Soluble thrombomodulin activity and soluble thrombomodulin antigen in plasma

Plasma thrombomodulin as a candidate biomarker for the diagnosis and prognosis of HBV-related acute-on-chronic liver failure

Background and Aim

Hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) is a complicated syndrome with high short-term mortality. Effective biomarkers are required for its early diagnosis and prognosis. This study aimed to determine the diagnostic and prognostic value of thrombomodulin (TM) in patients with HBV-ACLF.

Methods

The expression of TM during disease progression was evaluated through transcriptomics analysis. The plasma TM concentrations of 393 subjects with HBV-ACLF (n=213), acute-on-chronic hepatic dysfunction (ACHD, n=50), liver cirrhosis (LC, n=50) or chronic hepatitis B (CHB, n=50), and normal controls (NC, n=30) from a prospective multicenter cohort, were measured to verify the diagnostic and prognostic significance of plasma TM for HBV-ACLF patients by enzyme-linked immunosorbent assay (ELISA).

Results

TM mRNA was highly expressed in the HBV-ACLF group compared with the ACHD group (AUROC=0.710). High expression of TM predicted poor prognosis for HBV-ACLF patients at 28/90 days (AUROCs=0.823/0.788). Functional analysis showed that TM was significantly associated with complement activation and the inflammatory signaling pathway. External validation confirmed its high diagnostic accuracy for HBV-ACLF patients (AUROC=0.796). Plasma TM concentrations were correlated with organ failure, including coagulation and kidney failure. Plasma TM concentrations showed a potential prognostic value for 28-day mortality rates (AUROC=0.702). Risk stratification specifically identified HBV-ACLF patients with a high risk of death as having a plasma TM concentration of ≥8.4 ng/mL.

Conclusion

This study reveals that the plasma TM can be a candidate biomarker for early diagnosis and prognosis of HBV-ACLF, and might play a vital role in coagulation and inflammation.

THE NEUROENDOTHELIAL AXIS IN TRAUMATIC BRAIN INJURY: MECHANISMS OF MULTIORGAN DYSFUNCTION, NOVEL THERAPIES, AND FUTURE DIRECTIONS

ABSTRACT

Severe traumatic brain injury (TBI) often initiates a systemic inflammatory response syndrome, which can potentially culminate into multiorgan dysfunction. A central player in this cascade is endotheliopathy, caused by perturbations in homeostatic mechanisms governed by endothelial cells due to injury-induced coagulopathy, heightened sympathoadrenal response, complement activation, and proinflammatory cytokine release. Unique to TBI is the potential disruption of the blood-brain barrier, which may expose neuronal antigens to the peripheral immune system and permit neuroinflammatory mediators to enter systemic circulation, propagating endotheliopathy systemically. This review aims to provide comprehensive insights into the "neuroendothelial axis" underlying endothelial dysfunction after TBI, identify potential diagnostic and prognostic biomarkers, and explore therapeutic strategies targeting these interactions, with the ultimate goal of improving patient outcomes after severe TBI.

Clinical Biomarkers of Acute Vaso-Occlusive Sickle Cell Crisis

It is known that an inherited blood condition called sickle cell disease (SCD) is a result of one gene. A number of blood and urine biomarkers have been determined in association with lab and clinical history for SCD patients. SCD has numerous interacting pathways associated with it, which have been identified by biomarkers. These mechanisms consist of some examples, such as endothelial vasodilation response, hypercoagulability, hemolysis, inflammation, oxidative stress, vascular dysfunction, and reperfusion injury among others. To effectively manage SCD, a comprehensive panel of validated blood and urine biomarkers must be established. Despite its monogenic inheritance, the complex nature of the SCD phenotype has impeded progress in its treatment. However, significant strides have been made in clinical biotechnology, paving the way for potential breakthroughs. In SCD, a panel of verified blood and urine biomarkers must be established, however. Despite monogenic inheritance, the great complexity of the SCD phenotype has hindered progress in its management. With few exceptions, clinical biomarkers of illness severity have been found through epidemiological investigations; nevertheless, systematic integration of these biomarkers into clinical treatment algorithms has not occurred. Furthermore, sickle cell crisis, the primary acute consequence of SCD, has been difficult to diagnose with the biomarkers now in use. Inadequate care and a lack of appropriate outcome measures for clinical research are the consequences of these diagnostic constraints. A new chapter in SCD customized treatment has begun with recent advancements in molecular and imaging diagnostics. Strategies in precision medicine are especially relevant now that molecular therapies are within reach. The significance of biochemical indicators linked to clinical manifestation and sub-phenotype identification in SCD is reviewed in this research.

Promising results of a clinical feasibility study: CIRBP as a potential biomarker in pediatric cardiac surgery

Objective

Cold-inducible RNA binding Protein (CIRBP) has been shown to be a potent inflammatory mediator and could serve as a novel biomarker for inflammation. Systemic inflammatory response syndrome (SIRS) and capillary leak syndrome (CLS) are frequent complications after pediatric cardiac surgery increasing morbidity, therefore early diagnosis and therapy is crucial. As CIRBP serum levels have not been analyzed in a pediatric population, we conducted a clinical feasibility establishing a customized magnetic bead panel analyzing CIRBP in pediatric patients undergoing cardiac surgery.

Methods

A prospective hypothesis generating observational clinical study was conducted at the German Heart Center Berlin during a period of 9 months starting in May 2020 (DRKS00020885, https://drks.de/search/de/trial/DRKS00020885). Serum samples were obtained before the cardiac operation, upon arrival at the pediatric intensive care unit, 6 and 24 h after the operation in patients up to 18 years of age with congenital heart disease (CHD). Customized multiplex magnetic bead-based immunoassay panels were developed to analyze CIRBP, Interleukin-1β (IL-1β), Interleukin-6 (IL-6), Interleukin-8 (IL-8), Interleukin-10 (IL-10), Monocyte chemotactic protein 1 (MCP-1), Syndecan-1 (SDC-1), Thrombomodulin (TM), Vascular endothelial growth factor (VEGF-A), Angiopoietin-2 (Ang-2), and Fibroblast growth factor 23 (FGF-23) in 25 µl serum using the Luminex MagPix® system.

Results

19 patients representing a broad range of CHD (10 male patients, median age 2 years, 9 female patients, median age 3 years) were included in the feasibility study. CIRBP was detectable in the whole patient cohort. Relative to individual baseline values, CIRBP concentrations increased 6 h after operation and returned to baseline levels over time. IL-6, IL-8, IL-10, and MCP-1 concentrations were significantly increased after operation and except for MCP-1 concentrations stayed upregulated over time. SDC-1, TM, Ang-2, as well as FGF-23 concentrations were also significantly increased, whereas VEGF-A concentration was significantly decreased after surgery.

Discussion

Using customized magnetic bead panels, we were able to detect CIRBP in a minimal serum volume (25 µl) in all enrolled patients. To our knowledge this is the first clinical study to assess CIRBP serum concentrations in a pediatric population.

Complement and coagulation crosstalk - Factor H in the spotlight

The immune complement and the coagulation systems are blood-based proteolytic cascades that are activated by pathway-specific triggers, based on protein-protein interactions and enzymatic cleavage reactions. Activation of these systems is finely balanced and controlled through specific regulatory mechanisms. The complement and coagulation systems are generally viewed as distinct, but have common evolutionary origins, and several interactions between these homologous systems have been reported. This complement and coagulation crosstalk can affect activation, amplification and regulatory functions in both systems. In this review, we summarize the literature on coagulation factors contributing to complement alternative pathway activation and regulation and highlight molecular interactions of the complement alternative pathway regulator factor H with several coagulation factors. We propose a mechanism where factor H interactions with coagulation factors may contribute to both complement and coagulation activation and regulation within the haemostatic system and fibrin clot microenvironment and introduce the emerging role of factor H as a modulator of coagulation. Finally, we discuss the potential impact of these protein interactions in diseases associated with factor H dysregulation or deficiency as well as evidence of coagulation dysfunction.

Endotheliopathy in Acute COVID-19 and Long COVID

The pulmonary endothelium is a highly regulated organ that performs a wide range of functions under physiological and pathological conditions. Since endothelial dysfunction has been demonstrated to play a direct role in sepsis and acute respiratory distress syndrome, its role in COVID-19 has also been extensively investigated. Indeed, apart from the COVID-19-associated coagulopathy biomarkers, new biomarkers were recognised early during the pandemic, including markers of endothelial cell activation or injury. We systematically searched the literature up to 10 March 2023 for studies examining the association between acute and long COVID-19 severity and outcomes and endothelial biomarkers.

Endothelial dysfunction markers and immune response indices in cosmonauts' blood after long-duration space flights

Space flight factors are known to cause a malfunction in the human immune system and lead to damage to blood vessels. The hemostatic function of endothelium during space missions and its interaction with human immunity has not been determined so far. In this work, we investigated the markers of endothelial activation and damage (plasma concentrations of soluble thrombomodulin fraction (sTM), von Willebrand factor (vWF), highly sensitive C-reactive protein (hs-CRP)), as well as the level of D-dimer and compared them to the immunological parameters characterizing the state of human humoral and cellular immunity. The immune status of long-duration ISS crewmembers was assessed by whole-blood testing, and comprehensive postflight immune assessment included the analysis of leukocyte distribution. Flow cytometry was applied to determine the absolute counts and the percentage of lymphocyte subsets: B cells (CD19⁺), T cells (CD3⁺, CD3⁺CD4⁺, CD3⁺CD8⁺), NK cells (CD3^-CD16⁺CD56⁺, CD11b⁺CD56⁺), and activated subsets (CD3⁺CD25⁺ and CD3⁺HLA-DR⁺). The in vitro basal cytokine production was investigated in whole blood cell culture. The cytokines IFN-gamma, IL-1-beta, IL-4, IL-6, IL-10, IL-18, and TNF-alpha were measured in plasma and the 24-h supernatants by a sensitive enzyme-linked immunosorbent assay. A significant increase in the plasma levels of vWF and hs-CRP and a decrease in the concentration of sTM after spaceflights were detected. Divergent changes in the parameters characterizing the state of the immune system were observed. We propose that the changes revealed may lead to an increase in the procoagulant activity of blood plasma, suppression of protein C activation and thrombin inhibition, as well as to an increase in the adhesive-aggregate potential of platelets, especially in case of changes in the rheological characteristics of blood flow during re-adaptation to ground conditions. We also speculate that the immune system might play an important role in vessel damage during long-duration missions.

High plasma soluble thrombomodulin levels indicated poor prognosis of decompensated liver cirrhosis: a prospective cohort study

OBJECTIVE

Hepatic sinusoidal endothelial injury is a prominent characteristic of liver cirrhosis. We determined plasma soluble thrombomodulin (sTM) levels in cirrhosis patients to evaluate the relationship between vascular injury and long-term prognosis.

METHODS

A prospective single-center study was performed. The participants were followed up for every 6 months or until death or transplantation. A chemiluminescent enzyme immunoassay was used to establish a baseline sTM.

RESULTS

Among the 219 patients with decompensated liver cirrhosis, 53.42% were caused by hepatitis B and hepatitis C. Plasma sTM levels were much higher in cirrhosis than in healthy controls and increased parallel with Child-Pugh classification ( P < 0.01) and the amount of ascites ( P = 0.04). After adjusting for sex, age, international normalized ratio, bilirubin, and other potential factors, multivariate Cox regression revealed that per TU/ml elevation of plasma sTM causes an increase of 8% in mortality, and per-SD elevation of thrombomodulin causes a 53% increase in mortality. As the mortality rates in low (5.90-12.60 TU/ml) and medium (12.70-18.00 TU/ml) sTM levels were similar, so we chose the cutoff of 18.00 TU/ml to divide into two groups, and K-M analysis indicated that patients with sTM >18.0 TU/ml demonstrated an additional 2.01 times death risk (95% CI, 1.13-7.93; P = 0.01) than those with sTM ≤18.0 TU/ml.

CONCLUSION

Plasma sTM in cirrhosis was significantly increased in parallel with the severity of liver dysfunction. sTM elevation than 18 TU/ml indicated a poor prognosis of decompensated liver cirrhosis.

Downregulation of thrombomodulin-thrombin-activated protein C pathway as a mechanism for SARS-CoV-2 induced endotheliopathy and microvascular thrombosis

There is emerging evidence of microvascular thrombosis and thrombotic microangiopathy (TMA) induced by COVID-19, presumably from endothelial injury. Thrombomodulin (TM) is an endothelial glycoprotein that plays a dual role in maintaining healthy endothelium-as a natural anticoagulant by binding thrombin to activate protein C (APC) and a negative regulator of the alternate complement pathway (AP). TM is shed into the plasma as soluble TM (sTM) during endothelial injury. We hypothesize that SARS-CoV-2 spike proteins cause direct microvascular endothelial injury, leading to TM shedding, decreased activation of PC, and consequently, microvascular thrombosis in COVID-19. We conducted this study twofold: 1) in vivo, we assessed endothelial injury (by measuring sTM) and AP activation by quantifying Ba (cleavage product of AP component Factor B) in a cohort of critically ill COVID-19 pediatric patients and the implications on clinical outcomes; and 2)in vitro, we investigated endothelial injury (TM shedding) by SARS-COV-2 spike proteins and the subsequent functional consequence in activated PC (APC) levels and Ba levels. sTM and Ba in plasma samples from SARS-CoV-2 positive patients admitted to Texas Children's Hospital Pediatric Intensive Care Unit (n = 33) and from healthy controls (n = 38) were measured by ELISA. In vitro, confluent glomerular microvascular endothelial cells (GMVECs) were incubated for 48 h in the presence or absence (control) of purified SARS-CoV-2 spike proteins, S1 and S2. TM from the cell lysates while Ba and APC from the cell supernatants were measured by ELISA. sTM and Ba levels were significantly higher in the COVID-19 pediatric patients compared to healthy controls (p < 0.01 and p < 0.001, respectively). Among the COVID-19 patients, elevated sTM was associated with increased vasopressor use (p = 0.01) and elevated Ba was associated with increased duration of mechanical ventilation (p = 0.04). In vitro, surface bound TM and soluble APC were significantly lower in GMVECs after addition of spike proteins (p < 0.05), while Ba was undetectable in both control and spike proteins exposed GMVECs. In conclusion, we provide evidence of endothelial injury in COVID-19 pediatric patients and demonstrate a potential pathway of SARS-CoV-2 induced thrombosis. Decreased surface-bound TM results in lower amount of thrombin-TM complex, hence lesser activation of PC, likely leading to a pro-thrombotic state. These findings in GMVECs could explain the vulnerability of kidneys to COVID-19-induced TMA.

Circulating Thrombomodulin: Release Mechanisms, Measurements, and Levels in Diseases and Medical Procedures

Thrombomodulin (TM) is a type-I transmembrane protein that is mainly expressed on endothelial cells and plays important roles in many biological processes. Circulating TM of different forms are also present in biofluids, such as blood and urine. Soluble TM (sTM), comprised of several domains of TM, is the major circulating TM which is generated by either enzymatic or chemical cleavage of the intact protein under different conditions. Under normal conditions, sTM is present in low concentrations (<10 ng/mL) in the blood but is elevated in several pathological conditions associated with endothelial dysfunction such as cardiovascular, inflammatory, infection, and metabolic diseases. Therefore, sTM level has been examined for monitoring disease development, such as disseminated intravascular coagulation (DIC), sepsis and multiple organ dysfunction syndrome in patients with novel coronavirus disease 2019 (COVID-19) recently. In addition, microvesicles (MVs) that contain membrane TM (MV-TM) have been found to be released from activated cells which also contribute to levels of circulating TM in certain diseases. Several release mechanisms of sTM and MV-TM have been reported, including enzymatic, chemical, and TM mutation mechanisms. Measurements of sTM and MV-TM have been developed and explored as biomarkers in many diseases. In this review, we summarize all these advances in three categories as follows: (1) release mechanisms of circulating TM, (2) methods for measuring circulating TM in biological samples, and (3) correlation of circulating TM with diseases. Altogether, it provides a whole picture of recent advances on circulating TM in health and disease.

Soluble thrombomodulin ameliorates aberrant hemostasis after rewarming in a rat accidental hypothermia model

BACKGROUND

Accidental hypothermia (AH) sometimes leads to coagulation disorder, especially in severe AH. We previously demonstrated that intrasplenic platelet activation caused aberrant hemostasis and thrombus formation after rewarming in a murine AH model. However, no study has focused on the appropriate management of platelets causing coagulation activation after rewarming of AH. We investigated whether or not recombinant soluble thrombomodulin (rTM) can suppress thrombosis formation after rewarming using a rat AH model.

METHODS

Wistar rats were exposed to an ambient temperature of -20 °C under general anesthesia until their rectal temperature decreased to 26 °C. The Hypo group rats (n = 5) were immediately euthanized, while the Hypo/Re group (n = 5) and rTM group rats (n = 5), which were administered rTM (1 mg/kg) via the tail vein, were rewarmed until the rectal temperature returned to 34 °C and then euthanized 6 h later. Tissue and blood samples were collected from all rats for histopathological and coagulation analyses at euthanasia.

RESULTS

There was no significant change in the D-dimer level in the Hypo group rats, while the D-dimer level was significantly elevated at 6 h after rewarming in the Hypo/Re group rats (P = 0.015), and histopathology detected both fibrin and platelets in the renal glomerulus. However, the rTM group rats did not show any elevation of the D-dimer levels at 6 h after rewarming, and no fibrin was noted on histopathology.

CONCLUSIONS

rTM may be useful as an appropriate anticoagulant in cases of aberrant hemostasis after rewarming of AH.

Thrombomodulin in patients with mild to moderate bleeding tendency

Introduction

A massive increase of soluble thrombomodulin (sTM) due to variants in the thrombomodulin gene (THBD) has recently been identified as a novel bleeding disorder.

Aim

To investigate sTM levels and underlying genetic variants as a cause for haemostatic impairment and bleeding in a large number of patients with a mild to moderate bleeding disorder (MBD), including patients with bleeding of unknown cause (BUC).

Patients and methods

In 507 MBD patients, sTM levels, thrombin generation and plasma clot formation were measured and compared to 90 age‐ and sex‐matched healthy controls. In patients, genetic analysis of the THBD gene was performed.

Results

No difference in sTM levels between patients and controls was found overall (median ([IQR] 5.0 [3.8‐6.3] vs. 5.1 [3.7‐6.4] ng/ml, p = .762), and according to specific diagnoses of MBD or BUC, and high sTM levels (≥95th percentile of healthy controls) were not overrepresented in patients. Soluble TM levels had no impact on bleeding severity or global tests of haemostasis, including thrombin generation or plasma clot formation. In the THBD gene, no known pathogenic or novel disease‐causing variants affecting sTM plasma levels were identified in our patient cohort.

Conclusion

TM‐associated coagulopathy appears to be rare, as it was not identified in our large cohort of patients with MBD. Soluble TM did not arise as a risk factor for bleeding or altered haemostasis in these patients.

The Role of GPR15 Function in Blood and Vasculature

Since the first prominent description of the orphan G protein-coupled receptor 15 (GPR15) on lymphocytes as a co-receptor for the human immunodeficiency virus (HIV) type 1 and 2 and the first report about the GPR15-triggered cytoprotective effect on vascular endothelial cells by recombinant human thrombomodulin, several decades passed before the GPR15 has been recently deorphanized. Because of new findings on GPR15, this review will summarize the consequences of GPR15 signaling considering the variety of GPR15-expressing cell types and of GPR15 ligands, with a focus on blood and vasculature.

Coagulation Dysfunction in Acute Respiratory Distress Syndrome and Its Potential Impact in Inflammatory Subphenotypes

The Acute Respiratory Distress Syndrome (ARDS) has caused innumerable deaths worldwide since its initial description over five decades ago. Population-based estimates of ARDS vary from 1 to 86 cases per 100,000, with the highest rates reported in Australia and the United States. This syndrome is characterised by a breakdown of the pulmonary alveolo-epithelial barrier with subsequent severe hypoxaemia and disturbances in pulmonary mechanics. The underlying pathophysiology of this syndrome is a severe inflammatory reaction and associated local and systemic coagulation dysfunction that leads to pulmonary and systemic damage, ultimately causing death in up to 40% of patients. Since inflammation and coagulation are inextricably linked throughout evolution, it is biological folly to assess the two systems in isolation when investigating the underlying molecular mechanisms of coagulation dysfunction in ARDS. Although the body possesses potent endogenous systems to regulate coagulation, these become dysregulated and no longer optimally functional during the acute phase of ARDS, further perpetuating coagulation, inflammation and cell damage. The inflammatory ARDS subphenotypes address inflammatory differences but neglect the equally important coagulation pathway. A holistic understanding of this syndrome and its subphenotypes will improve our understanding of underlying mechanisms that then drive translation into diagnostic testing, treatments, and improve patient outcomes.

The associations between THBD c.1418C>T polymorphism and lower extremity deep vein thrombosis or endothelial progenitor cell

BACKGROUND

Studies have shown that the thrombomodulin gene (THBD) c.1418C>T polymorphism is associated with a variety of cardiovascular diseases. However, the study of THBD c.1418C>T polymorphism in deep vein thrombosis (DVT) is rare. This study aimed to reveal the correlation between the THBD c.1418C>T mutation and the occurrence of DVT, and to reveal partial molecular mechanism of endothelial progenitor cells (EPCs) participating in the onset of DVT.

METHODS

Whole blood samples of patients with lower extremity DVT (n = 100) and normal volunteers (n = 100) were collected to analyze the distribution of genotype of THBD c.1418C>T polymorphism using PCR and DNA sequencing. The pCMV6-entry vectors containing wild-type (WT) or mutated THBD cDNA (p. Ala473Val) were transfected into bone marrow derived EPCs. And the successful transfection of recombinant THBD and the stable expression of p. Ala473Val variant were determined by ELISA, respectively. Wound healing assay and Transwell migration assay were used to determine the migration ability of EPCs, and the cell angiogenesis ability was determined by tube formation assay. Western blotting was used to detect the expression level of related proteins.

RESULTS

The frequencies of CC, CT and TT genotypes were 56%, 36%, 8% in patients with lower extremity DVT and 72%, 25%, 3% in controls group, respectively, and THBD c.1418C>T polymorphism was related with increased risk of DVT, especially in women. High level of p. Ala473Val variant inhibited the EPCs migration, the p. Ala473Val variant significantly decreased the activation of protein C and the expressions of VEGFRs and MMP1, MMP2, MMP3. Furthermore, p. Ala473Val variant also weaken the angiogenesis of EPCs and decreased the expression level of VE-cadherin, Flk-1, eNOS, and TIE-2.

CONCLUSIONS

THBD c.1418C>T polymorphism is related with the lower extremity DVT, this may partially because of the inhibition of migration and angiogenesis of EPCs.

Effects of Thrombomodulin in Reducing Lethality and Suppressing Neutrophil Extracellular Trap Formation in the Lungs and Liver in a Lipopolysaccharide-Induced Murine Septic Shock Model

Neutrophil extracellular trap (NET) formation, an innate immune system response, is associated with thrombogenesis and vascular endothelial injury. Circulatory disorders due to microvascular thrombogenesis are one of the principal causes of organ damage. NET formation in organs contributes to the exacerbation of sepsis, which is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. We have previously reported that recombinant human soluble thrombomodulin (rTM) reduces lipopolysaccharide (LPS)-induced NET formation in vitro. Here, we aimed to show that thrombomodulin (TM)-mediated suppression of NET formation protects against organ damage in sepsis. Mice were injected intraperitoneally (i.p.) with 10 mg/kg LPS. rTM (6 mg/kg/day) or saline was administered i.p. 1 h after LPS injection. In the LPS-induced murine septic shock model, extracellular histones, which are components of NETs, were observed in the liver and lungs. In addition, the serum cytokine (interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), macrophage chemotactic protein-1 (MCP-1), and interleukin-10 (IL-10)) levels were increased. The administration of rTM in this model prevented NET formation in the organs and suppressed the increase in the levels of all cytokines except IL-1β. Furthermore, the survival rate improved. We provide a novel role of TM in treating inflammation and NETs in organs during sepsis.

Characterisation of a novel thrombomodulin c.1487delC,p.(Pro496Argfs*10) variant and evaluation of therapeutic strategies to manage the rare bleeding phenotype

INTRODUCTION

A novel variant in the thrombomodulin (TM) gene, c.1487delC,p.(Pro496Argfs*10), referred to as Pro496Argfs*10, was identified in a family with an unexplained bleeding disorder. The Pro496Argfs*10 variant results in loss of the transmembrane and intracellular segments of TM and is associated with an increase in soluble TM (sTM) in the plasma. The aim of this study was to characterise the effect of elevated sTM on thrombin generation (TG) and fibrinolysis, and to evaluate therapeutic strategies to manage the patients.

METHODS

Plasma samples were obtained from two patients carrying the variant. TG was triggered using 5 pM tissue factor and measured using the Calibrated Automated Thrombogram. A turbidity clot lysis assay was used to monitor fibrinolysis. TM antigen was quantified by ELISA.

RESULTS

Patients with the Pro496Argfs*10 variant had significantly elevated plasma sTM compared to controls (372.6 vs. 6.0 ng/ml). TG potential was significantly lower in patients but was restored by inhibition of activated protein C (APC) or addition of activated Factor VII (FVIIa) or platelet concentrates. In vitro experiments suggested that activated prothrombin complex concentrates (APCC) posed a risk of thrombosis. The time to 50% lysis was significantly prolonged in patients compared to controls, 69.7 vs. 42.3 min. Clot lysis time was shortened by inhibition of activated thrombin activatable fibrinolysis inhibitor (TAFIa).

CONCLUSIONS

Our data demonstrate that increased sTM enhances APC generation and reduces TG. Simultaneously, the rate of fibrinolysis is delayed due to increased TAFI activation by sTM. Treatment with platelet or FVIIa concentrates may be beneficial to manage this rare bleeding disorder.

Fibrinolysis Index as a new predictor of deep vein thrombosis after traumatic lower extremity fractures

BACKGROUND

Deep vein thrombosis (DVT) is a common complication in patients with traumatic injury. The purpose of this study was to develop a potential predictor of DVT.

METHODS

This case-control study enrolled adult trauma patients and healthy volunteers. Patients underwent angiography before surgery to diagnose DVT. Patients with or without DVT were matched by gender, age and fracture sites. Laboratory parameters included lysis potential (LP), lysis time (LT), blood cell counts, conventional coagulation tests, tissue plasminogen activator inhibitor complex (tPAIC) and others.

RESULTS

41 of 319 patients with DVT were matched with 41 patients without DVT and 80 healthy volunteers were controls. LP and LT were significantly decreased in patients with DVT than without (P = 0.043 and P = 0.014, respectively). The level of tPAIC in the DVT group was significantly higher than in patients without DVT (P = 0.042). We defined the Fibrinolysis Index as (-10.707) × LP + (-0.607) × LT (min) + 0.012 × fibrinogen (mg/dl) + 0.299 × tPAIC (ng/ml) + 9.917, and found that the area under the receiver operating characteristic curve for the Fibrinolysis Index was 0.802, making it a novel indicator.

CONCLUSION

The Fibrinolysis Index represents a new discriminator for predicting DVT after traumatic lower extremity fractures.

Thrombomodulin ameliorates transforming growth factor-β1-mediated chronic kidney disease via the G-protein coupled receptor 15/Akt signal pathway

Kidney fibrosis is the common consequence of chronic kidney diseases that inexorably progresses to end-stage kidney disease with organ failure treatable only with replacement therapy. Since transforming growth factor-β1 is the main player in the pathogenesis of kidney fibrosis, we posed the hypothesis that recombinant thrombomodulin can ameliorate transforming growth factor-β1-mediated progressive kidney fibrosis and failure. To interrogate our hypothesis, we generated a novel glomerulus-specific human transforming growth factor-β1 transgenic mouse to evaluate the therapeutic effect of recombinant thrombomodulin. This transgenic mouse developed progressive glomerular sclerosis and tubulointerstitial fibrosis with kidney failure. Therapy with recombinant thrombomodulin for four weeks significantly inhibited kidney fibrosis and improved organ function compared to untreated transgenic mice. Treatment with recombinant thrombomodulin significantly inhibited apoptosis and mesenchymal differentiation of podocytes by interacting with the G-protein coupled receptor 15 to activate the Akt signaling pathway and to upregulate the expression of anti-apoptotic proteins including survivin. Thus, our study strongly suggests the potential therapeutic efficacy of recombinant thrombomodulin for the treatment of chronic kidney disease and subsequent organ failure.

The protective role of estrogen on endothelial and glycocalyx barriers after shock conditions: A microfluidic study

BACKGROUND

Sexual dimorphism has been demonstrated after major trauma and hemorrhage shock with protective effects related to female sex or estrogen. Traumatic endotheliopathy is an important component of trauma-induced coagulopathy. Components of endothelial barrier dysfunction include degradation of the endothelial glycocalyx and endothelial cellular injury. Estrogen modulates endothelial function via its membrane and cellular receptors. The effects of estrogen on the vascular endothelial barrier after trauma and hemorrhage shock are, however, unknown. This topic was studied in an in vitro model under flow conditions.

METHODS

Monolayers of human umbilical vein endothelial cells were established in microfluidic flow devices. After overnight perfusion, cell monolayers were subjected to normoxic or hypoxic perfusion and then treated with either estrogen (as estradiol), testosterone (as dihydrotestosterone), or media alone. Endothelial activation/injury was indexed by soluble thrombomodulin and glycocalyx degradation by syndecan-1 and hyaluronic acid shedding as well as measurement of the thickness of the glycocalyx layer. The coagulation phenotype of the human umbilical vein endothelial cells was indexed by the relative values of the activities of tissue plasminogen activator and plasminogen activator inhibitor-1. Vascular endothelial growth factor was measured in cell culture supernatants using a solid-phase enzyme-linked immunosorbent assay.

RESULTS

Treatment with estrogen but not testosterone mitigated the adverse effect of shock on endothelial and glycocalyx barrier properties. Our biomimetic model suggests a beneficial effect of estrogen administration after trauma and hemorrhage shock on the glycocalyx and endothelial barriers.

CONCLUSION

Early estrogen treatment after trauma and hemorrhage shock may be a useful adjunct to mitigating the development of traumatic endotheliopathy.

High Soluble Thrombomodulin Is Associated with an Increased Risk of Major Bleeding during Treatment with Oral Anticoagulants: A Case-Cohort Study

BACKGROUND

 Major bleeding occurs in 1 to 3% of patients treated with oral anticoagulants per year. Biomarkers may help to identify high-risk patients. A proposed marker for major bleeding while using anticoagulants is soluble thrombomodulin (sTM).

METHODS

 Plasma was available from 16,570 patients of the BLEEDS cohort that consisted of patients who started treatment with vitamin K antagonists between 2012 and 2014. A case-cohort study was performed including all patients with a major bleed (n = 326) during follow-up and a random sample of individuals selected at baseline (n = 652). Plasma sTM levels were measured and stratified by percentiles. Patients were also categorized by international normalized ratio (INR). Adjusted hazard ratios (for age, sex, hypertension, and diabetes) with 95% confidence intervals (CIs) were estimated by means of Cox regression.

RESULTS

 Plasma sTM levels were available for 263 patients with a major bleed and 538 control subjects. sTM levels were dose-dependently associated with risk of major bleeding, with a 1.9-fold increased risk (95% CI: 1.1-3.1) for levels above the 85th percentile versus the <25th percentile. A high INR (≥4) in the presence of high (≥70th percentile) sTM levels was associated with a 7.1-fold (95% CI: 4.1-12.3) increased risk of major bleeding, corresponding with a bleeding rate of 14.1 per 100 patient-years.

CONCLUSION

 High sTM levels at the start of treatment are associated with major bleeding during vitamin K antagonist treatment, particularly in the presence of a high INR.

Pathophysiology of the Venous Thromboembolism Risk in Preeclampsia

Preeclampsia complicates up to 8% of pregnancies and is a leading cause of fetomaternal morbidity andmortality. Treatment options are limited, with supportive care and delivery of the placenta representing the cornerstone of current management strategies. Derangements in blood coagulation are wellrecognised in this disorder and appear to favour an increased risk of venous thromboembolism among affected women. This risk appears to be most significant in the postpartum period. The mechanisms underlying this increased thrombosis risk remain to be fully elucidated although increased expression of procoagulant factors, endothelial dysfunction, attenuation of endogenous anticoagulant activity and increased platelet activity have been implicated in the prothrombotic tendency. Preeclampsia is also occasionally complicated by life-threatening haemorrhagic events and current evidence suggests that in some severe manifestations of this disease a coagulopathy with a clinical bleeding tendency may be the predominant haemostatic abnormality. Identifying affected women at significant risk of thrombosis and managing the competing thrombotic and haemorrhagic risks continue to be a significant clinical challenge. Derangements in blood coagulation are also implicated in the pathogenesis of preeclampsia; however, the role of antiplatelet or anticoagulant drugs in the prevention and treatment of this disorder remains a source of considerable debate. In addition, the potential role of specific haemostatic markers as diagnostic or screening tools for preeclampsia has also yet to be determined. Further characterisation of the underlying molecular mechanisms would likely be of major translational relevance and could provide insights into the pathogenesis of this disease as well as the associated haemostatic dysfunction.

Complement-Mediated Disorders in Pregnancy

Complement-mediated disorders in pregnancy span a large spectrum and have been implicated in all three complement pathways: classical, lectin, and alternative. Our understanding of these disorders in recent years has advanced due to a better understanding of complement regulatory proteins, such as complement factor H, complement factor I, membrane cofactor protein, and thrombomodulin that particularly affect the alternative complement pathway. Enthusiasm in genotyping for mutations that encode these proteins has allowed us to study the presence of genetic variants which may predispose women to develop conditions such as pregnancy-associated hemolytic uremic syndrome (P-aHUS), thrombotic thrombocytopenic purpura, preeclampsia/hemolysis, elevated liver enzymes, low platelets (HELLP), systemic lupus erythematosus/antiphospholipid syndrome, and peripartum cardiomyopathy. The advent of the anti-C5-antibody eculizumab to quench the complement cascade has already proven in small case series to improve maternal kidney outcomes in complement-mediated obstetric catastrophes such as P-aHUS and HELLP. In this review, we will detail the pathogenesis behind these complement-mediated pregnancy disorders, the role of complement variants in disease phenotype, and the most up-to-date experience with eculizumab in this population.

Markers of endothelial cell activation and neutrophil extracellular traps are elevated in immune thrombocytopenia but are not enhanced by thrombopoietin receptor agonists

INTRODUCTION

Patients with immune thrombocytopenia (ITP) are at increased risk of thrombosis, which seems to be further enhanced by treatment with thrombopoietin-receptor-agonists (TPO-RAs). The underlying mechanisms of thrombosis in ITP are not fully understood. Endothelial cell activation and neutrophil extracellular traps (NETs) play important roles in thrombosis, however, their roles in ITP itself, or in TPO-RA-treatment, have not yet been fully explored. We aimed to investigate whether endothelial cell activation and NETs are involved in the hypercoagulable state of ITP, and whether TPO-RA-treatment enhances endothelial cell activation and NET formation.

MATERIAL AND METHODS

We measured markers of endothelial cell activation including intercellular adhesion molecule-1 (ICAM-1), vascular adhesion molecule-1 (VCAM-1) and thrombomodulin in 21 ITP patients, and E-selectin in 18 ITP patients. Markers of NET formation, citrullinated histone H3-DNA (H3Cit-DNA) and cell-free DNA (cfDNA), were measured in 15 ITP patients. All markers were measured before, and 2 and 6 weeks after initiation of TPO-RA-treatment in ITP patients, and in matched controls.

RESULTS

Higher levels of ICAM-1, thrombomodulin, and H3Cit-DNA were found in ITP patients, both before and after TPO-RA-treatment, compared with controls. No differences were found for VCAM-1, E-selectin or cfDNA. TPO-RA-treatment did not further increase markers of endothelial cell activation or NET formation.

CONCLUSIONS

This study showed that ITP patients have increased endothelial cell activation and NET formation, both of which may contribute to the intrinsic hypercoagulable state of ITP. TPO-RA-treatment, however, did not further increase endothelial cell activation or NET formation indicating that other drug-associated prothrombotic mechanisms are involved.

The association of endothelial injury and systemic inflammation with perioperative myocardial infarction

Background

Major surgery predisposes to endothelial glycocalyx injury. Endothelial glycocalyx injury associates with cardiac morbidity, including spontaneous myocardial infarction. However, the relation between endothelial glycocalyx injury and the development of perioperative myocardial infarction remains unknown.

Methods

Fifteen perioperative myocardial infarction patients and 60 propensity-matched controls were investigated in this prospective study. The diagnosis of perioperative myocardial infarction was based on repeated cardiac troponin T measurements, electrocardiographs and recordings of ischaemic signs and symptoms. We measured endothelial glycocalyx markers – soluble thrombomodulin, syndecan-1 and vascular adhesion protein 1 – and an inflammatory marker, namely interleukin-6, preoperatively and 6 h and 24 h postoperatively. We calculated the areas under the receiver operating characteristics curves (AUCs) to compare the performances of the different markers in predicting perioperative myocardial infarction. The highest value of each marker was used in the analysis.

Results

The interleukin-6 concentrations of perioperative myocardial infarction patients were significantly higher preoperatively and 6 and 24 h postoperatively ( P =  0.002, P =  0.002 and P =  0.001, respectively). The AUCs (95% confidence intervals) for the detection of perioperative myocardial infarction were 0.51 (0.34–0.69) for soluble thrombomodulin, 0.63 (0.47–0.79) for syndecan-1, 0.54 (0.37–0.70) for vascular adhesion protein 1 and 0.69 (0.54–0.85) for interleukin-6.

Conclusions

Systemic inflammation, reflected by interleukin-6, associates with cardiac troponin T release and perioperative myocardial infarction. Circulating interleukin-6 demonstrated some potential to predict perioperative myocardial infarction, whereas endothelial glycocalyx markers did not.

Thrombomodulin in disseminated intravascular coagulation and other critical conditions-a multi-faceted anticoagulant protein with therapeutic potential

Thrombomodulin plays a vital role in maintaining intravascular patency due to its anticoagulant, antiinflammatory, and cytoprotective properties. However, under pathological conditions such as sepsis and systemic inflammation, endothelial thrombomodulin expression is downregulated and its function impaired. As a result, administering thrombomodulin represents a potential therapeutic modality. Recently, the effect of recombinant thrombomodulin administration in sepsis-induced coagulopathy was evaluated in a randomized controlled study (SCARLET). A 2.6% 28-day absolute mortality reduction (26.8% vs. 29.4%) was reported in 800 patients studied that was not statistically significant; however, a post hoc analysis revealed a 5.4% absolute mortality reduction among the patients who fulfilled the entry criterion at baseline. The risk of bleeding did not increase compared to placebo control. Favorable effects of thrombomodulin administration have been reported not only in sepsis-induced coagulopathy but also in disseminated intravascular coagulations with various backgrounds. Interestingly, beneficial effects of recombinant thrombomodulin in respiratory, renal, and cardiovascular diseases might depend on its anti-inflammatory mechanisms. In this review, we summarize the accumulated knowledge of endogenous as well as recombinant thrombomodulin from basic to clinical aspects and suggest future directions for this novel therapeutic agent.

Postreperfusion plasma endothelial activation markers are associated with acute kidney injury after lung transplantation

Acute kidney injury (AKI) is common after lung transplantation, but molecular markers remain poorly studied. The endothelial activation markers soluble thrombomodulin (sTM), protein C, and plasminogen activator inhibitor-1 (PAI-1) are implicated in kidney microcirculatory injury in animal models of AKI. We tested the association of 6-hour postreperfusion plasma levels of these markers with posttransplant AKI severity in patients enrolled in the Lung Transplant Outcomes Group prospective cohort study at the University of Pennsylvania during two eras: 2004-06 (n = 61) and 2013-15 (n = 67). We defined AKI stage through postoperative day 5 using Kidney Disease Improving Global Outcomes creatinine criteria. We used multivariable ordinal logistic regression to determine the association of each biomarker with AKI, adjusted for primary graft dysfunction and extracorporeal life support. AKI occurred in 57 (45%) patients across both eras: 28 (22%) stage 1, 29 (23%) stage 2-3. Higher sTM and lower protein C plasma levels were associated with AKI stage in each era and remained so in multivariable models utilizing both eras (sTM: OR 1.76 [95% CI 1.19-2.60] per standard deviation, P = .005; protein C: OR 0.54 [1.19-2.60], P = .003). We conclude that 6-hour postreperfusion plasma sTM and protein C levels are associated with early postlung transplant AKI severity.

Exploring traditional and nontraditional roles for thrombomodulin

Thrombomodulin (TM) is an integral component of a multimolecular system, localized primarily to the vascular endothelium, that integrates crucial biological processes and biochemical pathways, including those related to coagulation, innate immunity, inflammation, and cell proliferation. These are designed to protect the host from injury and promote healing. The “traditional” role of TM in hemostasis was determined with its discovery in the 1980s as a ligand for thrombin and a critical cofactor for the major natural anticoagulant protein C system and subsequently for thrombin-mediated activation of the thrombin activatable fibrinolysis inhibitor (also known as procarboxypeptidase B2). Studies in the past 2 decades are redefining TM as a molecule with many properties, exhibited via its multiple domains, through its interacting partners, complex regulated expression, and synthesis by cells other than the endothelium. In this report, we review some of the recently reported diverse properties of TM and how these may impact on our understanding of the pathogenesis of several diseases.

Coordinated responses of natural anticoagulants to allogeneic stem cell transplantation and acute GVHD - A longitudinal study

Background

Allogeneic stem cell transplantation (SCT) enhances coagulation via endothelial perturbation and inflammation. Role of natural anticoagulants in interactions between coagulation and inflammation as well as in acute graft-versus-host disease (GVHD) are not well known. The purpose of this study was to define changes in natural anticoagulants over time in association with GVHD.

Patients and methods

This prospective study included 30 patients who received grafts from siblings (n = 19) or unrelated donors (n = 11). Eight patients developed GVHD. Standard clinical assays were applied to measure natural anticoagulants, represented by protein C (PC), antithrombin (AT), protein S (PS), complex of activated PC with its inhibitor (APC-PCI) and by markers of endothelial activation: Factor VIII coagulant activity (FVIII:C) and soluble thrombomodulin (s-TM) at 6–8 time points over three months.

Results

Overall, PC, AT and FVIII:C increased in parallel after engraftment. Significant correlations between PC and FVIII:C (r = 0.64–0.82, p<0.001) and between PC and AT (r = 0.62–0.81, p<0.05) were observed at each time point. Patients with GVHD had 21% lower PC during conditioning therapy and 55% lower APC-PCI early after transplantation, as well as 37% higher values of s-TM after engraftment. The GVHD group had also increases of PC (24%), FVIII: C (28%) and AT (16%) three months after transplantation.

Conclusion

The coordinated activation of natural anticoagulants in our longitudinal study indicates the sustained ability of adaptation to endothelial and inflammatory activation during allogenic SCT treatment. The suboptimal control of coagulation by natural anticoagulants at early stage of SCT may contribute to onset of GVHD.

Why patients with THBD c.1611C>A (p.Cys537X) nonsense mutation have high levels of soluble thrombomodulin?

Background

Recently our group has described a new autosomal dominant bleeding disorder characterized by very high plasma levels of soluble thrombomodulin (TM). The THBD c.1611C>A (p.Cys537X) mutation in heterozygous state was found in the propositus. This mutation leads to the synthesis of a truncated TM which has lost the last three amino-acids of the transmembrane domain and the cytoplasmic tail.

Objective

We investigated the mechanism responsible for TM shedding in endothelial cells with THBD c.1611C>A mutation.

Methods

Complementary DNA of TM wild type (TM-WT) was incorporated into a pcDNA3.1 vector for transient transfection in COS-1 cells. Mutagenesis was performed to create the c.1611C<A (TM_1-536) mutant and 4 other TM mutants (TM_1-515, TM_1-525, TM_1-533 and TM_1-537) with a transmembrane domain having different lengths. The effect of shear stress, metalloprotease inhibitor, certain proteases and reducing agents were tested on TM shedding.

Results

Western blot and immunofluorescent analysis showed that TM_1-536 was produced and a certain amount of TM_1-536 was anchored on the cell membrane. A significantly higher levels of soluble TM was observed in the TM_1-536 cell medium in comparison with TM-WT (56.3 +/- 5.2 vs 8.8 +/- 1.6 ng/mL, respectively, p = 0.001). The shedding of TM_1-536 was 75% decreased in cells cultured in the presence of a metalloprotease inhibitor. No difference was observed between TM_1-536 and TM-WT shedding after cell exposure to cathepsin G, elastase, several reducing agents and high shear stress (5000 s^-1). Significantly higher levels of soluble TM were observed in the cell media of TM_1-533, TM_1-525, TM_1-515 in comparison with TM-WT (p < 0.05).

Conclusion

The mechanism responsible for TM shedding is complex and is not completely understood: higher sensitivity of the TM_1-536 to the proteolysis by metalloproteases and a defect of synthesis due to the decreased size of the transmembrane domain might explain the high levels of soluble TM in plasma of the carriers.

Increased serum thrombomodulin level is associated with disease severity and mortality in pediatric sepsis

Background

Endothelial dysfunction plays an important role in the pathophysiology of sepsis. As previously reported, the serum thrombomodulin is elevated in diseases associated with endothelial injury.

Objective

The aim of this study was to investigate the association of serum thrombomodulin level in different pediatric sepsis syndromes and evaluate the relationship with disease severity and mortality.

Methods

We prospectively collected cases of sepsis treated in a pediatric intensive care unit from June 2012 to July 2015 at Chang Gung Children’s Hospital in Taoyuan, Taiwan. Clinical characteristics and serum thrombomodulin levels were analyzed.

Results

Increased serum thrombomodulin levels on days 1 and 3 of the diagnosis of sepsis were found in different pediatric sepsis syndromes. Patients with septic shock had significantly increased serum thrombomodulin levels on days 1 and 3 [day 1: median, 6.9 mU/ml (interquartile range (IQR): 5.8–12.8) and day 3: median, 5.8 mU/ml (IQR: 4.6–10.8)] compared to healthy controls [median, 3.4 mU/ml (IQR: 2.3–4.2)] (p = <0.001 and 0.001, respectively) and those with sepsis [day 1: median, 2.9 mU/ml (IQR: 1.8–4.7) and day 3: median, 3 mU/ml (IQR: 1.5–3.5)] and severe sepsis [day 1: median, 3.3 mU/ml (IQR: 1.3–8.6) and day 3: median, 4.4 mU/ml (IQR: 0.5–6)] (p = <0.001 and 0.001, respectively). There was also a significant positive correlation between serum thrombomodulin level on day 1 and day 1 PRISM-II, PELOD, P-MOD and DIC scores. The patients who died had significantly higher serum thrombomodulin levels on days 1 and 3 [day 1: median, 9.9 mU/ml (IQR: 6.2–15.6) and day 3: median, 10.4 mU/ml (IQR: 9.2–11.7)] than the survivors [day 1; median, 4.4 mU/ml (IQR: 2.2–7.5) and day 3: [median, 3.5 mU/ml (IQR: 1.6–5.7)] (p = 0.046 and 0.012, respectively).

Conclusion

Increased serum thrombomodulin levels were found in different pediatric sepsis syndromes and correlated with disease severity and mortality.

Plasma carboxypeptidase U (CPU, CPB2, TAFIa) generation during in vitro clot lysis and its interplay between coagulation and fibrinolysis

Carboxypeptidase U (CPU, CPB2, TAFIa) is a basic carboxypeptidase that is able to attenuate fibrinolysis. The inactive precursor procarboxypeptidase U is converted to its active form by thrombin, the thrombin-thrombomodulin complex or plasmin. The aim of this study was to investigate and characterise the time course of CPU generation in healthy individuals. In plasma of 29 healthy volunteers, CPU generation was monitored during in vitro clot lysis. CPU activity was measured by means of an enzymatic assay that uses the specific substrate Bz-o-cyano-Phe-Arg. An algorithm was written to plot the CPU generation curve and calculate the parameters that define it. In all individuals, CPU generation was biphasic. Marked inter-individual differences were present and a reference range was determined. The endogenous CPU generation potential is the composite effect of multiple factors. With respect to the first CPU activity peak characteristics, we found correlations with baseline proCPU concentration, proCPU Thr325Ile polymorphism, time to clot initiation and the clot lysis time. The second CPU peak related with baseline proCPU levels and with the maximum turbidity of the clot lysis profile. In conclusion, our method offers a technique to determine the endogenous CPU generation potential of an individual. The parameters obtained by the method quantitatively describe the different mechanisms that influence CPU generation during the complex interplay between coagulation and fibrinolysis, which are in line with the threshold hypothesis.

Blood markers of fibrinolysis and endothelial activation in canine babesiosis

Background

Canine babesiosis is a tick-borne disease caused by hemoprotozoan parasites of the genus Babesia. The disease can be clinically classified into uncomplicated and complicated forms. The aim of this study was to assess the level of endothelial activation and alterations in the fibrinolytic pathway during canine babesiosis.

Results

Blood samples were collected on the day of admission and on the 6th day after treatment with imidocarb propionate, from 30 dogs of various breeds and of both sexes with naturally occurring babesiosis caused by B. canis. In this prospective study, plasminogen activity was assessed using a chromogenic assay, and concentrations of high mobility group box-1 protein (HMGB-1), intercellular adhesive molecule-1 (ICAM-1), vascular adhesive molecule-1 (VCAM-1), soluble urokinase receptor of plasminogen activator (suPAR), thrombin activatable fibrinolysis inhibitor (TAFI), soluble thrombomodulin (TM) and plasminogen activator inhibitor-1 (PAI-1) were determined using a canine specific ELISA. Concentrations of TM, HMGB-1, VCAM-1 and suPAR were increased in dogs with babesiosis at admission compared to healthy dogs. After treatment, concentrations of TM were lower in infected dogs compared to healthy dogs. Dogs with babesiosis also had increased concentrations of TM, ICAM-1 and HMGB-1 and decreased plasminogen and PAI-1 at presentation compared to day 6 after treatment. Dogs with complicated babesiosis had higher concentrations of TM, HMGB1 and TAFI at admission compared to the 6th day.

Conclusions

Biomarkers of endothelial activation and fibrinolysis were altered in dogs with babesiosis. Further studies into their usefulness as biomarkers of disease severity or prognosis is warranted.

Impact of blood hypercoagulability on in vitro fertilization outcomes: a prospective longitudinal observational study

Background

Blood coagulation plays a crucial role in the blastocyst implantation process and its alteration may be related to in vitro fertilization (IVF) failure. We conducted a prospective observational longitudinal study in women eligible for IVF to explore the association between alterations of coagulation with the IVF outcome and to identify the biomarkers of hypercoagulability which are related with this outcome.

Methods

Thirty-eight women eligible for IVF (IVF-group) and 30 healthy, age-matched women (control group) were included. In the IVF-group, blood was collected at baseline, 5–8 days after administration of gonadotropin-releasing hormone agonist (GnRH), before and two weeks after administration of human follicular stimulating hormone (FSH). Pregnancy was monitored by measurement of βHCG performed 15 days after embryo transfer. Thrombin generation (TG), minimal tissue factor-triggered whole blood thromboelastometry (ROTEM®), procoagulant phospholipid clotting time (Procoag-PPL®), thrombomodulin (TMa), tissue factor activity (TFa), factor VIII (FVIII), factor von Willebrand (FvW), D-Dimers and fibrinogen were assessed at each time point.

Results

Positive IVF occurred in 15 women (40%). At baseline, the IVF-group showed significantly increased TG, TFa and TMa and significantly shorter Procoag-PPL versus the control group. After initiation of hormone treatment TG was significantly higher in the IVF-positive as compared to the IVF-negative group. At all studied points, the Procoag-PPL was significantly shorter and the levels of TFa were significantly higher in the IVF-negative group compared to the IVF-positive one. The D-Dimers were higher in the IVF negative as compared to IVF positive group. Multivariate analysis retained the Procoag-PPL and TG as predictors for the IVF outcome.

Conclusions

Diagnosis of women with hypercoagulability and their stratification to risk of IVF failure using a model based on the Procoag-PPL and TG is a feasible strategy for the optimization of IVF efficiency that needs to be validated in prospective trials.

Pathophysiology of trauma-induced coagulopathy: disseminated intravascular coagulation with the fibrinolytic phenotype

In severe trauma patients, coagulopathy is frequently observed in the acute phase of trauma. Trauma-induced coagulopathy is coagulopathy caused by the trauma itself. The pathophysiology of trauma-induced coagulopathy consists of coagulation activation, hyperfibrino(geno)lysis, and consumption coagulopathy. These pathophysiological mechanisms are the characteristics to DIC with the fibrinolytic phenotype.

Recombinant human thrombomodulin inhibits neutrophil extracellular trap formation in vitro

The aim of this study was to investigate the effects of recombinant human-soluble thrombomodulin (rTM) on lipopolysaccharide (LPS)-induced, platelet-dependent neutrophil extracellular trap (NET) formation (NETosis). Human peripheral blood neutrophils and platelets were co-incubated with or without LPS (0.2 μg/ml) in the presence and absence of rTM (2 μg/ml). NETosis was confirmed by immunostaining and confocal microscopy. In the absence of platelets, LPS did not induce NETosis in the neutrophils. NETosis, however, was induced by LPS when neutrophils were co-cultured with platelets (64 % of neutrophils). Notably, rTM was able to fully inhibit NETosis in neutrophils cultured with platelets and in the presence of LPS. rTM did not induce NETosis in this co-culture system (p < 0.01 versus LPS in the absence of rTM). These results show that rTM can suppress LPS-induced platelet-dependent NETosis in vitro.

Recombinant thrombomodulin for secondary thrombotic thrombocytopenic purpura

In the pathogenesis of thrombotic thrombocytopenic purpura (TTP), reductions in the enzyme activity of ADAMTS13, which cuts ultralarge von Willebrand multimers, generates shear stress on the microvascular endothelium, leading to platelet aggregation and the formation of a thrombus. ADAMTS13 activity is markedly decreased in typical TTP, but is only mildly reduced in secondary TTP, which concomitantly develops with primary disease. The latter develops with septic disseminated intravascular coagulation (DIC) and often causes organ failure. Recombinant thrombomodulin (rTM) is a drug that is used to treat DIC and may also remit TTP because it improves vascular endothelial dysfunction. Therefore, we herein investigated the efficacy of rTM in patients treated for the pathology of secondary TTP. Patients who were admitted to the Emergency and Critical Care Center of our hospital and met the following conditions were extracted and retrospectively analyzed: hemolytic anemia accompanied by fragmented red blood cells (Hb < 12 g/dL or lower); thrombocytopenia (<100 × 10/μL); and ADAMTS13 activity <50%. Sixteen patients were included and accompanied by Kidney Disease: Improving Global Outcomes (KDIGO) stage 2 or more severe nephropathy and DIC. Eleven and 5 patients treated with and without rTM (the rTM and non-rTM treatment groups, respectively) were compared, and no significant difference was noted in their basic characteristics, such as background disease and severity. No significant difference was observed in survival rates; however, the platelet count, which is an important outcome of treatments for TTP, significantly increased in the rTM treatment group: 3.3 ± 2.6→11.3 ± 14.6 versus 3.5 ± 3.7→5.7 ± 3.9 (×1000/μL) (P = 0.034). Thrombotic thrombocytopenic purpura originally requires invasive treatments and its prognosis is not favorable. Blood thrombomodulin levels also markedly increase due to vascular endothelial dysfunction, whereas rTM alleviates vascular endothelial dysfunction in TTP patients with high blood TM levels, suggesting the importance of administering rTM. Thus, rTM may be effective for secondary TTP and may be adopted as adjuvant therapy.

Noble-Collip Drum Trauma Induces Disseminated Intravascular Coagulation But Not Acute Coagulopathy of Trauma-Shock

BACKGROUND

There are two opposing possibilities for the main pathogenesis of trauma-induced coagulopathy: an acute coagulopathy of trauma shock and disseminated intravascular coagulation with the fibrinolytic phenotype.

OBJECTIVE

The objective of this study was to clarify the main pathogenesis of trauma-induced coagulopathy using a rat model of Noble-Collip drum trauma.

METHODS

Eighteen rats were divided into the control, trauma 0, and trauma 30 groups. The trauma 0 and 30 groups were exposed to Noble-Collip drum trauma. Blood samples were drawn without, immediately after, and 30 min after Noble-Collip drum trauma in the control, trauma 0, and trauma 30 groups, respectively. Coagulation and fibrinolysis markers were measured. Thrombin generation was assessed according to a calibrated automated thrombogram.

RESULTS

Spontaneous thrombin bursts resulting from circulating procoagulants were observed in the nonstimulated thrombin generation assay immediately after trauma. Soluble fibrin levels (a marker of thrombin generation in the systemic circulation) were 50-fold greater in the trauma groups than in the control group. The resultant coagulation activation consumed platelets, coagulation factors, and antithrombin. Endogenous thrombin potential and factor II ratio were significantly negatively correlated with antithrombin levels, suggesting insufficient control of thrombin generation by antithrombin. High levels of active tissue-type plasminogen activator induced hyperfibrin(ogen)olysis. Soluble thrombomodulin increased significantly. However, activated protein C levels did not change.

CONCLUSIONS

The systemic thrombin generation accelerated by insufficient antithrombin control leads to the consumption of platelets and coagulation factors associated with hyperfibrin(ogen)olysis. These changes are collectively termed disseminated intravascular coagulation with the fibrinolytic phenotype.

Enhanced expression of cell-specific surface antigens on endothelial microparticles in sepsis-induced disseminated intravascular coagulation

Sepsis-induced disseminated intravascular coagulation (DIC) is a major cause of death in patients admitted to intensive care units. Endothelial injury with microparticle production is reported in the pathogenesis of sepsis. Endothelial microparticles (EMPs) present several cell-specific surface antigens with different bioactivities, for example, tissue factor (TF), thrombomodulin (TM), and endothelial protein C receptor (EPCR). We investigated associations between these three different surface antigen-positive EMPs and sepsis-induced DIC. This cross-sectional study composed of 24 patients with sepsis and 23 healthy controls was conducted from November 2012 to September 2013. Blood samples were collected from patients within 24 h of diagnosis of severe sepsis and from healthy controls. Numbers of TF-positive EMPs (TF EMPs), TM-positive EMPs (TM EMPs), and EPCR-positive EMPs (EPCR EMPs) were measured by flow cytometry immediately thereafter. Acute Physiology and Chronic Health Evaluation II and Sequential Organ Failure Assessment scores were assessed in the severe sepsis patients at enrollment. We assessed DIC with the International Society of Thrombosis and Haemostasis (ISTH) overt DIC diagnostic criteria algorithm. Numbers of antigen-positive EMPs were increased significantly in both severe sepsis patients and controls and with the increase in ISTH DIC score. Numbers of TF EMPs and EPCR EMPs correlated significantly with Sequential Organ Failure Assessment score, and numbers of EPCR EMPs correlated significantly with Acute Physiology and Chronic Health Evaluation II score. Numbers of the three antigen-positive EMPs were increased significantly in severe sepsis patients versus those in healthy controls and with the increase of ISTH DIC score, suggesting that the specific bioactivity of each antigen-positive EMP may play a role in the progression of sepsis-induced DIC.

Elevated soluble thrombomodulin is associated with organ failure and mortality in children with acute respiratory distress syndrome (ARDS): a prospective observational cohort study

INTRODUCTION

The significance of endothelial injury in children with the acute respiratory distress syndrome (ARDS) has not been well studied. Plasma levels of soluble thrombomodulin (sTM), an endothelial surface protein involved in coagulation, have been associated with endothelial injury. We hypothesized that elevated plasma sTM would correlate with mortality and organ failure in children with ARDS.

METHODS

We conducted a multicenter prospective observational study of pediatric patients with ARDS between 2008 and 2014. sTM was measured in plasma collected less than 24 hours from ARDS diagnosis. Outcomes were intensive care unit mortality and organ dysfunction by pediatric logistic organ dysfunction scores. Logistic regression was used to adjust for clinically relevant covariates.

RESULTS

Plasma sTM was higher in patients with indirect lung injury compared to direct lung injury (100 ng/mL vs. 86 ng/mL, p = 0.02). Increased sTM levels were correlated with more organ dysfunction in the entire study population (Spearman's rho = 0.37, p < 0.01). Overall mortality was 16%. sTM levels were associated with increased mortality in patients with indirect lung injury (OR 2.7 per log(sTM), p = 0.02). These relationships were independent of age, oxygenation defect, or presence of acute kidney injury.

CONCLUSION

Elevated plasma sTM levels are associated with organ dysfunction in children with ARDS and with higher mortality in children with indirect lung injury. These findings highlight the importance of endothelial injury in children with ARDS and may guide the development of future therapies targeted toward endothelial stabilization, repair, or functional replacement in this population.

Decreased levels of procoagulant phospholipids in bleeding patients treated by vitamin K antagonists

International Normalized Ratio (INR) is currently used to monitor vitamin K antagonist therapy, and the bleeding incidence becomes exponential for INR>4.5. Inversely, more than 50% of patients with a supratherapeutic INR are asymptomatic. Therefore it could be of interest to identify patients with a higher bleeding risk. Microparticles derived from different cell types express procoagulant phospholipids (PPL) which can be evaluated by a chronometric coagulation assay where a shortening of the clotting times is associated with increased levels of PPL. In a series of 174 consecutive patients referred to our Emergency Department with an INR>5, median level of PPL was significantly (p=0.004) lower (38.2s) in the 119 asymptomatic patients than in patients with nonmajor (43.6s, n=35) or major bleeding (46.6s, n=19), indicating higher levels of procoagulant phospholipids in asymptomatic patients. By receiver operating characteristic curve analysis, a cut-off of 43.5s discriminated patients with higher haemorrhagic risk (area under the curve=0.648). In contrast, thrombomodulin levels, quantified either by immunological or functional assays were not significantly different between both groups. In conclusion, evaluation of PPL could be of interest to define the haemorrhagic risk of VKA- treated patients.

Thrombomodulin as an intravascular safeguard against inflammatory and thrombotic diseases

INTRODUCTION

Thrombomodulin is a transmembrane protein expressed on the surface of endothelial cells. It plays an important role in regulating inflammation as well as coagulation within blood vessels. Recently, a recombinant form of an extracellular fragment of thrombomodulin (rTM) has been developed and is expected to be useful for patients suffering from inflammatory and thrombotic diseases.

AREAS COVERED

We initially focus on the physiological and biochemical features of thrombomodulin, including its distribution, structure and function. We then discuss potential therapeutic applications of rTM.

EXPERT OPINION

Thrombomodulin exerts anticoagulant and anti-inflammatory effects, in part through activated protein C (APC)-dependent mechanisms. Although recombinant human APC (rhAPC) failed to improve the survival of patients with septic shock and has now been withdrawn from the market, rTM may have some advantages over rhAPC. First, rTM may have less risk of bleeding complications than rhAPC, because rTM needs thrombin to act as an anticoagulant and thus its anticoagulant power can be automatically adjusted by the amount of existing thrombin. Second, the APC-independent actions of rTM might confer benefits, including the suppression of complements, endotoxin (representative pathogen-associated molecular pattern) and high-mobility group box 1 protein (prototypical damage-associated molecular pattern) through the lectin-like domain of rTM.

Potential diagnostic markers for disseminated intravascular coagulation of sepsis

Disseminated intravascular coagulation (DIC) is an acquired thrombo-haemorrhagic disorder which arises in clinical scenarios like sepsis, trauma and malignancies. The clinic-laboratory diagnosis of DIC is made in a patient who develops the combination of laboratory abnormalities in the appropriate clinical scenario. The most common laboratory parameters in this setting have been the clotting profile, platelet count, serum fibrinogen and fibrin degradation markers. These tests had the advantage that they could be performed easily and in most laboratories. However, with the better understanding of the pathophysiology of DIC, in recent years, more specific tests have been suggested to be useful in this setting. The newer tests can also prove to be useful in prognostication in DIC. In addition, they may provide assistance in the selection and monitoring of patients diagnosed with DIC.

Thrombomodulin gene proximal promoter polymorphisms in premature acute coronary syndrome patients in Bahrain

Thrombomodulin is expressed on endothelial cells and monocytes (mTM) where it has an anticoagulant function. Enzymatic cleavage from the cell surface produces soluble thrombomodulin (sTM) in plasma. Abnormal levels of sTM and mutations in the thrombomodulin gene (THBD) are linked to cardiovascular disease. The aim of this study was to investigate THBD proximal promoter mutations and levels of sTM and mTM in men presenting with premature acute coronary syndrome (ACS). This prospective cross-sectional study included 100 adult men with premature ACS (age <55 years) and 60 healthy age-matched controls. Plasma sTM was assayed by ELISA. mTM expression was assessed by flow cytometry with CD141 antibody. The -33 G/A polymorphism was identified by PCR-restriction fragment length polymorphism analysis and the THBD proximal promoter region was sequenced. Significantly lower sTM (P < 0.001) and higher mTM (P < 0.001) were seen in ACS patients. Heterozygous THBD promoter polymorphisms -33 G/A and -9/-10 GG/AT were found in eight patients and five control individuals. In patients and control individuals, allele frequencies of A were 0.02 and 0.025, and that of AT were 0.025 and 0.017, respectively. There were no significant associations of these polymorphisms with ACS, sTM levels or mTM expression. THBD polymorphisms -33 G/A and -9/-10 GG/AT are present in low frequency in our patient population, and are more frequent in the South Asians as compared to the Arabs. The frequency of -33 G/A is lower, whereas that of -9/-10 GG/AT is higher than that reported in the Orientals. The presence of THBD proximal promoter polymorphisms do not explain variations in levels of sTM and mTM in this patient population.

Local hemostasis, immunothrombosis, and systemic disseminated intravascular coagulation in trauma and traumatic shock

Knowing the pathophysiology of trauma-induced coagulopathy is important for the management of severely injured trauma patients. The aims of this review are to provide a summary of the recent advances in our understanding of thrombosis and hemostasis following trauma and to discuss the pathogenesis of disseminated intravascular coagulation (DIC) at an early stage of trauma. Local hemostasis and thrombosis respectively act to induce physiological wound healing of injuries and innate immune responses to damaged-self following trauma. However, if overwhelmed by systemic inflammation caused by extensive tissue damage and tissue hypoperfusion, both of these processes foster systemic DIC associated with pathological fibrin(ogen)olysis. This is called DIC with the fibrinolytic phenotype, which is characterized by the activation of coagulation, consumption coagulopathy, insufficient control of coagulation, and increased fibrin(ogen)olysis. Irrespective of microvascular thrombosis, the condition shows systemic thrombin generation as well as its activation in the circulation and extensive damage to the microvasculature endothelium. DIC with the fibrinolytic phenotype gives rise to oozing-type non-surgical bleeding and greatly affects the prognosis of trauma patients. The coexistences of hypothermia, acidosis, and dilution aggravate DIC and lead to so-called trauma-induced coagulopathy.

He that would know what shall be must consider what has been.

The Analects of Confucius.

Thrombomodulin promotes diabetic wound healing by regulating toll-like receptor 4 expression

Keratinocyte-expressed thrombomodulin (TM) and the released soluble TM (sTM) have been demonstrated to promote wound healing. However, the effects of high glucose on TM expression in keratinocytes and the role of TM in diabetic ulcer remain unclear. In this study, we demonstrated that expressions of TM and Toll-like receptor 4 (TLR4) were both downregulated in high-glucose cultured human keratinocytes and in skin keratinocytes of diabetic patients. In addition, the wound-triggered upregulation of TM and sTM production was abolished in both high-glucose cultured human keratinocytes and streptozotocin-induced diabetic mouse skin. Furthermore, supplementation of recombinant sTM could increase TLR4 expression and promote cutaneous wound healing in both high-glucose cultured human keratinocytes and diabetic mice. However, in Tlr4-deleted mice, which exhibited delayed wound healing, the therapeutic benefit of recombinant sTM was abrogated. Moreover, our results showed that tumor necrosis factor-α (TNF-α) expression in keratinocytes was dose-dependently upregulated by glucose, and TNF-α treatment downregulated the expression of TM and TLR4. Taken together, high-glucose environment reduces the expression of TM and TLR4 in keratinocytes possibly through the action of TNF-α, and recombinant sTM can increase the TLR4 expression and promote wound healing under diabetic condition.

Plasma soluble thrombomodulin levels are associated with mortality in the acute respiratory distress syndrome

OBJECTIVE

Thombomodulin (TM) is an activator of protein C and a biomarker for endothelial injury. We hypothesized that (1) elevated plasma levels would be associated with clinical outcomes and (2) polymorphisms in the TM gene would be associated with plasma levels.

PATIENTS

We studied 449 patients enrolled in the Fluid and Catheter Treatment Trial (FACTT) for whom both plasma and DNA were available. We used logistic regression and receiver operator curves (ROC) to test for associations between soluble TM (sTM) and mortality at 60 days.

MEASUREMENTS AND RESULTS

Plasma sTM levels were higher in non-survivors than survivors at baseline [median 147 (IQR, 95-218) vs. 89 (56-129) ng/mL, p < 0.0001] and on day 3 after study enrollment [205 (146-302) vs. 127 (85-189), p < 0.0001]. The odds of death increased by 2.4 (95 % CI 1.5-3.8, p < 0.001), and by 2.8 (1.7-4.7, P < 0.001) for every log increase in baseline and day 3 sTM levels, respectively, after adjustment for age, race, gender, severity of illness, fluid management strategy, baseline creatinine, and non-pulmonary sepsis as the primary cause of ARDS. By ROC analysis, plasma sTM levels discriminated between non-survivors and survivors [AUC = 72 % (66-78 %) vs. AUC = 54 % for severity based on Berlin criteria). Addition of sTM improved discrimination based on APACHE III from 77 to 80 % (P < 0.03). sTM levels at baseline were not statistically different among subjects stratified by genotypes of tag SNPs in the TM gene.

CONCLUSIONS

Higher plasma sTM levels are associated with increased mortality in ARDS. The lack of association between the sTM levels and genetic variants suggests that the increased levels of sTM may reflect severity of endothelial damage rather than genetic heterogeneity. These findings underscore the importance of endothelial injury in ARDS pathogenesis and suggest that, in combination with clinical markers, sTM could contribute to risk stratification.

Characterization of an autosomal dominant bleeding disorder caused by a thrombomodulin mutation

We describe a family with an autosomal dominant disorder characterized by severe trauma- and surgery-related bleeding. The proband, who experienced life-threatening bleeding during a routine operation, had normal clotting times, but markedly reduced prothrombin consumption. Plasma levels of all coagulation factors and of the main coagulation inhibitors were normal. Thrombin generation at low triggers was severely impaired and mixing experiments suggested the presence of a coagulation inhibitor. Using whole exome sequencing, the underlying genetic defect was identified as the THBD c.1611C>A mutation (p.Cys537Stop), which predicts a truncated form of thrombomodulin that is shed from the vascular endothelium. The patient had decreased expression of endothelium-bound thrombomodulin, but extremely elevated levels of soluble thrombomodulin in plasma, impairing the propagation phase of coagulation via rapid activation of protein C and consequent inactivation of factors Va and VIIIa. The same thrombomodulin mutation has been recently described in an unrelated British family with strikingly similar features.

Changes in cardiac thrombomodulin and heat shock transcription factor 1 expression and peripheral thrombomodulin and catecholamines during hypothermia in rats

Effects of hypothermia and rewarming on thrombomodulin, catecholamines and heat shock transcription factor 1 (HSF1) were studied in rats. The aims of this study were to clarify whether cold stress, under anesthesia, is sufficient to change levels of thrombomodulin in healthy endothelium and in the circulation and whether adrenaline, noradrenaline and HSF1 could act as regulators in the process. Rats were divided into control, mild hypothermia (2 and 4.5 hours at + 21 °C; MH1, MH2), severe hypothermia (2 and 4.5 h at + 10 °C; SH1, SH2) and two rewarming groups (2 h at + 10 °C followed by 2 h at + 21 °C or 3 h at + 28 °C; SHW1, SHW2) (n = 15/group, except n = 6 in MH1). Fentanyl-fluanisone-midazolam was used as anesthetic. Low levels of thrombomodulin in plasma and myocardial arterioles/venules measured by ELISA and immunohistochemistry were associated with significant increase of thrombomodulin transcript level in SH1 rats analyzed by quantitative PCR. Plasma adrenaline correlated negatively with the relative amount of myocardial thrombomodulin transcripts and positively with plasma thrombomodulin in SH. Transcript levels of thrombomodulin and HSF1 correlated strongly (r = 0.83; p < 0.001) in SH. Plasma/urine ratio of thrombomodulin and plasma adrenaline (r = 0.87; p = 0.005) or noradrenaline (r = 0.78; p = 0.023) were strongly correlated in SHW1 rats. Hence, cellular and soluble levels of thrombomodulin are modified by cold stress in healthy rats, possibly via catecholamines and HSF1.