activated platelets
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Author(s):  
Yumeng Huang ◽  
Qian Ji ◽  
Yanyan Zhu ◽  
Shengqiao Fu ◽  
Shuangwei Chen ◽  
...  

Excessive neutrophil extracellular trap (NET) formation is an important contributor to sepsis-induced acute lung injury (ALI). Recent reports indicate that platelets can induce neutrophil extracellular trap formation. However, the specific mechanism remains unclear. Tph1 gene, which encodes the rate-limiting enzyme for peripheral 5-hydroxytryptophan (5-HT) synthesis, was knocked out in mice to simulate peripheral 5-HT deficiency. Cecal ligation and puncture (CLP) surgery was performed to induce sepsis. We found that peripheral 5-HT deficiency reduced NET formation in lung tissues, alleviated sepsis-induced lung inflammatory injury, and reduced the mortality rate of CLP mice. In addition, peripheral 5-HT deficiency was shown to reduce the accumulation of platelets and NETs in the lung of septic mice. We found that platelets from wild-type (WT), but not Tph1 knockout (Tph1−/−), mice promote lipopolysaccharide (LPS)-induced NET formation. Exogenous 5-HT intervention increased LPS-induced NET formation when Tph1−/− platelets were co-cultured with WT neutrophils. Therefore, our study uncovers a mechanism by which peripheral 5-HT aggravated sepsis-induced ALI by promoting NET formation in the lung of septic mice.


Immunity ◽  
2022 ◽  
Author(s):  
Valentina Poli ◽  
Marco Di Gioia ◽  
Martha Sola-Visner ◽  
Francesca Granucci ◽  
Andrew L. Frelinger ◽  
...  

2021 ◽  
Vol 12 ◽  
Author(s):  
Baranca Buijsers ◽  
Fadel Muhammad Garishah ◽  
Silvita Fitri Riswari ◽  
Rosalie M. van Ast ◽  
Setyo Gundi Pramudo ◽  
...  

BackgroundEndothelial hyper-permeability with plasma leakage and thrombocytopenia are predominant features of severe dengue virus infection. It is well established that heparanase, the endothelial glycocalyx degrading enzyme, plays a major role in various diseases with vascular leakage. It is yet to be elucidated whether heparanase activity plays a major role in dengue-associated plasma leakage. Moreover, the major source of heparanase secretion and activation in dengue remains elusive. Since a relatively high amount of heparanase is stored in platelets, we postulate that heparanase released by activated platelets contributes to the increased plasma heparanase activity during dengue virus infection.MethodsHeparanase activity (plasma and urine), and heparan sulfate and syndecan-1 (plasma levels) were measured in dengue patients with thrombocytopenia in acute phase (n=30), during course of disease (n=10) and in convalescent phase (n=25). Associations with clinical parameters and plasma leakage markers were explored. Platelets from healthy donors were stimulated with dengue non-structural protein-1, DENV2 virus and thrombin to evaluate heparanase release and activity ex vivo.ResultsHeparanase activity was elevated in acute dengue and normalized during convalescence. Similarly, glycocalyx components, such as heparan sulfate and syndecan-1, were increased in acute dengue and restored during convalescence. Increased heparanase activity correlated with the endothelial dysfunction markers heparan sulfate and syndecan-1, as well as clinical markers of plasma leakage such as ascites, hematocrit concentration and gall-bladder wall thickening. Notably, platelet number inversely correlated with heparanase activity. Ex vivo incubation of platelets with thrombin and live DENV2 virus, but not dengue virus-2-derived non-structural protein 1 induced heparanase release from platelets.ConclusionTaken together, our findings suggest that the increase of heparanase activity in dengue patients is associated with endothelial glycocalyx degradation and plasma leakage. Furthermore, thrombin or DENV2 activated platelets may be considered as a potential source of heparanase.


Author(s):  
Lin Zheng ◽  
Zhimin Duan ◽  
Dingjie Tang ◽  
Yanzhi He ◽  
Xu Chen ◽  
...  

Candida albicans is the most common fungal pathogen in humans, causing invasive disease and even potentially life-threatening systemic infections when tissue homeostasis is disrupted. Previous studies have identified an essential role of platelets in infection and immunity, especially when they are activated. However, it is still unclear whether platelets can be activated by C. albicans, and even less is known about the role of platelets in C. albicans infection. Herein, we showed that C. albicans induced platelet activation in vitro. C. albicans elevated the levels of AKT Ser473 phosphorylation, and inhibition of the PI3K-AKT signaling pathway reversed C. albicans-induced platelet activation. Surprisingly, C. albicans-induced platelet activation occurred in an integrin glycoprotein (GP) IIb/IIIa-dependent manner but was independent of the pattern recognition receptors toll-like receptor (TLR) 2 and TLR4. Interestingly, platelets enhanced the phagocytosis of human monocytes challenged with C. albicans and upregulated the expression of inflammatory cytokines, which were dependent on platelet activation mediated by GP IIb/IIIa. The present work provides new insights into the role of activated platelets in the defense against C. albicans, highlighting the importance of GP IIb/IIIa in the recognition of C. albicans.


Cells ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 3414
Author(s):  
Sarah Nasreen Schmidt ◽  
Wilfried Reichardt ◽  
Beat A. Kaufmann ◽  
Carolin Wadle ◽  
Dominik von Elverfeldt ◽  
...  

Previous mouse studies have shown the increased presence of platelets in the myocardium during early stages of myocarditis and their selective detection by MRI. Here, we aimed to depict early myocarditis using molecular contrast-enhanced ultrasound of activated platelets, and to evaluate the impact of a P2Y12 receptor platelet inhibition. Experimental autoimmune myocarditis was induced in BALB/c mice by subcutaneous injection of porcine cardiac myosin and complete Freund adjuvant (CFA). Activated platelets were targeted with microbubbles (MB) coupled to a single-chain antibody that binds to the “ligand-induced binding sites” of the GPIIb/IIIa-receptor (=LIBS-MB). Alongside myocarditis induction, a group of mice received a daily dose of 100 g prasugrel for 1 month. Mice injected with myosin and CFA had a significantly deteriorated ejection fraction and histological inflammation on day 28 compared to mice only injected with myosin. Platelets infiltrated the myocardium before reduction in ejection fraction could be detected by echocardiography. No selective binding of the LIBS-MB contrast agent could be detected by either ultrasound or histology. Prasugrel therapy preserved ejection fraction and significantly reduced platelet aggregates in the myocardium compared to mice without prasugrel therapy. Therefore, P2Y12 inhibition could be a promising early therapeutic target in myocarditis, requiring further investigation.


2021 ◽  
Vol 9 ◽  
Author(s):  
Deepak Ganesh ◽  
Prashant Jain ◽  
Chethan Devanur Shanthamurthy ◽  
Suraj Toraskar ◽  
Raghavendra Kikkeri

Selectins are type-I transmembrane glycoproteins that are ubiquitously expressed on activated platelets, endothelial cells, and leukocytes. They bind to cell surface glycoproteins and extracellular matrix ligands, regulate the rolling of leukocytes in the blood capillaries, and recruit them to inflammatory sites. Hence, they are potential markers for the early detection and inhibition of inflammatory diseases, thrombosis, cardiovascular disorders, and tumor metastasis. Fucosylated and sialylated glycans, such as sialyl Lewisx, its isoform sialyl Lewisa, and heparan sulfate, are primary selectin ligands. Functionalization of these selectin-binding ligands on multivalent probes, such as nanoparticles, liposomes, and polymers, not only inhibits selectin-mediated biological activity but is also involved in direct imaging of the inflammation site. This review briefly summarizes the selectin-mediated various diseases such as thrombosis, cancer and recent progress in the different types of multivalent probes used to target selectins.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Agata Rolnik ◽  
Bartosz Skalski ◽  
Anna Stochmal ◽  
Beata Olas

AbstractIncreased blood platelet activation plays an important role in cardiovascular diseases (CVDs). Recent experiments indicate that certain fruits and vegetables, including onion, garlic, and beetroot, have anti-platelet potential and therefore may reduce the likelihood of CVDs. While vegetables from the Cucuritaceae family are known to exerting beneficial antioxidant and anti-inflammatory effects, their effects on blood platelet activation are poorly understood. Therefore, the aim of the present study was to determine the effect on platelet adhesion of preparations from selected cucurbits: pumpkin (Cucurbita pepo; fruit without seeds), zucchini (Cucurbita pepo convar. giromontina; fruit with seeds), cucumber (Cucumis sativus; fruit with seeds), white pattypan squash (Cucurbita pepo var. patisoniana; fruit without seeds) and yellow pattypan squash (Cucurbita pepo var. patisoniana, fruit without seeds). It also evaluates the activity of these preparations on enzymatic lipid peroxidation in thrombin-activated washed blood platelets by TBARS assay. The study also determines the anti-platelet properties of these five cucurbit preparations in whole blood by flow cytometry and with the total thrombus-formation analysis system (T-TAS) and evaluates the cytotoxicity of the tested preparations against platelets based on LDH activity. The results indicate that the yellow Cucurbita pepo var. patisoniana preparation demonstrated stronger anti-platelet properties than the other tested preparations, reducing the adhesion of thrombin-activated platelets to collagen/fibrinogen, and inhibiting arachidonic acid metabolism and GPIIb/IIIa expression on 10 µM ADP-activated platelets. None of the preparations was found to cause platelet lysis. Our findings provide new information on the anti-platelet activity of the tested cucurbit preparations and their potential for treating CVDs associated with platelet hyperactivity.


2021 ◽  
Vol 6 (3) ◽  
pp. 96-107
Author(s):  
Abubakar Auwal Nasir ◽  
Erhabor Osaro ◽  
Ibrahim Mohammed ◽  
Ahmed Hamidu Marafa ◽  
Yakubu Abdulrahman

Atherosclerosis is a chronic inflammatory process that results in coronary artery disease, peripheral artery disease and in many cases of stroke. It is a disease that involves multiple inflammatory cytokine which is regarded as the primary underlying cause of cardiovascular diseases (CVD). CVD is the leading cause of death in the developed and developing countries like Nigeria. From pathological perspective, the chronic inflammatory condition of atherosclerosis occurs due to interplay between platelets, monocytes, macrophages. Physiologically platelets play a significant role in coagulation and repair of endothelial injury. Pathologically, studies have shown that activated platelets release multiple inflammatory cytokines and chemokines that serve as positive mediators of atherosclerosis. This chemokine is (RANTES, P-selectin and PF-4). Activated platelet release p-selectin that mediate platelet adhesion and rolling to injured endothelial cell, RANTES trigger the recruitment of monocytes into the sub- endothelium and PF4 promote the differentiation of monocytes into macrophages in the intimal layer of the endothelium which engulf ox-LDL to form FOAM cells. Thus, the aim of this review is to understand and describe the role of activated platelets in atherosclerosis as well as therapeutic target of these platelet inflammatory chemokines which is the major mediator of atherosclerosis in human.


Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 955-955
Author(s):  
Cristiane Maria de Souza ◽  
Carolina Lanaro ◽  
Irene Pereira dos Santos ◽  
Oladele Olatunya ◽  
Sara T Olalla Saad ◽  
...  

Abstract Extracellular vesicles (EVs) are submicron structures released in blood circulation by different cell types which have been found to be increased in sickle cell disease (SCD) and are associated with clinical complications. The most abundant EVs in SCD patients derive from platelets, endothelial cells, and red blood cells (RBCs) and EVs have been explored as biomarkers of clinical severity. Crizanlizumab is a monoclonal antibody against P-selectin, an adhesion molecule expressed in activated platelets and endothelial cells. P-selectin facilitates the formation of heterocellular aggregates and is implicated in the pathophysiology of vaso-occlusive episodes (VOEs) in SCD. This study aimed to investigate the circulating levels of EVs in patients with SCD on standard of care or treated with crizanlizumab. We collected peripheral blood samples from 20 adults with SCD (Non treated group: 7 patients on hydroxyurea treatment and 7 without it. Treated group: 6 patients undergoing treatment with crizanlizumab in combination with hydroxyurea). Patients received the last dose of crizanlizumab at least a month prior to the study. EVs were identified by lactadherin+calcein stain and quantified by flow cytometry to determine the immunophenotype of their parent cell (platelet, endothelial cell, and RBC, with CD41+; CD146+/CD45-; CD235+, respectively). EV quantification was calculated in number per ml of blood as previously described by our group (Olatunya et al., 2019). We found that patients on crizanlizumab had lower total circulating EV counts than patients not receiving the drug (62.670.000,00 ± 15.600.000,00 vs 13.100.000,00 ± 3.513.000,00/mL, respectively, p=0,0076). The difference was statistically significant in platelet-derived EVs levels (5.397.000,00 ± 953.875,00 vs 2.413.000,00 ± 745.165,00/mL, p=0,0169), but not in endothelium-derived or RBC-derived EVs (345714 ± 101817 vs 220000 ± 64291, and 2.189.000,00 ± 1.648.000,00 vs 1.013.000,00 ± 572775, respectively). Crizanlizumab therapy has been shown to reduce the incidence of VOEs in SCD. EVs have been recognized as bio-effectors involved in VOEs, contributing to a hypercoagulable state, chronic inflammation, and endothelial damage. Our findings show an association between the use of crizanlizumab and lower EV levels, particularly of the platelet-derived type. While the anti-P-selectin activity of crizanlizumab could be expected to help remove platelets from circulation, clinical studies have not reported a reduction in platelet counts in patients treated with crizanlizumab. Therefore, we speculate that crizanlizumab may decrease the release of EV by activated platelets, reduce platelet activation, or contribute to EV removal from circulation. Our findings suggest that crizanlizumab therapy may modulate EV levels in the plasma of SCD patients and provide, for the first time, data to support exploring the use of extracellular vesicles as biomarkers to monitor the clinical response to this drug in patients. Further studies on EV expression of P-selectin and how crizanlizumab interacts with EVs and platelets may help clarify this particular effect of this drug. Disclosures Benites: Novartis: Honoraria. Fertrin: Sanofi Genzyme: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Costa: Novartis: Consultancy.


Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 3142-3142
Author(s):  
Li Guo ◽  
Ben Berger ◽  
Jesse W Rowley ◽  
Neal D Tolley ◽  
Bhanu Kanth Manne ◽  
...  

Abstract Granulomatosis with polyangiitis (GPA), formerly known as Wegener's Granulomatosis, is characterized by vasculitis that predominantly affects small- and medium-sized blood vessels in the sinuses, lungs, and kidneys. In addition to vascular inflammation, GPA is also characterized by an increased risk of thrombosis. The role of platelets in GPA pathogenesis remains incompletely understood. We aimed to better understand the changes in platelet gene expression and function in patients with GPA. Forty-two patients diagnosed with GPA (n=9 with active GPA and n=33 with GPA in remission) and 25 healthy, age-, gender-, and race-matched donors were enrolled. Patients with GPA showed typical disease manifestations, with an average Birmingham Vasculitis Activity Score of 1.6 (Mean±SD 1.6±3.5). One sixth of GPA patients (7/42) had a history of thrombosis. When stimulated with thrombin receptor activating peptide (TRAP, 50nM), platelets from patients with GPA showed significantly increased expression of P-selectin as compared to healthy controls (P-selectin+% Mean±SEM: Healthy 15.50±1.84 vs GPA 25.71±16.05, P<0.05). This suggests increased platelet activation in GPA, consistent with previous findings of increased platelet aggregation in vitro in GPA. In addition, released chemokines sCD40L and platelet-derived growth factor (PDGF) by activated platelets were increased in patients with GPA when we measured the cytokines in the platelet poor plasma using the Miliplex human cytokine Assay [sCD40L (ng/mL) Mean±SEM: Healthy 63.05±6.63 vs GPA 100.40±11.86, P<0.05, PDGF-AA (pg/mL) Mean±SEM: Healthy 137.50±46.52 vs GPA 357.30±79.65, P=0.052]. Next, we performed RNA-sequencing on platelets from GPA patients (n=8, 3 with active GPA disease and 5 in remission) and, for comparison, 4 healthy donors. We identified 75 genes that were significantly differentially expressed between GPA patients and healthy donors. The top 30 genes are listed in Figure 1A. S100A8 and S100A9 were the top two significantly differentially expressed transcripts in patients with GPA (Fig. 1B). These two genes encode proteins that form a heterodimer S100A8/S100A9 (commonly known as calprotectin) known to be increased in the plasma of GPA patients and associated with disease activity. Interestingly, platelets have not been identified as the cellular source of plasma calprotectin in GPA previously. Significantly increased RNA and protein expression of S100A8 and S100A9 in GPA patients was independently validated by qRT-PCR and immunoblot, respectively. The mRNA expression of S100A8 and S100A9 in platelets were significantly correlated with p-ANCA and anti-MPO antibodies, indicating platelet S100A8/S100A9 promotes neutrophil activation and inflammation (Mann-Whitney nonparametric test, P<0.05). As previously reported, plasma levels of calprotectin were also increased in GPA patients. To further evaluate if plateletS100A8/S100A9 mediates endothelial inflammation and vasculitis, we co-cultured platelets activated with thrombin (which increases S100A8/S100A9 secretion) with endothelial cells in the presence or absence of an anti-S100A8/S100A9 blocking antibody. Activated platelets triggered endothelial cell inflammation (e.g., increased expression of ICAM-1) that was significantly reduced when S100A8/S100A9 was blocked. In summary, the platelet transcriptome is altered in patients with GPA, with S100A8 and S100A9 being the top upregulated genes. Platelet functional responses are enhanced in patients with GPA, and our data suggests that increased plasma calprotectin levels in GPA patients may be platelet derived. Platelets and platelet S100A8/S100A9 appear to mediate vascular inflammation and thrombosis in GPA. Figure 1 Figure 1. Disclosures Rondina: Novartis: Research Funding; Platelet Biogenesis: Membership on an entity's Board of Directors or advisory committees; Acticor Biotech: Membership on an entity's Board of Directors or advisory committees; Platelet Transcriptomics: Patents & Royalties.


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