PERTURBATION OF ENDOTHELIAL CELLS INDUCES THROMBIN FORMATION IN FLOWING BLOOD RESULTING IN PLATELET AGGREGATION ON THEIR MATRIX

1987 ◽  
Author(s):  
Jaap Jan Zwaginga ◽  
Martin J W IJsseldijk ◽  
Philip G de Groot ◽  
Jan J Sixma

Studies which try to measure the contribution of the vessel wall to thrombin formation in flowing blood and the consequences of the formed thrombin for thrombus formation can not be performed with native blood because the perfusion system itself causes thrombin formation. Therefore, we have collected blood into^a solution of low molecular weight heparin (20 U/ml, Fragmin , Kabi Vitrum) and used this blood for perfusion studies over endothelial cells (EC) and their extracellular matrix (ECM) in a flat perfusiqn chamber (J.Lab.Clin.Med. 1983, 102, 522-532).Cells (2 x 105 ) and matrices (3.2 cm2) wetje perfused with 12 ml blood for 5 min at a shear rate of 1300 s . No fibrinopeptide A (FPA) generation in the perfusate was seen after perfusion over EC, ECM or empty coverslips. Treatment of EC for 4 hours with 4-phorbol 12-myristate 13-acetate (PMA 20 µg/ml) caused a strong increase in FPA generation (50 ng/ml) which was decreased again after a 16 hour incubation (25 ng/ml). ECM of EC's treated for 4 h with PMA showed a comparable FPA generation as their EC's (40 ng/ml), however, the FPA generation increased with prolonged incubation with PMA. FPA generation was completely blocked by hirudin and with a specific antibody against FVIIa (Dr. Mertens, CLB). By incubation of the matrix with an antitissue factor serum (Dr. Bertina, AZL), FPA generation could be blocked. The effect of the locally formed thrombin on platelet adhesion to ECM of 16 h PMA treated EC was evaluated and showed that 47.1 ± 9.3 (SD)% of the surface was covered with platelets of which 22.0 ± 9.3% consisted of small (< 5 µm) and 3.1 ± 3.4% of larger (5-10 µm) aggregates. EM studies showed degranulation of platelets and fibrin formation around the aggregates. ECM of untreated EC showed a similar coverage 41.5 ± 5.5% but only 6.7% small aggregates. Anti FVIIa and anti tissue factor decreased aggregate height and number to the values found with untreated ECM; adhesion remained unchanged. These data indicate that PMA perturbation of EC induces a tissue factor dependent thrombin formation which is associated with the induction of local thrombus formation. This system may serve as an in vitro model for thrombosis.

Blood ◽  
2012 ◽  
Vol 120 (10) ◽  
pp. 2133-2143 ◽  
Author(s):  
Roxane Darbousset ◽  
Grace M. Thomas ◽  
Soraya Mezouar ◽  
Corinne Frère ◽  
Rénaté Bonier ◽  
...  

AbstractFor a long time, blood coagulation and innate immunity have been viewed as interrelated responses. Recently, the presence of leukocytes at the sites of vessel injury has been described. Here we analyzed interaction of neutrophils, monocytes, and platelets in thrombus formation after a laser-induced injury in vivo. Neutrophils immediately adhered to injured vessels, preceding platelets, by binding to the activated endothelium via leukocyte function antigen-1–ICAM-1 interactions. Monocytes rolled on a thrombus 3 to 5 minutes postinjury. The kinetics of thrombus formation and fibrin generation were drastically reduced in low tissue factor (TF) mice whereas the absence of factor XII had no effect. In vitro, TF was detected in neutrophils. In vivo, the inhibition of neutrophil binding to the vessel wall reduced the presence of TF and diminished the generation of fibrin and platelet accumulation. Injection of wild-type neutrophils into low TF mice partially restored the activation of the blood coagulation cascade and accumulation of platelets. Our results show that the interaction of neutrophils with endothelial cells is a critical step preceding platelet accumulation for initiating arterial thrombosis in injured vessels. Targeting neutrophils interacting with endothelial cells may constitute an efficient strategy to reduce thrombosis.


2015 ◽  
Vol 114 (07) ◽  
pp. 173-185 ◽  
Author(s):  
Kefeng Zhai ◽  
Youmei Tang ◽  
Yuanyuan Zhang ◽  
Fang Li ◽  
Yan Wang ◽  
...  

SummaryNon-muscle myosin heavy chain IIA (NMMHC IIA) has been shown to be involved in thrombus formation and inflammatory microparticle release in endothelial cells. However, the role of NMMHC IIA in regulating the expression of tissue factor (TF) and deep venous thrombosis remains to be elucidated. In the present study, endothelial cells were stimulated with tumour necrosis factor-α (TNF-α) to induce TF expression. Pretreatment with the NMMHC II inhibitor blebbistatin suppressed the mRNA and protein expressions as well as the procoagulant activity of TF in a dose-dependent manner. Blebbistatin enhanced Akt and GSK3β phosphorylation and inhibited NF-κB p65 nuclear translocation and IκBα degradation. These observations were similar to the effect of CHIR99021, a GSK3β inhibitor. TF downregulation by blebbistatin was antagonised by the PI3K inhibitor, wortmannin. Furthermore, siRNA knockdown of NMMHC IIA but not IIB or IIC, inhibited TF expression, activated Akt/GSK3β and suppressed NF-κB signalling pathways, whereas the overexpression of NMMHC IIA increased TF expression. The binding of NMMHC IIA and TNF receptor 2 mediated signal internalisation in TNF-α-stimulated endothelial cells. Importantly, blebbistatin decreased endothelium NMMHC IIA and TF expression, deactivated GSK3β by inducing its phosphorylation, suppressed p65 nuclear translocation, and inhibited thrombus formation in a mouse deep venous thrombosis model. Our findings provide solid evidence that inhibition of NMMHC II most likely NMMHC IIA impedes TF expression and venous thrombosis via Akt/GSK3β-NF-κB signalling pathways in the endothelium both in vitro and in vivo. NMMHC IIA might be a potential novel target for the treatment of thrombotic disorders.


1997 ◽  
Vol 77 (05) ◽  
pp. 0975-0980 ◽  
Author(s):  
Angel Gálvez ◽  
Goretti Gómez-Ortiz ◽  
Maribel Díaz-Ricart ◽  
Ginés Escolar ◽  
Rogelio González-Sarmiento ◽  
...  

SummaryThe effect of desmopressin (DDAVP) on thrombogenicity, expression of tissue factor and procoagulant activity (PCA) of extracellular matrix (ECM) generated by human umbilical vein endothelial cells cultures (HUVEC), was studied under different experimental conditions. HUVEC were incubated with DDAVP (1, 5 and 30 ng/ml) and then detached from their ECM. The reactivity towards platelets of this ECM was tested in a perfusion system. Coverslips covered with DD A VP-treated ECMs were inserted in a parallel-plate chamber and exposed to normal blood anticoagulated with low molecular weight heparin (Fragmin®, 20 U/ml). Perfusions were run for 5 min at a shear rate of 800 s1. Deposition of platelets on ECMs was significantly increased with respect to control ECMs when DDAVP was used at 5 and 30 ng/ml (p <0.05 and p <0.01 respectively). The increase in platelet deposition was prevented by incubation of ECMs with an antibody against human tissue factor prior to perfusion. Immunofluorescence studies positively detected tissue factor antigen on DDAVP derived ECMs. A chromogenic assay performed under standardized conditions revealed a statistically significant increase in the procoagulant activity of the ECMs produced by ECs incubated with 30 ng/ml DDAVP (p <0.01 vs. control samples). Northern blot analysis revealed increased levels of tissue factor mRNA in extracts from ECs exposed to DDAVP. Our data indicate that DDAVP in vitro enhances platelet adhesion to the ECMs through increased expression of tissue factor. A similar increase in the expression of tissue factor might contribute to the in vivo hemostatic effect of DDAVP.


2006 ◽  
Vol 95 (03) ◽  
pp. 434-440 ◽  
Author(s):  
Satu Hyytiäinen ◽  
Ulla Wartiovaara-Kautto ◽  
Veli-Matti Ulander ◽  
Risto Kaaja ◽  
Markku Heikinheimo ◽  
...  

SummaryThrombin regulation in newborns remains incompletely understood.We studied tissue factor-initiated thrombin formation in cord plasma in vitro, and the effects of Factor VLeiden (FVL) heterozygosity on thrombin regulation both in vitro and in vivo in newborns. Pregnant women with known thrombophilia (n=27) were enrolled in the study. Cord blood and venous blood at the age of 14 days were collected from 11 FVL heterozygous newborns (FVL-positive) and from 16 FVL-negative newborns. Prothrombin fragment F1+2 and coagulation factors were measured. Tissue factor-initiated thrombin formation was studied in cord platelet-poor plasma (PPP) of FVL-negative and -positive newborns, and in both PPP and platelet-rich plasma (PRP) of healthy controls. The endogenous thrombin potential (ETP) in cord PPP or PRP was ∼60% of that in adult plasma, while thrombin formation started ∼55% and ∼40% earlier in cord PPP and PRP, respectively. Further, in FVL-positive newborns thrombin formation started significantly earlier than in FVL-negative newborns. Exogenous activated protein C (APC) decreased ETP significantly more in cord than in adult PRP. In FVL-negative cord plasma 5nM APC decreased ETP by 17.4±3.5% (mean±SEM) compared with only 3.5±3.8% in FVL-positive cord plasma (p=0.01). FVL-positive newborns showed similar levels of F1+2 but significantly decreased levels of factor V compared with FVL negative newborns both in cord plasma (FV 0.82±0.07 U/ml vs. 0.98±0.05 U/ml, p=0.03) and at the age of two weeks (FV 1.15±0.04 U/ml vs. 1.32±0.05 U/ml, p=0.03). In conclusion, newborn plasma showed more rapid thrombin formation and enhanced sensitivity to APC compared with adult plasma. FVL conveyed APC resistance and a procoagulant effect in newborn plasma. Lack of elevated F1+2 levels in FVL-positive infants, however, suggested the existence of balancing mechanisms; one could be the observed lower level of factor V in FVL heterozygous newborns.


2015 ◽  
Vol 113 (06) ◽  
pp. 1312-1322 ◽  
Author(s):  
Sofia Nordling ◽  
Jaan Hong ◽  
Karin Fromell ◽  
Fredrik Edin ◽  
Johan Brännström ◽  
...  

SummaryIschaemia-reperfusion injury (IRI) poses a major challenge in many thrombotic conditions and in whole organ transplantation. Activation of the endothelial cells and shedding of the protective vascular glycocalyx during IRI increase the risk of innate immune activation, cell infiltration and severe thrombus formation, promoting damage to the tissue. Here, we present a novel one-step strategy to protect the vasculature by immobilisation of a unique multi-arm heparin conjugate to the endothelium. Applying a new in vitro blood endothelial cell chamber model, the heparin conjugate was found to bind not only to primary human endothelial cells but also directly to the collagen to which the cells adhered. Incubation of hypoxic endothelial cells with freshly drawn human blood in the blood chambers elicited coagulation activation reflected by thrombin anti-thrombin formation and binding of platelets and neutrophils. Immobilisation of the heparin conjugate to the hypoxic endothelial cells created a protective coating, leading to a significant reduction of the recruitment of blood cells and coagulation activation compared to untreated hypoxic endothelial cells. This novel approach of immobilising multi-arm heparin conjugates on the endothelial cells and collagen of the basement membrane ensures to protect the endothelium against IRI in thrombotic disorders and in transplantation.


Blood ◽  
2010 ◽  
Vol 115 (2) ◽  
pp. 161-167 ◽  
Author(s):  
Nicholas T. Funderburg ◽  
Elizabeth Mayne ◽  
Scott F. Sieg ◽  
Robert Asaad ◽  
Wei Jiang ◽  
...  

Abstract HIV infection is associated with an increased risk of thrombosis; and as antiretroviral therapy has increased the lifespan of HIV-infected patients, their risk for cardiovascular events is expected to increase. A large clinical study found recently that all-cause mortality for HIV+ patients was related to plasma levels of interleukin-6 and to D-dimer products of fibrinolysis. We provide evidence that this elevated risk for coagulation may be related to increased proportions of monocytes expressing cell surface tissue factor (TF, thromboplastin) in persons with HIV infection. Monocyte TF expression could be induced in vitro by lipopolysaccharide and flagellin, but not by interleukin-6. Monocyte expression of TF was correlated with HIV levels in plasma, with indices of immune activation, and with plasma levels of soluble CD14, a marker of in vivo lipopolysaccharide exposure. TF levels also correlated with plasma levels of D-dimers, reflective of in vivo clot formation and fibrinolysis. Thus, drivers of immune activation in HIV disease, such as HIV replication, and potentially, microbial translocation, may activate clotting cascades and contribute to thrombus formation and cardiovascular morbidities in HIV infection.


Author(s):  
Sistiana Aiello ◽  
Sara Gastoldi ◽  
Miriam Galbusera ◽  
Piero Luigi Ruggenenti ◽  
Valentina Portalupi ◽  
...  

Unrestrained activation of the complement system till the terminal products, C5a and C5b-9, plays a pathogenetic role in acute and chronic inflammatory diseases. In endothelial cells, complement hyperactivation may translate into cell dysfunction, favoring thrombus formation. The aim of this study was to investigate the role of the C5a/C5aR1 axis as opposite to C5b-9 in inducing endothelial dysfunction and loss of anti-thrombogenic properties. In vitro and ex vivo assays with serum from patients with atypical hemolytic uremic syndrome (aHUS) -a prototype rare disease of complement-mediated microvascular thrombosis due to genetically determined alternative pathway dysregulation- and cultured microvascular endothelial cells, demonstrated that the C5a/C5aR1 axis is a key player of endothelial thromboresistance loss. C5a added to normal human serum, fully recapitulated the pro-thrombotic effects of aHUS serum. Mechanistic studies showed that C5a caused RalA-mediated exocytosis of vWF and P-selectin from Weibel-Palade bodies, which favored further vWF binding on the endothelium and platelet adhesion and aggregation. In patients with severe COVID-19 -who suffered from acute activation of complement triggered by SARS-CoV-2 infection- we found the same C5a-dependent pathogenic mechanisms. These results highlight C5a/C5aR1 as a common pro-thrombogenic effector spanning from genetic rare diseases to viral infections, and may have clinical implications. Selective C5a/C5aR1 blockade could have advantages over C5 inhibition, since the former preserves the formation of C5b-9 that is critical to control bacterial infections that often develop as comorbidities in severely ill patients. (Clinicaltrials.gov identifier NCT02464891)


2003 ◽  
Vol 197 (11) ◽  
pp. 1585-1598 ◽  
Author(s):  
Shahrokh Falati ◽  
Qingde Liu ◽  
Peter Gross ◽  
Glenn Merrill-Skoloff ◽  
Janet Chou ◽  
...  

Using a laser-induced endothelial injury model, we examined thrombus formation in the microcirculation of wild-type and genetically altered mice by real-time in vivo microscopy to analyze this complex physiologic process in a system that includes the vessel wall, the presence of flowing blood, and the absence of anticoagulants. We observe P-selectin expression, tissue factor accumulation, and fibrin generation after platelet localization in the developing thrombus in arterioles of wild-type mice. However, mice lacking P-selectin glycoprotein ligand 1 (PSGL-1) or P-selectin, or wild-type mice infused with blocking P-selectin antibodies, developed platelet thrombi containing minimal tissue factor and fibrin. To explore the delivery of tissue factor into a developing thrombus, we identified monocyte-derived microparticles in human platelet–poor plasma that express tissue factor, PSGL-1, and CD14. Fluorescently labeled mouse microparticles infused into a recipient mouse localized within the developing thrombus, indicating that one pathway for the initiation of blood coagulation in vivo involves the accumulation of tissue factor– and PSGL-1–containing microparticles in the platelet thrombus expressing P-selectin. These monocyte-derived microparticles bind to activated platelets in an interaction mediated by platelet P-selectin and microparticle PSGL-1. We propose that PSGL-1 plays a role in blood coagulation in addition to its known role in leukocyte trafficking.


Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Giovanni Cimmino ◽  
Giovanni Ciccarelli ◽  
Stefano Conte ◽  
Grazia Pellegrino ◽  
Luigi Insabato ◽  
...  

Background: Activation of T-cells plays an important role in the pathophysiology of acute coronary syndromes (ACS). We have previously shown that plaques from ACS patients are characterized by a selective oligoclonal expansion of T-cells, indicating a specific, antigen-mediated recruitment of T-cells within the unstable lesions. We have also previously reported that activated T-cells in vitro express functional Tissue Factor (TF) on their surface. At the moment, however it is not known whether expression of TF by T-cells may contribute to thrombus formation in vivo. Methods: Blood was collected from the aorta and the coronary sinus of 13 NSTEMI and 10 stable CAD patients. CD3+ cells were selectively isolated and TF gene expression (real time PCR)and protein levels (western blot) were evaluated. In additional 7 STEMI patients, thrombotic formation material was obtained from the occluded coronary artery by catheter aspiration during primary PCI. TF expression in CD3+ cells was evaluated by immunohistochemistry and confocal microscopy. Results: Transcardiac TF expression in CD3+ cells was significantly higher in NSTEMI patients as compared to CD3+ cells obtained from stable CAD patients. Interestingly, thrombi aspirated from STEMI patients resulted enriched in CD3+cells, which expressed TF on their surface as shown in the figure. Conclusions: Our data demonstrate that in patients with ACS, T-lymphocytes may express surface TF, thus contributing to the process of thrombus formation. This finding may shed new light into the pathophysiologyof ACS.


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