Thrombin-antithrombin Complex Levels Research Articles

G6pdN126D Variant Increases the Risk of Developing VEGFR (Vascular Endothelial Growth Factor Receptor) Blocker-Induced Pulmonary Vascular Disease.

G6PD (glucose-6-phosphate-dehydrogenase) is a key enzyme in the glycolytic pathway and has been implicated in the pathogenesis of cancer and pulmonary hypertension-associated vascular remodeling. Here, we investigated the role of an X-linked G6pd mutation (N126D polymorphism), which is known to increase the risk of cardiovascular disease in individuals from sub-Saharan Africa and many others with African ancestry, in the pathogenesis of pulmonary hypertension induced by a vascular endothelial cell growth factor receptor blocker used for treating cancer. CRISPR-Cas9 genome editing was used to generate the G6pd variant (N126D; G6pdN126D) in rats. A single dose of the vascular endothelial cell growth factor receptor blocker sugen-5416 (SU; 20 mg/kg in DMSO), which is currently in a Phase 2/3 clinical trial for cancer treatment, was subcutaneously injected into G6pdN126D rats and their wild-type littermates. After 8 weeks of normoxic conditions, right ventricular pressure and hypertrophy, pulmonary artery remodeling, the metabolic profile, and cytokine expression were assessed. Right ventricular pressure and pulmonary arterial wall thickness were increased in G6PDN126D+SU/normoxic rats. Simultaneously, levels of oxidized glutathione, inositol triphosphate, and intracellular Ca2+ were increased in the lungs of G6PDN126D+SU/normoxic rats, whereas nitric oxide was decreased. Also increased in G6PDN126D+SU/normoxic rats were pulmonary levels of plasminogen activator inhibitor-1, thrombin-antithrombin complex, and expression of proinflammatory cytokines CCL3 (chemokine [C-C motif] ligand), CCL5, and CCL7. Our results suggest G6PDN126D increases inositol triphosphate-Ca2+ signaling, inflammation, thrombosis, and hypertrophic pulmonary artery remodeling in SU-treated rats. This suggests an increased risk of vascular endothelial cell growth factor receptor blocker-induced pulmonary hypertension in those carrying this G6PD variant.

Stable and Thin-Polymer-Based Modification of Neurovascular Stents with 2-Methacryloyloxyethyl Phosphorylcholine Polymer for Antithrombogenicity.

The advent of intracranial stents has revolutionized the endovascular treatment of cerebral aneurysms. The utilization of stents has rendered numerous cerebral aneurysm amenable to endovascular treatment, thereby obviating the need for otherwise invasive open surgical options. Stent placement has become a mainstream approach because of its safety and efficacy. However, further improvements are required for clinically approved devices to avoid the frequent occurrence of thrombotic complications. Therefore, controlling the thrombotic complications associated with the use of devices is of significant importance. Our group has developed a unique stent coated with a 2-methacryloyloxyethyl phosphorylcholine (MPC)-based polymer. In this study, the surface characteristics of the polymer coating were verified using X-ray photoelectron spectroscopy and atomic force microscopy. Subsequently, the antithrombotic properties of the coating were evaluated by measuring platelet count and thrombin-antithrombin complex levels of whole human blood after 3 h of incubation in a Chandler loop model. Scanning electron microscopy was utilized to examine thrombus formation on the stent surface. We observed that MPC polymer-coated stents significantly reduced thrombus formation as compared to bare stents and several clinically approved devices. Finally, the coated stents were further analyzed by implanting them in the internal thoracic arteries of pigs. Angiographic imaging and histopathological examinations that were performed one week after implantation revealed that the vascular lumen was well maintained and coated stents were integrated within the vascular endothelium without inducing adverse effects. Thus, we demonstrated the efficacy of MPC polymer coating as a viable strategy for avoiding the thrombotic risks associated with neurovascular stents.

Effects of dabigatran, rivaroxaban, and apixaban on fibrin network permeability, thrombin generation, and fibrinolysis

Introduction There are important pharmacological differences between direct oral anticoagulants (DOAC) and a deeper knowledge of how they influence different aspects of hemostasis in patients on treatment is desirable. Materials and methods Blood samples from patients on dabigatran (n = 23), rivaroxaban (n = 26), or apixaban (n = 20) were analyzed with a fibrin network permeability assay, a turbidimetric clotting and lysis assay, the calibrated automated thrombogram (CAT), plasma levels of thrombin-antithrombin complex (TAT) and D-dimer, as well as DOAC concentrations, PT-INR and aPTT. As a comparison, we also analyzed samples from 27 patients on treatment with warfarin. Results Patients on dabigatran had a more permeable fibrin network, longer lag time (CAT and turbidimetric assay), and lower levels of D-dimer in plasma, compared with patients on rivaroxaban- and apixaban treatment, and a more permeable fibrin network than patients on warfarin. Clot lysis time was slightly longer in patients on dabigatran than in patients on rivaroxaban. Warfarin patients formed a more permeable fibrin network than patients on apixaban, had longer lag time than patients on rivaroxaban (CAT assay), and lower peak thrombin and ETP compared to patients on treatment with both FXa-inhibitors. Conclusions Results from this study indicate dabigatran treatment is a more potent anticoagulant than apixaban and rivaroxaban. However, as these results are not supported by clinical data, they are probably more related to the assays used and highlight the difficulty of measuring and comparing the effect of anticoagulants.

Abstract 7652: Plasma markers of hemostasis, fibrinolysis, and angiogenesis prior to androgen deprivation therapy (ADT) in progressive prostate cancer (PC) and associations with long-term thrombotic events and survival

Abstract Background: PC is the third most common malignancy associated with thrombosis, procoagulants may play a role in tumorigenesis and progression, and patients (pts) with PC may have activation of the hemostatic system evident in plasma. The prognostic significance of these markers and their relationship to thrombotic events and overall survival (OS) are under-explored. Methods: Patients >18 years were included if they had progressive PC planned to start ADT, were >6 months from surgery or RT, with no history of prior VTE, unexplained bleeding, current or planned anticoagulation, or an additional active malignancy. Plasma samples were obtained via peripheral venipuncture in tubes containing 3.2% sodium citrate and immediately placed on ice. Samples were analyzed for D-dimer, thrombin-antithrombin complex (TAT), IL-6, IL-8, VEGF, and tissue factor (TF) levels by ELISA. Patients had markers drawn at baseline (prior to initiation of ADT), 1 month, and 6 months after initiation. Results: 40 patients were accrued with a median age of 68 years. At baseline, 29 (73%) had presence of metastases. Baseline median PSA was 15 and median PSA doubling time was 0.32. Baseline median hemoglobin was 13.85, platelets were 218, D-dimer was 322 ng/dL, IL-6 was 0 pg/mL, IL-8 was 0 pg/mL, TAT was 3 ug/L, VEGF was 21 pg/mL, and TF was 26 pg/mL. Median follow-up was 78 months. During follow up, 35 (87.5%) had metastases. 10 (25%) had thrombotic events (6 [15%] venous, 4 [10%] arterial) at median 37 months follow up. Median baseline age of pts with subsequent thrombotic events was 74, vs 67 in those without a thrombotic event. While there was no significant difference in baseline PSA between groups with and without clotting events, pretreatment PSA doubling time was significantly lower in pts with subsequent thrombosis (0.27 vs 0.35, p=0.047). Median baseline D-dimer and TF were higher in patients with subsequent thrombosis (D-dimer: 516 vs 282, p=0.10; TF: 36 vs 24, p=0.12). In univariate analysis, baseline IL-6 and VEGF were associated with OS (IL-6: HR=1.05, 95% CI [1.01,1.09], p=0.025; VEGF: HR=1.02, 95% CI [1.00,1.03], p=0.028). When controlling for presence of metastasis, baseline TAT was associated with OS (HR=1.05, 95% CI [1.00,1.11], p=0.055). Conclusions: Plasma markers of hemostatic activation, fibrinolysis, and angiogenesis prior to initiation of ADT are associated with subsequent thrombotic events and overall survival years later. Further analysis will examine how these markers change over time with hormonal therapy. Citation Format: Jessica S. Palmer, Charlene Thomas, Nicole Jacobs, David Nanus, Scott T. Tagawa. Plasma markers of hemostasis, fibrinolysis, and angiogenesis prior to androgen deprivation therapy (ADT) in progressive prostate cancer (PC) and associations with long-term thrombotic events and survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7652.

Role of microbiota-derived corisin in coagulation activation during SARS-CoV-2 infection

BackgroundCoagulopathy is a major cause of morbidity and mortality in COVID-19 patients. Hypercoagulability in COVID-19 results in deep vein thrombosis, thromboembolic complications, and diffuse intravascular coagulation. Microbiome dysbiosis influences the clinical course of COVID-19. However, the role of dysbiosis in COVID-19-associated coagulopathy is not fully understood. ObjectivesThe present study tested the hypothesis that the microbiota-derived proapoptotic corisin is involved in the coagulation system activation during SARS-CoV-2 infection. MethodsThis cross-sectional study included 47 consecutive patients who consulted for symptoms of COVID-19. A mouse acute lung injury model was used to recapitulate the clinical findings. A549 alveolar epithelial, THP-1, and human umbilical vein endothelial cells were used to evaluate procoagulant and anticoagulant activity of corisin. ResultsCOVID-19 patients showed significantly high circulating levels of corisin, thrombin-antithrombin complex, D-dimer, tumor necrosis factor-α, and monocyte-chemoattractant protein-1 with reduced levels of free protein S compared with healthy subjects. The levels of thrombin-antithrombin complex, D-dimer, and corisin were significantly correlated. A monoclonal anticorisin-neutralizing antibody significantly inhibited the inflammatory response and coagulation system activation in a SARS-CoV-2 spike protein-associated acute lung injury mouse model, and the levels of corisin and thrombin-antithrombin complex were significantly correlated. In an in vitro experiment, corisin increased the tissue factor activity and decreased the anticoagulant activity of thrombomodulin in epithelial, endothelial, and monocytic cells. ConclusionThe microbiota-derived corisin is significantly increased and correlated with activation of the coagulation system during SARS-CoV-2 infection, and corisin may directly increase the procoagulant activity in epithelial, endothelial, and monocytic cells.

Impact of Early Microparticle Release during Isolated Severe Traumatic Brain Injury: Correlation with Coagulopathy and Mortality.

Microparticles (MPs) have been implicated in thrombosis and endothelial dysfunction. Their involvement in early coagulopathy and in worsening of outcomes in isolated severe traumatic brain injury (sTBI) patients remains ill defined. We sought to quantify the circulatory MP subtypes derived from platelets (PMPs; CD42), endothelial cells (EMPs; CD62E), and those bearing tissue factor (TFMP; CD142) and analyze their correlation with early coagulopathy, thrombin generation, and in-hospital mortality. Prospective screening of sTBI patients was done. Blood samples were collected before blood and fluid transfusion. MP enumeration and characterization were performed using flow cytometry, and thrombin-antithrombin complex (TAT) levels were determined using enzyme-linked immunosorbent assay (ELISA). Circulating levels of procoagulant MPs were compared between isolated sTBI patients and age- and gender-matched healthy controls (HC). Patients were stratified according to their PMP, EMP, and TFMP levels, respectively (high ≥HC median and low < HC median). Isolated sTBI resulted in an increased generation of PMPs (456.6 [228-919] vs. 249.1 [198.9-404.5]; P = 0.01) and EMPs (301.5 [118.8-586.7] vs. 140.9 [124.9-286]; P = 0.09) compared to HCs. Also, 5.3% of MPs expressed TF (380 [301-710]) in HCs, compared to 6.6% MPs (484 [159-484]; P = 0.87) in isolated sTBI patients. Early TBI-associated coagulopathy (TBI-AC) was seen in 50 (41.6%) patients. PMP (380 [139-779] vs. 523.9 [334-927]; P = 0.19) and EMP (242 [86-483] vs. 344 [168-605]; P = 0.81) counts were low in patients with TBI-AC, compared to patients without TBI-AC. Our results suggest that enhanced cellular activation and procoagulant MP generation are predominant after isolated sTBI. TBI-AC was associated with low plasma PMPs count compared to the count in patients without TBI-AC. Low PMPs may be involved with the development of TBI-AC.

Immune Checkpoint Blockade Promotes Thrombosis Via T-Cell and Neutrophil Activation, and Tumor-Cell Associated Tissue Factor (TF) in a Murine Model of Colorectal Cancer

Background: Immune checkpoint blockade (ICB) is a paradigm shift in cancer therapy. Despite clinical benefit, various adverse events are associated with ICB using immune checkpoint inhibitors (ICI). Venous thrombosis is an emerging clinical problem in cancer patients receiving ICI. Little is known about how ICI promotes thrombosis in cancer. To define the underlying mechanisms of ICI-associated thrombosis (IAT), we assessed the ICI impact on blood hypercoagulability and tumor TF expression using a mouse thrombosis model of colorectal cancer. Methods: We developed a CT26 mouse thrombosis model with ICI (aPD-1+aCTLA4) administration. Systemic hypercoagulability was assessed by measurement of circulating nucleosomes (Nu.Q H3.1 Immunoassay), neutrophil extracellular traps (NETs) (CitH3 immunofluorescence), circulating neutrophil-platelet aggregates (immunophenotyping), and levels of thrombin-antithrombin (TAT) complexes in ICI-treated mice. Tumor-associated TF and TF activity in circulating extracellular vesicles (EV) were assessed by western blotting and Factor Xa generation assays. To gain mechanistic insights into TF induction by ICI, tumor cytokines were also profiled (proteome profiler array). The role of cancer cell-derived TF in IAT was determined using mice implanted with CRISPR/Cas9-mediated TF knockout (TFKO) CT26 tumor cells. Results: ICI treated tumor-bearing mice developed larger thrombi than control mice and demonstrated elevated levels of circulating nucleosomes (114 vs 82 ng/ml), NET (15.8 vs 6.8%), platelet-neutrophil aggregates (44.8 vs 22.3%), and TAT complexes (12.6 vs 7.9 ng/ml) compared to IgG-treated mice. Tumor TF expression was increased in tumor extracts. Cytokine profiling suggested enhanced production of IFNɣ (2-fold) and TNFα (5-fold), as well as CXCL11 (6.8-fold), an effector T cell-recruiting chemokine. IFNɣ-increased TF expression in cultured CT26 cells, suggesting that T-cell derived IFNɣ may play a role in enhancing tumor TF expression in vivo. Circulating EV TF antigen and procoagulant activity were increased by ICI. CRISPR/Cas9-mediated TF KO in CT26 cells resulted in complete loss of TF expression, and mice bearing these cells showed reduced tumor and EV-associated TF (Fig. A), associated with a significant decrease in thrombus formation after ICI treatment (24.2 vs 20.5 mg, Fig. B). There was no significant difference in growth of wild-type and TF KO CT26 tumors. Conclusions: Our findings provide insights into cellular and molecular mechanisms associated with ICI-induced thrombosis, and suggest a role for neutrophil and granulocyte activation, and tumor-associated TF. Additional studies are ongoing to further define these pathways in the murine model and in patients.

Validation of Townes As Mice As a Model of Chronic Kidney Disease and Venous Thrombosis Associated with Sickle Cell Trait

Individuals with sickle cell trait (SCT) are heterozygous carriers of the sickle beta-globin gene. Systematic analyses of large cohort studies over the past decade have established that SCT is a risk factor for a limited number of complications, most notably chronic kidney disease (CKD) and venous thrombosis (VT). SCT red blood cells (RBCs) can undergo sickling, although the degree and duration of hypoxia required to produce sickling are much greater than in sickle cell disease due to the lower intra-erythrocyte sickle hemoglobin beta (HbS) concentration of 25-45%. Hypoxia-mediated HbS polymerization can be enhanced by cellular dehydration, hyperosmolarity and/or acidosis that may be encountered in the renal inner medulla. Furthermore, prolonged exposure of SCT RBCs to profound hypoxia, such as in the nidus of a venous clot, will also result in sickling. The objective of this study was to determine if Townes AS mice manifest kidney dysfunction analogous to their SCT human counterparts. Furthermore, we evaluated whether VT was more pronounced in a well-described model of inferior vena cava (IVC) stasis. We used humanized male sickle cell trait (AS) and age-matched genetic control (AA) mice (n=7-16). Analysis of urinary renal biomarkers (albuminuria, proteinuria, kidney injury marker 1 (KIM-1), osmolality) and kidney function (transcutaneous measurement of glomerular filtration rate (GFR)) were conducted at 4-week intervals from 8 to 40 weeks of age. VT was induced by complete occlusion of the IVC in AA and AS mice. Sickling of RBCs was determined by histological and electron microscopy analysis of the IVC clot. Senicapoc, an oral Gardos channel inhibitor, was administered twice daily (20mg/kg, bid) for 2 weeks to prevent AS RBC dehydration and subsequent sickling. Human HbS accounts for 30.1% of total Hb expression in AS mice. Consistent with human SCT, peripheral blood counts did not differ from AA controls. Basal plasma thrombin-antithrombin complex levels were also not different between AA and AS mice. We performed a longitudinal study of renal structure and function in AA and AS mice over 40 weeks. At 8 weeks of age, AS mice exhibited no differences in any parameter compared to AA controls. However, AS mice subsequently developed albuminuria and a moderate but statistically significant increase in GFR (Figure 1). At 36 and 40 weeks of age, we observed progressive loss of kidney function demonstrated by statistically significant decreased GFR accompanied by a significant increase in albuminuria in AS mice (Figure 1). Over time, proteinuria gradually increased in AS mice, and had doubled by 40 weeks of age compared to AA controls (4.6 ±1.1 vs. 2.3 ±0.4 mg/24h, p&amp;lt;0.05). Increased levels of urinary KIM-1, a marker of tubular damage, were observed in AS mice throughout the duration of the study, with the highest levels at 16 weeks (228.3 ± 32.6 pg/24h vs. 53.8 ± 8.5 pg/24h, respectively, p˂0.05). Urine osmolality was not different at 8 weeks of age, but progressively declined in AS mice with statistically significant changes vs. controls starting at 24 weeks until the end of study (1946 ±63 vs. 2672 ±135 mOsm/kg at 40 weeks, p=0.002). Histologic analysis confirmed glomerular injury (congestion, glomerulosclerosis) and tubular injury (medullary congestion, interstitial fibrosis) in 40 week old AS mice. Following 24 hours of IVC stasis, thrombus weight was significantly increased (p&amp;lt;0.01) in AS mice (mean±SEM; 29.0 mg +/- 1.7; n=8) compared to AA controls (20.0 mg ± 1.7; n=7). Histologic and electron microscopic evaluation demonstrated that severe hypoxia (pO 2 ≈ 10 mm Hg) present in the nidus of venous thrombi was associated with extensive sickling of RBCs in AS mice. To determine if the enhancement of VT observed in AS mice was mediated by RBC sickling, mice were pretreated with Senicapoc or vehicle. Compared to vehicle-treated AS mice (27.3 mg ± 2.2 n=9) pre-treatment with Senicapoc significantly reduced (p&amp;lt;0.05) clot weight (18.1mg ± 1.1; n=7) to that observed in untreated AA controls. In aggregate, our data demonstrate that Townes AS murine nephropathy closely mimics the renal abnormalities (impaired urinary concentration and albuminuria with later onset loss of GFR) described in humans with SCT. Furthermore, we have established a mouse model of the venous thrombotic complications associated with SCT and have demonstrated that hypoxia-induced sickling of RBCs may contribute to enhanced VT observed in AS mice.

Accelerated arterial thrombus formation in Hutchinson Gilford Progeria Syndrome

Abstract Introduction Arterial thrombosis is an age-associated cause of myocardial infarction and stroke, which are the leading causes of mortality and morbidity worldwide. Hutchinson-Gilford Progeria Syndrome (HGPS) is a rare genetic disorder that is caused by a point mutation in the lamin A gene. It is characterized by progressive premature aging, in which caused a decreased life expectancy. Two most frequent causes of death of children with HGPS are myocardial infarction and ischemic stroke – cardiovascular events that are tightly linked to arterial thrombosis. Despite this fact, the effect of the specific lamin A gene mutation on arterial thrombus formation remains unknown. Methods Transgenic heterozygous LmnaG609G knock-in (HGPS) mice and the corresponding wild-type (WT) littermate controls underwent photochemically-induced carotid artery endothelial injury to trigger thrombosis. Coagulation and fibrinolytic factors were measured in these animals. Ex-vivo platelet activation assay was also performed. Results HGPS mice displayed accelerated thrombus formation as underlined by shortened time to occlusion compared to WT littermates (Figure 1A-B). The level of tissue factor and von Willebrand factors are comparable between groups. No significant differences were found on factors involved in the fibrinolytic system, which was confirmed by the comparable level of D-dimers in both groups. A higher level of thrombin-antithrombin complex was observed, accompanied by lower level of antithrombin. Interestingly, HGPS animals displayed enhanced platelet activation markers expression upon ADP, collagen, and thrombin stimulation compared to WT group, demonstrating a higher platelet reactivity in progeria animals (Figure 1C). Conclusions Our study demonstrated an increased arterial thrombotic response in HGPS mice as compared to WT littermates which is, at least in part, mediated by higher platelet reactivity. This novel observation may provide a mechanistic explanation for the increased incidence of acute cardiovascular events observed in children with HGPS and warrant further clinical investigations also in consideration of available antiplatelet therapies.

Qingjin Huatan decoction attenuates lipopolysaccharide-induced acute lung injury in mice by controlling platelet-associated formation of neutrophil extracellular traps

Abstract Background Acute lung injury (ALI) is a severe and life-threatening lung inflammation with high morbidity and mortality, underscoring the importance to develop effective drugs. Qingjin Huatan decoction (QJHTD), as a classic ancient prescription, has been widely used for treating respiratory diseases. However, the role and mechanism of QJHTD against ALI remain unclear. Objective This study aimed to explore the therapeutic effect of QJHTD on lipopolysaccharide (LPS)-induced ALI in mice and uncover its mechanism. Methods The therapeutic effect of QJHTD on LPS-induced ALI in mice was evaluated by the histopathological changes in the lung tissue, the lung wet/dry weight ratio, and the levels of inflammatory cytokines and thrombin-antithrombin complexes. Transcriptomics was used to predict the mechanism of QJHTD in treating ALI. The expression levels of citrullinated histone 3 in the lung tissue, the content of cell-free DNA in the bronchoalveolar lavage fluid (BALF), and the platelet-associated formation of neutrophil extracellular traps (NETs) in vitro were determined. Results Qingjin Huatan decoction exerted protective effect against LPS-induced ALI by suppressing interstitial edema, maintaining the alveolar-capillary barrier, inhibiting the infiltration of neutrophils and platelets in the lung tissue, and lowering the levels of tumor necrosis factor α, interleukin 1β, interleukin 6, and thrombin-antithrombin complexes in BALF. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis indicated that the formation of NETs was the main regulatory pathway for QJHTD against ALI. Qingjin Huatan decoction could treat ALI by inhibiting the release of NETs via reducing the content of citrullinated histone 3 in lung tissue and cell-free DNA in BALF in vivo, and suppressing the NETs formation induced by LPS-stimulated platelets under flow and static conditions in vitro. The formation of NETs was considered to bridge the interactions between neutrophils and platelets. Conclusions This research demonstrated the effects of QJHTD in treating ALI and provided new insights for clarifying the complex regulation of neutrophils, platelets, and NETs in ALI.

Tissue factor activates the coagulation cascade in mouse models of acute promyelocytic leukemia

AbstractAcute promyelocytic leukemia (APL) is associated with a high risk of bleeding and thrombosis. APL patients have an activated coagulation system, hyperfibrinolysis, and thrombocytopenia. APL cells express tissue factor (TF), a receptor and cofactor for factor VII/VIIa. This study had 2 goals. Firstly, we measured biomarkers of coagulation and fibrinolysis activation as well as platelet counts and bleeding in both mouse xenograft and allograft models of APL. Secondly, we determined the effect of inhibiting TF on the activation of coagulation in these models. We observed increased levels of plasma thrombin-antithrombin complexes (TAT), D-dimer, and plasmin-antiplasmin complexes, reduced platelet counts, and increased tail bleeding in both mouse models of APL. Fibrinogen levels decreased in the xenograft model but not in the allograft model. In contrast, the red blood cell count decreased in the allograft model but not in the xenograft model. Inhibition of APL-derived human TF with an anti-human TF monoclonal antibody reduced the level of TAT, increased platelet count, and normalized tail bleeding in a xenograft model. Inhibition of all sources of TF (APL cells and host cells) in the allograft model with a rat anti-mouse TF monoclonal antibody decreased the levels of TAT but did not affect the platelet count. Our study demonstrates that TF plays a central role in the activation of coagulation in both the xenograft and allograft mouse models of APL. These APL mouse models can be used to investigate the mechanisms of coagulopathy and thrombocytopenia in APL.

Serpin family proteins as potential biomarkers and therapeutic drugs in stroke: A systematic review and meta-analysis on clinical/preclinical studies.

Serpin is a superfamily of serine proteinase inhibitors. They have anticoagulative activities and immunoregulatory effects. The family has been widely studied in stroke patients and animal stroke models. However, results from clinical and preclinical studies are controversial. The systematic review and meta-analysis aimed to determine whether serpin activities are affected by stroke and whether members of the serpin family could be used in stroke treatment. Literature was systematically searched in six databases until September 5, 2022. In the included studies, 47 clinical studies (8276 subjects) reported concentrations of serpin proteins in stroke patients and healthy controls. In total, 41 preclinical studies (742 animals) reported neurological outcomes in animal models with serpin treatment and vehicle. Meta-analysis of clinical studies showed that both ischemic (IS) and hemorrhagic stroke patients had higher thrombin-antithrombin complex (TAT) levels and lower antithrombin (AT) levels which were persistent in the acute and subacute phase of IS. Meta-analysis of preclinical studies reported the efficacy of serpins in treating stroke. C1-INH and FUT175 reduced brain infarct size and improved sensorimotor and motor behavior in a dose- and time-dependent manner in the MCAO models. Our study confirmed the important roles serpin family proteins played in the onset, progression, and treatment of stroke. Among serpins, AT and TAT may be used as blood biomarkers in the early diagnosis of stroke. C1-INH and FUT175 could be potential medications for IS.

THE EFFECTS OF DNASE I AND LOW-MOLECULAR-WEIGHT HEPARIN IN A MURINE MODEL OF POLYMICROBIAL ABDOMINAL SEPSIS.

Introduction: Cell-free DNA (CFDNA) has emerged as a prognostic biomarker in patients with sepsis. Circulating CFDNA is hypothesized to be associated with histones in the form of nucleosomes. In vitro, DNA activates coagulation and inhibits fibrinolysis, whereas histones activate platelets and are cytotoxic to endothelial cells. Previous studies have targeted CFDNA or histones in animal models of sepsis using DNase I or heparins, respectively, which has reduced inflammatory and thrombosis markers, thereby improving survival. In this study, we explored the possibility that the combination of DNase I and a low-molecular weight heparin (LMWH) may be a better therapeutic approach than monotherapy in a murine model of abdominal sepsis. Methods: C57Bl/6 mice (8-12 weeks old, both sexes) were subjected to either cecal ligation and puncture or sham surgery. Mice were given antibiotics, fluids, and either saline, DNase I (intraperitoneally, 20 mg/kg/8 h), LMWH (dalteparin, subcutaneously 500 IU/kg/12 h), or a combination of both (n = 12-31). Mice were monitored over 72 h for survival. Organs and blood were harvested for analysis. Levels of LMWH, CFDNA, IL-6, citrullinated histone-H3, thrombin-antithrombin complexes, and protein C were measured in plasma. Results: Administration of either DNase I (81.8%) or LMWH (83.3%, prophylactic range of 0.12 ± 0.07 IU/mL achieved) improved the survival of septic mice compared with saline- (38.7%) and combination-treated mice (48.8%, P < 0.05). Combination-treated mice also showed a small but insignificant improvement in survival compared with saline-treated cecal ligation and puncture mice. Monotherapies may be improving survival by reducing blood bacterial loads, citrullinated histone-H3, and thrombin-antithrombin complexes, and improving protein C levels. Conclusions: Compared with saline- and combination-treated mice, administration of monotherapies to septic mice improved survival. These findings suggest that there may be a negative drug-drug interaction between DNase I and LMWH when DNase I is administered intraperitoneally in a murine model of polymicrobial abdominal sepsis.

Inflammation as an exacerbation marker and target for prophylaxis against Coronavirus Disease 2019-related thrombosis

Objectives: There are currently no appropriate markers and target for prophylaxis against COVID-19-related thrombosis, especially in the not-severe cases. We tested the hypothesis that inflammation is a suitable marker and target for prophylaxis against COVID-19-related thrombosis. Methods: Data of all 32 COVID-19 patients admitted to Saitama Medical Center between January 1 and March 30, 2021, were analyzed. Patients were divided into severe (requiring oxygen, n=12) and non-severe (no requirement for oxygen, n=20), and also those with high C-reactive protein (CRP) level (cutoff value: 30 mg/L, n=21) and low-CRP (n=11). We also compared the clinical and laboratory data of a 46-year-old post-liver transplant male patient, who was treated with a combination of immunosuppressants (methylprednisolone, fludrocortisone, cyclosporine, and everolimus) with those of other COVID-19 patients, using the Smirnoff-Grubbs and Box plots tests. Results: The levels of CRP, ferritin, lactate dehydrogenase, aspartate aminotransferase, and thrombin-antithrombin complex (TAT) were significantly higher in the high-severity group than the low-severity group; while other coagulation parameters were comparable. The time between onset of illness and blood levels of lactate dehydrogenase, fibrinogen, D-dimer, TAT, and plasmin alpha2-plasmin inhibitor complex (PIC) were significantly higher whereas lymphocyte count was significantly lower in the high-CRP group. Extremely low levels of TAT, PIC, and plasminogen activator inhibitor-1 (PAI-1) were recorded in the liver transplant patient treated with immunosuppressants. The TAT, PIC, and PAI-1 levels were deemed outliers. Conclusions: Inflammation is a potentially suitable marker and target for prophylaxis against COVID-19-related thrombosis.

Role of Nebulised Heparin as an Adjunct in Critically-ill COVID-19 Patients: A Randomised Controlled Trial

Introduction: Coronavirus Disease 2019 (COVID-19) is associated with an increased risk of Venous Thromboembolism (VTE) and coagulopathy. The available studies have shown the anticoagulant and mucolytic effects of nebulised heparin in non COVID-19 patients. Hence it was decided to conducted to study the efficacy of nebulised heparin in patients suffering from COVID-19 pneumonia requiring mechanical ventilation. Aim: To evaluate the safety and efficacy of nebulised heparin administered to patients with COVID-19. Materials and Methods: A double-blinded randomised controlled trial was conducted at Basaveshwara Medical College and Hospital in Chitradurga, Karnataka, India among 100 patients with COVID-19 who required mechanical ventilation from February 2021 to May 2021. They were randomly assigned to two equal groups of 50 patients each. One group received nebulised heparin, and the other group received a placebo. The patients were compared for baseline characteristics, coagulation characteristics, and Oxygen Saturation (SpO2 ). Data were analysed using Statistical Package for Social Sciences (SPSS) version 22.0, expressed as frequency and percentages, and displayed in tables and figures. The association between two variables was determined using the Chi-square test and paired t-test. Results: The two groups did not differ significantly in terms of age, sex, respiratory failure, vasopressin use, and severity score. Respiratory failure was present in 54% of the heparin group and 38% of the placebo group. Vasopressin was used in 64% of the heparin group and 56% of the placebo group. The severity score was 4.44 in the heparin group and 4.42 in the placebo group. Activated Partial Thromboplastin Time (APTT) levels did not differ significantly between the groups. None of these parameters showed significant differences between the heparin and placebo groups. However, both groups showed a significant difference in Thrombin Antithrombin (TAT) complex levels from baseline to follow-up (p&lt;0.05). D-Dimer levels decreased during follow-up, and Spo2 improved significantly in the nebulised heparin group compared to the placebo group. Conclusion: Nebulised heparin used as an adjunct in critically ill COVID-19 patients was shown to decrease TAT and D-Dimer levels. Nebulised heparin also significantly improved oxygenation levels. Importantly, heparin nebulisation was not associated with any adverse events, even when administered with systemic heparin.

Increased In Vivo Thrombin Generation in Patients with Localized Non-Small Cell Lung Cancer Unfit for Surgery.

Patients with lung cancer face a substantially increased risk of thromboembolic disease. Patients with localized non-small cell lung cancer (NSCLC) who are unfit for surgery due to age or comorbidity have additional thrombotic risk factors. Thus, we aimed to investigate markers of primary and secondary hemostasis, since this could assist in treatment decisions. We included 105 patients with localized NSCLC. Ex vivo thrombin generation was determined by calibrated automated thrombogram and in vivo thrombin generation was determined by measurement of thrombin-antithrombin complex (TAT) levels and prothrombin fragment F1 + 2 concentrations (F1 + 2). Platelet aggregation was investigated by impedance aggregometry. Healthy controls were used for comparison. TAT and F1 + 2 concentrations were significantly higher in NSCLC patients than in healthy controls (P < .001). The levels of ex vivo thrombin generation and platelet aggregation were not increased in the NSCLC patients. Patients with localized NSCLC considered unfit for surgery had significantly increased in vivo thrombin generation. This finding should be further investigated as it could be relevant for the choice of thromboprophylaxis in these patients.

In vitro Effect of Dalteparin and Argatroban on Hemostasis in Critically Ill Sepsis Patients with New-Onset Thrombocytopenia.

Thrombocytopenia is common among critically ill sepsis patients, while they also hold an increased risk for thromboembolic events. Thus, the choice of anticoagulant prophylaxis for this patient population is challenging. We investigated the in vitro effect of low-molecular-weight heparin (dalteparin) and direct thrombin inhibitor (argatroban) on the hemostasis in blood from sepsis patients with new-onset thrombocytopenia. Thrombocytopenia was defined as a platelet count drop of ≥30% and/or from >100 × 10 9 /L to 30 to 100 × 10 9 /L within 24 hours prior to inclusion. We included five healthy individuals and ten patients. Analyses of thrombin generation (Calibrated Automated Thrombogram), thrombin-antithrombin (TAT) complex levels, prothrombin fragment 1+2 (F1+2), and rotational thromboelastometry (ROTEM) were performed. Based on dose-response relationships investigated in healthy blood, patient samples were spiked with prophylactic (0.25 IU/mL) and therapeutic (0.75 IU/mL) dalteparin and low (0.25 µg/mL) and high (0.50 µg/mL) argatroban concentrations, each with a sample without anticoagulant. In patients, the endogenous thrombin potential was markedly lower in therapeutic dalteparin samples than in samples without anticoagulant [median (range): 29 (0-388) vs. 795 (98-2121) nM × min]. In high argatroban concentration samples, thrombin lag time was longer than in samples without anticoagulant [median (range): 15.5 (10.5-20.2) versus 5.3 (2.8-7.3) min]. Dalteparin and argatroban both increased clotting time but did not affect maximum clot firmness in the ROTEM INTEM assay. Six patients had elevated TAT and eight patients had elevated F1 + 2. In conclusion, dalteparin mainly affected the amount of thrombin generated and argatroban delayed clot initiation in critically ill sepsis patients with new-onset thrombocytopenia. Neither anticoagulant affected clot strength.

Hemostatic Profile at Diagnosis in Childhood Acute Lymphoblastic Leukemia: A Meta-Analysis of Cases from the Literature

Introduction Acute lymphoblastic leukemia (ALL) is the most common type of childhood cancer with, an incidence rate of 7.55 cases per 100,000 person-years for males aged 0-4 in the Canadian population. Thromboembolism (TE) is a well-recognized serious complication associated with ALL that results in significant morbidity and occasionally mortality. In patients with ALL, the reported incidence of symptomatic and asymptomatic TE is as high as 16% and 37%, respectively. At diagnosis, there is evidence of increased thrombin generation in children with ALL. Patients often present with a hypercoagulable state and this prothrombotic condition persists during the treatment period, indicating a possible interaction of the disease and therapy. Since the efficacy and safety of thromboprophylaxis during ALL treatment are still being explored, understanding the biology of the disease is crucial for defining the optimal strategy for prevention and management of ALL-associated thrombosis. In this study, we aim to explore a better understanding of how ALL affects the hemostatic balance. Due to the low incidence of leukemia, single-center studies are not adequately powered to detect significance. This meta-analysis was conducted to comprehensively evaluate the hemostatic profile at the time of diagnosis in pediatric ALL patients. Method PubMed database was searched on December 2021 with the following keywords: "acute lymphoblastic leukemia", "coagulation", "fibrinolysis" and "hemostatic." The inclusion criteria were: 1) study participants with childhood ALL, 2) hemostatic parameters were measured and reported at the time of diagnosis, 3) there is a comparator group of healthy subjects, and 4) there is no other reported comorbidities. Non-human studies, non-English articles and studies without healthy comparators were excluded. Data on coagulation profile at diagnosis were collected and meta-analyzed. The statistical method was random-effect inverse-variance weighting. The results were reported as mean difference with 95% confidence intervals (CIs) Result The initial search yielded 643 articles. Of these, 505 studies were excluded from title/abstract screening. The fulltexts of the remaining studies were screened, and 33 studies were included for the final analysis. D-dimer levels were elevated in the Leukemic group by 533.73 ng/ml [95% CIs: 283.1-782.35], p<0.01, n=216,193. Thrombin-antithrombin complex levels were also increased in the Leukemic group by 109.89 ug/L [95% CIs: 77.89-141.89], p<0.01, n=149,136. In addition, the levels of natural anticoagulants were reduced in the Leukemic group. Protein C activities were lower in the Leukemic group by 20.29% [95% CIs: 2.14-38.44], p<0.01, n=146,115. Protein S activities were lower in the Leukemic group by 29.11% [95% CIs: -1.28-59.5], p<0.01, n=146,115. Furthermore, markers of endothelial dysfunction were elevated in the Leukemic group. VWF levels were increased by 28.26% [95% CIs: -1.64-58.17], p<0.01, n=133,205 while tPA levels were reduced by 631.15 pg/ml [95% CIs: 296.22-966.09], p<0.01, n=122,80. Significance Children with ALL already present with hemostatic imbalance at diagnosis, favoring a hypercoagulable state. Interestingly, there has been little research on thrombin markers prior to chemotherapy in childhood ALL. The majority of data were extracted from prospective studies investigating the effect of therapy on thrombosis. Our study highlights significant differences from healthy control levels in D-dimer, Thrombin-antithrombin complex, protein C activity, protein S activity, VWF and tPA levels in children with ALL at diagnosis. Better tools of prediction would allow prospective identification of patients in whom prophylaxis might reduce the risk of thrombosis. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Parmodulin, an Allosteric Inhibitor of Protease Activated Receptor 1 (PAR1) Protects Sickle Cell Mice from Thromboinflammation and Endothelial Dysfunction

Protease activated receptor 1 (PAR1) couples the coagulation cascade to endothelial inflammation in many diseases, including sickle cell disease (SCD). PAR1 is a GPCR activated by proteolytic cleavage of an extracellular N-terminus, and demonstrates biased signaling. Activation of PAR1 by thrombin stimulates prothrombotic and proinflammatory signaling, whereas activation by activated protein C (APC) stimulates cytoprotective and anti-inflammatory pathways. The ideal PAR-1 targeted therapy would inhibit detrimental signaling while preserving beneficial signaling. 3K3A-APC is a signaling selective variant of APC that activates cytoprotective PAR1 signaling with minimal anticoagulant effects, demonstrated to have a beneficial role in stroke models. Parmodulin 2 (PM2) is a small molecule allosteric inhibitor of PAR1 that simultaneously blocks detrimental signaling and activate beneficial cytoprotective signaling similar to that induced by APC. We previously demonstrated that endogenous APC-PAR1 signaling contributes to thrombin generation and inflammation in a mouse model of SCD, whereas thrombin-PAR signaling enhances these pathways. We hypothesize that inducing cytoprotective PAR1 signaling with either 3K3A-APC and PM2 will reduce thrombo-inflammation in sickle cell mice at steady state. Townes wild type (HbAA) and sickle (HbSS) mice (male and female, 4 months old) were used in the studies. In the first experiment, HbAA and HbSS (n=4-5 per group) mice were treated daily with either saline (SAL) or 3K3A-APC (0.2mg/kg, BW) for 4 days. Samples were collected 1 hour after final dose. As previously demonstrated, plasma levels of thrombin-anti thrombin (TAT) complexes, the proinflammatory cytokine IL-6, high mobility group box 1 (HMGB1), and, soluble vascular cell adhesion molecule (sVCAM), were increased in HbSS mice compared to HbAA controls. Surprisingly 3K3A-APC treatment did reduce any of these parameters in HbSS mice. APC and its variant 3K3A-APC require binding to the endothelial protein C receptor (EPCR) to activate PAR1; it is known that SCD causes increased EPCR shedding. Indeed, we found that both SAL- and 3K3A-APC treated HbSS mice had elevated sEPCR levels compared to HbAA controls. Together, these data indicate that 3K3A-APC does not affect thrombo-inflammation in HbSS mice at steady state most likely due to by reduced ECPR expression on the endothelium. In the second experiment, HbAA and HbSS (male and female, 4 months old) mice (n=8-11 per group) were treated with vehicle (20% DMSO, 20% PEG800, 60% PBS) or PM2 (10 mg/kg, BW) every other day for 1 week. The last dose was administered on the 8th day 1 hour prior to collecting plasma samples. As expected, HbSS mice had elevated plasma TAT levels compared to HbAA mice (11.04 ± 1.4 vs 45.19 ± 6.3, p<0.05) which was significantly attenuated by PM2 treatment in SS mice (16.17 ± 2, p<0.05). Similar results were observed for IL-6 (AA: 2.06 ± 0.7 vs SS: 29.12 ± 9.6 vs SS+PM2: 5.83 ± 2.9; p<0.05); sVCAM (AA: 330.6 ± 31.5 vs SS: 571.4 ± 50.4 vs SS+PM2: 403.3 ± 41.22; p<0.05) and HMGB1 (AA: 11.46 ± 1.1 vs SS: 25.37 ± 1.5 vs SS+PM2: 19.12 ± 1.7; p<0.05). PM2 had no effect on markers of anemia in HbSS mice including RBC, hematocrit, and reticulocyte counts. In the present study ,3K3A-APC did not attenuate thrombin generation and cytokine production in HbSS mice; this might be due to the shedding of EPCR which is important co-receptor for the protective APC-PAR1 signaling. In contrast, PM2-mediated allosteric inhibition of thrombin/PAR1 and simultaneous induction of APC-like cytoprotective signaling attenuated levels of TAT, IL-6, HMGB1, and sVCAM in HbSS mice. Future studies towards evaluating the effect of PM2 on downstream targets of PAR1 signaling in sickle mice will provide more insight into the mechanism of this protective effect.

The Role of Fibrin-Related Markers in Disseminated Intravascular Coagulation Due to Sepsis

Sepsis leads to local and systemic activation of different response systems, including coagulation and fibrinolysis. An overwhelming inflammatory response may lead to organ failure, and the coagulation and fibrinolysis involvement may lead to Disseminated Intravascular Coagulation (DIC). Special regard is given to the diagnosis of DIC by the use of scoring systems, which are, APACHE II, SAPS II, International Society of Thrombosis and Hemostasis (ISTH), and Japanese Ministry of Health and Welfare (JMHW). A large variety of fibrin compounds can be detected in plasma from septic patients with intravascular coagulation activation. Coagulation activation is indicated by elevated plasma levels of D-dimer, prothrombin fragments, and Thrombin-Antithrombin (TAT) complexes. Fibrin-Related Markers (FRMs) identified in sepsis are D-dimer, fibrinogen, Soluble Fibrin Monomer (SFM), and Fibrin Degradation Products (FDP). Hemostatic molecular markers, such as TAT, Plasmin-Plasmin Inhibitor Complex (PPIC), D-dimer, and SFM are better for the diagnosis of pre-DIC. No single biomarker of sepsis may be ideal, but many are helpful in terms of at least identifying critically ill patients who need more careful monitoring. As each biomarker has limited sensitivity and specificity, it may be interesting to combine several biomarkers. The purpose of this literature review was to increase knowledge about laboratory tests of FRMs and provide current knowledge and insight into these biomarkers related to DIC-sepsis. The method used in this literature review was a traditional review. Search, identify, and select relevant literature on PubMed–CBI and Google Scholar based on keywords, 30 journals were obtained from the two search engines.