermedia (TI) and fewer thalassemia major (TM) patients. Even a mild PHT can further impair cardiac function in these patients with a frequent left heart disease. Yet, understanding of the pathogenesis, early detection and treatment of established PHT are inadequate. Previous reports and autopsies in patients with PHT, suggest thrombotic obstruction of pulmonary arteries, more so in splenectomized non-transfused TI patients.25 patients, 7 TI and 18 transfused TM patients ages 10 to 47 years (mean 26±10 years) were screened for PHT by Doppler echocardiogram. A right ventricular (RV) pressure of 25mmHg or higher, corresponding to 2.5meter/second (m/sec) tricuspid jet velocity (TJV) was used as the threshold for presence of increased pulmonary artery pressure indicating PHT. In order to determine that hypercoagulability has an important role in the pathogenesis and progression of PHT, we evaluated specific markers of platelet activation and hypercoagulability and their association with PHT. We measured P-selectin levels, a marker for platelet activation; thrombin-anti thrombin III (TAT), indicating increased thrombin generation; abnormal fibrinolysis as indicated by plasminogen activator inhibitor-1 (PAI-1) and by elevated d-dimers, and vWF:Ag a marker for endothelial cell activation/platelet adhesion. PHT was found in seventeen out of twenty five patients (68%). Mean pulmonary artery pressure was 39.8±5.4mmHg (range 33–53mmHg), corresponding to a TJV of 2.5 to 3.6 m/sec. The remaining 8 patients had only trace or no tricuspid regurgitation.PHT was strongly associated with prior splenectomy, noted in 16 of the 17 patients, and was more severe in older patients: 7/17 (41%) with a pressure of ≥40mmHg, were over 30 years old. Surprisingly, a high proportion of patients 10/17 (58%), was on regular transfusions. Elevated P-selectin levels were significantly associated with PHT (p<0.0001) and higher in non-transfused TI patients (67.8±13 ng/ml) compare to transfused ones (47±19 ng/ml). Elevated P slectin and PHT were associated with absence of spleen. TAT Levels were higher in patients with PHT at 16±33μg/L, compare to those with normal pulmonary artery pressure 13±6μg/L (nl <4μg/L). Increased fibrinolysis was not associated with PHT as indicated by normal PAI-1 activity (mean 13.2±3.9) and non elevated d-dimers values. There was a trend of elevated vWF:Ag levels among patients with PHT; 128±35% Vs 100±12% (nl 50-150%).Our data shows a high prevalence of mild to moderate PHT in adult thalassemia patients, even in the ones on regular transfusions, implying that regular transfusions do not prevent but rather attenuate the progression of increased pulmonary pressure. The impact of even modest PHT is crucial in these patients who have a limited ability to tolerate cardiac dysfunction due to other cardiac and systemic manifestations of their disease. This preliminary data confirms the presence of platelet activation and a procoagulant state in patients with PHT, correlating with prior splenectomy, and suggests that endothelial disruption is involved in the pathogenesis. Moreover, P-selectin, a marker of platelet activation and a direct inducer of procoagulant activity, proved to be a sensitive marker for the presence of PHT. Future interventional studies with direct P-selectin inhibitors may be an effective treatment modality.

Platelet activity measured by plasma levels of beta-thromboglobulin and platelet factor 4 in seasonal allergic rhinitis during natural pollen exposure.

Upon activation, platelets release mediators with potent inflammatory properties in IgE-mediated immune responses. Moreover, the atopic state leads towards functional abnormalities of these cells. The aim of our study was to examine the degree of activation of circulating platelets in patients with seasonal allergic rhinitis (SAR) during the symptomatic period, to improve the understanding of platelet function in atopy. Plasma levels of beta-thromboglobulin (beta-TG) and platelet factor 4 (PF4) - specific markers of platelet activation were measured by enzyme-linked immunoassay in 20 patients suffering from SAR and in 15 healthy, nonatopic subjects. There were no significant differences in peripheral blood platelet numbers and plasma levels of beta-TG and PF4 in SAR patients when compared with control subjects. It seems that increased in vivo platelet activity, assessed by measuring plasma beta-TG and PF4, may not occur during allergic inflammation that is associated with SAR.

Serial Measurement of Surface Expressions of CD63, P-Selectin and CD40 Ligand on Platelets in Atherosclerotic Ischemic Stroke

Background: Platelet activation is a key step in the progression of atherosclerosis. The CD40 ligand (CD40L) on platelets may be a critical factor to develop the acute vascular events from atheroma. Methods: To determine the role of CD40L on platelets in atherosclerotic ischemic stroke, we serially measured the expressions of CD63, P-selectin and CD40L on platelets in patients with atherosclerotic ischemic stroke (n = 25) and compared them with those in patients with asymptomatic carotid stenosis (n = 20) and in normal subjects (n = 24). Results: The expressions of CD63 and P-selectin on platelets were significantly higher in patients with atherosclerotic ischemic stroke (n = 25) than in normal subjects (n = 24). The extents of surface expressions of CD63 and P-selectin on platelets showed no significant differences between atherosclerotic ischemic stroke and asymptomatic carotid stenosis. However, the CD40L expression on platelets was significantly higher in atherosclerotic ischemic stroke when compared to that in asymptomatic carotid stenosis. Conclusions: In our data, among the population with large artery atherosclerosis, the patients with symptomatic ischemic events showed a significantly elevated expression of CD40L on platelets compared to those without ischemic events. Therefore, the upregulation of CD40L on platelets may be a specific marker of platelet activation to provoke ischemic stroke from large artery atherosclerosis.

Platelet activation in congenital heart diseases.

The research presented here investigated platelet activation in cyanotic and acyanotic congenital heart diseases (CHD). Children with cyanotic CHD are prone to both thrombosis and hemorrhage. However, patients with acyanotic CHD may also have a mild bleeding disorder. The platelet activation in CHD was investigated in support of a hypothesis that platelet activation may play a role in the hemostatic abnormalities reported in these patients. Platelet activation was determined by using flow cytometry with anti-CD62 monoclonal antibody (mAb), which has been shown to be a specific marker of platelet activation. Thirteen children with cyanotic CHD, 33 children with acyanotic CHD and 17 healthy children serving as controls were studied. Platelet activation was significantly higher in the cyanotic group and also in the acyanotic group compared with the healthy children (P = 0.0000 and P = 0.019, respectively). In the cyanotic group, platelet activation showed a direct correlation with arterial O2 saturation (SaO2) (P = 0.014). There was no correlation between platelet activation and erythrocyte related parameters in either group. Platelet activation occurs in CHD, particularly in patients with cyanotic CHD (even in patients with no evidence of clinical thrombosis) and it may play a role in the pathogenesis of thrombotic disorders seen in these patients.

Platelet Activation and Fibrinopeptide Formation in Pulmonary Hypertension

Intravascular thrombosis is postulated to cause or to contribute to the development of uncharacterized ("primary") pulmonary hypertension (PPH). To assess whether there is ongoing platelet-fibrin thrombosis in patients with PPH, we measured specific markers of platelet activation: platelet factor 4 (PF4) and beta-thromboglobulin (BTG); of fibrin formation: fibrinopeptide A (FPA); and of fibrin dissolution: fibrinopeptide BB1-42 (FPBB1-42) in peripheral venous blood from 10 patients with PPH (group 2). Results were compared with those of normal volunteers (group 1, n = 9) and with results from patients with pulmonary hypertension secondary to congenital heart disease (group 3, n = 7). Both groups 2 and 3 exhibited severe pulmonary hypertension (mean pulmonary arterial pressure = 62 +/- 20 mm Hg and 70 +/- 13 mm Hg, respectively). Mean level of PF4, BTG, FPA, and FPBB1-42 in patients with pulmonary hypertension, either primary or secondary to congenital heart disease, did not differ from levels in normal subjects. Within group 2, levels of platelet proteins and fibrinopeptides did not differ between patients who were classified clinically as having plexogenic arteriopathy vs thromboembolic disease. These observations suggest that a sustained state of abnormal platelet activation and fibrin formation or dissolution is not present in patients with established pulmonary hypertension.