Thrombomodulin as an intravascular safeguard against inflammatory and thrombotic diseases

Thrombomodulin Improves Cognitive Deficits in Heat-Stressed Mice

BACKGROUND

Thrombomodulin (TM) exerts anticoagulant and anti-inflammatory effects to improve the survival of patients with septic shock. Heat stroke resembles septic shock in many aspects. We tested whether TM would improve cognitive deficits and related causative factors in heat-stressed (HS) mice.

METHODS

Adult male mice were exposed to HS (33°C for 2 hours daily for 7 consecutive days) to induce cognitive deficits. Recombinant human soluble TM (1 mg/kg, i.p.) was administered immediately after the first HS trial and then once daily for 7 consecutive days. We performed the Y-maze, novel objective recognition, and passive avoidance tests to evaluate cognitive function. Plasma levels of lipopolysaccharide (LPS), high-mobility group box 1 (HMGB1), coagulation parameters, and both plasma and tissue levels of inflammatory and oxidative stress markers were biochemically measured. The duodenum and hippocampus sections were immunohistochemically stained. The intestinal and blood-brain barrier permeability were determined.

RESULTS

Compared with controls, HS mice treated with TM had lesser extents of cognitive deficits, exacerbated stress reactions, gut barrier disruption, endotoxemia, blood-brain barrier disruption, and inflammatory, oxidative, and coagulatory injury to heart, duodenum, and hippocampal tissues, and increased plasma HMGB1. In addition to reducing cognitive deficits, TM therapy alleviated all the abovementioned complications in heat-stressed mice.

CONCLUSIONS

The findings suggest that HS can lead to exacerbated stress reactions, endotoxemia, gut barrier disruption, blood-brain barrier disruption, hippocampal inflammation, coagulopathy, and oxidative stress, which may act as causative factors for cognitive deficits. TM, an anti-inflammatory, antioxidant, and anti-coagulatory agent, inhibited heat stress-induced cognitive deficits in mice.

Trauma diagnostic-related target proteins and their detection techniques

Trauma is a significant health issue that not only leads to immediate death in many cases but also causes severe complications, such as sepsis, thrombosis, haemorrhage, acute respiratory distress syndrome and traumatic brain injury, among trauma patients. Target protein identification technology is a vital technique in the field of biomedical research, enabling the study of biomolecular interactions, drug discovery and disease treatment. It plays a crucial role in identifying key protein targets associated with specific diseases or biological processes, facilitating further research, drug design and the development of treatment strategies. The application of target protein technology in biomarker detection enables the timely identification of newly emerging infections and complications in trauma patients, facilitating expeditious medical interventions and leading to reduced post-trauma mortality rates and improved patient prognoses. This review provides an overview of the current applications of target protein identification technology in trauma-related complications and provides a brief overview of the current target protein identification technology, with the aim of reducing post-trauma mortality, improving diagnostic efficiency and prognostic outcomes for patients.

The Coagulopathy of Acute Promyelocytic Leukemia: An Updated Review of Pathophysiology, Risk Stratification, and Clinical Management

Acute promyelocytic leukemia (APL) has a well-established mechanism and a long-term prognosis that exceeds that of any other acute leukemia. These improving outcomes are due, in part, to all-trans retinoic acid (ATRA) and arsenic trioxide (ATO), two targeted and highly active agents in this disease. However, there remains a considerable morbidity and mortality risk in APL secondary to clinically significant hemorrhagic and/or thrombotic events. Prevention and treatment of these coagulopathic complications remain significant impediments to further progress in optimizing outcomes for patients with APL. Moreover, the relative rarity of APL hinders adequately powered randomized controlled trials for evaluating APL coagulopathy management strategies. This review draws from peer-reviewed works falling between initial descriptions of APL in 1957 and work published prior to January 2023 and provides an updated overview of the pathophysiology of hemorrhagic and thrombotic complications in APL, outlines risk stratification parameters, and compiles current clinical best practices. An improved understanding of the pathophysiologic mechanisms driving hemorrhage and thrombosis along with the completion of well-designed trials of management strategies will assist clinicians in developing interventions that mitigate these devastating complications in an otherwise largely curable disease.

α1-Adrenergic Stimulation Increases Platelet Adhesion to Endothelial Cells Mediated by TRPC6

Stimulation of a1-adrenergic nervous system is increased during systemic inflammation and other pathological conditions with the consequent adrenergic receptors (ARs) activation. It has been reported that a1-stimulation contributes to coagulation since a1-AR blockers inhibit coagulation and its organic consequences. Also, coagulation induced by a1-AR stimulation can be greatly decreased using a1-AR blockers. In health, endothelial cells (ECs) perform anticoagulant actions at cellular and molecular level. However, during inflammation, ECs turn dysfunctional promoting a procoagulant state. Endothelium-dependent coagulation progresses at cellular and molecular levels, promoting endothelial acquisition of procoagulant properties to potentiate coagulation by means of prothrombotic and antifibrinolytic proteins expression increase in ECs releasing them to circulation, the thrombus formation is strengthened. Calcium signaling is a main feature of coagulation. Inhibition of ion channels involved in Ca²⁺ entry severely decreases coagulation. The transient receptor potential canonical 6 (TRPC6) is a non-selective Ca²⁺-permeable ion channel. TRPC6 activity is induced by diacylglycerol, suggesting that is regulated by a1-ARs. Furthermore, a1-ARs stimulation elicits a TRPC-like current in rat mesenteric artery smooth muscle and mesangial cells. However, whether TRPC6 could promote an ECs-mediated platelet adhesion induced by a1-adrenergic stimulation is currently not known. Therefore, the aim of this study was to examine if the TRPC6 calcium channel mediates platelet adhesion induced by a1-adrenergic stimulation. Our results suggest that platelet adhesion to ECs is enhanced by the a1-adrenergic stimulation evoked by phenylephrine mediated by TRPC6 activity. We conclude that TRPC6 is a molecular determinant in platelet adhesion to ECs with implications in systemic inflammatory diseases treatment.

Effect of Therapeutically Related Drugs on Coagulation-Anticoagulation Balance in Acute Promyelocytic Leukemia

Acute promyelocytic leukemia (APL) usually presents with a series of coagulation-anticoagulation disturbance. Early administration of All-trans retinoic acid (ATRA) can reduce the risk of bleeding, but the potential for thrombosis needs to be addressed in some cases. The role of arsenic agent in correcting coagulation disorder remains to be studied, but oral arsenic agent shows potential advantages in coagulation recovery compared with intravenous agent, and chemotherapy can aggravate the progress of coagulation disease. In addition to early application of ATRA, avoiding invasive procedures and transfusion support can reduce the risk of bleeding. Whether the administration of heparin, thrombomodulin, recombinant factor VIIa or antifibrinolytics reduces the risk of bleeding and thrombosis associated with APL remains to be further explored, and their routine use outside of clinical trials is not recommended. This article reviews the effects of related drugs on coagulation-anticoagulation balance in APL patients.

An evaluation of circulating activated TAFI in septic DIC: a case series and review of the literature

Background

Administration of recombinant human soluble thrombomodulin (rTM) is often used in Japan to treat septic disseminated intravascular coagulation (DIC). Thrombin-activatable fibrinolysis inhibitor (TAFI) is a fibrinolysis inhibitor activated by the thrombin-thrombomodulin complex, however, it is unknown whether circulating activated TAFI is increased after rTM administration in patients with DIC. Furthermore, the relationship between TAFI activation and the prognosis of septic DIC is not defined yet.

Case presentation

We report a series of 8 patient’s TAFI activation with septic DIC treated by rTM. We sought to investigate the effect of rTM on TAFI activation and the association of plasma activated TAFI (TAFIa/ai) levels with the prognosis of septic DIC.

Using plasma samples from clinical studies conducted from May 2016–March 2017 on eight patients with septic DIC at Kagoshima University Hospital, we measured plasma levels of total TAFI, TAFIa/ai, thrombin-antithrombin complex (TAT), prothrombin fragment 1 + 2 (F1 + 2), soluble fibrin (SF), antithrombin (AT), protein C (PC), protein S (PS), and plasminogen activator inhibitor-1 (PAI-1) before and after intravenous rTM administration. Then, we evaluated the relationship of these marker levels to prognosis. The thrombin-rTM complex activated TAFI in vitro in plasma from a healthy volunteer. However, TAFIa/ai levels did not significantly increase over baseline in the septic DIC patients after intravenous rTM administration. Baseline TAFIa/ai levels in non-survivors were significantly higher than those in survivors.

Conclusions

Plasma TAFIa/ai did not increase with rTM administration. Elevated baseline TAFIa/ai concentration may be a negative prognostic indicator in septic DIC. Larger studies are needed to confirm the in vivo effect of rTM on TAFI activation.

Signaling pathways and intervention therapies in sepsis

Sepsis is defined as life-threatening organ dysfunction caused by dysregulated host systemic inflammatory and immune response to infection. Over decades, advanced understanding of host-microorganism interaction has gradually unmasked the genuine nature of sepsis, guiding toward new definition and novel therapeutic approaches. Diverse clinical manifestations and outcomes among infectious patients have suggested the heterogeneity of immunopathology, while systemic inflammatory responses and deteriorating organ function observed in critically ill patients imply the extensively hyperactivated cascades by the host defense system. From focusing on microorganism pathogenicity, research interests have turned toward the molecular basis of host responses. Though progress has been made regarding recognition and management of clinical sepsis, incidence and mortality rate remain high. Furthermore, clinical trials of therapeutics have failed to obtain promising results. As far as we know, there was no systematic review addressing sepsis-related molecular signaling pathways and intervention therapy in literature. Increasing studies have succeeded to confirm novel functions of involved signaling pathways and comment on efficacy of intervention therapies amid sepsis. However, few of these studies attempt to elucidate the underlining mechanism in progression of sepsis, while other failed to integrate preliminary findings and describe in a broader view. This review focuses on the important signaling pathways, potential molecular mechanism, and pathway-associated therapy in sepsis. Host-derived molecules interacting with activated cells possess pivotal role for sepsis pathogenesis by dynamic regulation of signaling pathways. Cross-talk and functions of these molecules are also discussed in detail. Lastly, potential novel therapeutic strategies precisely targeting on signaling pathways and molecules are mentioned.

A novel homozygous variant of the thrombomodulin gene causes a hereditary bleeding disorder

We report a 19-year-old Vietnamese woman who experienced several life-threatening bleeding events, including ovarian hemorrhage. Blood analysis revealed a decreased fibrinogen level with markedly elevated fibrinogen/fibrin degradation products and D-dimer levels. Despite hemostatic surgery and administration of several medications, such as nafamostat mesylate, tranexamic acid, and unfractionated heparin, the coagulation abnormalities were not corrected, and the patient experienced repeated hemorrhagic events. We found that administration of recombinant human thrombomodulin (rhTM) remarkably improved the patient's pathophysiology. Screening and sequencing of the TM gene (THBD) revealed a previously unreported homozygous variation: c.793T>A (p.Cys265Ser). Notably, the Cys265 residue forms 1 of 3 disulfide bonds in the epidermal growth factor (EGF)-like domain 1 of TM. Transient expression experiments using COS-1 cells demonstrated markedly reduced expression of TM-Cys265Ser on the plasma membrane relative to wild-type TM. The TM-Cys265Ser mutant was intracellularly degraded, probably because of EGF-like domain 1 misfolding. The reduced expression of TM on the endothelial cell membrane may be responsible for the disseminated intravascular-coagulation-like symptoms observed in the patient. In summary, we identified a novel TM variant, c.793T>A (p.Cys265Ser). Patients homozygous for this variant may present with severe bleeding events; rhTM should be considered a possible treatment option for these patients.

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.

Specific detection of high mobility group box 1 degradation product with a novel ELISA

BACKGROUND

During sepsis or sterile tissue injury, the nuclear protein high mobility group box 1 (HMGB1) can be released to the extracellular space and ultimately into systemic circulation, where it mediates systemic inflammation and remote organ failure. The proinflammatory effects of HMGB1 can be suppressed by recombinant thrombomodulin (rTM), in part through a mechanism involving thrombin-rTM-mediated degradation of HMGB1. Given that HMGB1 is proinflammatory but the HMGB1 degradation product (desHMGB1) is not, an analytical method that discriminates between these two molecules may provide a more in-depth understanding of HMGB1-induced pathogenicity as well as rTM-mediated therapeutic efficiency.

METHODS

A peptide that has a shared amino-terminal structure with desHMGB1 was synthesized. C3H/lpr mice were immunized with the desHMGB1 peptide conjugate, and antibody-secreting hybridoma cells were developed using conventional methods. The reactivity and specificity of the antibodies were then analyzed using antigen-coated enzyme-linked immunosorbent assay (ELISA) as well as antibody-coated ELISA. Next, plasma desHMGB1 levels were examined in a cecal ligation and puncture (CLP)-induced septic mouse model treated with rTM.

RESULTS

Through a series of screening steps, we obtained a monoclonal antibody that recognized desHMGB1 but did not recognize intact HMGB1. ELISA using this antibody specifically detected desHMGB1, which was significantly increased in CLP-induced septic mice treated with rTM compared with those treated with saline.

CONCLUSIONS

In this study, we obtained a desHMGB1-specific monoclonal antibody. ELISA using the novel monoclonal antibody may be an option for the in-depth analysis of HMGB1-induced pathogenicity as well as rTM-mediated therapeutic efficiency.

Elevated plasma levels of syndecan-1 and soluble thrombomodulin predict adverse outcomes in thrombotic thrombocytopenic purpura

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a potentially fatal blood disorder resulting from acquired deficiency of plasma ADAMTS13 activity. Despite recent advances in early diagnosis and novel therapeutics, the mortality rate of acute iTTP remains as high as 10% to 20%. Moreover, a reliable clinical and laboratory parameter that predicts disease severity and outcomes is lacking. We show in the present study that plasma levels of syndecan-1 (Sdc-1) and soluble thrombomodulin (sTM) on admission were dramatically increased in patients with acute iTTP and remained substantially elevated in a subset of patients compared with healthy controls. The elevated admission plasma levels of Sdc-1 and sTM were associated with abnormal Glasgow coma scale scores, low estimated glomerular filtration rates, the need for intensive care, and in-hospital mortality rates. Moreover, a further simultaneous increase in plasma Sdc-1 and sTM levels at the time of clinical response/remission (eg, when normalization of platelet counts and substantial reduction of serum lactate dehydrogenase activity were achieved) was highly predictive of iTTP recurrence. These results demonstrate that endothelial injury, resulting from disseminated microvascular thromboses, is severe and persistent in patients with acute iTTP. Plasma levels of Sdc-1 and sTM on admission and in remission are predictive of in-hospital mortality and recurrence of acute iTTP, respectively. Thus, an incorporation of such novel plasma biomarkers into the risk assessment in acute iTTP may help implement a more vigorous and intensive therapeutic strategy for these patients.

Recombinant Thrombomodulin Attenuates Preeclamptic Symptoms by Inhibiting High-Mobility Group Box 1 in Mice

Preeclampsia (PE) is a common gestational complication that involves systemic endothelial dysfunction and inflammatory responses primarily due to placental damage. Recombinant thrombomodulin (rTM), a novel anticoagulant clinically used for disseminated intravascular coagulation, is reported to have a unique anti-inflammatory endothelial repair function by inhibiting proinflammatory mediator high-mobility group box 1 (HMGB1). Despite the severe patient outcomes, there are currently no effective therapeutic options to treat PE. Here, we verified the efficacy of rTM as a novel therapeutic agent for PE using a murine model and human trophoblast cells. We revealed the therapeutic potential of rTM in an angiotensin II(Ang II)-induced PE mouse model. Injection of rTM significantly attenuated clinical features of PE, such as hypertension, proteinuria, fetal growth restriction, and impaired placental vasculature. Elevation of maternal soluble fms-like tyrosine kinase-1 (sFlt-1), a well-accepted causal factor of PE that induces systemic endothelial dysfunction, was suppressed in response to rTM treatment. Supporting these findings, our in vitro experiments revealed that rTM reduces Ang II-triggered overproduction of sFlt-1 in human trophoblast cells. Moreover, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), well-known key inflammatory mediators in PE pathogenesis, were diminished by rTM. SiRNA knockdown experiments further determined that these processes were directly mediated by HMGB1. Our studies demonstrate that rTM exerts its clinical effect as HMBG1 inhibitor and ameliorates placental dysfunction, which is central to PE pathogenesis. Our findings suggest that rTM could be a promising therapeutic that significantly improve the outcomes of PE patients.

Effects of thrombomodulin alfa on hemostatic parameters in disseminated intravascular coagulation: Post hoc analysis of a phase 3 randomized controlled trial

BACKGROUND

The efficacy and safety of thrombomodulin alfa (TM-α), a cofactor protein promoting thrombin-mediated protein C activation, have been examined in a phase 3 randomized, double-blinded, parallel-group trial in Japan. We have previously reported that TM-α is noninferior to heparin for the resolution of disseminated intravascular coagulation (DIC).

OBJECTIVE

To investigate the basis for the efficacy of TM-α in the phase 3 clinical trial in Japan through post hoc analysis of coagulation and fibrinolysis parameters.

PATIENTS/METHODS

The 227 patients of the full analysis set population described in the original phase 3 trial in Japan were included in this analysis. Changes in parameters between before and after TM-α or heparin administration in each of the two patient groups, with underlying diseases of either hematologic malignancy or infection, were studied separately and results were compared between TM-α and heparin treatment groups in a post hoc manner.

RESULTS

TM-α administration did not prolong activated partial thromboplastin time but significantly decreased thrombin-antithrombin complex levels compared with heparin treatment. TM-α administration reduced consumption of endogenous anticoagulants such as antithrombin and protein C by DIC, compared with the heparin group. DIC scores were decreased in both TM-α and heparin groups during the 6-day treatment.

CONCLUSION

TM-α can alleviate intravascular coagulation and consumption of anticoagulants without extending coagulation times. This may be associated with the relatively low risk of bleeding during TM-α treatment.

Recombinant Thrombomodulin in Disseminated Intravascular Coagulation Associated with Stage IV Solid Tumors: A Nationwide Observational Study in Japan

OBJECTIVE

 The terminal stage of solid tumors sometimes induces disseminated intravascular coagulation (DIC); however, no useful therapeutic strategies have been established. This study investigated the relationship between mortality and recombinant human soluble thrombomodulin (rTM) therapy for patients with DIC associated with stage IV solid tumors using a large nationwide inpatient database.

METHODS

 Using the Japanese Diagnosis Procedure Combination Inpatient Database, patients with stage IV solid tumors who developed DIC were identified. Those who received rTM within 3 days of admission were included in the treatment group; the remaining were included in the control group. The primary outcome was the 28-day in-hospital mortality.

RESULTS

 Of 25,299 eligible patients, 1 to 4 propensity score matching was used to select 1,979 rTM users and 7,916 nonusers. There was no significant difference in the 28-day mortality (control vs. rTM: 37.4% vs. 34.3%; hazard ratio, 0.95; 95% confidence interval [CI], 0.88-1.04) and critical bleeding rate (control vs. rTM: 3.7% vs. 3.8%; odds ratio, 1.04; 95% CI, 0.75-1.42) between groups. Subgroup analyses showed that the 28-day mortality rate among patients with colorectal and gynecological cancer was significantly lower in the rTM than in the control group (p for interaction 0.033 and 0.010, respectively).

CONCLUSION

 Although we identified a possibly beneficial association between rTM administration and mortality in specific populations of patients with colorectal and gynecological cancer, no such association was found when considering the entire cohort of patients with DIC associated with stage IV solid tumors.

A critical role of the Gas6-Mer axis in endothelial dysfunction contributing to TA-TMA associated with GVHD

Endothelial dysfunction in the early phases of hematopoietic stem cell transplantation (HSCT) contributes to a common pathology between transplant-associated thrombotic microangiopathy (TA-TMA) and graft-versus-host disease (GVHD), which are serious complications of HSCT. Growth arrest-specific (Gas) 6 structurally belongs to the family of plasma vitamin K-dependent proteins working as a cofactor for activated protein C, and has growth factor-like properties through its interaction with receptor tyrosine kinases of the TAM family: Tyro3, Axl, and Mer. Serum Gas6 levels were significantly increased in HSCT patients with grade II to IV acute GVHD (aGVHD), and Gas6 and Mer expression levels were upregulated in aGVHD lesions of the large intestine and skin. The increased serum Gas6 levels were also correlated with elevated lactate dehydrogenase, d-dimer, and plasmin inhibitor complex values in HSCT patients with aGVHD. In human umbilical vein endothelial cells (ECs), exogenous Gas6 or the exposure of sera isolated from patients with grade III aGVHD to ECs induced the downregulation of thrombomodulin and the upregulation of PAI-1, as well as the upregulation of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1, which were inhibited by UNC2250, a selective Mer tyrosine kinase inhibitor. In mouse HSCT models, we observed hepatic GVHD with hepatocellular apoptosis, necrosis, and fibrosis, as well as TA-TMA, which is characterized pathologically by thrombosis formation in the microvasculature of the liver and kidney. Of note, intravenous administration of UNC2250 markedly suppressed GVHD and TA-TMA in these mouse HSCT models. Our findings suggest that the Gas6-Mer axis is a promising target for TA-TMA after GVHD.

Role of high-mobility group box 1 and its modulation by thrombomodulin/thrombin axis in neuropathic and inflammatory pain

High-mobility group box 1 (HMGB1), a nuclear protein, once released to the extracellular space, facilitates pain signals as well as inflammation. Intraplantar or intraspinal application of HMGB1 elicits hyperalgesia/allodynia in rodents by activating the advanced glycosylation end-product specific receptor (receptor for advanced glycation end-products; RAGE) or Toll-like receptor 4 (TLR4). Endogenous HMGB1 derived from neurons, perineuronal cells or immune cells accumulating in the dorsal root ganglion or sensory nerves participates in somatic and visceral pain consisting of neuropathic and/or inflammatory components. Endothelial thrombomodulin (TM) and recombinant human soluble TM, TMα, markedly increase thrombin-dependent degradation of HMGB1, and systemic administration of TMα prevents and reverses various HMGB1-dependent pathological pain. Low MW compounds that directly inactivate HMGB1 or antagonize HMGB1-targeted receptors would be useful to reduce various forms of intractable pain. Thus, HMGB1 and its receptors are considered to serve as promising targets in developing novel agents to prevent or treat pathological pain. LINKED ARTICLES: This article is part of a themed issue on Neurochemistry in Japan. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.4/issuetoc.

Extracellular HMGB1: a therapeutic target in severe pulmonary inflammation including COVID-19?

BACKGROUND

The 2019 novel coronavirus disease (COVID-19) causes for unresolved reasons acute respiratory distress syndrome in vulnerable individuals. There is a need to identify key pathogenic molecules in COVID-19-associated inflammation attainable to target with existing therapeutic compounds. The endogenous damage-associated molecular pattern (DAMP) molecule HMGB1 initiates inflammation via two separate pathways. Disulfide-HMGB1 triggers TLR4 receptors generating pro-inflammatory cytokine release. Extracellular HMGB1, released from dying cells or secreted by activated innate immunity cells, forms complexes with extracellular DNA, RNA and other DAMP or pathogen-associated molecular (DAMP) molecules released after lytic cell death. These complexes are endocytosed via RAGE, constitutively expressed at high levels in the lungs only, and transported to the endolysosomal system, which is disrupted by HMGB1 at high concentrations. Danger molecules thus get access to cytosolic proinflammatory receptors instigating inflammasome activation. It is conceivable that extracellular SARS-CoV-2 RNA may reach the cellular cytosol via HMGB1-assisted transfer combined with lysosome leakage. Extracellular HMGB1 generally exists in vivo bound to other molecules, including PAMPs and DAMPs. It is plausible that these complexes are specifically removed in the lungs revealed by a 40% reduction of HMGB1 plasma levels in arterial versus venous blood. Abundant pulmonary RAGE expression enables endocytosis of danger molecules to be destroyed in the lysosomes at physiological HMGB1 levels, but causing detrimental inflammasome activation at high levels. Stress induces apoptosis in pulmonary endothelial cells from females but necrosis in cells from males.

CONCLUSION

Based on these observations we propose extracellular HMGB1 to be considered as a therapeutic target for COVID-19.

Bone marrow mesenchymal stem cells combine with normothermic machine perfusion to improve rat donor liver quality-the important role of hepatic microcirculation in donation after circulatory death

Donation after circulatory death (DCD) can expand the donor pool effectively. A gap remains in outcome between DCD livers and living donor livers, warranting improved DCD liver quality and urgent resolution. Bone marrow mesenchymal stem cells (BMMSCs) can regulate immunity, participate in the anti-inflammatory response, and secrete cytokines. We investigated the effect of BMMSCs combined with normothermic machine perfusion (NMP) on DCD liver quality, and the role of microcirculation therein. Rat thoracic aortas were clipped to obtain DCD livers, and a rat NMP system was established. The DCD livers were grouped by preservation method: normal, static cold storage (SCS), NMP (P), and BMMSCs plus NMP (BP); storage time was up to 8 h. Liver function in outflow perfusate was detected by biochemical methods; liver tissue histopathology was observed by hematoxylin–eosin staining; hepatocyte ultrastructure was observed by transmission electron microscopy; hepatocyte apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling; liver microcirculation–related indicators were detected by immunofluorescence, immunohistochemistry, Western blotting, and enzyme-linked immunosorbent assay. Compared with SCS, P and BP significantly improved liver function and liver histological damage, reduced hepatocyte apoptosis, and repaired hepatocyte mitochondrial damage after 6 h in vitro. BP also significantly inhibited intrahepatic macrophage activation and intercellular adhesion, improved endothelial damage, and significantly improved endothelin 1–nitric oxide balance and microcirculation perfusion. In conclusion, BP can improve DCD liver microcirculation and quality. The mechanism may be the improvement of improve hepatic sinusoidal endothelial injury and microcirculation perfusion by inhibiting macrophage activation and intercellular adhesion.

HMGB1 and its membrane receptors as therapeutic targets in an intravesical substance P-induced bladder pain syndrome mouse model

HMGB1, a nuclear protein, once released to the extracellular space, promotes somatic and visceral pain signals. We thus analyzed the role of HMGB1 in an intravesical substance P-induced bladder pain syndrome (BPS) mouse model. Intravesical administration of substance P caused referred hyperalgesia/allodynia in the lower abdomen and hindpaw without producing severe urothelial damage, which was prevented by an anti-HMGB1-neutralizing antibody, thrombomodulin α capable of inactivating HMGB1 and antagonists of RAGE or CXCR4. The HMGB1 inactivation or RAGE blockade also reversed the established bladder pain symptoms. HMGB1 and RAGE are thus considered to serve as therapeutic targets for BPS.

Berberine protects Kawasaki disease-induced human coronary artery endothelial cells dysfunction by inhibiting of oxidative and endoplasmic reticulum stress

Kawasaki disease (KD) is an acute febrile illness characterized by systemic vasculitis especially in coronary arteries. Berberine (BBR) shows several beneficial effects on cardiovascular system. The present study is to investigate whether BBR exerts protective effect against KD-induced damage of human coronary artery endothelial cell (HCAECs) and the underlying mechanisms. HCAECs exposed to medium with 15% serum from KD patients or healthy volunteers for 24 h. Stimulated HCAECs were treated with vehicle (without BBR) and BBR (20 μM) for 24 h, the cell apoptosis, cell cycle, induction of intracellular reactive oxygen species (ROS) and protein expression were examined by flow cytometry and western blot. The KD-induced differentially expressed proteins in HCAECs were determined by quantitative proteomics. BBR inhibited HCAECs from apoptosis and arrested cell cycle at G0/G1 stage. BBR protected HCAECs from injury by inhibiting expression of THBD, vWF and EDN1. Bioinformatics analysis suggested that the oxidative and ER stress were involved in KD-induced damage in HCAECs. ROS production and the protein expression of ATF4, p-EIF2α, p-PERK, XBP1, p-IRE1, HSP90B1, HSPG2, DNAJC3, P4HB and VCP were increased by serum from KD patients and decreased by BBR treatment. BBR exerts its protective effects on KD-induced damage of HCAECs through its inhibitory effects on oxidative and ER stress indicating BBR as a therapeutic candidate for KD.

Biomarkers of Vascular Injury and Type 2 Diabetes: A Prospective Study, Systematic Review and Meta-Analysis

Data on biomarkers of vascular injury and type 2 diabetes (T2D) risk from prospective studies are lacking. We evaluated seven biomarkers of vascular injury in relation to T2D. Additionally, a meta-analysis was performed. From the EPIC–Heidelberg cohort, 2224 participants were followed-up from baseline for 16 (median) years. E-Selectin, P-Selectin, intercellular adhesion molecule 3 (ICAM3), thrombomodulin, thrombopoietin, glycoprotein IIb/IIIa and fibrinogen levels were measured in baseline blood samples. The systematic review and meta-analysis included prospective studies identified through MEDLINE and Web of Science that investigated the association between mentioned biomarkers and T2D. The study population included 55% women, median age was 50 years, and 163 developed T2D. ICAM3 was associated with lower T2D risk (fully adjusted HR_{highest vs. lowest} tertile 0.62 (95% CI: 0.43, 0.91)), but no other studies on ICAM3 were identified. Overall, fifteen studies were included in the systematic review and meta-analysis (6,171 cases). E-Selectin was associated with higher T2D risk HR_{per SD}: 1.34 (95% CI: 1.16, 1.54; I² = 63%, n = 9 studies), while thrombomodulin was associated with lower risk HR_{per SD}: 0.82 (95% CI: 0.71, 0.95; I² = 0%, n = 2 studies). In the EPIC–Heidelberg, ICAM3 was associated with lower T2D risk. The meta-analysis showed a consistent positive association between E-Selectin and T2D. It was also suggestive of an inverse association between thrombomodulin and T2D, although further studies are needed to corroborate this finding.

Role of non-macrophage cell-derived HMGB1 in oxaliplatin-induced peripheral neuropathy and its prevention by the thrombin/thrombomodulin system in rodents: negative impact of anticoagulants

Background

Macrophage-derived high mobility group box 1 (HMGB1), a damage-associated molecular pattern (DAMP) protein, plays a key role in the development of chemotherapy-induced peripheral neuropathy (CIPN) caused by paclitaxel in rodents. Endothelial thrombomodulin (TM) promotes thrombin-induced degradation of HMGB1, and TMα, a recombinant human soluble TM, abolishes peripheral HMGB1-induced allodynia in mice. We thus examined whether HMGB1, particularly derived from macrophages, contributes to oxaliplatin-induced neuropathy in mice and analyzed the anti-neuropathic activity of the TM/thrombin system.

Methods

CIPN models were created by the administration of oxaliplatin in mice and rats, and the nociceptive threshold was assessed by von Frey test or paw pressure test. Macrophage-like RAW264.7 cells were stimulated with oxaliplatin in vitro. Proteins were detected and/or quantified by Western blotting, immunostaining, or enzyme-linked immunosorbent assay.

Results

Intraperitoneal administration of an anti-HMGB1-neutralizing antibody (AB) at 1 mg/kg prevented the oxaliplatin-induced allodynia in mice and rats. Antagonists of Toll-like receptor (TLR) 4, receptor for advanced glycation end products (RAGE) and CXCR4 among the HMGB1-targeted pro-nociceptive receptors, also mimicked the anti-neuropathic activity of AB in mice. Macrophage accumulation in the sciatic nerve was observed in mice treated with paclitaxel, but not oxaliplatin, and neither macrophage depletion nor inhibitors of macrophage activation affected oxaliplatin-induced allodynia. Oxaliplatin was 10- to 100-fold less potent than paclitaxel in releasing HMGB1 from macrophage-like RAW264.7 cells. Like AB, TMα at 10 mg/kg prevented the oxaliplatin-induced allodynia in mice as well as rats, an effect abolished by argatroban at 10 mg/kg, a thrombin inhibitor. The anti-neuropathic activity of TMα in oxaliplatin-treated mice was suppressed by oral anticoagulants such as warfarin at 1 mg/kg, dabigatran at 75 mg/kg, and rivaroxaban at 10 mg/kg, but not antiplatelet agents such as aspirin at 50 mg/kg and clopidogrel at 10 mg/kg. Repeated administration of the anticoagulants gradually developed neuropathic allodynia and elevated plasma HMGB1 levels in mice treated with a subeffective dose of oxaliplatin.

Conclusions

Our data thus suggests a causative role of HMGB1 derived from non-macrophage cells in oxaliplatin-induced peripheral neuropathy and a thrombin-dependent anti-neuropathic activity of exogenous TMα and, most probably, endogenous TM.

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.

Perioperative management of patients with atrial fibrillation receiving anticoagulant therapy

The number of patients with atrial fibrillation (AF) and the number of patients indicated for anticoagulant therapy have been increasing because AF would affect patient survival due to thromboembolism. Once AF develops, following the disappearance of pulsation, the circumstances within the atrium become prothrombotic and thrombus formation within the left atrium occurs in patients with AF. In recent years, not only warfarin but also new oral anticoagulants were introduced clinically and have become used as oral anticoagulants. In the perioperative period, the risk of major hemorrhage needs to be reduced. On the other hand, the suspension of anticoagulant therapy and neutralization of anticoagulant effects elevate the risk of thrombosis. The perioperative management of patients receiving anticoagulant therapy is different from that of scheduled surgery and emergency surgery. In addition, knowledge of the characteristics of each oral anticoagulant is required at drug cessation and resumption. Unlike warfarin, which has been used in the past five decades, direct oral anticoagulants (DOACs) do not have sensitive indicators such as prothrombin time-international normalized ratio. To avoid major hemorrhages and thromboembolism, quantitative assays can be implemented for DOAC monitoring and for reversal therapies in perioperative settings.

Cell and tissue responses at the interface with a chitosan hydrogel intended for vascular applications: in vitro and in vivo exploration

AIMS

The need for small caliber vessels to treat cardiovascular diseases has grown. However, synthetic polymers perform poorly in small-diameter applications. Chitosan hydrogels can provide a novel biological scaffold for vascular engineering. The goal of this study was to explore host cell and tissue behavior at the interface with chitosan-based scaffolds in vitro and in vivo.

METHODS AND RESULTS

in vitro, we assessed the ability of endothelial cells lining chitosan hydrogels to produce tissue factor (TF), thrombomodulin (TM) and nitric oxide. We showed that endothelial cells behave as a native endothelium since under stimulation, TF and TM expression increased and decreased, respectively. Endothelial cells seeded on chitosan produced nitric oxide, but no change was observed under stimulation. After in vivo subcutaneous implantation of chitosan hydrogels in rats, macrophage activation phenotypes, playing a crucial role in biomaterial/tissue, were explored by immunohistochemistry. Our results suggested a balance between pro- and anti-inflammatory signals since we observed an inflammatory response in favor of macrophage M2 phenotype.

CONCLUSION

in vitro exploration of endothelial cell response at the interface with chitosan hydrogel showed a functional endothelium and in vivo exploration of tissue response revealed a biointegration of chitosan hydrogels.

Thromboinflammation: challenges of therapeutically targeting coagulation and other host defense mechanisms

Thrombosis with associated inflammation (thromboinflammation) occurs commonly in a broad range of human disorders. It is well recognized clinically in the context of superficial thrombophlebitis (thrombosis and inflammation of superficial veins); however, it is more dangerous when it develops in the microvasculature of injured tissues and organs. Microvascular thrombosis with associated inflammation is well recognized in the context of sepsis and ischemia-reperfusion injury; however, it also occurs in organ transplant rejection, major trauma, severe burns, the antiphospholipid syndrome, preeclampsia, sickle cell disease, and biomaterial-induced thromboinflammation. Central to thromboinflammation is the loss of the normal antithrombotic and anti-inflammatory functions of endothelial cells, leading to dysregulation of coagulation, complement, platelet activation, and leukocyte recruitment in the microvasculature. α-Thrombin plays a critical role in coordinating thrombotic and inflammatory responses and has long been considered an attractive therapeutic target to reduce thromboinflammatory complications. This review focuses on the role of basic aspects of coagulation and α-thrombin in promoting thromboinflammatory responses and discusses insights gained from clinical trials on the effects of various inhibitors of coagulation on thromboinflammatory disorders. Studies in sepsis patients have been particularly informative because, despite using anticoagulant approaches with different pharmacological profiles, which act at distinct points in the coagulation cascade, bleeding complications continue to undermine clinical benefit. Future advances may require the development of therapeutics with primary anti-inflammatory and cytoprotective properties, which have less impact on hemostasis. This may be possible with the growing recognition that components of blood coagulation and platelets have prothrombotic and proinflammatory functions independent of their hemostatic effects.

Effects of recombinant thrombomodulin therapy and soluble human leukocyte antigen-G levels during hematopoietic stem cell transplantation

BACKGROUND

Conditioning chemotherapies for hematopoietic stem cell transplantation (HSCT), especially those that include total body irradiation, can result in serious complications such as graft-versus-host disease (GVHD). Human leukocyte antigen G (HLA-G) is a non-classical class I molecule with multiple immunoregulatory functions.

METHODS

We measured interleukin (IL)-10, transforming growth factor (TGF)β₁, and soluble HLA-G (sHLA-G) in HSCT patients and examined the relationship between sHLA-G levels and acute GVHD (aGVHD). Additionally, we investigated the effect of recombinant soluble thrombomodulin (rTM) therapy on sHLA-G levels. Our study cohort included 135 patients who underwent allogeneic HSCT at several institutions in Japan.

RESULTS

Serum levels of IL-10 and TGFβ₁ exhibited no significant changes following HSCT. In contrast, levels of sHLA-G were significantly increased at days 21 and 28 post-HSCT. For patients with confirmed complications, the frequency of aGVHD was significantly lower in those with a > 2.8-fold increase in sHLA-G levels at day 28 relative to day 7 post-HSCT. sHLA-G levels in patients who received rTM therapy were significantly higher at days 21 and 28 post-HSCT compared with those in patients who did not receive rTM therapy.

CONCLUSION

These data suggest that HLA-G/sHLA-G participate in prevention of GVHD, and that rTM may prevent aGVHD following HSCT by promoting elevation of sHLA-G.

Levels of circulating microparticles in septic shock and sepsis-related complications: a case-control study

BACKGROUND

Microparticles (MP) have been largely studied as potential biomarkers in septic shock (SS) though their biological and clinical relevance is still unclear. This case-control study describes the trend of various MP subtypes during SS to evaluate their possible association with severity of illness and sepsis-related complications (disseminated intravascular coagulation [DIC] and acute kidney injury [AKI]).

METHODS

Forty patients admitted to the Intensive Care Unit with SS and 40 matched healthy volunteers were recruited. AnnexinV+, E-selectin+, thrombomodulin (TM+), leukocyte-derived (CD45+, CD36+) and platelet-derived MP (PMP-expressed as PMP/platelets ratio) were measured by flow-cytometry at baseline, on day 1, 3 and 7 after diagnosis. Severity of illness was assessed by Sequential Organ Failure Assessment Score, duration of vasoactive support and mechanical ventilation. Sepsis-related complications were considered.

RESULTS

Overall, septic patients showed higher levels of all MP considered compared to controls. TM+MP were significantly lower in more severe sepsis, while CD36+MP and PMP/platelets ratio were significantly increased in patients requiring longer vasoactive support and mechanical ventilation. As for sepsis-related complications, a higher PMP/platelets ratio in patients who developed DIC and increased E-selectin+MP in subjects who developed AKI were observed. PMP/platelets ratio at baseline was significantly associated with longer vasoactive support (OR=1.59 [1.05-2.42]), longer mechanical ventilation (OR=1.6 [1.06-2.42]) and DIC occurrence (OR=1.45 [1.08-1.96]).

CONCLUSIONS

A global response through extra-vesiculation of endothelial cells, leukocytes and platelets during the early stages of SS was confirmed. The cellular activation was detected until day 3 after diagnosis. PMP/platelets ratio at diagnosis may be useful to evaluate SS severity and DIC occurrence.

Phosphodiesterase type 5 inhibitors improve microvascular dysfunction markers in pulmonary arterial hypertension associated with congenital heart disease

BACKGROUND

Ideally, vasodilator therapies for pulmonary arterial hypertension (PAH) should have a favorable impact on markers of vascular dysfunction, in addition to their known effects on hemodynamics, cardiac function, and patient's physical capacity.

METHODS

We analyzed circulating (plasma) markers of endothelial and platelet activation/dysfunction (enzyme-linked immunoassays) in the specific setting of advanced PAH associated with congenital heart disease, during the course of sildenafil and tadalafil therapies. Thirty-one patients were enrolled (age 10-54 years), most of them with chronic hypoxemia and elevated hematocrit. Drugs were administered orally for 6 months (sildenafil [n = 16], 20 mg t.i.d.; tadalafil [n = 15], single daily dose of 40 mg). Measurements were performed at baseline, and 90 and 180 days.

RESULTS

Compared to controls, patients had elevated baseline β-thromboglobulin (β-TG, P = .002), P-selectin (P = .027), tissue-type plasminogen activator (t-PA, P = .009), and von Willebrand factor antigen (VWF:Ag, P = .010). Thrombomodulin was importantly reduced (TM, P < .001), while soluble CD40 Ligand was not changed (P = .320). Tadalafil administration was associated with improvement of β-TG (P = .004), t-PA (P = .003) and TM (P = .046) levels, while P-selectin was improved by sildenafil treatment only (P = .034). VWF:Ag improved transiently in the sildenafil group (P = .019). Both therapies were associated with improvement of the physical capacity (functional class and distance walked during the 6-minute test, P < .05), hematocrit and hemoglobin level (P < .05), and health-related quality of life (physical and mental components, P < .05).

CONCLUSION

In PAH associated with congenital heart disease, phosphodiesterase 5 inhibitors seem to have beneficial actions at microcirculatory level, beyond the proposed effects as vasodilators.

Circulating activated protein C levels are not increased in septic patients treated with recombinant human soluble thrombomodulin

Background

Recombinant human soluble thrombomodulin (rTM) has been used for the treatment of disseminated intravascular coagulation in Japan, and an international phase III clinical trial for rTM is currently in progress. rTM mainly exerts its anticoagulant effects through an activated protein C (APC)-dependent mechanism, but the circulating APC levels after rTM treatment have not been clarified. This prospective observational study investigated plasma APC levels after rTM treatment.

Methods

Plasma levels of soluble thrombomodulin, thrombin-antithrombin complex (TAT), protein C, and APC were measured in eight septic patients treated with rTM. APC generation in vitro was assessed in the presence or absence of rTM.

Results

rTM significantly increased thrombin-mediated APC generation in vitro. In septic patients, soluble thrombomodulin levels were significantly increased during a 30–60-min period of rTM treatment and TAT levels were decreased. However, APC activity was not increased during the treatment period.

Conclusions

Plasma APC activity is not increased in septic patients treated with rTM. It is possible that APC acts locally and does not circulate systemically.

Electronic supplementary material

The online version of this article (10.1186/s12959-018-0178-0) contains supplementary material, which is available to authorized users.

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.

Innate networking: Thrombotic microangiopathy, the activation of coagulation and complement in the sensitized kidney transplant recipient

Thrombotic microangiopathy (TMA) is a histological feature of antibody-mediated rejection and has the potential to cause problematic graft dysfunction, particularly for highly sensitized cross-match positive kidney transplant recipients. Prompt recognition of pertinent histopathological and systemic features of TMA in kidney transplantation is necessary. Underlying mechanisms of this process involve the activation of both complement and coagulation systems as a response to HLA antibody. As serine proteases, coagulation and complement cascades exhibit similar characteristics with respect to homeostatic function. Increasing evidence now exists for the interaction between these innate defenses in both activation and regulation, lending scope for intervention. Understanding the complexities of these interactions remains a challenge. This review provides an overview of the current understanding, particularly with respect to the activation of coagulation and complement by HLA antibody in the setting of highly sensitized kidney transplantation.

Effects of probucol on atherosclerotic plaque and soluble thrombomodulin in patients with coronary heart disease

This study explored the effects of probucol on atherosclerotic plaques and soluble thrombomodulin in patients with coronary heart disease (CHD). Five hundred and eighty-three patients with CHD who were admitted to Jining First People's Hospital from February 2013 to February 2014. A total of 300 of them received conventional treatment, and were assigned to the control group, while the remaining 283 patients were treated with probucol in addition to the conventional treatment, and were assigned to the observation group. A retrospective analysis was performed on the total cholesterol levels, atherosclerotic plaque sizes, and soluble thrombomodulin levels. Probucol was administered at a dose of 500 mg twice a day for a period of 16 weeks. The total cholesterol level decreased gradually over time during the treatment. After 8 weeks of treatment, the total cholesterol level in the observation group was lower than that in the control group (P<0.05). After 8 weeks of treatment, the atherosclerotic plaque area in the observation group decreased compared with that before treatment (P<0.05). After 8 and 16 weeks of treatment, the plaque area in the observation group was smaller than that in the control group (P<0.05). The soluble thrombomodulin level at any time-point after treatment was lower than that before treatment in both groups (P<0.05). At the same time-point, the level in the observation group was lower than that in the control group (P<0.05). The total cholesterol and soluble thrombomodulin levels were positively correlated with the atherosclerotic plaque area (r=0.841, P=0.001; r=0.725, P=0.008). When patients with CHD were treated with probucol in addition to the conventional treatment, a reduction of the atherosclerotic plaque area, as well as a decrease of both the total cholesterol and soluble thrombomodulin levels, was observed. Overall, patients with CHD experienced improved symptoms following treatment with probucol.

Local Production of Activated Factor X in Atherosclerotic Plaque Induced Vascular Smooth Muscle Cell Senescence

Our previous study demonstrated that coagulation factor Xa (FXa) induced endothelial cell senescence, resulting in inflammation and impaired angiogenesis. This mechanism is dictated through protease-activated receptors, PARs, insulin-like growth factor-binding protein 5 (IGFBP-5), and p53. Activation of PARs contributes to the pathophysiology of several chronic inflammatory diseases, including atherosclerosis. Thus, we speculated that similar mechanism might participate in the progression of atherosclerotic plaques. In the present study, we successfully identified the cells that produced FX/Xa in atherosclerosis using human atherosclerotic plaques obtained from carotid endarterectomy. In situ hybridization for FX revealed that FX was generated in vascular smooth muscle cells (VSMC), inflammatory cells, and endothelial cells. Then, we examined the effects of FXa on the growth of VSMC in vitro. The present study revealed that chronic FXa stimulation significantly induced the senescence of VSMC with concomitant upregulation of IGFBP-5 and p53. Inhibition of FXa signaling with rivaroxaban or knock down of IGFBP-5 significantly reduced FXa-induced VSMC senescence and inflammatory cytokine production. Finally, we confirmed that FXa and IGFBP-5 are co-distributed in atherosclerotic plaques. In conclusion, induction of senescence of VSMC induced by locally produced FX/Xa may contribute to the progression of atherosclerosis.

The fifth epidermal growth factor like region of thrombomodulin alleviates LPS-induced sepsis through interacting with GPR15

Thrombomodulin (TM) exerts cytoprotection via the fifth region of epidermal growth factor (EGF)-like domain of TM (TME5) by interacting with G-protein coupled receptor 15 (GPR15) expressed on cell surface of vascular endothelial cells. TM is also implied to mediate anti-inflammatory functions by unknown mechanism. By applying a lipopolysaccharide (LPS)-induced murine sepsis model, we assessed the role of TME5 in septic inflammation and coagulation. We found that TME5 treatment protected mice in association with ameliorating inflammation and coagulopathy in LPS-induced sepsis. Further study confirmed that TME5 bound GPR15 in vitro. Knock out of GPR15 abolished protective role of TME5 in sepsis model. GPR15 mediated anti-inflammatory function of TME5 through suppression of phosphorylation of IκBα, nuclear translocation of NF-κB and release of pro-inflammatory cytokines in macro-phages (Macs). Knock out of GPR15 resulted in dysregulated immune response of Macs, characterised by excessive expression of pro-inflammatory genes and failing to limit immune response. This study indicates that TME5 exerts anti-inflammatory function through inhibition of NF-κB in a GPR15-dependent manner. The use of TME5 may be a potential therapeutic option for treatment of sepsis.

Supplementary Material to this article is available online at www.thrombosis-online.com.

Effects of alloantibodies to human leukocyte antigen on endothelial expression and serum levels of thrombomodulin

Essentials The effect of alloantibodies on the endothelial expression of thrombomodulin is unknown. Thrombomodulin was quantified in stimulated endothelial cells and measured in serum samples. Anti-human leukocyte antigen (HLA) I vs. II antibodies have different effects on thrombomodulin. Anti-HLA II antibodies may promote a prothrombotic state and contribute to microangiopathy.

SUMMARY

Rationale Thrombomodulin (TBM) is an anticoagulant and anti-inflammatory transmembrane protein expressed on endothelial cells. Donor-specific alloantibodies, particularly those against human leukocyte antigen (HLA) class II, are associated with microvascular endothelial damage in solid allografts. Objective Our aim was to characterize the effects of anti-HLA antibodies on endothelial expression of TBM, and in particular, the differential effects of anti-HLA class I compared with those of anti-HLA class II. Methods We used human glomerular microvascular endothelial cells to examine TBM expression on anti-HLA-treated cells, and we tested sera from transplant recipients for soluble TBM. Results We found that whereas membrane TBM expression increased in a dose-dependent manner in the presence of anti-HLA class I antibodies, treatment with anti-HLA class II led to minimal TBM expression on the endothelial surface but to a cytosolic accumulation. Platelet adhesion studies confirmed the functional impact of anti-HLA class II. Quantitative densitometry of the membrane lysates further suggested that anti-HLA class II impairs TBM glycosylation. Furthermore, we found a significant association between the presence of circulating anti-HLA class II antibodies in transplant recipients and low serum levels of TBM. Conclusion These results indicate that ligation of anti-HLA class I and II antibodies produces different effects on the endothelial expression of TBM and on serum levels of TBM in transplant recipients. Anti-HLA class II antibodies may be associated with a prothrombotic state, which could explain the higher occurrence of microangiopathic lesions in the allograft and the poor outcomes observed in patients with these alloantibodies.

Activated Factor X Induces Endothelial Cell Senescence Through IGFBP-5

Uncontrolled coagulation contributes to the pathophysiology of several chronic inflammatory diseases. In these conditions, senescent cells are often observed and is involved in the generation of inflammation. The coincidence of hyper-coagulation, cell senescence, and inflammation suggests the existence of a common underlying mechanism. Recent evidence indicates that activated coagulation factor X (FXa) plays a role in the processes beyond blood coagulation. This non-hematologic function entails the mediation of inflammation and tissue remodeling. We therefore tested the hypothesis that FXa induces cell senescence resulting in tissue inflammation and impaired tissue regeneration. Human umbilical vein endothelial cells were stimulated with FXa for 14 days. The proliferation of cells treated with FXa was significantly smaller, and the fraction of senescence-associated β-galactosidase-positive cells was increased as compared to the control group. RT-qPCR array revealed that FXa increased the expression of IGFBP-5, EGR-1, p53, and p16^INK4a. Inhibition of FXa by a direct FXa inhibitor, rivaroxaban, or IGFBP-5 by siRNA decreased FXa-induced cell senescence, restoring cell proliferation. Moreover, in an ischemic hind limb mouse model, FXa inhibited neovascularization by endothelial progenitor cell. However, rivaroxaban significantly restored FXa-induced impaired angiogenesis. In summary, FXa induced endothelial cell senescence through IGFBP-5, resulting in impaired angiogenesis.

Benefit profile of anticoagulant therapy in sepsis: a nationwide multicentre registry in Japan

BACKGROUND

Little evidence supports anticoagulant therapy as effective adjuvant therapy to reduce mortality overall in sepsis. However, several studies suggest that anticoagulant therapy may reduce mortality in specific patients. This study aimed to identify a subset of patients with high benefit profiles for anticoagulant therapy against sepsis.

METHODS

This post hoc subgroup analysis of a nationwide multicentre retrospective registry was conducted in 42 intensive care units in Japan. Consecutive adult patients with sepsis were included. Treatment effects of anticoagulants, e.g. antithrombin, recombinant thrombomodulin, heparin, and protease inhibitors, were evaluated by stratifying patients according to disseminated intravascular coagulation (DIC) and Sequential Organ Failure Assessment (SOFA) score. Intervention effects of anticoagulant therapy on in-hospital mortality and bleeding complications were analysed using Cox regression analysis stratified by propensity scores.

RESULTS

Participants comprised 2663 consecutive patients with sepsis; 1247 patients received anticoagulants and 1416 received none. After adjustment for imbalances, anticoagulant administration was significantly associated with reduced mortality only in subsets of patients diagnosed with DIC, whereas similar mortality rates were observed in non-DIC subsets with anticoagulant therapy. Favourable associations between anticoagulant therapy and mortality were observed only in the high-risk subset (SOFA score 13-17; adjusted hazard ratio 0.601; 95 % confidence interval 0.451, 0.800) but not in the subsets of patients with sepsis with low to moderate risk. Although the differences were not statistically significant, there was a consistent tendency towards an increase in bleeding-related transfusions in all SOFA score subsets.

CONCLUSIONS

The analysis of this large database indicates anticoagulant therapy may be associated with a survival benefit in patients with sepsis-induced coagulopathy and/or very severe disease.

TRIAL REGISTRATION

University Hospital Medical Information Network Clinical Trial Registry (UMIN-CTR ID: UMIN000012543 ). Registered on 10 December 2013.