Microparticle-associated Tissue Factor Research Articles

Microparticle-associated tissue factor activity correlates with the inflammatory response in septic disseminated intravascular coagulation patients.

Sepsis is often accompanied by the formation of disseminated intravascular coagulation (DIC). Microparticles can exert their procoagulant and proinflammatory properties in a variety of ways. The purpose of this study was to investigate the relationship between microparticle-associated tissue factor activity (TF+-MP activity) and the inflammatory response. Data from a total of 31 DIC patients with sepsis and 31 non-DIC patients with sepsis admitted to the ICU of the First Affiliated Hospital of Harbin Medical University from December 2017 to March 2019 were collected. Blood samples were collected and DIC scores were calculated on the day of enrollment. The hospital's clinical laboratory completed routine blood, procalcitonin, and C-reactive protein tests. TF+-MP activity was measured using a tissue factor-dependent FXa generation assay. Interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) levels were determined using ELISA kits. Compared with the non-DIC group, the DIC group had higher levels of leukocytes, neutrophils, procalcitonin, C-reactive protein, IL-1β, and TNF-α, and more severe inflammatory reactions. TF+-MP activity in the DIC group was higher than that in the non-DIC group. In sepsis patients, TF+-MP activity was strongly correlated with inflammatory response indices and DIC scores. TF+-MP activity may play a major role in promoting inflammatory response in septic DIC.

Coagulation Activation in Brain Neoplasms

Introduction:Cancer patients are at increased risk for venous thromboembolism (VTE), and patients with brain tumors have a VTE risk of up to 30% over the course of the disease. Factors contributing to VTE risk include age ≥60 years, obesity, glioblastoma histology, large tumor size, subtotal resection, leg paresis and treatment with surgery, radiation or chemotherapy.Coagulation activation occurs in cancer patients via several mechanisms including up-regulation of tumor or microparticle-associated tissue factor (TF) and procoagulant molecules, downregulation of tissue factor pathway inhibitor (TFPI), thrombomodulin (TM), increased plasminogen activator inhibitor (PAI-1), all resulting in increased thrombin generation and a systemic prothrombotic state.We hypothesized that patients with glioblastoma multiforme (GBM), a high-grade malignant brain tumor, exhibit increased systemic coagulation activation compared to healthy individuals and patients with benign meningiomas. We tested this hypothesis by measuring thrombin generation (TG) as a surrogate marker of systemic coagulation activation in patients with GBM and meningiomas and in age and sex matched healthy controls for comparison.Methods:This study was supported by grants from the Northern New England Clinical Oncology Society and the Neuro-oncology section at Dartmouth-Hitchcock Medical Center. The primary objective was to compare the pre-surgical peak TG in the GBM and healthy control groups. Secondary objectives were to 1) compare pre-surgical peak TG in the meningioma and healthy control groups and 2) compare tumor volumes on MRI with TG in patients with GBM and meningiomas.Patients with a new GBM or meningioma (W.H.O. grade 1 or 2) for whom a debulking procedure or surgical resection was planned were eligible. Patients with an additional active malignancy, history of idiopathic VTE at any time or provoked VTE within 5 years of entry, current treatment with an anticoagulant for any reason within the last 90 days or a surgical procedure other than a skin biopsy within the previous 30 days were excluded.After informed consent, 20 mL of blood was collected from subjects in 3.2% sodium citrate tubes prior to surgery. An additional 20 ml of blood was collected from GBM subjects 3 to 6 weeks after surgery. Platelet-poor plasma was prepared by centrifugation and stored at -80°C until analysis. TG was measured in nanomoles (nm) with a calibrated automated thrombogram assay (Thrombinoscope BV, Maastricht, Netherlands) using 1 pM TF and 4 uM phospholipids to trigger coagulation reactions. Statistical analysis was performed using Student's t-test for comparisons between groups.All GBM and meningioma subjects had pre-operative MRI scans. The highest resolution available gadolinium-enhanced anatomic scan (MPRAGE, T1-FLAIR, BRAVO, etc) was manually segmented by one of two trained segmenters to label tumor areas, with results reviewed, adjusted, and confirmed by a practicing neuroradiologist. Tumor volumes were then calculated as the number of labeled voxels times voxel volume (0.39-4.64 mm^3).Results:Fifty-eight patients consented to participate in the study. There were 15 screen failures and of the 43 patients included in the study, 20 had GBM and 23 had meningiomas. Blood from one age and sex-matched healthy blood donor was obtained for each study subject. The mean peak pre-op TG was 290 +/- 53 nm in the GBM cohort and 186 +/- 41 nm in controls; 242 +/- 55 nm in the meningioma cohort and 177 +/- 57 in controls. The p-value was <0.001 for all three pairwise comparisons. Only 9 post-op GBM samples were available for analysis. In this group, the mean pre-op TG was 323 nm +/- 38 nM and 273 nm +/- 47 nM post-op (p < 0.001). Two patients in the GBM group developed VTE with a mean peak TG of 364 nm compared to 290 nm for GBM patients without VTE (P = 0.04). We found no association between tumor volumes and pre-op TG.Conclusions:Peak TG was significantly higher in patients with GBM than in either patients with meningioma or healthy controls. TG decreased after tumor debulking surgery in GBM patients. Moreover, our results suggest that TG may be a useful marker for systemic coagulation activation in patients with GBM. Though our early results showing increased TG in GBM patients with VTE are provocative, more study is required to determine whether TG can be used to reliably predict VTE risk in this population. DisclosuresNo relevant conflicts of interest to declare.

Vascular and Hemostatic Alterations Associated with Pulmonary Hypertension in β-Thalassemia Hemoglobin E Patients Receiving Regular Transfusion and Iron Chelation

Background: β-thalassemia hemoglobin E (β-thal/HbE) is currently the commonest β-thalassemia disease worldwide. Pulmonary hypertension (PH) is the most common cardiovascular complication in this genotype, especially in splenectomized patients. Yet the pathogenesis of this major complication remains poorly characterized. Most of the previous reports investigated pathophysiology of PH in β-thal/HbE with inadequate transfusion. In this study we aimed to define the prevalence and comprehensively explore mechanisms of PH in β-thal/HbE patients receiving regular transfusion and iron chelation which were reported to alleviate PH. Our findings will provide deeper insights into pathogenesis and identify targets for management of persistent PH in thalassemia patients after adequate transfusion and chelation.Methods: β-thal/HbE patients who received regular transfusion ≥ 1 unit per month and any forms of iron chelation over 1 year were eligible for the study. Normal healthy subjects were used as controls. Blood sample collection and echocardiographic assessment were performed on the same days. Patients at risk for PH were defined by the tricuspid regurgitant jet velocity (TRV) ≥ 2.5 m/s.Results: There were 68 β-thal/HbE and 38 healthy controls enrolled between May and September 2015. The ages (mean ± SD) were 34.1 ± 12.6, ranging from 19-67 years, and 37.2 ± 8.6 years, ranging from 18-70 years, respectively. Among 68 β-thal/HbE, the average transfusion duration was 8.1 ± 2.2, ranging from 2.2-10.6 years, and the quantity of transfusion was 22.3 ± 9.6 units per year. The pre-transfusion hemoglobin (Hb) level was 8.1 ± 1.3 g/dL. There were 31 (45.6%) splenectomized patients. β-thal/HbE showed markedly increased erythropoiesis (growth differentiation factor, GDF15, and soluble transferrin receptor, sTfR, levels) and iron load (serum ferritin) compared to controls, all p < 0.001. Thrombin antithrombin (TAT) complex and microparticle's procoagulant activity (MPA) were significantly elevated (both p < 0.001), but total tissue factor antigen (TFAg) and microparticle-associated tissue factor activity (MPTFA) were not different from those of controls, suggesting TF-independent hypercoagulability. Serum nitric oxide metabolites (NOx) and prostaglandin E2 (PGE2) levels were significantly lower than those of controls (both p < 0.001), while soluble thrombomodulin (sTM) levels were significantly elevated (p= 0.045). Serum endothelin-1 (ET-1) and soluble p-selectin levels were not different between patients and controls. Echocardiographic profiles demonstrated preserved biventricular systolic functions in β-thal/HbE with a significant increase in TRV (p < 0.001).Among β-thal/HbE, there were 29 (42.6%; 16 non-splenectomized and 13 splenectomized) cases at risk for PH. Duration and amount of transfusion, pre-transfusion Hb, GDF15 and sTfR levels were not statistically different between PH and non-PH subgroups indicating the similar degree of erythropoiesis. Notably, β-thal/HbE with PH had a significant reduction in NOx levels (p < 0.001) but elevations in TAT, ET-1 and sTM levels compared to those without PH (p= 0.046, 0.005 and 0.026, respectively). Additionally, TRV was significantly correlated with NOx, TAT, sTM and ET-1 levels (r = -0.514, p < 0.001; r = 0.281, p= 0.004; r = 0.313, p= 0.001; and r = 0.245, p= 0.012, respectively). Serum ferritin, MPA, MPTFA, TFAg and PGE2 levels were not statistically different between PH and non-PH subgroups. Surprisingly, there were no differences in any biomarkers and echocardiographic profiles between splenectomized and non-splenectomized patients as well as no significant associations between splenectomy statuses and PH (Χ2 = 0.012, p= 0.914).We reviewed another β-thal/HbE cohort with available flow mediated dilatation (FMD) data. 9 β-thal/HbE with PH had significantly lower FMD (3.43%) compared to 18 β-thal/HbE without PH (6.37%) and 27 age-sex matched controls (9.87%; p= 0.025 and p < 0.001, respectively) indicating a greater degree of endothelial dysfunction in β-thal/HbE having PH. In addition, TRV was significantly correlated with FMD (r = -0.474, p < 0.001).Conclusions: PH is still prevalent in β-thal/HbE patients receiving long-term regular transfusion and iron chelation. In this group, PH is not associated with splenectomy statuses but correlated with NO depletion, TF-independent hypercoagulation and endothelial dysfunction. [Display omitted] DisclosuresSutcharitchan:Chulalongkorn University: Consultancy, Employment; Celgene: Research Funding.

Biomarkers of Platelet Activation and Their Prognostic Value in Patients With Sepsis-Associated Disseminated Intravascular Coagulopathy

Sepsis-associated disseminated intravascular coagulation (DIC) is related to marked hemostatic changes such as transient thrombocytopenia secondary to the endogenous activation and consumption of platelets. This study measured markers of platelet function in 103 adult ICU patients with clinically established sepsis-associated DIC to determine the biomarker association with disease severity. Patients were categorized as having no DIC, nonovert DIC, or overt DIC using the International Society of Thrombosis and Hemostasis scoring system. Plasma levels of CD40L, platelet factor 4 (PF4), platelet-derived microparticles, and microparticle-associated tissue factor were quantified. Markers of platelet activation were significantly elevated in patients with DIC compared to healthy individuals. This increase was independent of platelet count. Levels of PF4 differed based on the severity of DIC and differentiated nonsurvivors and survivors. These findings suggest that the markers of platelet activation in DIC may not be regulated by the number of circulating platelets and may be independent of the factors leading to their consumption.

Longitudinal Dynamics of Coagulation and Angiogenesis Markers in Cancer Patients During and After Chemotherapy.

Hemostatic parameters have been investigated as molecular determinants of tumor progression. To analyze the dynamics of microparticle-associated tissue factor activity (MPTF), tissue factor antigen (TF-Ag), and angiopоietin-2 (ANG-2) in cancer patients before, during, and after active treatment and to explore their potential as biomarkers for metastatic occurrence and death. Blood for the analysis of MPTF, TF-Ag, ANG-2, and conventional hemostatic tests was sampled in 111 patients with various cancers at 4 consecutive visits: before first chemotherapy cycle, after 3 courses, at the sixth course, and 3 months after chemotherapy cessation. Patients were followed up until metastatic progression/death or the end of the study. MPTF did not change during chemotherapy, but increased significantly after treatment cessation. Total TF-Ag and ANG-2 decreased throughout active treatment. Significant drop of their levels was observed 3 months post therapy cessation. Progressive disease was significantly associated with higher pre-chemotherapy TF-Ag and fibrinogen. Elevated baseline levels of fibrinogen were associated with increased risk of shortened progression free survival. Cessation of chemotherapy is associated with significant change of hemostatic parameters. Pre-chemotherapy levels of TF-Ag and fibrinogen may be informative of disease state and prognosis.

Prognostic significance of tissue factor in patients with pancreatic cancer: a systematic review protocol.

IntroductionPancreatic cancer is a highly aggressive digestive system tumour with poor prognosis. Venous thromboembolism (VTE) is a well-known complication of pancreatic cancer, and tissue factor (TF) contributes to the generation of a hypercoagulable state and thrombotic disease in pancreatic cancer. Several studies showed that an elevated TF level was related to the development of VTE and influenced the survival of patients with pancreatic cancer. Thus, we wish to conduct a systematic review of literature to clarify the prognostic significance of TF in pancreatic cancer.Methods and analysisStudies comparing the circulating microparticle-associated TF (MP TF) level between patients who had pancreatic cancer with and without VTE will be included to evaluate the roles of TF in VTE development. Studies comparing the survival data between patients with high TF expression and low TF expression will also be included to explore the association of TF expression with patient survival. The outcomes are plasma MP TF level and survival endpoints (overall and progression-free survival), respectively. Primary studies of any type published in English will be included. Two reviewers will search Medline, EMBASE and Cochrane databases from inception to June 2020, retrieve relevant studies, and independently select the literatures and extract data from the included studies. The quality of each included study will be assessed by the Newcastle-Ottawa Scale score. The HR and 95% CI of each study will be pooled for survival outcome, and the standardised mean difference (SMD) with 95% CIs will be used for continuous outcomes. If meta-analysis is inappropriate, the result will only be reported qualitatively. Subgroup and sensitivity analyses will be considered to identify sources of heterogeneity. The Grades of Recommendation, Assessment, Development and Evaluation method will be applied to assess the level of evidence of this systematic review.Ethics and disseminationThere are no concerning ethical issues. The results will be published.PROSPERO registration numberCRD42019133665.

Microparticle-associated tissue factor activity in dogs with disseminated intravascular coagulation.

Microparticle (MP)-associated tissue factor (TF) activity in plasma might play a role in human disseminated intravascular coagulation (DIC). The aim of this study was to compare MP-TF activity between non-DIC and DIC groups. Ten clinically healthy beagles and 26 diseased dogs were enrolled. The proportion of dogs with increased MP-TF activity was significantly higher in the DIC group than the non-DIC group (P=0.014). MP-TF activity in the DIC group was significantly higher than the non-DIC group (P=0.021). MP-TF activity positively correlated with plasma D-dimer concentration (r=0.42, P=0.034). Moreover, MP-TF activity was decreased by the time of recovery in some dogs with DIC. Larger prospective studies are warranted to assess its value as a diagnostic and prognostic biomarker in DIC.

Ozone effects on blood biomarkers of systemic inflammation, oxidative stress, endothelial function, and thrombosis: The Multicenter Ozone Study in oldEr Subjects (MOSES).

The evidence that exposure to ozone air pollution causes acute cardiovascular effects is mixed. We postulated that exposure to ambient levels of ozone would increase blood markers of systemic inflammation, prothrombotic state, oxidative stress, and vascular dysfunction in healthy older subjects, and that absence of the glutathione S-transferase Mu 1 (GSTM1) gene would confer increased susceptibility. This double-blind, randomized, crossover study of 87 healthy volunteers 55–70 years of age was conducted at three sites using a common protocol. Subjects were exposed for 3 h in random order to 0 parts per billion (ppb) (filtered air), 70 ppb, and 120 ppb ozone, alternating 15 min of moderate exercise and rest. Blood was obtained the day before, approximately 4 h after, and approximately 22 h after each exposure. Linear mixed effect and logistic regression models evaluated the impact of exposure to ozone on pre-specified primary and secondary outcomes. The definition of statistical significance was p<0.01. There were no effects of ozone on the three primary markers of systemic inflammation and a prothrombotic state: C-reactive protein, monocyte-platelet conjugates, and microparticle-associated tissue factor activity. However, among the secondary endpoints, endothelin-1, a potent vasoconstrictor, increased from pre- to post-exposure with ozone concentration (120 vs 0 ppb: 0.07 pg/mL, 95% confidence interval [CI] 0.01, 0.14; 70 vs 0 ppb: -0.03 pg/mL, CI -0.09, 0.04; p = 0.008). Nitrotyrosine, a marker of oxidative and nitrosative stress, decreased with increasing ozone concentrations, with marginal significance (120 vs 0 ppb: -41.5, CI -70.1, -12.8; 70 vs 0 ppb: -14.2, CI -42.7, 14.2; p = 0.017). GSTM1 status did not modify the effect of ozone exposure on any of the outcomes. These findings from healthy older adults fail to identify any mechanistic basis for the epidemiologically described cardiovascular effects of exposure to ozone. The findings, however, may not be applicable to adults with cardiovascular disease.

Altered fibrin clot properties in advanced lung cancer: strong impact of cigarette smoking

BackgroundDense fibrin networks resistant to lysis have been reported in patients at high risk of thromboembolism. Little is known about fibrin clot properties in cancer. We investigated fibrin clot properties and their determinants in patients with inoperable lung cancer.MethodsWe enrolled 150 patients with advanced lung cancer prior to therapy and 90 control subjects matched by age, sex, cardiovascular disease, and diabetes. Plasma clot permeability (Ks), turbidimetric analysis of clot formation, clot lysis time (CLT), microparticle-associated tissue factor (MP-TF) activity, thrombin generation, and serum cotinine levels were determined.ResultsLung cancer patients, compared with controls, formed at a faster rate (− 8.1% lag phase) denser plasma fibrin networks (− 27.2% Ks) that displayed impaired lysis (+ 26.5% CLT), along with 19.5% higher MP-TF activity and 100% higher peak thrombin generated, also after adjustment for potential confounders. Cotinine levels were associated with fibrin maximum absorbance (r = 0.20, p = 0.016) and Ks (r = − 0.50, p < 0.0001) in cancer patients. On multivariate regression analysis, an increase in cotinine levels was a predictor of low Ks (the lower quartile, < 5.8 × 10−9 cm2; odds ratio = 1.21 per 10 ng/ml, 95% confidence interval 1.02–1.46), but not CLT.ConclusionAdvanced lung cancer is associated with the prothrombotic plasma clot phenotype largely driven by smoking.

Association of Inflammatory and Hemostatic Biomarkers with Inflammasomes in Septic Patients at Risk for Development of Coagulopathy

Sepsis is a catastrophic complication of infection that results in systemic inflammatory responses. Inflammasomes initiate the inflammatory cascade that results in the activation of caspase 1, leading to the upregulation of inflammatory cytokines such as interleukins B and 18. The NRLP-3 inflammasome contributes to the innate immune response identification of pattern recognition receptors on pathogens including bacteria and viruses. Whereas the role of inflammasome in the inflammatory response is known, it is not clear how inflammasome contributes to the hemostatic dysregulation observed in sepsis-associated coagulopathy. The purpose of this study was to quantitate inflammasome levels in defined sepsis-associated patients and to determine its potential relevance to various biomarkers of hemostatic dysregulation. Plasma samples from 52 adults with sepsis and suspected coagulopathy were analyzed. Samples were collected from intensive care unit patients on day 0, under an Institution Review Board-approved protocol. Samples were stored at −80°C before analysis. Platelet count was determined as part of standard clinical practice. Healthy control samples were purchased from George King Bio-Medical (Overland, Kan). Prothrombin time and international normalized ratio were measured using recombiplastin reagent. Fibrinogen was measured using a clot-based method on ACL ELITE (Instrumentation Laboratory, Bedford, Mass) coagulation analyzer. Cortisol, D-dimer, plasminogen activator inhibitor 1 (PAI-1), NLRP-3 inflammasomes, microparticle-associated tissue factor, fibronectin, and CD40L were measured using commercially available enzyme-linked immunosorbent assays. In comparing patients with sepsis and suspected disseminated intravascular coagulation (DIC) with the normal plasma samples, there was a significant elevation in NLRP-3 inflammasome levels in the sepsis cohort (P < .0001). The Fig shows that the NLRP-3 inflammasome concentration in the sepsis cohort did not correlate with other biomarkers. An elevated level of NLRP-3 inflammasomes was significantly associated with increased levels of PAI-1 (P < .0004). No other inflammatory or hemostatic markers were significantly correlated with NLRP-3 inflammasomes. This is depicted in the Table. The study shows a significant relationship between inflammasomes and PAI-1 levels in patients with sepsis-associated coagulopathy. The positive correlation between NLRP-3 inflammasomes and PAI-1 shows that the activation of inflammasomes may have a role in the upregulation of PAI-1 and the observed hemostatic dysregulation. The strong association between NLRP-3 inflammasome and PAI-1 in baseline samples of patients with sepsis and DIC also suggests that NLRP-3 inflammasome may contribute to the fibrinolytic dysregulation in sepsis and DIC.TableInflammatory and hemostatic biomarkers correlated with NLRP-3 inflammasome levels in patients with sepsis and suspected disseminated intravascular coagulation (DIC)NLRP-3 inflammasome correlationP (Mann-Whitney)Spearman rCD40L.5716−0.08028PAI-1.00410.3915MP-TF.14910.2528Fibrinogen.76850.04314Fibronectin.8291−0.03067Cortisol.07580.2484D-Dimer.32720.1495MP-TF, Microparticle-associated tissue factor; PAI-1, plasminogen activator inhibitor 1. Open table in a new tab

Altered fibrin clot properties in advanced lung cancer: impact of chemotherapy.

Faster formation of dense and poorly lyzable fibrin networks have been reported in patients at risk of thromboembolism, including cancer patients. We sought to investigate whether chemotherapy affects plasma fibrin clot properties and their determinants in lung cancer patients. In this observational study we enrolled 83 consecutive patients with advanced inoperable lung cancer. Plasma fibrin clot permeability (Ks), turbidimetric analysis of clot formation, clot lysis time (CLT), microparticle-associated tissue factor (MP-TF) activity, and thrombin generation parameters were investigated at enrolment and 3-4 months after standard chemotherapy. Lung cancer patients after 4 (range, 4-5) cycles of chemotherapy had 35.6% higher D-dimer, 22.1% lower MP-TF activity, and unaltered fibrinogen compared with baseline. Chemotherapy resulted also in 7.5% increased Ks, 8.6% prolonged lag phase, and 5.4% shortened CLT, while thrombin generation was unchanged. Chemotherapy-related differences in clot structure were confirmed by scanning electron microscopy images. Fibrin clot properties after chemotherapy did not differ among histological types of lung cancer, cancer stages or chemotherapy regimens. Interestingly, never smoking (n=13, 16%) was associated with looser post-treatment fibrin structure as reflected by 12.3% higher Ks. Multiple linear regression showed that more advanced cancer stage, higher peak thrombin generation, and higher white blood cell count determined post-treatment change in Ks, while active smoking was associated with change in CLT. Three-month chemotherapy in lung cancer patients improves clot properties despite unaffected thrombin generation, suggesting that anticancer treatment might quickly produce antithrombotic actions.

Predictive value of microparticle-associated tissue factor activity for permeability glycoprotein-mediated multidrug resistance in cancer.

Multidrug resistance (MDR) protein 1, which is also known as permeability glycoprotein (Pgp), and tissue factor (TF) are recurrently overexpressed on the surface of cancer cells, likely in response to stimuli such as chemotherapy. Microparticles (MPs) released from cancer cells into the bloodstream express tumour markers on their surface that may be useful as predictive biomarkers for evaluating disease progression. The present study measured the level of TF/factor VII (FVII)-dependent coagulation of MPs isolated from the plasma of cancer patients with various tumours, who were undergoing chemotherapy. Furthermore, Pgp expression on the surface of MPs was evaluated by immunohistochemistry. A total of 50 cancer patients, as well as 10 healthy volunteers, were enrolled in the present study. MP-associated TF/FVII-dependent coagulation pathways were evaluated as the effect of an anti-FVII antibody on the time to thrombin generation, as compared with controls treated with saline. The significantly lengthened times of coagulation [obtained in 20/50 samples (36.5 ± 16%) after treatment with anti-FVIIa when compared with controls] suggest the presence of TF activity is associated with circulating MPs. Furthermore, the 20 MP/TF-positive samples were associated with Pgp overexpression on their surface. Conversely, in the remaining samples (n=30), treatment with the anti-FVIIa antibody did not significantly lengthen the time to clotting (<10%), and Pgp overexpression was not detected. In addition, in the control samples from healthy individuals, Pgp expression at the plasma membrane and clotting in the presence of the anti-FVII antibody were not observed, indicating the absence of MPs. The present study demonstrated that MPs in the blood of cancer patients promoted fibrin generation via TF/FVII-dependent pathways, thus suggesting that the evaluation of MP-TF activity may have a predictive value for Pgp-mediated MDR in various cancer types. Although further studies are required, the measurement of plasma MP-associated TF activity as a predictive biomarker may provide novel therapeutic perspectives to improve the prognosis and effectiveness of anti-cancer drugs in patients who are at a high-risk of Pgp-mediated MDR.

Effect of cigarette smoke on monocyte procoagulant activity: Focus on platelet-derived brain-derived neurotrophic factor (BDNF)

Cigarette smoke (CS) activates platelets, promotes vascular dysfunction, and enhances Tissue Factor (TF) expression in blood monocytes favoring pro-thrombotic states. Brain-derived neurotrophic factor (BDNF), a member of the family of neurotrophins involved in survival, growth, and maturation of neurons, is released by activated platelets (APLTs) and plays a role in the cardiovascular system. The effect of CS on circulating levels of BDNF is controversial and the function of circulating BDNF in atherothrombosis is not fully understood. Here, we have shown that human platelets, treated with an aqueous extract of CS (CSE), released BDNF in a dose-dependent manner. In addition, incubation of human monocytes with BDNF or with the supernatant of platelets activated with CSE increased TF activity by a Tropomyosin receptor kinase B (TrkB)-dependent mechanism. Finally, comparing serum and plasma samples of 12 male never smokers (NS) and 29 male active smokers (AS) we observed a significant increase in microparticle-associated TF activity (MP-TF) as well as BDNF in AS, while in serum, BDNF behaved oppositely. Taken together these findings suggest that platelet-derived BDNF is involved in the regulation of TF activity and that CS plays a role in this pathway by favoring a pro-atherothrombotic state.

Tissue factor-bearing microparticles and CA19.9: two players in pancreatic cancer-associated thrombosis?

Background:Cancer-related venous thromboembolism (VTE) heralds a poor prognosis, especially in pancreatic adenocarcinoma (PAC). Tissue factor (TF) is implicated as one of the main culprits in PAC-associated VTE and disease progression.Methods:In a prospective cohort study of 79 PAC patients, we measured plasma CA19–9 and microparticle-associated TF activity (MP-TF activity). In addition, we enumerated TF+MPs and MUC1+MPs in plasma (n=55), and studied the expression of TF, MUC1, CD31 and CD68 in tumour tissue (n=44).Results:Plasma MP-TF activity was markedly elevated in PAC patients with VTE compared with those without (median: 1925 vs 113 fM Xa min−1; P<0.001) and correlated with the extent of thromboembolic events, metastatic disease and short survival. Similar results were found for CA19–9. Patients with massively progressing thrombosis and cerebral embolisms despite anticoagulant therapy (n=3) had the highest MP-TF activities (12 118–40 188 fM Xa min−1) and CA19–9 (40 730–197 000 kU l−1). All tumours expressed MUC1 and TF. MP-TF activity did not correlate with intensity of TF expression in adenocarcinoma cells, but corresponded with numbers of TF+ macrophages in the surrounding stroma.Conclusions:Circulating TF+MPs and mucins may concertedly aggravate coagulopathy in PAC. Understanding of underlying mechanisms may result in new treatment strategies for VTE prevention and improvement of survival.

Particulate matter induces prothrombotic microparticle shedding by human mononuclear and endothelial cells

Particulate airborne pollution is associated with increased cardiopulmonary morbidity. Microparticles are extracellular vesicles shed by cells upon activation or apoptosis involved in physiological processes such as coagulation and inflammation, including airway inflammation. We investigated the hypothesis that particulate matter causes the shedding of microparticles by human mononuclear and endothelial cells.Cells, isolated from the blood and the umbilical cords of normal donors, were cultured in the presence of particulate from a standard reference. Microparticles were assessed in the supernatant as phosphatidylserine concentration. Microparticle-associated tissue factor was assessed by an one-stage clotting assay. Nanosight technology was used to evaluate microparticle size distribution.Particulate matter induces a dose- and time- dependent, rapid (1h) increase in microparticle generation in both cells. These microparticles express functional tissue factor. Particulate matter increases intracellular calcium concentration and phospholipase C inhibition reduces microparticle generation. Nanosight analysis confirmed that upon exposure to particulate matter both cells express particles with a size range consistent with the definition of microparticles (50–1000nm).Exposure of mononuclear and endothelial cells to particulate matter upregulates the generation of microparticles at least partially mediated by calcium mobilization. This observation might provide a further link between airborne pollution and cardiopulmonary morbidity.

Potent irreversible P2Y12 inhibition does not reduce LPS-induced coagulation activation in a randomized, double-blind, placebo-controlled trial.

Platelets play an important role in the activation of coagulation. P2Y12 receptor inhibition may be beneficial in inflammatory states. Prasugrel, a potent irreversible inhibitor of P2Y12 receptor-induced platelet activation may reduce activation of coagulation in a human LPS (lipopolysaccharide) model. A double-blind, randomized, crossover trial with a minimum washout period of 6weeks was performed. Sixteen subjects were randomly assigned to a treatment group that received prasugrel or placebo 2h before infusion of a bolus of LPS (2ng/kg of body weight), whereas four subjects were assigned to a control group receiving prasugrel or placebo without LPS. hcDNA (histone-complexed DNA), coagulation and platelet-specific parameters were measured by enzyme immunoassay. Leucocyte aggregate formation was analysed by flow cytometry, and thromboelastometry was performed. LPS infusion markedly activated coagulation. However, prasugrel did not reduce changes in prothrombin fragments 1 and 2 (F1+2), thrombin-antithrombin complexes, microparticle-associated tissue factor, CD40 ligand, P-selectin, platelet-leucocyte aggregation, hcDNA levels or the coagulation profile measured by thromboelastometry. hcDNA plasma levels increased approximately 6-fold after LPS infusion in both treatment groups, but not in the control groups. Potent irreversible P2Y12 inhibition by prasugrel does not affect LPS-induced coagulation activation. The 6-fold increased hcDNA plasma levels after infusion of LPS indicates the formation of neutrophil extracellular traps during sterile inflammation.

Fas-induced apoptosis increases hepatocyte tissue factor procoagulant activity in vitro and in vivo.

Hepatocyte (HPC) apoptosis occurs in association with hepatotoxic responses and chronic liver disease, and is coupled to activation of the blood coagulation cascade. HPCs have been shown to express tissue factor (TF), the primary activator of blood coagulation, in a form that lacks procoagulant activity. In this study, we determined the effect of inducing HPC apoptosis on the procoagulant activity of TF. Treatment of primary mouse HPCs with the Fas death receptor agonist (anti-CD95 antibody, Jo2) triggered apoptosis as shown by cleavage of caspase-3, increased caspase-3 proteolytic activity, and cell surface exposure of phosphatidylserine (PS). Jo2-induced apoptosis significantly increased TF-dependent factor Xa generation by HPCs. Moreover, Jo2 treatment was associated with increased levels of microparticle-associated TF procoagulant activity in the culture medium. Pretreatment with a caspase-3 inhibitor significantly reduced Jo2-induced HPC TF activity and prevented the increase in microparticle-associated TF procoagulant activity. Application of the high-affinity PS-binding protein lactadherin inhibited TF-dependent factor Xa generation by Jo2-treated HPCs and dramatically reduced microparticle-associated TF procoagulant activity. Treatment of wild-type mice with a sublethal dose of Jo2 was associated with a robust increase in the activation of coagulation as measured by plasma thrombin-antithrombin (TAT) levels; whereas mice with liver-specific TF deficiency had significantly lower TAT levels. Overall, the results indicate that Fas-initiated, caspase-3-dependent HPC apoptosis increases TF procoagulant activity through a mechanism involving PS externalization. This suggests that activation of liver TF likely contributes to the procoagulant state associated with HPC apoptosis in liver toxicity and disease.

Microparticle-associated tissue factor activity in patients with acute unprovoked deep vein thrombosis and during the course of one year

BackgroundTissue factor (TF) is the main in-vivo initiator of blood coagulation. Microparticles (MPs) are small procoagulant membrane vesicles. Elevated TF-bearing MPs have been found in different prothrombotic conditions and MP-associated TF activity may contribute to the pathogenesis of unprovoked deep vein thrombosis (DVT). ObjectiveTo determine MP-TF activity levels at diagnosis of DVT and at four additional time points during the course of one year in a well-defined group of patients with unprovoked DVT of the lower limb. Patients/MethodsIn this study, 41 patients with acute unilateral symptomatic and unprovoked DVT of the lower limb were included and followed for 1year. Venous blood samples for determination of MP-TF activity were drawn at diagnosis of acute DVT, and 1-, 3-, 6-, and 12months later. In addition, 10 young and healthy control subjects were included. ResultsThe median MP-TF activity was 0.06pg/mL (25th-75th percentile: 0.0-0.53) in patients with acute DVT and 0.18pg/mL (0.07-0.33) in healthy controls, and did not differ significantly (p=0.35). No significant changes in MP-TF activity were found in the follow-up measurements. MP-TF activity did also not differ significantly between patients with proximal- or distal DVT and between those with- or without residual DVT after 6months. ConclusionsMP-TF activity is low at the acute event in patients with unprovoked DVT of the lower limb and remains unchanged during the course of the disease. Our data do not support the hypothesis that TF-bearing MPs play a determining role in the pathogenesis of unprovoked DVT.

Procoagulant, tissue factor-bearing microparticles in bronchoalveolar lavage of interstitial lung disease patients: an observational study.

Coagulation factor Xa appears involved in the pathogenesis of pulmonary fibrosis. Through its interaction with protease activated receptor-1, this protease signals myofibroblast differentiation in lung fibroblasts. Although fibrogenic stimuli induce factor X synthesis by alveolar cells, the mechanisms of local posttranslational factor X activation are not fully understood. Cell-derived microparticles are submicron vesicles involved in different physiological processes, including blood coagulation; they potentially activate factor X due to the exposure on their outer membrane of both phosphatidylserine and tissue factor. We postulated a role for procoagulant microparticles in the pathogenesis of interstitial lung diseases. Nineteen patients with interstitial lung diseases and 11 controls were studied. All subjects underwent bronchoalveolar lavage; interstitial lung disease patients also underwent pulmonary function tests and high resolution CT scan. Microparticles were enumerated in the bronchoalveolar lavage fluid with a solid-phase assay based on thrombin generation. Microparticles were also tested for tissue factor activity. In vitro shedding of microparticles upon incubation with H2O2 was assessed in the human alveolar cell line, A549 and in normal bronchial epithelial cells. Tissue factor synthesis was quantitated by real-time PCR. Total microparticle number and microparticle-associated tissue factor activity were increased in interstitial lung disease patients compared to controls (84±8 vs. 39±3 nM phosphatidylserine; 293±37 vs. 105±21 arbitrary units of tissue factor activity; mean±SEM; p<.05 for both comparisons). Microparticle-bound tissue factor activity was inversely correlated with lung function as assessed by both diffusion capacity and forced vital capacity (r2 = .27 and .31, respectively; p<.05 for both correlations). Exposure of lung epithelial cells to H2O2 caused an increase in microparticle-bound tissue factor without affecting tissue factor mRNA.Procoagulant microparticles are increased in interstitial lung diseases and correlate with functional impairment. These structures might contribute to the activation of factor X and to the factor Xa-mediated fibrotic response in lung injury.

Clinical evidence for a link between microparticle-associated tissue factor activity and overt disseminated intravascular coagulation in patients with acute myelocytic leukemia

Microparticles (MPs) are small procoagulant membrane vesicles that are shed from cells when they are activated or undergo apoptosis [1]. Tissue factor (TF) is a transmembrane receptor and the main initiator of the blood coagulation cascade [2]. Highly elevated MP-associated TF activity was found in the blood of cancer patients with acute venous thromboembolism (VTE) [3–7].