Macrophage Migration Inhibitory Factor Promotes Thromboinflammation and Predicts Fast Progression of Aortic Stenosis.

BACKGROUND: Aortic stenosis (AS) is driven by progressive inflammatory and fibrocalcific processes regulated by circulating inflammatory and valve resident endothelial and interstitial cells. The impact of platelets, platelet-derived mediators, and platelet-monocyte interactions on the acceleration of local valvular inflammation and mineralization is presently unknown. METHODS: We prospectively enrolled 475 consecutive patients with severe symptomatic AS undergoing aortic valve replacement. Clinical workup included repetitive echocardiography, analysis of platelets, monocytes, chemokine profiling, aortic valve tissue samples for immunohistochemistry, and gene expression analysis. RESULTS: The patients were classified as fast-progressive AS by the median ∆Vmax of 0.45 m/s per year determined by echocardiography. Immunohistological aortic valve analysis revealed enhanced cellularity in fast-progressive AS (slow- versus fast-progressive AS; median [interquartile range], 247 [142.3-504] versus 717.5 [360.5-1234]; P<0.001) with less calcification (calcification area, mm2: 33.74 [27.82-41.86] versus 20.54 [13.52-33.41]; P<0.001). MIF (macrophage migration inhibitory factor)-associated gene expression was significantly enhanced in fast-progressive AS accompanied by significantly elevated MIF plasma levels (mean±SEM; 6877±379.1 versus 9959±749.1; P<0.001), increased platelet activation, and decreased intracellular MIF expression indicating enhanced MIF release upon platelet activation (CD62P, %: median [interquartile range], 16.8 [11.58-23.8] versus 20.55 [12.48-32.28], P=0.005; MIF, %: 4.85 [1.48-9.75] versus 2.3 [0.78-5.9], P<0.001). Regression analysis confirmed that MIF-associated biomarkers are strongly associated with an accelerated course of AS. CONCLUSIONS: Our findings suggest a key role for platelet-derived MIF and its interplay with circulating and valve resident monocytes/macrophages in local and systemic thromboinflammation during accelerated AS. MIF-based biomarkers predict an accelerated course of AS and represent a novel pharmacological target to attenuate progression of AS.

Utility of thromboelastography with platelet mapping (TEG-PM) for monitoring platelet transfusion in qualitative platelet disorders.

BACKGROUND: Patients with pathogenic variants in RASGRP2 (inherited platelet disorder (IPD)-18) have normal platelet counts but show impaired platelet aggregation due to diminished activation of αIIbß3 integrin. This defect results in moderate to severe bleeding episodes, especially following surgical procedures, which require patients to be transfused with platelets and/or pro-hemostatic agents. We recently demonstrated that hemostatic efficacy of transfused platelets is limited by dysfunctional endogenous platelets in a mouse model of IPD-18 (Rasgrp2-/- mice), as dysfunctional platelets were recruited to the forming hemostatic plug but did not participate in clot contraction. Consequently, higher amounts of transfused platelets were required to outcompete these dysfunctional cells and to reverse bleeding. OBJECTIVE: We here studied the usefulness of thromboelastography with platelet mapping (TEG-PM), a method to evaluate platelet-dependent clot contraction, for ex vivo monitoring of the hemostatic potential in Rasgrp2-/- mice transfused with various amounts of wild-type (WT) platelets. RESULTS: Rasgrp2-/- whole blood samples did not contract in TEG-PM, consistent with a critical role of this protein in αIIbß3 activation. Addition of WT platelets improved TEG parameters (K time, α-angle, MA) in a ratio dependent manner, consistent with our recent in vivo studies showing impaired hemostasis at a 5:1, but not at a 2:1 ratio of mutant to WT platelets. K and α values were identified as better predictors of transfusion efficacy than MA, the most platelet-dependent TEG parameter. CONCLUSION: This proof-of-concept study supports the use of TEG-PM to monitor platelet transfusion ratios and hemostatic potential in IPD-18 and potentially other platelet disorders.

Platelet Angiopoietin-1 Protects Against Murine Models of Tumor Metastasis.

BACKGROUND: In addition to their fundamental roles in preserving vascular integrity, platelets also contribute to tumor angiogenesis and metastasis. However, despite being a reservoir for angiogenic and metastatic cytokines, platelets also harbor negative regulators of tumor progression. Angpt1 (angiopoietin-1) is a cytokine essential for developmental angiogenesis that also protects against tumor cell metastasis through an undefined mechanism. Although activated platelets release Angpt1 from α-granules into circulation, the contributions of platelet Angpt1 to tumor growth, angiogenesis, and metastasis have not been investigated. METHODS: Using cytokine arrays and ELISAs, we first compared platelet Angpt1 levels in breast and melanoma mouse tumor models to tumor-free controls. We then assessed tumor growth and metastasis in mice lacking megakaryocyte and platelet Angpt1 (Angpt1Plt KO). The spontaneous metastasis of mammary-injected tumor cells to the lungs was quantified using RT-PCR. The lung colonization of intravenously injected tumor cells and tumor cell extravasation were determined using fluorescent microscopy and flow cytometry. RESULTS: Platelet Angpt1 is selectively upregulated in the PyMT (polyoma middle tumor antigen) breast cancer mouse model, and platelets are the principal source of Angpt1 in blood circulation. While primary tumor growth and angiogenesis were unaffected, Angpt1Plt KO mice had both increased spontaneous lung metastasis and tumor cell lung colonization following mammary or intravenous injection, respectively. Although platelet Angpt1 did not affect initial tumor cell entrapment in the lungs, Angpt1Plt KO mice had increased tumor cell retention and extravasation. Serum from Angpt1Plt KO mice increased endothelial permeability and reduced VE-cadherin expression at endothelial junctions compared with serum from control mice (Angpt1WT). CONCLUSIONS: Platelets provide an intravascular source of Angpt1 that restrains tumor metastasis by preserving the lung microvasculature to limit tumor cell extravasation.

Time-Dependent Changes in Pulmonary Turnover of Thrombocytes During Critical COVID-19.

OBJECTIVES BACKGROUND: Under normal conditions, pulmonary megakaryocytes are an important source of circulating thrombocytes, causing thrombocyte counts to be higher in arterial than venous blood. In critical COVID-19, thrombocytes may be removed from the circulation by the lungs because of immunothrombosis, possibly causing venous thrombocyte counts to be higher than arterial thrombocyte counts. In the present study, we investigated time-dependent changes in pulmonary turnover of thrombocytes during critical COVID-19 by measuring arteriovenous thrombocyte differences. We hypothesized that the early stages of the disease would be characterized by a net pulmonary removal of circulating thrombocytes because of immunothrombosis and that later stages would be characterized by a net pulmonary release of thrombocytes as normal pulmonary function is restored. DESIGN: Cohort study with repeated measurements of arterial and central venous thrombocyte counts. SETTING: ICU in a large university hospital. PATIENTS: Thirty-one patients with critical COVID-19 that were admitted to the ICU and received invasive or noninvasive mechanical ventilation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We found a significant positive association between the arteriovenous thrombocyte difference and time since symptom debut. This finding indicates a negative arteriovenous thrombocyte difference and hence pulmonary removal of thrombocytes in the early stages of the disease and a positive arteriovenous thrombocyte difference and hence pulmonary release of thrombocytes in later stages. Most individual arteriovenous thrombocyte differences were smaller than the variance coefficient of the analysis. CONCLUSIONS: The results of this study support our hypothesis that early stages of critical COVID-19 are characterized by pulmonary removal of circulating thrombocytes because of immunothrombosis and that later stages are characterized by the return of normal pulmonary release of thrombocytes. However, in most cases, the arteriovenous thrombocyte difference was too small to say anything about pulmonary thrombocyte removal and release on an individual level.

Fibrin Network and Platelets Densities in Platelet-Rich Fibrin (PRF) Membranes Produced from Plastic Tubes Without Additives: A New Approach to PRF Clinical Use.

Background/Purpose: The present study aimed to investigate plastic tubes without additives as alternatives to glass and silica-coated plastic tubes, in the production of PRF membranes. Materials and Methods: Nine blood samples were collected from eight volunteers (n = 8) separated into three groups, according to tube material: glass, silica-coated plastic, and plastic without additives. In each group, the samples were centrifuged using different relative centrifugation forces: L-PRF (700 g/12 min), A-PRF (200 g/14 min), and A-PRF + (200 g/8 min). The generated membranes were evaluated by histomorphometry, considering the fibrin network, platelet aggregates, and cellular morphology, by light microscopy. The ultrastructural cellular morphology integrity was evaluated by transmission electron microscopy. Results: The L-PRF (p < 0.019) and A-PRF (p < 0.001) membranes showed a significantly lower fibrin network density in plastic tubes without additives compared to glass and silica-coated plastic tubes. Plastic tubes without additives revealed a significantly higher platelet percentage, regardless of the protocol (p < 0.005). In all groups, TEM analysis showed preserved normal morphological ultrastructure, maintaining the integrity of cellular components. Conclusion: Plastic tubes without additives offer a viable alternative for producing PRF membranes. They exhibited a higher platelet density and demonstrated fibrin network and cellular morphology similar to those of glass and silica-coated plastic tubes, irrespective of the centrifugation protocol.

Platelet-Rich Plasma (PRP) and Injectable Platelet-Rich Fibrin (i-PRF) in the Non-Surgical Treatment of Periodontitis-A Systematic Review.

The gold standard in the non-surgical treatment of periodontitis is scaling and root planing (SRP). In recent years, the use of autogenous platelet concentrates has spread over many specialties in dentistry and, thus, has also been gaining popularity in periodontal treatment. Its two main fractions are platelet-rich plasma (PRP) and platelet-rich fibrin (PRF), which, since 2014, can also be used via injection as injectable platelet-rich fibrin (i-PRF). The authors conducted a comprehensive systematic review in accordance with the PRISMA 2020 guidelines. It involved searching PubMed, Embase, Scopus, and Google Scholar databases using the phrases ("Root Planing" OR "Subgingival Curettage" OR "Periodontal Debridement") AND ("Platelet-Rich Plasma"). Based on the authors' inclusion and exclusion criteria, 12 results were included in the review, out of 1170 total results. The objective of this review was to ascertain the impact of utilizing PRP and i-PRF in SRP. The results revealed that both the incorporation of PRP and i-PRF were found to be significantly associated with are duction in gingival pocket depth and again in clinical attachment level; however, i-PRF demonstrated superiority in improving clinical parameters. Furthermore, i-PRF demonstrated notable bactericidal efficacy against Porphyromonas gingivalis. On the other hand, PRP proved inferior to an Nd:YAG laser in clinical parameter improvement; however, it demonstrated significant efficiency as well. This literature review led the authors to the conclusion that autologous platelet concentrates might be competent agents for improving the therapeutic outcomes of SRP.

Evaluation of the quality of platelet concentrates obtained in a Peruvian hospital.

Introduction: Platelet concentrates are blood products obtained from donor's blood, and their conservation must be subject to a strict quality control process to guarantee a safe and high-performance product in treating diseases that require their use. Methods: We designed a cross-sectional study to determine the total compliance rate in platelet concentrates obtained in the blood bank of the Cayetano Heredia Hospital in Lima during November and December of 2019. The Buffy method Coat obtained the platelet concentrates, and parameters such as platelet count and residual leukocytes, pH, and swirling effect were evaluated according to the National Hemotherapy and Blood Bank Program criteria. Results: The platelet count had a mean of 6.66 ± 3.94 x 10¹°/µL, the platelet concentrates had a mean of 56.30 ± 6.22 mL, and all, without exception, had the presence of the Swirling phenomenon. The pH had a mean of 7.64 ± 0.15, while the leukocyte count had a mean of 4.22 ± 3.51 x 107/µL. Regarding compliance by the parameters evaluated, it was evident that the platelet and leukocyte count had moderate compliance rates of 43.6% and 24.1%, while the pH and swirling effect had rates of 100% in both cases. The total compliance rate was 54.9% (95% confidence interval: 46.0 to 63.5). Conclusions: The compliance rate of platelet concentrates is moderate, and it is necessary to implement a process of continuous quality improvement in the blood bank.

Introducción: Los concentrados plaquetarios son hemoderivados obtenidos de la sangre, y su conservación debe estar supeditada a un estricto proceso de control de calidad para garantizar un producto inocuo y de alto rendimiento en el tratamiento de enfermedades que requieran su uso. Métodos: Diseñamos un estudio transversal que tuvo por objetivo determinar la tasa de conformidad total en concentrados plaquetarios obtenidos en el banco de sangre del Hospital Cayetano Heredia de Lima durante los meses de noviembre y diciembre del año 2019. Los concentrados plaquetarios fueron obtenidos por el método de Buffy Coat y se evaluaron parámetros como el recuento de plaquetas y leucocitos residuales, pH y efecto swirling, según criterios del Programa Nacional de Hemoterapia y Bancos de Sangre. Resultados: El recuento de plaquetas tuvo una media de 6.66 ± 3.94 x1010/µL y los concentrados plaquetarios tuvieron una media de 56.30 ± 6.22 mL, y todos sin excepción tuvieron presencia de fenómeno Swirling. El pH tuvo una media de 7.64 ± 0.15, mientras que el recuento de leucocitos tuvo una media de 4.22 ± 3.51 x107/µL. En cuanto al cumplimiento por parámetro evaluado, se evidenció que el recuento de plaquetas y leucocitos tuvieron tasas de conformidad de 43.6% y 24.1%, mientras que el pH y efecto swirling tuvieron tasas del 100% en ambos casos. La tasa de conformidad total fue 54.9% (CI95%: 46.0 a 63.5). Conclusiones: La tasa de conformidad de los concentrados plaquetarios es moderada, y se requiere implementar un proceso de mejora continua de la calidad en el banco de sangre.

Interactions between platelets and the cancer immune microenvironment.

Cancer is a leading cause of death in both China and developed countries due to its high incidence and low cure rate. Immune function is closely linked to the development and progression of tumors. Platelets, which are primarily known for their role in hemostasis, also play a crucial part in the spread and progression of tumors through their interaction with the immune microenvironment. The impact of platelets on tumor growth and metastasis depends on the type of cancer and treatment method used. This article provides an overview of the relationship between platelets and the immune microenvironment, highlighting how platelets can either protect or harm the immune response and cancer immune escape. We also explore the potential of available platelet-targeting strategies for tumor immunotherapy, as well as the promise of new platelet-targeted tumor therapy methods through further research.

Gelsolin regulates receptor-mediated and fluid-phase endocytosis in platelets.

BACKGROUND AND OBJECTIVE: Endocytosis is the process by which platelets incorporate extracellular molecules into their secretory granules. Endocytosis is mediated by the actin cytoskeleton in nucleated cells, however, the endocytic mechanisms in platelets are undefined. To better understand platelet endocytosis, we studied gelsolin (Gsn), an actin-severing protein that promotes actin assembly. METHODS: Mouse platelets from gelsolin-null (Gsn-/-) and wild-type (WT) controls were used. The uptake of fluorescent cargo molecules was compared as a measure of their endocytic efficiency. Receptor-mediated endocytosis was measured by the uptake of fibrinogen and transferrin; fluid-phase endocytosis was monitored by the uptake of fluorescent dextrans. RESULTS: ADP-stimulated WT platelets readily internalized both receptor-mediated and fluid-phase cargo. In contrast, Gsn-/- platelets showed a severe defect in the endocytosis of both types of cargo. The treatment of WT platelets with the actin-disrupting drugs cytochalasin D and jasplankinolide also reduced endocytosis. Notably, the individual and combined effects of Gsn deletion and drug treatment were similar for both receptor-mediated and fluid-phase endocytosis, indicating that Gsn mediates endocytosis via its action on the actin cytoskeleton. CONCLUSION: Our study demonstrates that Gsn plays a key role in the uptake of bioactive mediators by platelets.

Heterogeneity of platelets and their responses.

There has been increasing recognition of heterogeneity in blood platelets and their responses, particularly in recent years, where next-generation technologies and advanced bioinformatic tools that interrogate "big data" have enabled large-scale studies of RNA and protein expression across a growing list of disease states. However, pioneering platelet biologists and clinicians were already hypothesizing upon and investigating heterogeneity in platelet (and megakaryocyte) activity and platelet metabolism and aggregation over half a century ago. Building on their foundational hypotheses, in particular Professor Marian A. Packham's pioneering work and a State of the Art lecture in her memoriam at the 2023 International Society on Thrombosis and Haemostasis Congress by Anandi Krishnan, this review outlines the key features that contribute to the heterogeneity of platelets between and within individuals. Starting with important epidemiologic factors, we move stepwise through successively smaller scales down to heterogeneity revealed by single-cell technologies in health and disease. We hope that this overview will urge future scientific and clinical studies to recognize and account for heterogeneity of platelets and aim to apply methods that capture that heterogeneity. Finally, we summarize other exciting new data presented on this topic at the 2023 International Society on Thrombosis and Haemostasis Congress.

Differential Impact In Vivo of Pf4-ΔCre-Mediated and Gp1ba-ΔCre-Mediated Depletion of Cyclooxygenase-1 in Platelets in Mice.

BACKGROUND: Low-dose aspirin is widely used for the secondary prevention of cardiovascular disease. The beneficial effects of low-dose aspirin are attributable to its inhibition of platelet Cox (cyclooxygenase)-1-derived thromboxane A2. Until recently, the use of the Pf4 (platelet factor 4) Cre has been the only genetic approach to generating megakaryocyte/platelet ablation of Cox-1 in mice. However, Pf4-ΔCre displays ectopic expression outside the megakaryocyte/platelet lineage, especially during inflammation. The use of the Gp1ba (glycoprotein 1bα) Cre promises a more specific, targeted approach. METHODS: To evaluate the role of Cox-1 in platelets, we crossed Pf4-ΔCre or Gp1ba-ΔCre mice with Cox-1flox/flox mice to generate platelet Cox-1-/- mice on normolipidemic and hyperlipidemic (Ldlr-/-; low-density lipoprotein receptor) backgrounds. RESULTS: Ex vivo platelet aggregation induced by arachidonic acid or adenosine diphosphate in platelet-rich plasma was inhibited to a similar extent in Pf4-ΔCre Cox-1-/-/Ldlr-/- and Gp1ba-ΔCre Cox-1-/-/Ldlr-/- mice. In a mouse model of tail injury, Pf4-ΔCre-mediated and Gp1ba-ΔCre-mediated deletions of Cox-1 were similarly efficient in suppressing platelet prostanoid biosynthesis. Experimental thrombogenesis and attendant blood loss were similar in both models. However, the impact on atherogenesis was divergent, being accelerated in the Pf4-ΔCre mice while restrained in the Gp1ba-ΔCres. In the former, accelerated atherogenesis was associated with greater suppression of PGI2 biosynthesis, a reduction in the lipopolysaccharide-evoked capacity to produce PGE2 (prostaglandin E) and PGD2 (prostanglandin D), activation of the inflammasome, elevated plasma levels of IL-1ß (interleukin), reduced plasma levels of HDL-C (high-density lipoprotein receptor-cholesterol), and a reduction in the capacity for reverse cholesterol transport. By contrast, in the latter, plasma HDL-C and α-tocopherol were elevated, and MIP-1α (macrophage inflammatory protein-1α) and MCP-1 (monocyte chemoattractant protein 1) were reduced. CONCLUSIONS: Both approaches to Cox-1 deletion similarly restrain thrombogenesis, but a differential impact on Cox-1-dependent prostanoid formation by the vasculature may contribute to an inflammatory phenotype and accelerated atherogenesis in Pf4-ΔCre mice.

A mouse model of the protease-activated receptor 4 Pro310Leu variant has reduced platelet reactivity.

BACKGROUND: Protease-activated receptor 4 (PAR4) mediates thrombin signaling on platelets and other cells. Our recent structural studies demonstrated that a single nucleotide polymorphism in extracellular loop 3 and PAR4-P310L (rs2227376) leads to a hyporeactive receptor. OBJECTIVES: The goal of this study was to determine how the hyporeactive PAR4 variant in extracellular loop 3 impacts platelet function in vivo using a novel knock-in mouse model (PAR4-322L). METHODS: A point mutation was introduced into the PAR4 gene F2rl3 via CRISPR/Cas9 to create PAR4-P322L, the mouse homolog to human PAR4-P310L. Platelet response to PAR4 activation peptide (AYPGKF), thrombin, ADP, and convulxin was monitored by αIIbß3 integrin activation and P-selectin translocation using flow cytometry or platelet aggregation. In vivo responses were determined by the tail bleeding assay and the ferric chloride-induced carotid artery injury model. RESULTS: PAR4-P/L and PAR4-L/L platelets had a reduced response to AYPGKF and thrombin measured by P-selectin translocation or αIIbß3 activation. The response to ADP and convulxin was unchanged among genotypes. In addition, both PAR4-P/L and PAR4-L/L platelets showed a reduced response to thrombin in aggregation studies. There was an increase in the tail bleeding time for PAR4-L/L mice. The PAR4-P/L and PAR4-L/L mice both showed an extended time to arterial thrombosis. CONCLUSION: PAR4-322L significantly reduced platelet responsiveness to AYPGKF and thrombin, which is in agreement with our previous structural and cell signaling studies. In addition, PAR4-322L had prolonged arterial thrombosis time. Our mouse model provides a foundation to further evaluate the role of PAR4 in other pathophysiological contexts.

The study of platelet aggregation using a microtiter plate reader ‒ methodological considerations.

Optical aggregometry by 96-well plate assay, the microplate method, is a fast, efficient, and readily available method for measuring the pharmacological effects of antiplatelet drugs. Even though recent years have witnessed growing interest in adopting the microplate method for widespread use, it remains in the shadow of the standard light transmission aggregometry (LTA). Regardless of the method used, the results of platelet aggregation depend on a variety of factors and often vary among laboratories worldwide. While several methodological papers have examined the microplate method, no standards have been established, most likely because the approach is not used as a diagnostic tool. Currently, the microplate method is recommended by researchers to be used in conjunction with LTA or as an adjunct to LTA. This raises the question of whether an optimal protocol exists for microplate aggregometry, and what are the key considerations in a good experimental protocol for obtaining reliable results? This article attempts to address these questions by summarizing the knowledge accumulated in this field over the last three decades.

Role of platelet-to-lymphocyte ratio at the time of arrival to the emergency room as a predictor of short-term mortality in trauma patients with severe trauma team activation.

BACKGROUND: Platelet-to-Lymphocyte ratio (PLR) has been studied as a prognostic factor for various diseases and traumas. This study examined the utility of PLR as a tool for predicting 30-day mortality in patients experiencing severe trauma. METHODS: This study included 139 patients who experienced trauma and fulfilled ≥1 criteria for activation of the hospital's severe trauma team. Patients were divided into non-survivor and survivor groups. Mean PLR values were compared between the groups, the optimal PLR cut-off value was determined, and mortality and survival analyses were performed. Statistical analyses were performed using SPSS ver. 26.0. The threshold of statistical significance was P<0.05. RESULTS: There was a significant difference in mean (±standard deviation) PLR between the non-survivor (n=36) and survivor (n=103) groups (53.4±30.1 vs. 89.9±53.3, respectively; P<0.001). Receiver operating characteristic (ROC) curve analysis revealed an optimal PLR cut-off of 65.35 (sensitivity, 0.621; specificity, 0.694, respectively; area under the ROC curve, 0.742), and Kaplan-Meier survival analysis revealed a significant difference in mortality rate between the two groups. CONCLUSIONS: PLR can be calculated quickly and easily from a routine complete blood count, which is often performed in the emergency department for individuals who experience trauma. The PLR is useful for predicting 30-day mortality in trauma patients with severe trauma team activation.

Quantitative and structural changes of blood platelet cytoskeleton proteins in multiple sclerosis (MS).

Epidemiological studies show that cardiovascular events related to platelet hyperactivity remain the leading causes of death among multiple sclerosis (MS) patients. Quantitative or structural changes of platelet cytoskeleton alter their morphology and function. Here, we demonstrated, for the first time, the structural changes in MS platelets that may be related to their hyperactivity. MS platelets were found to form large aggregates compared to control platelets. In contrast to the control, the images of overactivated, irregularly shaped MS platelets show changes in the cytoskeleton architecture, fragmented microtubule rings. Furthermore, MS platelets have long and numerous pseudopodia rich in actin filaments. We showed that MS platelets and megakaryocytes, overexpress ß1-tubulin and ß-actin mRNAs and proteins and have altered post-translational modification patterns. Moreover, we identified two previously undisclosed mutations in the gene encoding ß1-tubulin in MS. We propose that the demonstrated structural changes of platelet cytoskeleton enhance their ability to adhere, aggregate, and degranulate fueling the risk of adverse cardiovascular events in MS.

Immunothrombosis versus thrombo-inflammation: platelets in cerebrovascular complications.

A State-of-the Art lecture titled "Thrombo-Neuroinflammatory Disease" was presented at the International Society on Thrombosis and Haemostasis Congress in 2023. First, we would like to advocate for discrimination between immunothrombosis and thrombo-inflammation, as immunothrombosis describes an overshooting inflammatory reaction that results in detrimental thrombotic activity. In contrast, thrombo-inflammation describes the interplay of platelets and coagulation with the immunovascular system, resulting in the recruitment of immune cells and loss of barrier function (hence, hallmarks of inflammation). Both processes can be observed in the brain, with cerebral venous thrombosis being a prime example of immunothrombosis, while infarct progression in response to ischemic stroke is a paradigmatic example of thrombo-inflammation. Here, we review the pathomechanisms underlying cerebral venous thrombosis and ischemic stroke from a platelet-centric perspective and discuss translational implications. Finally, we summarize relevant new data on this topic presented during the 2023 International Society on Thrombosis and Haemostasis Congress.

The Effect of Leukocyte Removal and Matrix Metalloproteinase Inhibition on Platelet Storage Lesions.

The reasons for unfavorable changes in platelet concentrate (PC) quality during storage are not fully understood yet. We aimed to evaluate whether leukocytes and matrix metalloproteinases (MMPs) lead to a decrease in the quality of PCs and examine whether MMP inhibition will slow down the platelets' aging. Nine PCs were divided into three parts: (1) leukocyte-depleted (F) PCs, (2) PCs with no additional procedures (NF), and (3) PCs with the addition of an MMP inhibitor-doxycycline (D). Each PC was stored for 144 h, and a sample for testing was separated from each part on the day of preparation and after 24, 48, 72 and 144 h of storage. Blood morphological analysis, platelet aggregation, and the expression of activation markers were evaluated. MMP-2 and MMP-9 concentration, activity, and gene expression were assessed. Platelet aggregation decreased, and platelet activation marker expression increased during the storage. D concentrates showed the lowest level of platelet activation. In turn, leukocyte-depleted PCs showed the highest level of platelet activation in general. MMP-9 platelet activity was higher in leukocyte-containing concentrates at the end of the storage period. We concluded that the filtration process leads to a higher platelet activation level. The presence of doxycycline in PCs reduces the expression of the activation markers as compared to leukocyte-depleted concentrates.

New light on changes in the number and function of blood platelets stimulated by cocoa and its products.

Hyperactivation of blood platelets, one of the causes of heart attack, and other cardiovascular diseases (CVDs), is influenced by various dietary components, including phenolic compounds from vegetables, fruits, teas, wines, cocoa and its products, including chocolate. The present paper sheds new light on the effect of cocoa and its products, especially dark chocolate, on the number and function of blood platelets, and the anti-platelet activity of their constituent phenolic compounds. A review was performed of papers identified in various electronic databases, including PubMed, Science Direct, Scopus, Web of Knowledge, and Google Scholar, with the aim of determining whether their anti-platelet activity may serve as part of a sweet strategy in countering CVDs. Various studies demonstrate that cocoa consumption, especially in the form of dark chocolate, with a high flavanol concentration, has anti-platelet activity and may play a significant role in cardioprotection; they also note that cocoa consumption may be a good strategy in diminishing cardiovascular risk, including hyperactivation of blood platelets.

Estimated Intake of Potassium, Phosphorus and Zinc with the Daily Diet Negatively Correlates with ADP-Dependent Whole Blood Platelet Aggregation in Older Subjects.

The aggregation of blood platelets is the pivotal step that leads to thrombosis. The risk of thrombotic events increases with age. Available data suggest that minerals taken with diet can affect the course of thrombosis. However, little is known about the relationship between platelet aggregability and mineral intake with diet among elderly people. Thus, we evaluated the associations between the reactivities of platelets to arachidonic acid, collagen or ADP and the estimated quantities of minerals consumed as a part of the daily diet in 246 subjects aged 60-65 years (124 men and 122 women). The found simple (not-adjusted) Spearman's rank negative correlations are as follows: 1. arachidonate-dependent aggregation and the amounts of potassium, zinc, magnesium, phosphorus, iron, copper and manganese; 2. collagen-dependent aggregation and the amounts of potassium, phosphorus, iron and zinc; and 3. ADP-dependent aggregation and the amounts of potassium, phosphorus and zinc. The negative associations between ADP-dependent platelet reactivity and the amount of potassium, phosphorus and zinc and between collagen-dependent aggregability and the amount of phosphorus were also noted after adjusting for a bunch of cardiovascular risk factors. Overall, in older subjects, the intake of minerals with diet is negatively related to blood platelet reactivity, especially in response to ADP. Diet fortification with some minerals may possibly reduce the thrombotic risk among elderly patients.