Platelet Activation Parameters Research Articles

Effect of plateletcrit and methylenetetrahydrofolate reductase (MTHFR) C677T genotypes on folic acid efficacy in stroke prevention

Previous studies have shown that low platelet count combined with high plasma total homocysteine (tHcy) increased stroke risk and can be lowered by 73% with folic acid. However, the combined role of other platelet activation parameters and the methylenetetrahydrofolate reductase (MTHFR) C677T genotypes on stroke risk and folic acid treatment benefit remain to be examined. This study aimed to investigate if platelet activation parameters and MTHFR genotypes jointly impact folic acid treatment efficacy in first stroke prevention. Data were derived from the China Stroke Primary Prevention Trial. This study includes a total of 11,185 adult hypertensive patients with relevant platelet activation parameters and MTHFR genotype data. When simultaneously considering both platelet activation parameters (plateletcrit, platelet count, mean platelet volume, platelet distribution width) and MTHFR genotypes, patients with both low plateletcrit (Q1) and the TT genotype had the highest stroke incidence rate (5.6%) in the enalapril group. This subgroup significantly benefited from folic acid treatment, with a 66% reduction in first stroke (HR: 0.34; 95% CI: 0.14–0.82; p = 0.016). Consistently, the subgroup with low plateletcrit (Q1) and the CC/CT genotype also benefited from folic acid treatment (HR: 0.40; 95% CI: 0.23–0.70; p = 0.001). In Chinese hypertensive adults, low plateletcrit can identify those who may greatly benefit from folic acid treatment, in particular, those with the TT genotype, a subpopulation known to have the highest stroke risk.

Comprehensive investigation of platelet function in patients with cirrhosis

Cirrhosis presents with thrombocytopenia and possibly thrombocytopathy. Previous studies exploring platelet function gave conflicting results and most controversies are explained by the variety of methods employed for investigation. We sought to assess in-vitro the overall platelet function in cirrhosis.We investigated 34 patients by using the following tests. (i)Aggregometry. (ii)Measurement of the content of platelet granules. (iii)Cytometric platelet activation. (iv)Plasmatic markers of in-vivo platelet activation. (v)Platelet procoagulant activity by thrombin generation (TG) in platelet-rich plasma (PRP).TG measured in PRP for patients and controls was similar. Platelets from patients with cirrhosis showed reduction of aggregation and secretion of ATP. Similar results were observed for platelet activation parameters such as P-selectin expression and PAC-1 platelet binding. Plasma levels of βeta-thromboglobulin and soluble P-selectin, were increased in patients-vs-controls. In contrast, there were no patients-vs-controls differences for plasmatic platelet-factor-4. Results are consistent with a state of in-vivo platelet activation and decreased in-vitro aggregation. Since bleeding events following invasive procedures are uncommon in cirrhosis, we speculate that in-vitro aggregometry testing does not reflect the situation occurring in-vivo. Results of the study and pathophysiological considerations support the conclusion that platelet function in cirrhosis as determined by aggregometry, although somewhat impaired, may support the overall hemostatic potential, which is needed for most invasive interventions. These conclusions are in line with the recommendations of international guidelines, warning against indiscriminate use of prophylactic preprocedural administration of platelets before invasive procedures. Decision on platelet support should not be made based on in-vitro laboratory testing for platelet function.

Effect of semaglutide on global longitudinal strain and global myocardial work efficiency in patients with uncontrolled type 2 diabetes mellitus and obesity

Abstract Background Type 2 Diabetes mellitus (T2DM) increases of two-to three-fold the risk of cardiovascular disease (CVD). Cardiovascular outcome trials (CVOTs) demonstrated that glucagon-like peptide 1-receptor agonists (GLP1-RAs), as semaglutide in SUSTAIN-6 study, have effectively reduced CV risk in T2DM patients, so their use is recommended by guidelines. Purpose The objective of our work was to evaluate the effect of Semaglutide administration in a cohort of uncontrolled diabetic patients (within 5 years from diagnosis) on oxidative stress validated markers (8-isoprostane and NOX-2), platelet activation indicators (Sp-Selectin) and subclinical myocardial damage evaluated by measurement of deformation and efficiency parameters, obtained by speckle tracking echocardiography (STE). Methods We enrolled 70 Caucasian patients (mean age 65.5±8.2) with T2DM and obesity, 54 men and 16 women, 85.7% with hypertension, 14.2% with chronic obstructive pulmonary disease, 57.1% with sleep apnea syndrome, 18.5% with chronic kidney disease, and 41.4% with dyslipidemia. All patients were treated with statins and metformin, 42.8% with insulin, 24.2% with diuretics, 37.1% with ACE inhibitors, and 48.5% with angiotensin receptor antagonists. In the study the mean dose of semaglutide was 0.59±0.29 mg/week, no serious adverse events were reported. Results After 6 months of follow-up a significant improvement in fasting plasma glucose, insulinemia, HOMA, IGF-1, HbA1c and BMI (p<0.0001) was reported. In addition, there was a significant reduction in biomarkers of oxidative stress such as 8-isoprostane, Nox-2 and uric acid (p<0.0001), biomarkers of platelet activity such as Sp-Selectin and high-sensitivity C-reactive protein (hs-CRP) (p<0.0001). Moreover, we observed a significant improvement in left ventricular myocardial deformation parameters such as Global longitudinal strain (GLS) (p<0.0001) and global myocardial work efficiency (GWE) (p<0.0001). The linear correlation analysis showed that variation (Δ) GLS was inversely correlated with ΔHOMA (p=0.011), Δuric acid (p=0.025) and ΔSp-selectin (p<0.0001); ΔGWE was inversely correlated with ΔHOMA (p=0.011), Δuric acid (p=0.025) and ΔSp-selectin (p<0.0001). From stepwise multivariate linear regression model, ΔSp-selectin, ΔHOMA and Δuric acid justifying 27.8%(p<0.0001), 5.6%(p=0.010) and 4.4%(p=0.023) of ΔGLS variation, respectively. Instead ΔNOX-2, Δhs-CRP and ΔBMI justifying 22.3%(p<0.0001), 15.6%(p<0.0001), and 4.0%(p=0.022) of ΔGWE variation, respectively. Conclusion Treatment for 6 months with Semaglutide, in patients with uncontrolled T2DM and obesity, improved GLS and GWE. It’s plausible that this improvement may be justified by the reduction of inflammatory, oxidative stress and platelet activation parameters together with favorable metabolic changes; thus promoting coronary microcirculation protection with positive effects on myocardial contractility.

High-Fat Diet Enhances Platelet Activation and Is Associated with Proprotein Convertase Subtilisin Kexin 9: An Animal Study.

Platelet activation and proprotein convertase subtilisin kexin 9 (PCSK9) play pivotal roles in the progression of atherosclerosis to cardiovascular events. It has been reported that hyperlipidemia, a well-documented risk factors for cardiovascular diseases, tends increase platelet activation and PCSK9 expression. However, little is known about this specific mechanism, particularly how nutrition affects platelet activation and PCSK9 levels in hyperlipidemia conditions. This study aimed to assess how a high-fat diet influences platelet activation, its association with PCSK9, and the effects on blood pressure in an animal model. Here, male Wistar rats were divided into four groups, subjected to different high-fat diets for ten weeks with varying nutrient components. The results showed that high-fat diet-induced hypercholesterolemia and hypertriglyceridemia significantly increased the plasma levels of β-thromboglobulin (β-TG), p-selectin, and platelet factor 4 (PF-4). The blood pressure readings were also elevated post high-fat diet induction. Interestingly, the group with the highest percentage of saturated fatty acid and trans-fat exhibited the highest PCSK9 levels, along with the highest increase in plasma cholesterol, triglycerides, and platelet activation parameters. These findings confirm that high-fat diet-induced hypercholesterolemia and hypertriglyceridemia stimulate platelet activity and PCSK9 levels. Moreover, our results suggest that PCSK9, implicated in hypercholesterolemia and hypertriglyceridemia, may synergistically mediate platelet hyperactivity, aligning with clinical studies. Notably, our results highlight the association between a high-fat diet and PCSK9, providing insights for drug discovery targeting platelet activation in atherosclerosis-induced cardiovascular diseases.

Resistance training reduces platelet activation in hypertensive women: the role of purinergic signaling.

Essential arterial hypertension is a risk factor for stroke, myocardial infarction, heart failure, and arterial aneurysm, which are related to the activation of platelets. Purinergic signaling has a central role in platelet aggregation. Although ATP and ADP can act as a proaggregant agent, adenosine inhibits platelet aggregation and reduces vascular injury. Physical exercise exhibits antiaggregant properties and can modulate purinergic system. The aim of this study was to evaluate the effect of 6 months of resistance training on purinergic system components in platelets and on platelet activation, hemodynamic and anthropometric parameters in hypertensive woman. A total of 31 hypertensive and 28 normotensive middle-aged sedentary women were submitted to 6 months of resistance training. Purinergic enzymes activities were assessed in platelets; ATP and Tromboxane B2 (TXB2) levels were measured in serum. Blood pressure (BP), BMI, and body fat were also measured. All variables were statistically analyzed, considering P value less than 0.05. Six months of resistance training was able to significantly reduce BP, ATP, and TXB2 levels as well as NTPDase, ecto-5'nucleotidase, and ADA activities in hypertensive group. After 6 months of resistance training, purinergic system components and TXB2 of hypertensive group were similar to normotensive group in platelets, demonstrating that resistance training was able to modulate platelet activation. A positive correlation was found between BP, enzyme activities, and levels of ATP and TXB2. Our findings demonstrated the relationship between purinergic signaling and platelet activation in hypertension and suggests that resistance training serve as tool to reduce platelet aggregation in hypertensive woman by modulating purinergic system.

The rate of platelet activation determines thrombus size and structure at arterial shear

BackgroundThe response of platelets to activating stimuli and pharmaceutical agents varies greatly within the normal population. Current platelet function tests are used to measure end-point levels of platelet activation without taking the speed at which platelets activate into account, potentially missing vital metrics to characterize platelet reactivity. ObjectivesTo identify variability, to agonists and among individuals, in platelet activation kinetics and assess the impact of this on thrombus formation. MethodsWe have developed a bespoke real-time flow cytometry assay and analysis package to measure the rate of platelet activation over time using 2 parameters of platelet activation, fibrinogen binding and P-selectin exposure. ResultsThe rate of platelet activation varied considerably within the normal population but did not correlate with maximal platelet activation, demonstrating that platelet activation rate is a separate and novel metric to describe platelet reactivity. The relative rate of platelet response between agonists was strongly correlated, suggesting that a central control mechanism regulates the rate of platelet response to all agonists. ConclusionFor the first time, we have shown that platelet response rate corresponds to thrombus size and structure, wherein faster responders form larger, more densely packed thrombi at arterial, but crucially not venous, shear. We have demonstrated that the rate of platelet activation is an important metric in stratifying individual platelet responses and will provide a novel focus for the design and development of antiplatelet therapy, targeting high-shear thrombosis without exacerbating bleeding at low shear.

Platelet Parameters as Biomarkers for Thrombosis Risk in Cancer: A Systematic Review and Meta-analysis.

Cancer-associated thrombosis (CAT) is a major cause of both morbidity and mortality in cancer patients. Platelet count has been investigated as a predictor of CAT in various settings while knowledge on platelet activation parameters is sparse. This report provides a systematic review and meta-analysis on available literature on associations between platelet count and/or function and arterial and venous thrombosis in adult cancer patients. The review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. PubMed and Embase were searched up to March 2022. The National Heart, Lung, and Blood Institute's tools were used for quality assessment. In total, 100 studies were included which investigated the association between CAT and platelet count (n = 90), platelet indices (n = 19), and platelet function/activation markers (n = 13) in patients with solid cancers (n = 61), hematological cancers (n = 17), or mixed cancer types (n = 22). Eighty-one studies had venous thrombosis as their outcome measure, while 4 had arterial thrombosis and 15 studies had both. We found significantly elevated odds ratio of 1.50 (95% confidence interval: 1.19-1.88) for thrombosis with higher platelet counts. We saw a tendency toward an association between markers of platelet activation in forms of mean platelet volume and soluble P selectin and both arterial and venous thrombosis. Only one study investigated dynamic platelet function using flow cytometry. In conclusion, platelet count is associated with CAT across different cancer types and settings. Platelet function or activation marker analysis may be valuable in assisting thrombosis risk assessment in cancer patients but is sparsely investigated so far.

Indications that the Antimycotic Drug Amphotericin B Enhances the Impact of Platelets on Aspergillus.

ABSTRACTPlatelets are currently thought to harbor antimicrobial functions and might therefore play a crucial role in infections, e.g., those caused by Aspergillus or mucormycetes. The incidence of invasive fungal infections is increasing, particularly during the coronavirus disease 2019 (COVID-19) pandemic, and such infections continue to be life-threatening in immunocompromised patients. For this reason, the interaction of antimycotics with platelets is a key issue to evaluate modern therapeutic regimens. Amphotericin B (AmB) is widely used for the therapy of invasive fungal infections either as deoxycholate (AmB-D) or as a liposomal formulation (L-AmB). We showed that AmB strongly activates platelets within a few minutes. AmB concentrations commonly measured in the blood of patients were sufficient to stimulate platelets, indicating that this effect is highly relevant in vivo. The stimulating effect was corroborated by a broad spectrum of platelet activation parameters, including degranulation, aggregation, budding of microparticles, morphological changes, and enhanced adherence to fungal hyphae. Comparison between the deoxycholate and the liposomal formulation excluded the possibility that the liposomal part of L-Amb is responsible for these effects, as no difference was visible. The induction of platelet activation and alteration by L-AmB resulted in the activation of other parts of innate immunity, such as stimulation of the complement cascade and interaction with granulocytes. These mechanisms might substantially fuel the antifungal immune reaction in invasive mycoses. On the other hand, thrombosis and excessive inflammatory processes might occur via these mechanisms. Furthermore, the viability of L-AmB-activated platelets was consequently decreased, a process that might contribute to thrombocytopenia in patients.

Effect of melatonin on selected parameters of platelet activation, clot formation and overall potential of fibrinolysis

Introduction: Melatonin produced in the pineal gland plays a key role in regulating sleep and wake hours. Synthetic melatonin is used as an adjunct to treat sleep disorders, regulate the sleep-wake rhythm and prevent ailments related to changing time zones or shift work. Its other applications are more widely described, including antioxidant and immunomodulatory properties – therefore melatonin supplementation may be beneficial in alleviating symptoms associated with the occurrence of COVID-19. However, reports on the influence of exogenous melatonin on the platelet, plasma and vascular hemostasis are ambiguous. Aim: The aim of the study was to evaluate the in vitro influence of melatonin on spontaneous and ADP-induced adhesion of platelets to fibrinogen, kinetic parameters of ADP-induced aggregation and selected elements of plasma haemostasis: general potential for clot formation and fibrinolysis, as well as kinetic parameters of the clot formation process, its stabilization and fibrinolysis. Material and methods: The study were performed with the use of the previously described research model, which includes the method of assessing platelet adhesion, a multi-parameter test for assessing platelets aggregation and a test that enables kinetic assessment of the clot formation process, the period of fibrin stabilization and its lysis. Results: Our preliminary studies indicated that melatonin at concentrations: 0.2-10 nmol/L does not show a significant and direct impact on the assessed kinetic parameters of the studied processes, important for platelet and plasma hemostasis. Conclusions: The pleiotropic effects of melatonin are increasingly applied, especially its antioxidant and immunomodulating properties, therefore further and in-depth in vitro as well as in vivo hemostasis studies followed by clinical observations of patients using melatonin are needed.

Aspartame and Platelets in Type II Diabetic Patients

Background: For type II diabetes (T2D) subjects to better regulate carbohydrate consumption and manage blood glucose levels, a non-nutritive sweetener (aspartame) is prescribed as an alternative to natural sugar. Previous studies show that there was a 68% rise in the probability of aspartame consumers developing T2D compared with non-consumers. In diabetes and inflammation, deformed red blood cells (RBCs) and atypical fibrin fibre formation or an altered fibrin structure are especially prevalent. Objective: The aim of this study was to investigate, in subjects with T2D taking aspartame, clot viscoelasticity and platelet structure. Methodology: Blood was drawn from 12 T2D subjects from the diabetic clinic at the Steve Biko Academic Hospital, South Africa. Blood was used to perform a full blood count, thromboelastography (TEG) and scanning electron microscopy (SEM). Results: SEM showed increased platelet activation and abnormal TEG parameters in T2D consuming aspartame. Conclusion: A hypercoagulable state can increase the risk of thromboembolic complications and an increased incidence of vascular disease. This knowledge may be used to build awareness among consumers of aspartame.

Dietary alpha‐linolenic acid reduces platelet activation and collagen‐mediated cell adhesion in sickle cell disease mice

BackgroundSickle cell disease (SCD) is a genetic hemoglobinopathy associated with high morbidity and mortality. The primary cause of hospitalization in SCD is vaso‐occlusive crisis (VOC), mediated by alteration of red blood cells, platelets, immune cells and a pro‐adhesive endothelium. ObjectivesWe investigated the potential therapeutic use of the plant‐derived omega‐3 alpha‐linolenic acid (ALA) in SCD. MethodsBerkeley mice were fed a low‐ or high‐ALA diet for 4 weeks, followed by analysis of liver fibrosis, endothelial activation, platelet activation and formation of platelet‐neutrophils aggregates. Aggregation of platelets over collagen under flow after high‐ALA was compared to a blocking P‐selectin Fab. ResultsDietary high‐ALA was able to reduce the number of sickle cells in blood smear, liver fibrosis, and the expression of adhesion molecules on the endothelium of aorta, lungs, liver and kidneys (VCAM‐1, ICAM‐1 and vWF). Specific parameters of platelet activation were blunted after high‐ALA feeding, notably P‐selectin exposure and the formation of neutrophil‐platelet aggregates, along with a correspondingly reduced expression of PSGL‐1 on neutrophils. By comparison, in vivo treatment of SCD mice with the anti‐P‐selectin Fab was able to similarly reduce the formation of neutrophil‐platelet aggregates, but did not reduce GpIbα shedding nor the activation of the αIIbβ3 integrin in response to thrombin. Both ALA feeding and P‐selectin blocking significantly reduced collagen‐mediated cell adhesion under flow. ConclusionsDietary ALA is able to reduce the pro‐inflammatory and pro‐thrombotic state occurring in the SCD mouse model and may represent a novel, inexpensive and readily available therapeutic strategy for SCD.

Evolution of platelet activation parameters during septic shock in intensive care unit

During severe sepsis, platelet activation may induce disseminate microvascular thrombosis, which play a key role in critical organ failure. Crucially, most of the studies in this field have explored platelet–leukocyte interactions in animal models, or explored platelets under the spectrum of thrombocytopenia or disseminated intravascular coagulation and have not taken into account the complex interplay that might exist between platelets and leukocytes during human septic shock nor the kinetics of platelet activation. Here, we assessed platelet activation parameters at the admission of patients with sepsis to the intensive care unit (ICU) and 48 hours later. Twenty-two patients were enrolled in the study, thirteen (59.1%) of whom were thrombocytopenic. The control group was composed of twelve infection-free patients admitted during the study period. The activation parameters studied included platelet-leukocyte interactions, assessed by flow cytometry in whole blood, as well as membrane surface and soluble platelet activation markers measured by flow cytometry and dedicated ELISA kits. We also investigated platelet aggregation and secretion responses of patients with sepsis following stimulation, compared to controls. At admission, the level of circulating monocyte-platelet and neutrophil-platelet heterotypic aggregates was significantly higher in sepsis patients compared to controls and returned to a level comparable to controls or even below 48 hours later. Basal levels of CD62P and CD63 platelet membrane exposure at admission and 48 hours later were low and similar to controls. In contrast, plasma level of soluble GPVI and soluble CD40 ligand was significantly increased in septic patients, at the two times of analysis, reflecting previous platelet activation. Platelet aggregation and secretion responses induced by specific agonists were significantly decreased in septic conditions, particularly 48 hours after admission. Hence, we have observed for the first time that critically ill septic patients compared to controls have both an early and durable platelet activation while their circulating platelets are less responsive to different agonists.

In vitro antiplatelet activity of extract and its fractions of Paulownia Clone in Vitro 112 leaves

BackgroundPaulownia Clone in Vitro 112, also known as Oxytree is a hybrid of Paulownia elongata and Paulownia fortunei, developed under laboratory conditions. Its seeds are sterile, making it a noninvasive variety that can only be propagated in the laboratory. In China, species from the Paulownia genus (Paulowniaceae) are widely used in traditional medicine for the treatment of infectious diseases, such as gonorrhea and erysipelas. It has a broad spectrum of bioactivity, including neuroprotective, antioxidant, antibacterial, antiphlogistic, antiviral, and cytotoxic actions. However, the antiplatelet potential of Paulownia Clone in Vitro 112 has not yet been described. Study designThe aim of our study was thus to examine the effect of an extract and four fractions from leaves of Paulownia Clone in Vitro 112 on various parameters of platelet activation in an in vitro model. MethodsComposition of the investigated extract and fractions was determined by UHPLC-UV-MS. The following parameters of platelet activation were investigated: nonenzymatic lipid peroxidation in resting platelets; enzymatic lipid peroxidation (AA metabolism) in platelets activated by thrombin; superoxide anion (O2−.) generation in the resting and activated platelets; platelet adhesion to collagen type I and fibrinogen; platelet aggregation stimulated by various physiological agonists, such as ADP, collagen, and thrombin. The effect of the extract and fractions on extracellular LDH activity, a marker of cell damage, was also determined. ResultsVerbascoside a phenylethnanoid glycoside, was the main secondary metabolite of the extract from leaves of oxytree (constituting approximately 45 % of all compounds). There were also iridoids, such as catalpol, aucubin, and 7-hydroxytomentoside, as well as flavonoids, such as luteolin and apigenin glycosides. Moreover, the extract had stronger antiplatelet properties than the fractions. For example, the extract at 10 μg/mL inhibited five parameters of platelet activation. ConclusionsOur results show that Paulownia Clone in Vitro 112 leaves are a new valuable source of compounds with antiplatelet potential.

Platelet Activation in Ocular Behçet's Patients with Posterior Segment Involvement.

PURPOSE:The aim of the present study was to assess platelet activation by analyzing three platelet activation parameters in ocular Behçet's disease (BD): mean platelet volume (MPV), platelet distribution width (PDW), and plateletcrit (PCT).METHODS:Twenty-nine patients with active ocular BD (Group 1), 40 patients with inactive ocular BD (Group 2), and 40 healthy adult individuals serving as controls (Group 3) were evaluated. All of the individuals had been performed the complete ophthalmologic evaluation. The levels of MPV, PDW, and PCT were measured in each group.RESULTS:The mean MPV level was 8.40 ± 0.97 in Group 1, 8.32 ± 1.04 in Group 2, and 7.77 ± 0.72 in Group 3. The mean PDW level was 15.12 ± 1.09 in Group 1, 14.97 ± 1.02 in Group 2, and 14.52 ± 0.82 in Group 3. The mean PCT level was 0.23 ± 0.07 in Group 1, 0.21 ± 0.04 in Group 2, and 0.18 ± 0.03 in Group 3. MPV, PDW, and PCT levels were significantly higher in ocular BD patients than controls (P < 0.05).CONCLUSION:Platelet activation may affect vascular occlusion in ocular Behçet's patients with posterior segment involvement. This result may be important in evaluating ocular BD patients.

CD11b expression on monocytes and data of inflammatory parameters after Transcatheter Aortic Valve Implantation in dependence of early mortality.

An inflammatory systemic reaction is common after Transcatheter Aortic Valve Implantation (TAVI). We recently reported about an involvement of Mon2-monocytes, the CD11b expression on monocytes and parameters of systemic inflammation before TAVI correlating with early mortality after TAVI. Here, we provide data of monocyte subpopulations, CD11b expression and parameters of a systemic inflammation in dependence of three-month mortality after TAVI. With this, we provide further insights into inflammatory mechanism after TAVI. The data were collected by flow-cytometric quantification analyses of peripheral blood in 120 consecutive patients who underwent TAVI (on day 1 and 7 after TAVI). Monocyte-subsets were identified by their CD14 and CD16 expression and monocyte-platelet-aggregates (MPA) by CD14/CD41 co-expression. The extent of monocyte activation was determined by quantification of CD11b-expression (activate epitope). Additionally, pro-inflammatory cytokines such as interleukin (IL)-6, IL-8, C-reactive protein, procalcitonin were measured using the cytometric bead array method or standard laboratory tests. Additionally, we report procedural outcomes in dependence of three-month mortality. Furthermore, correlations of CD11b-expression on monocytes with parameters of platelet activation or further inflammatory parameters are presented. For further interpretation of the presented data, please see the research article “Mon2-Monocytes and Increased CD-11b Expression Before Transcatheter Aortic Valve Implantation are Associated with Earlier Death” by Pfluecke et al.[1]

Mon2-monocytes and increased CD-11b expression before transcatheter aortic valve implantation are associated with earlier death

BackgroundIn the first three months after Transcatheter aortic valve implantation (TAVI), a remarkable number of patients have an unfavorable outcome. An inflammatory response after TAVI is suspected to have negative effects. The exact mechanisms remain unclear. We examined the influence of monocyte subpopulations on the clinical outcome, along with the degree of monocyte activation and further parameters of inflammation and platelet activation. MethodsFlow-cytometric quantification analyses of peripheral blood were done in 120 consecutive patients who underwent TAVI (one day before TAVI and on day 1 and 7 after TAVI). Monocyte-subsets were defined by their CD14 and CD16 expression, monocyte-platelet-aggregates (MPA) by CD14/CD41 co-expression. The extent of monocyte activation was determined by quantification of CD11b-expression (activation epitope). Additionally, pro-inflammatory cytokines such as interleukin (IL)-6, IL-8, C-reactive protein were measured with the cytometric bead array method or standard laboratory tests. ResultsElevated Mon2 (CD14++CD16+) - monocytes (38 vs. 62 cells/μl, p < 0.001) and a high expression of CD11b prior to TAVI (MFI 50.1 vs. 84.6, p < 0.05) were independently associated with death 3 months after TAVI. Mon2 showed the highest CD11b-expression and CD11b correlated with platelet activation and markers of systemic inflammation. Even CRP and IL-8 before TAVI were associated with death after TAVI. In contrast, a systemic inflammation response shortly after TAVI was not associated with early death. ConclusionsElevated Mon2-monocytes and a high level of monocyte activation before TAVI are associated with early mortality after TAVI. Chronic inflammation in aging patients seems to be an important risk factor after TAVI.

The association between leptin concentration and blood coagulation: Results from the NEO study

BackgroundThe adipocyte-derived hormone leptin has been associated with altered blood coagulation in in vitro studies. However, it is unclear whether this association is relevant in vivo and to what extent this association is influenced by total body fat. Therefore, we aimed to examine the association between serum leptin and blood coagulation while taking total body fat into account in a population-based cohort study. MethodsWe performed a cross-sectional analysis with baseline measurements of 5797 participants of the Netherlands Epidemiology of Obesity (NEO) study, a population-based cohort of middle-aged men and women. We examined associations between serum leptin concentration and coagulation factor concentrations and parameters of platelet activation in linear regression analyses. All analyses were adjusted for multiple covariates, including total body fat. ResultsIn multivariable adjusted analyses a 1 μg/L higher serum leptin concentration was associated with a 0.22 IU/dL (95% CI: 0.11, 0.32) higher FVIII concentration and a 0.20 IU/dL (95% CI: 0.14, 0.27) higher FIX concentration (3.5 IU/dL FVIII and 3.2 IU/dL FIX per SD leptin). Serum leptin concentration was not associated with FXI, fibrinogen, platelet count, mean platelet volume and platelet distribution width in multivariable adjusted analyses. DiscussionThis study showed that serum leptin concentration was associated with higher concentrations of FVIII and FIX in an observational study, which could be clinically relevant.

Evaluation of blood collection methods and anticoagulants for platelet function analyses on C57BL/6J laboratory mice

The exploration of thrombotic mechanisms relies on the application of blood collection methods from laboratory mice with a minimal pre-activation of platelets and the clotting system. So far, very little is known on how the blood collection method and the anticoagulant used influence pre-activation of mouse platelets and coagulation. To determine the most suitable blood collection method, we systematically compared blood collection by heart puncture, Vena cava puncture, and puncture of the retro-orbital vein plexus and the use of citrate, heparin, and EDTA as frequently used anticoagulants with regard to platelet activation and whole blood clotting parameters. The activation of platelet-rich plasma diluted in Tyrode’s buffer was analyzed by flow cytometry, analyzing the exposure of P-selectin and activated integrin αIIbβ3. Clotting of whole blood was profiled by thrombelastometry. Puncture of the retro-orbital vein plexus by plastic capillaries is not superior in terms of blood volume and platelet pre-activation, whereas heart puncture and Vena cava puncture resulted in similarly high blood volumes. Cardiac puncture and Vena cava puncture did not result in pre-activated platelets with citrate as an anticoagulant, but the use of EDTA resulted in increased levels of integrin αIIbβ3 activation. Puncture of the retro-orbital vein plexus by plastic capillaries resulted in increased platelet integrin αIIbβ3 activation, which could be prevented by soaking with citrate or coating with heparin. Further, activation of coagulation in citrated whole blood by puncture of the retro-orbital vein plexus using a blunt plastic capillary was observed by thromboelastometry. The use of citrate is the optimal anticoagulant in mouse platelet assays. Blood collections from the heart or Vena cava represent reliable alternatives to retro-orbital puncture of the vein plexus to avoid pre-activation of platelets and coagulation.

5 Conservative treatment for PAD - Risk factor management.

5 Conservative treatment for PAD - Risk factor management.

The anti-oxidative and hemostasis-related multifunctionality of L-chicoric acid, the main component of dandelion: An in vitro study of its cellular safety, antioxidant and anti-platelet properties, and effect on coagulation

Abstract All dandelion (Taraxacum officinale) organs, i.e. the roots, leaves and flowers, are rich in L-chicoric acid, and nowadays are commonly included in dietary products and pharmaceutical preparations. However, little is known of the effects of dandelion leaves and petals, or L-chicoric acid itself, on the biological activity hemostasis elements such as blood platelets and plasma. Therefore, the aim of the present study was to examine the effect of chicoric acid extracted from dandelion on the biological properties of human plasma and blood platelets in vitro. Briefly, the study evaluated the effects of four phenolic fractions, obtained from leaves (fraction A and B) and petals (fraction C and D), with different concentrations of chicoric acid, as well as L-chicoric acid isolated from dandelion leaves, on biomarkers of oxidative stress, parameters of coagulation and blood platelet activation. Chicoric acid offers novel antioxidant and anti-adhesive potential without cytotoxicity.