Tissue Factor Pathway Inhibitor Research Articles

A new look at TFPI inhibition of factor X activation.

Blood coagulation is a vital physiological process involving a complex network of biochemical reactions, which converge to form a blood clot that repairs vascular injury. This process unfolds in three phases: initiation, amplification, and propagation, ultimately leading to thrombin formation. Coagulation begins when tissue factor (TF) is exposed on an injured vessel's wall. The first step is when activated factor VII (VIIa) in the plasma binds to TF, forming complex TF:VIIa, which activates factor X. Activated factor X (Xa) is necessary for coagulation, so the regulation of its activation is crucial. Tissue Factor Pathway Inhibitor (TFPI) is a critical regulator of the initiation phase as it inhibits the activation of factor X. While previous studies have proposed two pathways-direct and indirect binding-for TFPI's inhibitory role, the specific biochemical reactions and their rates remain ambiguous. Many existing mathematical models only assume an indirect pathway, which may be less effective under physiological flow conditions. In this study, we revisit datasets from two experiments focused on activated factor X formation in the presence of TFPI. We employ an adaptive Metropolis method for parameter estimation to reinvestigate a previously proposed biochemical scheme and corresponding rates for both inhibition pathways. Our findings show that both pathways are essential to replicate the static experimental results. Previous studies have suggested that flow itself makes a significant contribution to the inhibition of factor X activation. We added flow to this model with our estimated parameters to determine the contribution of the two inhibition pathways under these conditions. We found that direct binding of TFPI is necessary for inhibition under flow. The indirect pathway has a weaker inhibitory effect due to removal of solution phase inhibitory complexes by flow.

Coagulopathy and acute pancreatitis: pathophysiology and clinical treatment.

Coagulopathy is a critical pathophysiological mechanism of acute pancreatitis (AP), arising from the complex interplay between innate immune, endothelial cells and platelets. Although initially beneficial for the host, uncontrolled and systemic activation of coagulation cascade in AP can lead to thrombotic and hemorrhagic complications, ranging from subclinical abnormalities in coagulation tests to severe clinical manifestations, such as disseminated intravascular coagulation. Initiation of coagulation activation and consequent thrombin generation is caused by expression of tissue factor on activated monocytes and is ineffectually offset by tissue factor pathway inhibitor. At the same time, endothelial-associated anticoagulant pathways, in particular the protein C system, is impaired by pro-inflammatory cytokines. Also, fibrin removal is severely obstructed by inactivation of the endogenous fibrinolytic system, mainly as a result of upregulation of its principal inhibitor, plasminogen activator inhibitor type 1. Finally, increased fibrin generation and impaired break down lead to deposition of (micro) vascular clots, which may contribute to tissue ischemia and ensuing organ dysfunction. Despite the high burden of coagulopathy that have a negative impact on AP patients' prognosis, there is no effective treatment yet. Although a variety of anticoagulants drugs have been evaluated in clinical trials, their beneficial effects are inconsistent, and they are also characterized by hemorrhagic complications. Future studies are called to unravel the pathophysiologic mechanisms involved in coagulopathy in AP, and to test novel therapeutics block coagulopathy in AP.

Plasma proteome and incident myocardial infarction: sex-specific differences.

Few population-based cohort studies, including both men and women, have explored circulating proteins associated with incident myocardial infarction (MI). This study investigated the relationships between circulating cardiometabolic-related proteins and MI risk using cohort-based and Mendelian randomization (MR) analyses and explored potential sex-specific differences. The discovery cohort included 11 751 Swedish adults (55-93 years). Data on 259 proteins assessed with Olink proximity extension assays, biochemical, and questionnaire-based information were used. Participants were followed up for incident MI and death over 8 years through linkage to Swedish registers. Replication analyses were conducted on the UK Biobank sample (n = 51 613). In MR analyses, index cis-genetic variants strongly related to the proteins were used as instrumental variables. Genetic association summary statistic data for MI were obtained from the CARDIoGRAMplusC4D consortium and FinnGen. Forty-five proteins were associated with incident MI in discovery and replication samples following adjustment for potential confounders and multiple testing. In the secondary analysis, 13 of the protein associations were sex-specific, with most associations identified among women. In MR analysis, genetically predicted higher levels of renin, follistatin, and retinoic acid receptor responder protein 2 were linked to an increased risk of MI. Tissue factor pathway inhibitor, tumor necrosis factor receptors 1 and 2, placenta growth factor had an inverse association with MI. This study identified both new and confirmed previously established associations between circulating proteins and incident MI and, for the first time, suggested sex-specific patterns in multiple protein-MI associations.

Multifocal osteonecrosis due to the synergistic impact of inherited thrombophilia, autoimmunity and pregnancy: a case report.

Multifocal osteonecrosis is a rare entity which can lead to bone fragility, fractures and considerable morbidity. The objective of this report is to describe the presentation, evaluation and management of a case of multifocal osteonecrosis. A 34-year-old lady presented with multiple fractures and bone pain which was exacerbated during pregnancy. She was found to have osteonecrosis involving multiple sites. Investigation revealed that she had an undefined autoimmune condition with antinuclear antibody and anti-Ro (SS-A) positivity, not fulfilling criteria for diagnosis of Sjogren syndrome. She had low Protein S levels for age and gender (confirmed on 2 occasions 12 weeks apart outside pregnancy). She had a novel variant in the PROS1 gene (NM_000313.4:c.1513G>A; p.Gly505Ser) which is associated with heterozygous Protein S (PS) deficiency. She had a good response to treatment with anticoagulation. The combination of inherited thrombophilia, autoimmunity and the thrombophilic state induced by pregnancy probably contributed to the severe phenotype in this patient. The variant was identified in the Lamin G1 domain, which is instrumental in PS binding to tissue factor pathway inhibitor and C4 binding protein, thus playing a role in both the coagulation and complement pathway, and could explain the coexistence of autoimmunity with thrombophilia. This variant is present in 0.034% of South Asians in the gnomAD population database, and may represent an important cause of inherited thrombophilia in this group.

Extracellular vesicle tissue factor and tissue factor pathway inhibitor are independent discriminators of sepsis-induced coagulopathy

BackgroundSepsis-induced disseminated intravascular coagulopathy (DIC) remains a challenging clinical entity associated with significant morbidity and mortality. Endothelial injury or activation and extracellular vesicles (EV) are postulated as important determinants of DIC. However, there is limited research available which specifically tests the discriminatory ability of these characteristics in sepsis-induced coagulopathy. MethodsIn this prospective, single-centre study we collected plasma samples within 24 hours after sepsis diagnosis and followed these patients for five consecutive days. Overt DIC was determined by the ISTH-DIC score. 87 sepsis patients were recruited (35 with overt DIC) and presented with increased levels of EV, EV-associated TF activity (TF-PCA), E-selectin, TF and TFPI at admission compared to healthy subjects. ResultsOnly TFPI levels and TF-PCA discriminated between sepsis patients with or without DIC (AUC 0.76, p = 0.0002). Increased TF-PCA was not sensitive in detecting sepsis-associated DIC, however levels above 1.38 pg/mL showed a high specificity in this cohort (sensitivity 27%, specificity 95%). The hazard ratio to progress to DIC over five days was 1.14 (95% CI 0.64 – 2.07) for TF-PCA levels of 0.5 pg/mL or higher and 3.18 (95% CI 1.74 – 5.79) for TFPI levels of 22.28 ng/mL or higher at admission. ConclusionThese findings highlight the critical balance between pro- and anticoagulant factors, especially the pivotal roles of TF-PCA and TFPI in an early phase of sepsis-induced DIC. Only EV-associated and functionally active TF and not TF antigen levels showed a predictive potential regarding DIC. These novel results might support the improvement of diagnostic or even therapeutic strategies to mitigate the devastating consequences of DIC in septic patients.

Inhibition of the AP-1/TFPI2 axis contributes to alleviating cerebral ischemia/reperfusion injury by improving blood-brain barrier integrity.

Reperfusion after cerebral ischemia leads to secondary damage to the nervous system, called cerebral ischemia/reperfusion injury (CIRI). The blood-brain barrier (BBB) consists of endothelial cells and tight junction (TJ) proteins, and its disruption aggravates CIRI. Two GSE datasets identified Tissue Factor Pathway Inhibitor 2 (TFPI2) as a differentially upregulated gene (Log2FC > 1, p < 0.01) in the cerebral cortex of ischemic rats, and TFPI2 affects angiogenesis of endothelial cells. Moreover, genes (c-Jun, c-Fos, FosL1) encoding subunits of Activator Protein-1 (AP-1), a transcription factor involved in IRI, were highly expressed in ischemic samples. Thus, the effects of the AP-1/TFPI2 axis on CIRI were explored. We determined increased TFPI2 expression in the cerebral cortex of rats receiving middle cerebral artery occlusion (MCAO) for 90min and reperfusion (R) for 48h. Then AAV2-shTFPI2 particles (5 × 1010 vg) were injected into the right lateral ventricle of rats 3weeks before MCAO/R. TFPI2 knockdown decreased infarct size and neuronal injury in ischemic rats. It improved BBB integrity, demonstrated by reduced FITC-dextran leakage in brain tissues of MCAO/R-operated rats. Furthermore, it increased the expression of TJ proteins (Occludin, Claudin-5, TJP-1) in the cerebral cortex of rats with CIRI. Consistently, we found that TFPI2 knockdown mitigated cell damage in mouse endothelial bEND.3 cells with oxygen and glucose deprivation (ODG) for 6h and reoxygenation (R) for 18h (OGD/R) treatment. High co-expression of c-Jun and c-Fos significantly elevated TFPI2 promoter activity. c-Jun knockdown inhibited TFPI2 expression in OGD/R-treated bEND.3 cell. Collectively, our findings demonstrate that inhibition of the AP-1/TFPI2 axis alleviates CIRI.

Mathematical modeling identifies clotting factor combinations that modify thrombin generation in normal and factor VIII-, IX-, or XI-deficient blood

BackgroundIn healthy individuals, plasma levels of clotting proteins naturally vary within a range of 50% to 150% of their mean values. We do not know how these variations modify thrombin generation. ObjectivesTo assess the impact of protein level variations on simulated thrombin generation in normal and factor (F)VIII-, FIX-, or FXI-deficient blood. MethodsWe used a mathematical model of flow-mediated coagulation to simulate thrombin generation with all possible combinations of clotting protein variations within the normal range and for various tissue factor levels. We selected, analyzed, and ranked combinations that enhanced thrombin generation compared with baseline. ResultsProtein variations most strongly affected thrombin generation at intermediate tissue factor levels. Low tissue factor levels prevented coagulation initiation, while high tissue factor levels always triggered thrombin generation. At intermediate levels, we identified protein variations that substantially modified thrombin generation. Low-normal FV shortened lag times and increased thrombin generation, whereas high-normal FV lengthened lag times and reduced thrombin generation. With severe FVIII and FIX deficiencies, low-normal tissue factor pathway inhibitor α and antithrombin amplified the effect of low-normal FV. For moderate FVIII and FIX deficiencies, high-normal tissue factor pathway inhibitor α and antithrombin enhanced the impact of high-normal FV in reducing thrombin production. In normal and FXI-deficient blood, high-normal FVIII and FIX significantly boosted thrombin generation. ConclusionOur mathematical model predicted how variations in clotting protein levels, within the normal range, could contribute to the variability of bleeding phenotypes observed with clotting factor deficiencies. Our study generated experimentally testable hypotheses that could aid in developing new therapies toward normal hemostasis.

Unfolded von Willebrand factor binds protein S and reduces anticoagulant activity

AbstractThe critical plasma anticoagulant protein S (PS) circulates in 2 functionally distinct pools: free (anticoagulant) or bound to complement component 4b-binding protein (C4BP; anti-inflammatory). Acquired free PS deficiency is detected in several viral infections, but its cause is unclear. Here, we used biochemical approaches and human patient plasma samples to identify an interaction between PS and von Willebrand factor (VWF), which causes free PS deficiency and reduced PS anticoagulant activity. We first identified a shear-dependent interaction between PS and VWF by mass spectrometry. Consistently, PS and VWF could be crosslinked together in plasma, and plasma PS and VWF comigrated in gel electrophoresis. The PS/VWF interaction was blocked by and tissue factor pathway inhibitor but not activated protein C, suggesting an interaction with the sex hormone binding globulin region of PS. Microfluidic systems demonstrated that PS stably binds VWF because VWF unfolds under turbulent flow. PS/VWF complexes also localized to platelet thrombi under laminar arterial flow. In thrombin generation–based assays, shearing plasma decreased PS activity, an effect not seen in the absence of VWF. Finally, free PS deficiency in patients with COVID-19 correlated with changes in VWF, but not C4BP, and with thrombin generation. Our data indicate that PS binds to a shear-exposed site on VWF, thus sequestering free PS and decreasing its anticoagulant activity, which would account for the increased thrombin generation potential. Because many viral infections present with free PS deficiency, elevated circulating VWF, and increased vascular shear, we propose that the PS/VWF interaction reported here is a likely contributor to virus-associated thrombotic risk.

Tissue factor pathway inhibitor 2 as a serum biomarker for endometrial cancer: a single-center retrospective study

BackgroundEndometrial cancer is the most common gynecological malignancy; however, there is no useful blood diagnostic biomarker. This study aimed to determine the utility of tissue factor pathway inhibitor 2 (TFPI2), a biomarker of ovarian cancer, as a diagnostic marker for endometrial cancer.MethodsWe examined serum TFPI2 levels in patients with endometrial cancer (n = 328) compared to those in healthy controls (n = 65) and evaluated the performance of serum TFPI2 levels as a diagnostic marker. We investigated the clinicopathological characteristics of patients with TFPI2-negative and TFPI2-positive endometrial cancer. Using immunohistochemistry (IHC), we examined TFPI2 expression in tumor tissues of 105 patients with type II endometrial carcinoma and evaluated the correlation between serum and tissue TFPI2 positivity.ResultsPatients with endometrial cancer had significantly higher serum TFPI2 levels than controls (196.7 pg/mL vs. 83.3 pg/mL; p < 0.001). The sensitivity and specificity were 54.3% and 95.4%, respectively (cutoff value, 191 pg/mL). Serum TFPI2 levels were significantly elevated along with the stage progression (stage I, 189.6 pg/mL; stage III, 230.9 pg/mL; stage IV, 312.5 pg/mL; p < 0.001). Patients with high-risk histology showed significantly elevated serum TFPI2 levels than those with low-risk histology (220.8 pg/mL vs. 187.7 pg/mL; p < 0.001). The positivity rate for TFPI2 was the highest among tumor markers, including CA125, CA19-9, and CEA. Serum TFPI2 and CA125 levels were almost independent (r = 0.203, p < 0.001), and the combined sensitivity increased to 58.8%. The 5-year survival rate was significantly worse in TFPI2-positive patients (≥ 191 pg/mL, n = 178) than in TFPI2-negative patients (< 191 pg/mL, n = 150) (hazard ratio, 8.22; 95% confidence interval, 2.49–27.1; p < 0.001). TFPI2 immunostaining revealed that 37.1% (39/105) of the samples were positive for TFPI2, with an IHC score of > 0. There was no significant difference in the immunostaining score according to histological type. Serum TFPI2 levels and immunostaining score showed poor agreement (kappa coefficient, -0.039).ConclusionsThe serum TFPI2 level is a promising marker for diagnosing and predicting the prognosis of endometrial cancer. No correlation exists between serum and tissue TFPI2 levels. Further multicenter clinical trials are needed to test the utility of TFPI2 as a diagnostic marker.

Tissue factor pathway inhibitor - cofactor-dependent regulation of the initiation of coagulation.

In humans, tissue factor pathway inhibitor (TFPI) exists in two alternatively spliced isoforms, TFPIα and TFPIβ. TFPIα consists of three Kunitz domains (K1, K2 and K3) and a highly basic C-terminal tail. K1 inhibits the tissue factor-activated factor VII complex, K2 specifically inhibits activated factor X, K3 is essential for interaction with its cofactor, protein S, and the basic C-terminus is binds factor V-short (FV-short) with high affinity. TFPIβ consists of K1 and K2 that is glycosylphosphatidylinositol anchored directly to cell surfaces. This review explores the structure/function of TFPI and its cofactors (protein S and FV-short), and the relative contributions that different TFPI isoforms may play in haemostatic control. Recent data have underscored the importance of TFPIα function and its reliance on its cofactors, protein S and FV-short, in influencing haemostatic control as well as bleeding and thrombotic risk. TFPIα is likely the most important pool of TFPI in modifying the risk of thrombosis and bleeding. TFPIα forms a trimolecular complex with FV-short and protein S in plasma. FV-short expression levels control the circulating levels of TFPIα, whereas protein S exerts essential cofactor mediated augmentation of it anticoagulant function.

Restoration of TFPI2 by LSD1 inhibition suppresses tumor progression and potentiates antitumor immunity in breast cancer

Histone lysine-specific demethylase 1 (LSD1) is frequently overexpressed in triple negative breast cancer (TNBC), which is associated with worse clinical outcome in TNBC patients. However, the underlying mechanisms by which LSD1 promotes TNBC progression remain to be identified. We recently established a genetically engineered murine model by crossing mammary gland conditional LSD1 knockout mice with Brca1-deficient mice to explore the role of LSD1 in TNBC pathogenesis. Cre-mediated Brca1 loss led to higher incidence of tumor formation in mouse mammary glands, which was hindered by concurrent depletion of LSD1, indicating a critical role of LSD1 in promoting Brca1-deficient tumors. We also demonstrated that the silencing of a tumor suppressor gene, Tissue Factor Pathway Inhibitor 2 (TFPI2), is functionally associated with LSD1-mediated TNBC progression. Mouse Brca1-deficient tumors exhibited elevated LSD1 expression and decreased TFPI2 level compared to normal mammary tissues. Analysis of TCGA database revealed that TFPI2 expression is significantly lower in aggressive ER-negative or basal-like BC. Restoration of TFPI2 through LSD1 inhibition increased H3K4me2 enrichment at the TFPI2 promoter, suppressed tumor progression, and enhanced antitumor efficacy of chemotherapeutic agent. Induction of TFPI2 by LSD1 ablation downregulates activity of matrix metalloproteinases (MMPs) that in turn increases the level of cytotoxic T lymphocyte attracting chemokines in tumor environment, leading to enhanced tumor infiltration of CD8+ T cells. Moreover, induction of TFPI2 potentiates antitumor effect of LSD1 inhibitor and immune checkpoint blockade in poorly immunogenic TNBC. Together, our study identifies previously unrecognized roles of TFPI2 in LSD1-mediated TNBC progression, therapeutic response, and immunogenic effects.

Activated platelets retain and protect most of their factor XIII-A cargo from proteolytic activation and degradation

AbstractPlatelet factor XIII-A (FXIII-A) is a major cytoplasmic protein (∼3% of total), representing ∼50% of total circulating FXIII. However, mobilization of FXIII-A during platelet activation is not well defined. To determine mechanisms mediating the retention vs release of platelet FXIII-A, platelets from healthy humans and mice (F13a1−/−, Fga−/−, Plg−/−, Stim1fl/flPf4-Cre, and respective controls) were stimulated with thrombin, convulxin plus thrombin, or calcium ionophore (A23187), in the absence or presence of inhibitors of transglutaminase activity, messenger RNA (mRNA) translation, microtubule rearrangement, calpain, and Rho GTPase. Platelet releasates and pellets were separated by (ultra)centrifugation. FXIII-A was detected by immunoblotting and immunofluorescence microscopy. Even after strong dual agonist (convulxin plus thrombin) stimulation of human platelets, >80% platelet FXIII-A remained associated with the platelet pellet. In contrast, essentially all tissue factor pathway inhibitor, another cytoplasmic protein in platelets, was released to the supernatant. Pellet-associated FXIII-A was not due to de novo synthesis via platelet F13A1 mRNA. The proportion of platelet FXIII-A retained by vs released from activated platelets was partly dependent on STIM1 signaling, microtubule rearrangement, calpain, and RhoA activation but did not depend on the presence of fibrinogen or plasminogen. Immunofluorescence microscopy confirmed the presence of considerable FXIII-A within the activated platelets. Although released FXIII-A was cleaved to FXIII-A∗ and could be degraded by plasmin, platelet-associated FXIII-A remained uncleaved. Retention of substantial platelet-derived FXIII-A by activated platelets and its reduced susceptibility to thrombin- and plasmin-mediated proteolysis suggest platelet FXIII-A is a protected pool with biological role(s) that differs from plasma FXIII.

Plasma microRNA Environment Linked to Tissue Factor Pathway and Cancer-Associated Thrombosis: Prognostic Significance in Ovarian Cancer.

Ovarian cancer (OC) is a leading cause of death among gynaecological malignancies. The haemostatic system, which controls blood flow and prevents clotting disorders, paradoxically drives OC progression while increasing the risk of venous thromboembolism (VTE). MicroRNAs (miRNAs) have emerged as crucial in understanding VTE pathogenesis. Exploring the connection between cancer and thrombosis through these RNAs could lead to novel biomarkers of cancer-associated thrombosis (CAT) and OC, as well as potential therapeutic targets for tumour management. Thus, this study examined the impact of eight plasma miRNAs targeting the tissue factor (TF) coagulation pathway-miR-18a-5p, -19a-3p, -20a-5p, -23a-3p, -27a-3p, -103a-3p, -126-5p and -616-3p-in 55 OC patients. Briefly, VTE occurrence post-OC diagnosis was linked to shorter disease progression time (log-rank test, p = 0.024) and poorer overall survival (OS) (log-rank test, p < 0.001). High pre-chemotherapy levels of miR-20a-5p (targeting coagulation factor 3 (F3) and tissue factor pathway inhibitor 2 (TFPI2)) and miR-616-3p (targeting TFPI2) predicted VTE after OC diagnosis (χ2, p < 0.05). Regarding patients' prognosis regardless of VTE, miR-20a-5p independently predicted OC progression (adjusted hazard ratio (aHR) = 6.13, p = 0.005), while miR-616-3p significantly impacted patients' survival (aHR = 3.72, p = 0.020). Further investigation is warranted for their translation into clinical practice.

MEK1/2- and ERK1/2-Mediated Lung Endothelial Injury and Altered Hemostasis Promote Diffuse Alveolar Hemorrhage in Murine Lupus.

About 3% of patients with lupus develop severe diffuse alveolar hemorrhage (DAH) with pulmonary vasculitis. C57BL/6 (B6) mice with pristane-induced lupus also develop DAH, but BALB/c mice are resistant. DAH is independent of Toll-like receptor signaling and other inflammatory pathways. This study examined the role of the MEK1/2 pathway (MEK1/2-ERK1/2, JNK, p38). B6 and BALB/c mice were treated with pristane with or without inhibitors of MEK1/2 (trametinib/GSK1120212 [GSK]), ERK1/2 (SCH772984 [SCH]), JNK, or p38. Effects on lung hemorrhage and hemostasis were determined. GSK and SCH abolished DAH, whereas JNK and p38 inhibitors were ineffective. Apoptotic cells were present in lung samples from pristane-treated mice but not in mice receiving pristane and GSK, and endothelial dysfunction was normalized. Expression of the ERK1/2-regulated transcription factor early growth response 1 increased in pristane-treated B6, but not BALB/c, mice and was normalized by GSK. Pristane also increased expression of the anticoagulant genes Tfpi and Thbd in B6 mice. The ratio of Tfpi to tissue factor (F3) to Tfpi increased in B6 (but not BALB/c) mice and was normalized by GSK. Circulating thrombomodulin protein levels increased in B6 mice and returned to normal after GSK treatment. Consistent with augmented endothelial anticoagulant activity, pristane treatment increased tail bleeding in B6 mice. Pristane treatment promotes lung endothelial injury and DAH in B6 mice by activating the MEK1/2-ERK1/2 pathway and impairing hemostasis. The hereditary factors determining susceptibility to lung injury and bleeding in pristane-induced lupus are relevant to the pathophysiology of life-threatening DAH in systemic lupus erythematosus and may help to optimize therapy.

Circadian misalignment disrupts biomarkers of cardiovascular disease risk and promotes a hypercoagulable state.

The circadian system regulates 24-h time-of-day patterns of cardiovascular physiology, with circadian misalignment resulting in adverse cardiovascular risk. Although many proteins in the coagulation-fibrinolysis axis show 24-h time-of-day patterns, it is not understood if these temporal patterns are regulated by circadian or behavioral (e.g., sleep and food intake) cycles, or how circadian misalignment influences these patterns. Thus, we utilized a night shiftwork protocol to analyze circadian versus behavioral cycle regulation of 238 plasma proteins linked to cardiovascular physiology. Six healthy men aged 26.2±5.6 years (mean ± SD) completed the protocol involving two baseline days with 8-h nighttime sleep opportunities (circadian alignment), a transition to shiftwork day, followed by 2days of simulated night shiftwork with 8-h daytime sleep opportunities (circadian misalignment). Plasma was collected for proteomics every 4h across 24 h during baseline and during daytime sleep and the second night shift. Cosinor analyses identified proteins with circadian or behavioral cycle-regulated 24-h time-of-day patterns. Five proteins were circadian regulated (plasminogen activator inhibitor-1, angiopoietin-2, insulin-like growth factor binding protein-4, follistatin-related protein-3, and endoplasmic reticulum resident protein-29). No cardiovascular-related proteins showed regulation by behavioral cycles. Within the coagulation pathway, circadian misalignment decreased tissue factor pathway inhibitor, increased tissue factor, and induced a 24-h time-of-day pattern in coagulation factor VII (all FDR <0.10). Such changes in protein abundance are consistent with changes observed in hypercoagulable states. Our analyses identify circadian regulation of proteins involved in cardiovascular physiology and indicate that acute circadian misalignment could promote a hypercoagulable state, possibly contributing to elevated cardiovascular disease risk among shift workers.

Future directions for xenotransplantation in lungs.

Advancements in preclinical xenotransplant studies have opened doors for clinical heart and kidney xenotransplantation. This review assesses recent progress in lung xenotransplantation research and its potential clinical implications. The efficacy of the humanized von Willebrand factor in reducing platelet sequestration in ex-vivo and in-vivo lung xenotransplant models was showcased. Combining human tissue factor pathway inhibitor and CD47 expression with selectin and integrin inhibition delayed neutrophil and platelet sequestration. Enhanced expression of human complement regulatory proteins and thrombomodulin in genetically engineered pig lungs improved graft survival by reducing platelet activation and modulating coagulation disruptions. Knocking out the CMAH gene decreased antibody-mediated inflammation and coagulation activation, enhancing compatibility for human transplantation. Furthermore, CMAH gene knockout in pigs attenuated sialoadhesin-dependent binding of human erythrocytes to porcine macrophages, mitigating erythrocyte sequestration and anemia. Meanwhile, in-vivo experiments demonstrated extended survival of xenografts for up to 31 days with multiple genetic modifications and comprehensive treatment strategies. Experiments have uncovered vital insights for successful xenotransplantation, driving further research into immunosuppressive therapy and genetically modified pigs. This will ultimately pave the way for clinical trials designed to improve outcomes for patients with end-stage lung disease.

Dual Role of Tissue Factor Pathway Inhibitor 2—A Novel Serodiagnostic Marker for Ovarian Cancer—In Human Cancers

Dual Role of Tissue Factor Pathway Inhibitor 2—A Novel Serodiagnostic Marker for Ovarian Cancer—In Human Cancers

Associations of tissue factor and tissue factor pathway inhibitor with organ dysfunctions in septic shock

Coagulopathy, microvascular alterations and concomitant organ dysfunctions are hallmarks of sepsis. Attempts to attenuate coagulation activation with an inhibitor of tissue factor (TF), i.e. tissue factor pathway inhibitor (TFPI), revealed no survival benefit in a heterogenous group of sepsis patients, but a potential survival benefit in patients with an international normalized ratio (INR) < 1.2. Since an increased TF/TFPI ratio determines the procoagulant activity specifically on microvascular endothelial cells in vitro, we investigated whether TF/TFPI ratio in blood is associated with INR alterations, organ dysfunctions, disseminated intravascular coagulation (DIC) and outcome in septic shock. Twenty-nine healthy controls (HC) and 89 patients with septic shock admitted to a tertiary ICU were analyzed. TF and TFPI in blood was analyzed and related to organ dysfunctions, DIC and mortality. Patients with septic shock had 1.6-fold higher levels of TF and 2.9-fold higher levels of TFPI than HC. TF/TFPI ratio was lower in septic shock compared to HC (0.003 (0.002–0.005) vs. 0.006 (0.005–0.008), p < 0.001). Non-survivors had higher TFPI levels compared to survivors (43038 (29354–54023) vs. 28041 (21675–46582) pg/ml, p = 0.011). High TFPI levels were associated with acute kidney injury, liver dysfunction, DIC and disease severity. There was a positive association between TF/TFPI ratio and troponin T (b = 0.531 (0.309–0.754), p < 0.001). A high TF/TFPI ratio is exclusively associated with myocardial injury but not with other organ dysfunctions. Systemic TFPI levels seem to reflect disease severity. These findings point towards a pathophysiologic role of TF/TFPI in sepsis-induced myocardial injury.

Deletion of tissue factor pathway inhibitor isoform beta or gamma, but not alpha, improves clotting in hemophilic mice

BackgroundTissue factor pathway inhibitor (TFPI) regulates tissue factor–triggered coagulation. Humans and mice express transcripts encoding for multidistributed (endothelial, platelet, and plasma) 3-Kunitz domain TFPIα and endothelial membrane–anchored 2-Kunitz TFPIβ. Mice express a third transcript, γ, that encodes plasma lipoprotein–associated 2-Kunitz TFPI. In humans, proteolysis of α and/or β produces plasma lipoprotein–associated 2-Kunitz TFPI at lower levels. In clinical trials, monoclonal antibodies that target all TFPI isoforms extend coagulation and correct bleeding in hemophilic patients but with some thrombosis risks. ObjectivesTo determine the impact of TFPI isoform-specific deletions on promoting clotting in hemophilic mice. MethodsEngineered TFPI isoform–specific, hemophilic (factor VIII-null) mice were evaluated for clotting. ResultsMice expressing any single TFPI isoform were healthy. Thrombin generation assays identified TFPIγ as the dominant anticoagulation isoform in mouse plasma. Hemostasis was assessed by serial bleeding times from a tail vein laceration. Repeatedly, after a clot forms, it was manually disrupted; the number of clots/disruptions occurring over a 15-minute period were reported. C57BL/6 and hemophilic mice clot on average 25.6 vs 5.4 times, respectively. On a hemophilia background, TFPIβ or TFPIγ-specific deletion improved clotting to 14.6 and 15.2 times, respectively (P < .0001). TFPIα-specific deletion was without impact, clotting 5.1 times. Heterozygous deletion of TFPIβ was effective, clotting 11.8 times (P < .0001). Heterozygous deletion of TFPIα or TFPIγ alone was ineffective, clotting 3.0 and 6.1 times, respectively, but heterozygous TFPIαγ deletion improved clotting to 11.2 times (P < .001). ConclusionIn hemophilic mice, endothelial TFPIβ and plasma γ-derived 2-Kunitz TFPI individually contribute more to bleeding than total TFPIα.

Lethal pulmonary thromboembolism in mice induced by intravenous human umbilical cord mesenchymal stem cell-derived large extracellular vesicles in a dose- and tissue factor-dependent manner.

Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have obvious advantages over MSC therapy. But the strong procoagulant properties of MSC-EVs pose a potential risk of thromboembolism, an issue that remains insufficiently explored. In this study, we systematically investigated the procoagulant activity of large EVs derived from human umbilical cord MSCs (UC-EVs) both in vitro and in vivo. UC-EVs were isolated from cell culture supernatants. Mice were injected with UC-EVs (0.125, 0.25, 0.5, 1, 2, 4 μg/g body weight) in 100 μL PBS via the tail vein. Behavior and mortality were monitored for 30 min after injection. We showed that these UC-EVs activated coagulation in a dose- and tissue factor-dependent manner. UC-EVs-induced coagulation in vitro could be inhibited by addition of tissue factor pathway inhibitor. Notably, intravenous administration of high doses of the UC-EVs (1 μg/g body weight or higher) led to rapid mortality due to multiple thrombus formations in lung tissue, platelets, and fibrinogen depletion, and prolonged prothrombin and activated partial thromboplastin times. Importantly, we demonstrated that pulmonary thromboembolism induced by the UC-EVs could be prevented by either reducing the infusion rate or by pre-injection of heparin, a known anticoagulant. In conclusion, this study elucidates the procoagulant characteristics and mechanisms of large UC-EVs, details the associated coagulation risk during intravenous delivery, sets a safe upper limit for intravenous dose, and offers effective strategies to prevent such mortal risks when high doses of large UC-EVs are needed for optimal therapeutic effects, with implications for the development and application of large UC-EV-based as well as other MSC-EV-based therapies.