Sepsis-induced coagulation in the baboon lung is associated with decreased tissue factor pathway inhibitor

Protective effects of tissue factor pathway inhibitor on mice with lipopolysaccharide-induced acute lung injury

Acute lung injury (ALI) resulting from bacterial infection poses a significant risk, and its etiology involves the complex interplay of harmful immune responses and blood coagulation. Despite this understanding, the roles and mechanisms of tissue factor pathway inhibitor (TFPI) in LPS-induced ALI remain insufficiently elucidated. In this study, we aimed to explore the effects of TFPI in LPS-induced ALI. Our investigations revealed that TFPI exerts multiple beneficial effects in LPS-induced ALI. Specifically, TFPI reduces microvascular permeability, Myeloperoxidase (MPO) activity, and cytokine production while inhibiting blood coagulation. Moreover, TFPI demonstrates the capacity to promote proliferation and suppress apoptosis in Human microvascular endothelial cells (HMEC-1) and Human umbilical vein endothelial cells (HUVEC) through the inhibition of the caspase pathway and mitochondrial apoptosis pathway. Furthermore, our findings indicate a correlation between tissue factor (TF) and TFPI expression, with TFPI regulation observed in HMEC-1 cells following LPS treatment. This novel insight suggests that TFPI plays a regulatory role in TF expression. Overall, the protective effect of TFPI on LPS-induced ALI is unveiled by its ability to enhance endothelial cell proliferation and inhibit apoptosis through the modulation of caspase and Bcl-2/Bax pathways. These results underscore the potential of TFPI as a promising therapeutic target for ALI treatment.

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

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

Plasma tissue factor pathway inhibitor levels in coronavirus disease 2019 patients: a systematic review and meta-analysis

Studies have suggested a relationship between tissue factor pathway inhibitor (TFPI) and coronavirus disease 2019 (COVID-19) severity. However, there is inconsistency in the findings of the studies. To enhance comprehension of this relationship, a meta-analysis was conducted. PubMed, Web of Science, and Scopus databases were searched to identify eligible studies. The mean difference was employed as effect measures and the standardized mean difference (SMD) and the 95% confidence interval (CI) were utilized as a summary statistic. Heterogeneity was assessed through the application of the chi-square test and the I2 statistic. The included studies' quality and risk of bias were assessed using the Newcastle-Ottawa assessment scale, adapted for case-control studies. A total of six studies were included with 684 cases and healthy controls (180 healthy controls and 504 COVID-19 patients with different severity, 76 mild, 292 moderate, and 136 severe). The analysis revealed a significant increase in the TFPI level in COVID-19 patients with moderate severity compared with healthy controls (SMD = 0.95 ng/ml, 95% confidence interval (CI) 0.27, 1.63 ng/ml; I2 : 87.2%). The increased TFPI level in mild and moderate COVID-19 was not significant, SMD = 0.68 ng/ml, 95% CI -0.64 to 2.0 ng/ml; I2 92.9% and SMD = 0.62 ng/ml, 95% CI -0.62 to 1.86 ng/ml; I2 91.5%, respectively. In addition, most studies indicate an association of the increased TFPI concentrations with increased markers of inflammation, endothelial damage, and hypercoagulation. Considering the anticoagulant and anti-inflammatory roles of TFPI, its increase seems to be aimed at modulating COVID-19-induced hyper-inflammation and hyper-coagulation state.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42023437353.

Exploring the Role of Different Cell-Death-Related Genes in Sepsis Diagnosis Using a Machine Learning Algorithm

Sepsis, a disease caused by severe infection, has a high mortality rate. At present, there is a lack of reliable algorithmic models for biomarker mining and diagnostic model construction for sepsis. Programmed cell death (PCD) has been shown to play a vital role in disease occurrence and progression, and different PCD-related genes have the potential to be targeted for the treatment of sepsis. In this paper, we analyzed PCD-related genes in sepsis. Implicated PCD processes include apoptosis, necroptosis, ferroptosis, pyroptosis, netotic cell death, entotic cell death, lysosome-dependent cell death, parthanatos, autophagy-dependent cell death, oxeiptosis, and alkaliptosis. We screened for diagnostic-related genes and constructed models for diagnosing sepsis using multiple machine-learning models. In addition, the immune landscape of sepsis was analyzed based on the diagnosis-related genes that were obtained. In this paper, 10 diagnosis-related genes were screened for using machine learning algorithms, and diagnostic models were constructed. The diagnostic model was validated in the internal and external test sets, and the Area Under Curve (AUC) reached 0.7951 in the internal test set and 0.9627 in the external test set. Furthermore, we verified the diagnostic gene via a qPCR experiment. The diagnostic-related genes and diagnostic genes obtained in this paper can be utilized as a reference for clinical sepsis diagnosis. The results of this study can act as a reference for the clinical diagnosis of sepsis and for target discovery for potential therapeutic drugs.

Pathophysiology of Disseminated Intravascular Coagulation in Sepsis: A Clinically Focused Overview

Sepsis is a major global health problem that results from a dysregulated and uncontrolled host response to infection, causing organ failure. Despite effective anti-infective therapy and supportive treatments, the mortality rate of sepsis remains high. Approximately 30-80% of patients with sepsis may develop disseminated intravascular coagulation (DIC), which can double the mortality rate. There is currently no definitive treatment approach for sepsis, with etiologic treatment being the cornerstone of therapy for sepsis-associated DIC. Early detection, diagnosis, and treatment are critical factors that impact the prognosis of sepsis-related DIC. Over the past several decades, researchers have made continuous efforts to better understand the mechanisms of DIC in sepsis, as well as improve its quantitative diagnosis and treatment. This article aims to provide a comprehensive overview of the current understanding of sepsis-related DIC, focusing on common causes and diagnoses, with the goal of guiding healthcare providers in the care of patients with sepsis.

Status of major hemostatic components in the setting of COVID-19: the effect on endothelium, platelets, coagulation factors, fibrinolytic system, and complement

The coagulation, fibrinolytic, anticoagulation, and complement systems are in delicate balance with the vessel wall endothelium ensuring appropriate hemostasis. Coagulopathy in coronavirus disease 2019 (COVID-19) is not a simple disorder of one hemostatic component but a complicated process affecting most of the hemostasis system. COVID-19 disturbs the balance between the procoagulant systems and the regulatory mechanisms. Here, we investigate the effect of COVID-19 on key hemostatic components, including platelets, endothelial cells, coagulation factors, fibrinolytic system, anticoagulant protein system, and complement system, to improve our understanding of the pathophysiological processes underlying COVID-19 coagulopathy based on evidence.

Heparan sulfates and heparan sulfate binding proteins in sepsis

Heparan sulfates (HSs) are the main components in the glycocalyx which covers endothelial cells and modulates vascular homeostasis through interactions with multiple Heparan sulfate binding proteins (HSBPs). During sepsis, heparanase increases and induces HS shedding. The process causes glycocalyx degradation, exacerbating inflammation and coagulation in sepsis. The circulating heparan sulfate fragments may serve as a host defense system by neutralizing dysregulated Heparan sulfate binding proteins or pro-inflammatory molecules in certain circumstances. Understanding heparan sulfates and heparan sulfate binding proteins in health and sepsis is critical to decipher the dysregulated host response in sepsis and advance drug development. In this review, we will overview the current understanding of HS in glycocalyx under septic condition and the dysfunctional heparan sulfate binding proteins as potential drug targets, particularly, high mobility group box 1 (HMGB1) and histones. Moreover, several drug candidates based on heparan sulfates or related to heparan sulfates, such as heparanase inhibitors or heparin-binding protein (HBP), will be discussed regarding their recent advances. By applying chemical or chemoenzymatic approaches, the structure-function relationship between heparan sulfates and heparan sulfate binding proteins is recently revealed with structurally defined heparan sulfates. Such homogenous heparan sulfates may further facilitate the investigation of the role of heparan sulfates in sepsis and the development of carbohydrate-based therapy.

Vascular Proteome Responses Precede Organ Dysfunction in a Murine Model of Staphylococcus aureus Bacteremia

Vascular dysfunction and organ failure are two distinct, albeit highly interconnected, clinical outcomes linked to morbidity and mortality in human sepsis. The mechanisms driving vascular and parenchymal damage are dynamic and display significant molecular cross talk between organs and tissues. Therefore, assessing their individual contribution to disease progression is technically challenging. Here, we hypothesize that dysregulated vascular responses predispose the organism to organ failure. To address this hypothesis, we have evaluated four major organs in a murine model of Staphylococcus aureus sepsis by combining in vivo labeling of the endothelial cell surface proteome, data-independent acquisition (DIA) mass spectrometry, and an integrative computational pipeline. The data reveal, with unprecedented depth and throughput, that a septic insult evokes organ-specific proteome responses that are highly compartmentalized, synchronously coordinated, and significantly correlated with the progression of the disease. These responses include abundant vascular shedding, dysregulation of the intrinsic pathway of coagulation, compartmentalization of the acute phase response, and abundant upregulation of glycocalyx components. Vascular cell surface proteome changes were also found to precede bacterial invasion and leukocyte infiltration into the organs, as well as to precede changes in various well-established cellular and biochemical correlates of systemic coagulopathy and tissue dysfunction. Importantly, our data suggest a potential role for the vascular proteome as a determinant of the susceptibility of the organs to undergo failure during sepsis. IMPORTANCE Sepsis is a life-threatening response to infection that results in immune dysregulation, vascular dysfunction, and organ failure. New methods are needed for the identification of diagnostic and therapeutic targets. Here, we took a systems-wide approach using data-independent acquisition (DIA) mass spectrometry to track the progression of bacterial sepsis in the vasculature leading to organ failure. Using a murine model of S. aureus sepsis, we were able to quantify thousands of proteins across the plasma and parenchymal and vascular compartments of multiple organs in a time-resolved fashion. We showcase the profound proteome remodeling triggered by sepsis over time and across these compartments. Importantly, many vascular proteome alterations precede changes in traditional correlates of organ dysfunction, opening a molecular window for the discovery of early markers of sepsis progression.

ZNF354C Mediated by DNMT1 Ameliorates Lung Ischemia-Reperfusion Oxidative Stress Injury by Reducing TFPI Promoter Methylation to Upregulate TFPI

Background

Pulmonary ischemia reperfusion- (I/R-) induced dysfunction is a significant clinical problem after lung transplantation. In this study, we aim to explore the molecular mechanism of lung I/R injury (LIRI).

Methods

Bioinformatic analysis of gene involved in oxidative stress. A HUVEC oxygen glucose deprivation/reoxygenation (OGD/R) model and I/R mouse model were first established via I/R. The cellular proliferation, migration, reactive oxygen species (ROS), and parameters of lung injury were assessed via CCK-8, EdU staining, Transwell, cellular ROS kit, and H&E staining. We also confirmed related gene expressions and protein levels and the interaction between the tissue factor pathway inhibitor (TFPI) promotor and ZNF354C.

Results

Bioinformatic analysis results showed TFPI contributed to oxidative stress. OGD/R caused a reduction in cell viability and migration, hypermethylation of TFPI, increased ROS, and downregulation of ZNF354C, TFPI, and DNA methyltransferases (DNMTs) in HUVECs. Besides, ZNF354C could directly bind to the TFPI promoter, enhance proliferation and migration, and inhibit ROS in OGD/R-induced HUVECs by upregulating TFPI. More importantly, we discovered that 5-Aza could reduce TFPI methylation, upregulate TFPI, and enhance the binding of ZNF354C to the TFPI promoter in LIRI. Furthermore, DNMT1 silencing could induce proliferation and migration and prevent ROS in OGD/R-induced HUVECs by upregulating ZNF354C. Additionally, we verified that ZNF354C could alleviate LIRI by preventing DNA methylation in vivo.

Conclusions

ZNF354C overexpression induced proliferation and migration, as well as suppressed ROS in OGD/R-induced HUVECs, and alleviated LIRI in mice by inhibiting TFPI promoter methylation to upregulate TFPI. Therefore, ZNF354C and TFPI methylation might be promising molecular markers for LIRI therapy.

Endothelial Activation and Microcirculatory Disorders in Sepsis

The vascular endothelium is crucial for the maintenance of vascular homeostasis. Moreover, in sepsis, endothelial cells can acquire new properties and actively participate in the host's response. If endothelial activation is mostly necessary and efficient in eliminating a pathogen, an exaggerated and maladaptive reaction leads to severe microcirculatory damage. The microcirculatory disorders in sepsis are well known to be associated with poor outcome. Better recognition of microcirculatory alteration is therefore essential to identify patients with the worse outcomes and to guide therapeutic interventions. In this review, we will discuss the main features of endothelial activation and dysfunction in sepsis, its assessment at the bedside, and the main advances in microcirculatory resuscitation.

Disseminated intravascular coagulation and its immune mechanisms

Disseminated intravascular coagulation (DIC) is a syndrome triggered by infectious and noninfectious pathologies characterized by excessive generation of thrombin within the vasculature and widespread proteolytic conversion of fibrinogen. Despite diverse clinical manifestations ranging from thrombo-occlusive damage to bleeding diathesis, DIC etiology commonly involves excessive activation of blood coagulation and overlapping dysregulation of anticoagulants and fibrinolysis. Initiation of blood coagulation follows intravascular expression of tissue factor or activation of the contact pathway in response to pathogen-associated or host-derived, damage-associated molecular patterns. The process is further amplified through inflammatory and immunothrombotic mechanisms. Consumption of anticoagulants and disruption of endothelial homeostasis lower the regulatory control and disseminate microvascular thrombosis. Clinical DIC development in patients is associated with worsening morbidities and increased mortality, regardless of the underlying pathology; therefore, timely recognition of DIC is critical for reducing the pathologic burden. Due to the diversity of triggers and pathogenic mechanisms leading to DIC, diagnosis is based on algorithms that quantify hemostatic imbalance, thrombocytopenia, and fibrinogen conversion. Because current diagnosis primarily assesses overt consumptive coagulopathies, there is a critical need for better recognition of nonovert DIC and/or pre-DIC states. Therapeutic strategies for patients with DIC involve resolution of the eliciting triggers and supportive care for the hemostatic imbalance. Despite medical care, mortality in patients with DIC remains high, and new strategies, tailored to the underlying pathologic mechanisms, are needed.

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.

Lidocaine Alleviates Sepsis-Induced Acute Lung Injury in Mice by Suppressing Tissue Factor and Matrix Metalloproteinase-2/9

Acute lung injury (ALI) is one of the fatal symptoms of sepsis. However, there were no effective clinical treatments. TF accumulation-induced fibrin deposit formations and coagulation abnormalities in pulmonary vessels contribute to the lethality of ALI. Suppressor of cytokine signaling 3 (SOCS3) acts as an endogenous negative regulator of the TLR4/TF pathway. We hypothesized that inducing SOCS3 expression using lidocaine to suppress the TLR4/TF pathway may alleviate ALI. Hematoxylin and eosin (H&E), B-mode ultrasound, and flow cytometry were used to measure the pathological damage of mice. Gelatin zymography was used to measure matrix metalloproteinase-2/9 (MMP-2/9) activities. Western blot was used to assay the expression of protein levels. Here, we show that lidocaine could increase the survival rate of ALI mice and ameliorate the lung injury of ALI mice including reducing the edema, neutrophil infiltration, and pulmonary thrombosis formation and increasing blood flow velocity. Moreover, in vitro and in vivo, lidocaine could increase the expression of p-AMPK and SOCS3 and subsequently decrease the expression of p-ASK1, p-p38, TF, and the activity of MMP-2/9. Taken together, our study demonstrated that lidocaine could inhibit the TLR4/ASK1/TF pathway to alleviate ALI via activating AMPK-SOCS3 axis.

Insights into the Functional Role of ADTRP (Androgen-Dependent TFPI-Regulating Protein) in Health and Disease

The novel protein ADTRP, identified and described by us in 2011, is androgen-inducible and regulates the expression and activity of Tissue Factor Pathway Inhibitor, the major inhibitor of the Tissue Factor-dependent pathway of coagulation on endothelial cells. Single-nucleotide polymorphisms in ADTRP associate with coronary artery disease and myocardial infarction, and deep vein thrombosis/venous thromboembolism. Some athero-protective effects of androgen could exert through up-regulation of ADTRP expression. We discovered a critical role of ADTRP in vascular development and vessel integrity and function, manifested through Wnt signaling-dependent regulation of matrix metalloproteinase-9. ADTRP also hydrolyses fatty acid esters of hydroxy-fatty acids, which have anti-diabetic and anti-inflammatory effects and can control metabolic disorders. Here we summarize and analyze the knowledge on ADTRP and try to decipher its functions in health and disease.

CD14 inhibition improves survival and attenuates thrombo-inflammation and cardiopulmonary dysfunction in a baboon model of Escherichia coli sepsis

BACKGROUND

During sepsis, gram-negative bacteria induce robust inflammation primarily via lipopolysacharride (LPS) signaling through TLR4, a process that involves the glycosylphosphatidylinositol (GPI)-anchored receptor CD14 transferring LPS to the Toll-like receptor 4/myeloid differentiation factor 2 (TLR4/MD-2) complex. Sepsis also triggers the onset of disseminated intravascular coagulation and consumptive coagulopathy.

OBJECTIVES

We investigated the effect of CD14 blockade on sepsis-induced coagulopathy, inflammation, organ dysfunction, and mortality.

METHODS

We used a baboon model of lethal Escherichia (E) coli sepsis to study two experimental groups (n = 5): (a) E coli challenge; (b) E coli challenge plus anti-CD14 (23G4) inhibitory antibody administered as an intravenous bolus 30 minutes before the E coli.

RESULTS

Following anti-CD14 treatment, two animals reached the 7-day end-point survivor criteria, while three animals had a significantly prolonged survival as compared to the non-treated animals that developed multiple organ failure and died within 30 hours. Anti-CD14 reduced the activation of coagulation through inhibition of tissue factor-dependent pathway, especially in the survivors, and enhanced the fibrinolysis due to strong inhibition of plasminogen activator inhibitor 1. The treatment prevented the robust complement activation induced by E coli, as shown by significantly decreased C3b, C5a, and sC5b-9. Vital signs, organ function biomarkers, bacteria clearance, and leukocyte and fibrinogen consumption were all improved at varying levels. Anti-CD14 reduced neutrophil activation, cell death, LPS levels, and pro-inflammatory cytokines (tumor necrosis factor, interleukin (IL)-6, IL-1β, IL-8, interferon gamma, monocyte chemoattractant protein-1), more significantly in the survivors than non-surviving animals.

CONCLUSIONS

Our results highlight the crosstalk between coagulation/fibrinolysis, inflammation, and complement systems and suggest a protective role of anti-CD14 treatment in E coli sepsis.

The role of endothelial shear stress on haemodynamics, inflammation, coagulation and glycocalyx during sepsis

Sepsis is a multifactorial syndrome primarily determined by the host response to an invading pathogen. It is common, with over 48 million cases worldwide in 2017, and often lethal. The sequence of events in sepsis begins with the damage of endothelium within the microvasculature, as a consequence of the inflammatory and coagulopathic responses to the pathogen that can progress to multiple organ failure and death. Most therapeutic interventions target the inflammation and coagulation pathways that act as an auto-amplified vicious cycle, which, if unchecked can be fatal. Normal blood flow and shear stress acting on a healthy endothelium and intact glycocalyx have anti-inflammatory, anticoagulant and self-repairing effects. During early stages of sepsis, the vascular endothelium and its glycocalyx become dysfunctional, yet they are essential components of resuscitation and recovery from sepsis. The effects of shear forces on sepsis-induced endothelial dysfunction, including inflammation, coagulation, complement activation and microcirculatory breakdown are reviewed. It is suggested that early therapeutic strategies should prioritize on the restoration of shear forces and endothelial function and on the preservation of the endothelial-glycocalyx barrier.

Extensive Changes in Transcriptomic "Fingerprints" and Immunological Cells in the Large Organs of Patients Dying of Acute Septic Shock and Multiple Organ Failure Caused by Neisseria meningitidis

Background: Patients developing meningococcal septic shock reveal levels of Neisseria meningitidis (10⁶-10⁸/mL) and endotoxin (10¹-10³ EU/mL) in the circulation and organs, leading to acute cardiovascular, pulmonary and renal failure, coagulopathy and a high case fatality rate within 24 h. Objective: To investigate transcriptional profiles in heart, lungs, kidneys, liver, and spleen and immunostain key inflammatory cells and proteins in post mortem formalin-fixed, paraffin-embedded (FFPE) tissue samples from meningococcal septic shock patients. Patients and Methods: Total RNA was isolated from FFPE and fresh frozen (FF) tissue samples from five patients and two controls (acute non-infectious death). Differential expression of genes was detected using Affymetrix microarray analysis. Lung and heart tissue samples were immunostained for T-and B cells, macrophages, neutrophils and the inflammatory markers PAI-1 and MCP-1. Inflammatory mediators were quantified in lysates from FF tissues. Results: The transcriptional profiles showed a complex pattern of protein-coding and non-coding RNAs with significant regulation of pathways associated with organismal death, cell death and survival, leukocyte migration, cellular movement, proliferation of cells, cell-to-cell signaling, immune cell trafficking, and inflammatory responses in an organ-specific clustering manner. The canonical pathways including acute phase response-, EIF2-, TREM1-, IL-6-, HMBG1-, PPAR signaling, and LXR/RXR activation were associated with acute heart, pulmonary, and renal failure. Fewer genes were regulated in the liver and particularly in the spleen. The main upstream regulators were TNF, IL-1β, IL-6, RICTOR, miR-6739-3p, and CD3. Increased numbers of inflammatory cells (CD68+, MPO+, CD3+, and CD20+) were found in lungs and heart. PAI-1 inhibiting fibrinolysis and MCP-1 attracting leukocyte were found significantly present in the septic tissue samples compared to the controls. Conclusions: FFPE tissue samples can be suitable for gene expression studies as well as immunostaining of specific cells or molecules. The most pronounced gene expression patterns were found in the organs with highest levels of Neisseria meningitidis DNA. Thousands of protein-coding and non-coding RNA transcripts were altered in lungs, heart and kidneys. We identified specific biomarker panels both protein-coding and non-coding RNA transcripts, which differed from organ to organ. Involvement of many genes and pathways add up and the combined effect induce organ failure.

Role of ADTRP (Androgen-Dependent Tissue Factor Pathway Inhibitor Regulating Protein) in Vascular Development and Function

Background

The physiological function of ADTRP (androgen‐dependent tissue factor pathway inhibitor regulating protein) is unknown. We previously identified ADTRP as coregulating with and supporting the anticoagulant activity of tissue factor pathway inhibitor in endothelial cells in vitro. Here, we studied the role of ADTRP in vivo, specifically related to vascular development, stability, and function.

Methods and Results

Genetic inhibition of Adtrp produced vascular malformations in the low‐pressure vasculature of zebrafish embryos and newborn mice: dilation/tortuosity, perivascular inflammation, extravascular proteolysis, increased permeability, and microhemorrhages, which produced partially penetrant lethality. Vascular leakiness correlated with decreased endothelial cell junction components VE‐cadherin and claudin‐5. Changes in hemostasis in young adults comprised modest decrease of tissue factor pathway inhibitor antigen and activity and increased tail bleeding time and volume. Cell‐based reporter assays revealed that ADTRP negatively regulates canonical Wnt signaling, affecting membrane events downstream of low‐density lipoprotein receptor‐related protein 6 (LRP6) and upstream of glycogen synthase kinase 3 beta. ADTRP deficiency increased aberrant/ectopic Wnt/β‐catenin signaling in vivo in newborn mice and zebrafish embryos, and upregulated matrix metallopeptidase (MMP)‐9 in endothelial cells and mast cells (MCs). Vascular lesions in newborn Adtrp^−/− pups displayed accumulation of MCs, decreased extracellular matrix content, and deficient perivascular cell coverage. Wnt‐pathway inhibition reversed the increased mmp9 in zebrafish embryos, demonstrating that mmp9 expression induced by Adtrp deficiency was downstream of canonical Wnt signaling.

Conclusions

Our studies demonstrate that ADTRP plays a major role in vascular development and function, most likely through expression in endothelial cells and/or perivascular cells of Wnt‐regulated genes that control vascular stability and integrity.

Endothelial PAI-1 (Plasminogen Activator Inhibitor-1) Blocks the Intrinsic Pathway of Coagulation, Inducing the Clearance and Degradation of FXIa (Activated Factor XI)

Objective- Activation of coagulation FXI (factor XI) by FXIIa (activated factor XII) is a prothrombotic process. The endothelium is known to play an antithrombotic role by limiting thrombin generation and platelet activation. It is unknown whether the antithrombotic role of the endothelium includes sequestration of FXIa (activated factor XI) activity. This study aims to determine the role of endothelial cells (ECs) in the regulation of the intrinsic pathway of coagulation. Approach and Results- Using a chromogenic assay, we observed that human umbilical veins ECs selectively blocked FXIa yet supported kallikrein and FXIIa activity. Western blotting and mass spectrometry analyses revealed that FXIa formed a complex with endothelial PAI-1 (plasminogen activator inhibitor-1). Blocking endothelial PAI-1 increased the cleavage of a chromogenic substrate by FXIa and the capacity of FXIa to promote fibrin formation in plasma. Western blot and immunofluorescence analyses showed that FXIa-PAI-1 complexes were either released into the media or trafficked to the early and late endosomes and lysosomes of ECs. When baboons were challenged with Staphylococcus aureus to induce a prothrombotic phenotype, an increase in circulating FXIa-PAI-1 complex levels was detected by ELISA within 2 to 8 hours postchallenge. Conclusions- PAI-1 forms a complex with FXIa on ECs, blocking its activity and inducing the clearance and degradation of FXIa. Circulating FXIa-PAI-1 complexes were detected in a baboon model of S. aureus sepsis. Although ECs support kallikrein and FXIIa activity, inhibition of FXIa by ECs may promote the clearance of intravascular FXIa. Visual Overview- An online visual overview is available for this article.

Nonhuman primate species as models of human bacterial sepsis

Sepsis involves a disordered host response to systemic infection leading to high morbidity and mortality. Despite intense research, targeted sepsis therapies beyond antibiotics have remained elusive. The cornerstone of sepsis research is the development of animal models to mimic human bacterial infections and test novel pharmacologic targets. Nonhuman primates (NHPs) have served as an attractive, but expensive, animal to model human bacterial infections due to their nearly identical cardiopulmonary anatomy and physiology, as well as host response to infection. Several NHP species have provided substantial insight into sepsis-mediated inflammation, endothelial dysfunction, acute lung injury, and multi-organ failure. The use of NHPs has usually focused on translating therapies from early preclinical models to human clinical trials. However, despite successful sepsis interventions in NHP models, there are still no FDA-approved sepsis therapies. This review highlights major NHP models of bacterial sepsis and their relevance to clinical medicine.

Treatment for bacterial sepsis remains limited beyond the use of antibiotics. Lingye Chen, Karen Welty-Wolf, and Bryan Kraft review nonhuman primate models of sepsis and highlight their advantages and limitations compared to other preclinical models.

Post-transcriptional, post-translational and pharmacological regulation of tissue factor pathway inhibitor

: Tissue factor (TF) pathway inhibitor (TFPI) is an endogenous natural anticoagulant that readily inhibits the extrinsic coagulation initiation complex (TF-FVIIa-Xa) and prothrombinase (FXa, FVa and calcium ions). Alternatively, spliced TFPI isoforms (α, β and δ) are expressed by vascular and extravascular cells and regulate thrombosis and haemostasis, as well as cell signalling functions of TF complexes via protease-activated receptors (PARs). Proteolysis of TFPI plays an important role in regulating physiological roles of the TF pathway in host defense and possibly haemostasis. Elimination of TFPI inhibition has therefore been proposed as an approach to improve haemostasis in haemophilia patients. In this review, we focus on posttranscription and translational modification of TFPI and its function in thrombosis and how pharmacological inhibitors and endogenous proteases interfere with TFPI and alter haemostasis.

Tissue Factor Facilitates Wound Healing in Human Airway Epithelial Cells

BACKGROUND

Tissue factor (TF) canonically functions as the initiator of the coagulation cascade. TF levels are increased in inflamed airways and seem to be important for tumor growth and metastasis. We hypothesized that airway epithelia release TF as part of a wound repair program.

OBJECTIVES

The goal of this study was to evaluate whether airway epithelia release TF in response to pro-inflammatory stimuli and to investigate roles of TF in cell growth and repair.

METHODS

Airway epithelial cells were exposed to 10 μg/mL of lipopolysaccharide or 1 ng/mL of transforming growth factor β (TGF-β). TF and TGF-β messenger RNA and protein were measured in cell lysate and culture media, respectively. Signaling pathways were evaluated by using selective agonists and inhibitors. Airway epithelia were mechanically injured in the presence of TF and tissue factor pathway inhibitor to investigate their roles in wound repair.

RESULTS

TF protein levels increased in cell media after exposure to lipopolysaccharide (P < .01) but only in growing cells, and this action was blocked when exposed to an extracellular signal-regulated kinase inhibitor or a "small" worm phenotype and mothers against Decapentaplegic inhibitor. TF protein also increased in the presence of TGF-β (P < .05). Exposure to TF pathway inhibitor decreased the rate of cell growth by 60% (P < .05), and exposure to TF increased the rate of airway healing after injury by 19% (P < .05).

CONCLUSIONS

Growing airway epithelia release TF when exposed to lipopolysaccharide or TGF-β. TF reduces wound-healing time in airway epithelia and therefore may be important to airway recovery after injury.

Anticoagulant Therapy in Sepsis. The Importance of Timing

Sepsis associated coagulopathy is due to the inflammation-induced activation of coagulation pathways concomitant with dysfunction of anticoagulant and fibrinolytic systems, leading to different degrees of haemostasis dysregulation. This response is initially beneficial, contributing to antimicrobial defence, but when control is lost coagulation activation leads to widespread microvascular thrombosis and subsequent organ failure. Large clinical trials of sepsis-related anticoagulant therapies failed to show survival benefits, but posthoc analysis of databases and several smaller studies showed beneficial effects of anticoagulants in subgroups of patients with early sepsis-induced disseminated intravascular coagulation. A reasonable explanation could be the difference in timing of anticoagulant therapy and patient heterogeneity associated with large trials. Proper selection of patients and adequate timing are required for treatment to be successful. The time when coagulation activation changes from advantageous to detrimental represents the right moment for the administration of coagulation-targeted therapy. In this way, the defence function of the haemostatic system is preserved, and the harmful effects of overwhelming coagulation activation are avoided.

Sepsis-Associated Coagulopathy

Systemic inflammatory activation in sepsis often leads to coagulation activation, but the relationship is bilateral, as coagulation also modulates the inflammatory response. This close associate has significant consequences for the pathogenesis of microvascular thrombosis and organ dysfunction in sepsis. While coagulation activation can be beneficial for immune defense, it can also be detrimental once it becomes widespread and uncontrolled. The knowledge of the pathophysiologic mechanisms involved in the interaction between infection and coagulation may lead to the better timing for the administration of targeted antithrombotic therapies in septic patients. This brief review highlights the pathophysiologic pathways leading to the prothrombotic state in sepsis and the mechanisms that play a role in the interaction between infection and coagulation.

Disseminated intravascular coagulation - new pathophysiological concepts and impact on management

INTRODUCTION

Disseminated intravascular coagulation (DIC) is an intermediary mechanism of disease which develops secondary to many causes including sepsis, trauma and malignancies. This review attempts to summarise the new pathophysiological developments and the impact they have on the current and future management of DIC.

AREAS COVERED

Several publications detailing the pathophysiology of DIC and the clinical management were identified using a pubmed search. Expert commentary: In recent years, on the initiatives of the international society of thrombosis and haemostasis, important advances have been made on the diagnostic aspect of DIC. In addition, several researchers have focused on the pathophysiology of the condition which is likely to provide better diagnostic markers and targeted therapy. However, some confusion still exists in the definition and management of DIC since various specialists understands the mechanisms involved in DIC from different perspectives.

Sepsis and disseminated intravascular coagulation

Sepsis is frequently complicated by coagulopathy and, in about 35 % of severe cases, by disseminated intravascular coagulation (DIC). In Japan, aggressive treatment of septic DIC is encouraged using antithrombin and recombinant thrombomodulin. The macrophages, monocytes, and neutrophils are a source of TF and participate in the direct activation of the coagulation cascade in the early phases of sepsis. And activated factor X (FXa), which is involved in hemostasis, thrombogenesis, inflammation, and cellular immune responses, induces TF expression in human peripheral monocytes and, conversely, that inhibition of FXa activity reduces TF expression. Both inflammation and coagulation play an important role in DIC due to sepsis. In addition to inflammatory cytokines (TNF-α, IL-1 and so on), HMGB1 has recently been shown to mediate the lethal late phase of sepsis and caused coagulopathy. TM not only binds HMGB1 but also aids the proteolytic cleavage of HMGB1 by thrombin. There have been many reports of the efficacy of recombinant TM and antithrombin for treatment of septic DIC from Japan. Further investigation of the efficacy of recombinant TM and AT in countries other than Japan, as well as the monitoring of medical costs incurred during hospitalization, will help validate the use of TM and AT for treatment of septic DIC.

Plasma Glycoproteomics Reveals Sepsis Outcomes Linked to Distinct Proteins in Common Pathways

OBJECTIVE

Sepsis remains a predominant cause of mortality in the ICU, yet strategies to increase survival have proved largely unsuccessful. This study aimed to identify proteins linked to sepsis outcomes using a glycoproteomic approach to target extracellular proteins that trigger downstream pathways and direct patient outcomes.

DESIGN

Plasma was obtained from the Lactate Assessment in the Treatment of Early Sepsis cohort. N-linked plasma glycopeptides were quantified by solid-phase extraction coupled with mass spectrometry. Glycopeptides were assigned to proteins using RefSeq (National Center of Biotechnology Information, Bethesda, MD) and visualized in a heat map. Protein differences were validated by immunoblotting, and proteins were mapped for biological processes using Database for Annotation, Visualization and Integrated Discovery (National Institute of Allergy and Infectious Diseases, National Institutes of Health; Bethesda, MD) and for functional pathways using Kyoto Encyclopedia of Genes and Genomes (Kanehisa Laboratories, Kyoto, Japan) databases.

SETTING

Hospitalized care.

PATIENTS

Patients admitted to the emergency department were enrolled in the study when the diagnosis of sepsis was made, within 6 hours of presentation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 501 glycopeptides corresponding to 234 proteins were identified. Of these, 66 glycopeptides were unique to the survivor group and corresponded to 54 proteins, 60 were unique to the nonsurvivor group and corresponded to 43 proteins, and 375 were common responses between groups and corresponded to 137 proteins. Immunoblotting showed that nonsurvivors had increased total kininogen; decreased total cathepsin-L1, vascular cell adhesion molecule, periostin, and neutrophil gelatinase-associated lipocalin; and a two-fold decrease in glycosylated clusterin (all p < 0.05). Kyoto Encyclopedia of Genes and Genomes analysis identified six enriched pathways. Interestingly, survivors relied on the extrinsic pathway of the complement and coagulation cascade, whereas nonsurvivors relied on the intrinsic pathway.

CONCLUSION

This study identifies proteins linked to patient outcomes and provides insight into unexplored mechanisms that can be investigated for the identification of novel therapeutic targets.

The coagulopathy of acute sepsis

PURPOSE OF REVIEW

Sepsis, defined by the presence of infection and host inflammation, is a lethal clinical syndrome with an increasing mortality rate worldwide. In severe disease, the coagulation system becomes diffusely activated, with consumption of multiple clotting factors resulting in disseminated intravascular coagulation (DIC). When present, DIC portends a higher mortality rate. Understanding the mechanisms that tie inflammation and diffuse thrombosis will allow therapeutic interventions to be developed. The coagulopathy of acute sepsis is a dynamic process that is time and disease burden specific. Whole-blood testing of coagulation may provide more clinically useful information than the classical tests. Natural anticoagulants that regulate thrombosis are downregulated in sepsis. Patients may benefit from the modulation of the coagulation system when systemic inflammation and hypercoagulopathy exist. Proper timing of anticoagulant therapy may ultimately lead to decreased incidence of multisystem organ dysfunction.

RECENT FINDINGS

The pathogenesis of coagulopathy in sepsis is driven by an upregulation of procoagulant mechanisms and simultaneous downregulation of natural anticoagulants. Inflammation caused by the invading organism is a natural host defense that cannot be eliminated during treatment. Successful strategies to prevent multisystem organ dysfunction center on stratifying patients at high risk for DIC and restoring the balance of inflammation and coagulation.

SUMMARY

The prevention of DIC in septic patients is a key therapeutic target in preventing death from multisystem organ failure. Stratifying patients for therapy using thromboelastometry, specific markers for DIC, and composite scoring systems is an area of growing research.

Complement inhibition decreases early fibrogenic events in the lung of septic baboons

Acute respiratory distress syndrome (ARDS) induced by severe sepsis can trigger persistent inflammation and fibrosis. We have shown that experimental sepsis in baboons recapitulates ARDS progression in humans, including chronic inflammation and long-lasting fibrosis in the lung. Complement activation products may contribute to the fibroproliferative response, suggesting that complement inhibitors are potential therapeutic agents. We have been suggested that treatment of septic baboons with compstatin, a C3 convertase inhibitor protects against ARDS-induced fibroproliferation. Baboons challenged with 10⁹ cfu/kg (LD50) live E. coli by intravenous infusion were treated or not with compstatin at the time of challenge or 5 hrs thereafter. Changes in the fibroproliferative response at 24 hrs post-challenge were analysed at both transcript and protein levels. Gene expression analysis showed that sepsis induced fibrotic responses in the lung as early as 24 hrs post-bacterial challenge. Immunochemical and biochemical analysis revealed enhanced collagen synthesis, induction of profibrotic factors and increased cell recruitment and proliferation. Specific inhibition of complement with compstatin down-regulated sepsis-induced fibrosis genes, including transforming growth factor-beta (TGF-β), connective tissue growth factor (CTGF), tissue inhibitor of metalloproteinase 1 (TIMP1), various collagens and chemokines responsible for fibrocyte recruitment (e.g. chemokine (C-C motif) ligand 2 (CCL2) and 12 (CCL12)). Compstatin decreased the accumulation of myofibroblasts and proliferating cells, reduced the production of fibrosis mediators (TGF-β, phospho-Smad-2 and CTGF) and inhibited collagen deposition. Our data demonstrate that complement inhibition effectively attenuates collagen deposition and fibrotic responses in the lung after severe sepsis. Inhibiting complement could prove an attractive strategy for preventing sepsis-induced fibrosis of the lung.

Toll-like receptor 9 signaling regulates tissue factor and tissue factor pathway inhibitor expression in human endothelial cells and coagulation in mice

Supplemental Digital Content is available in the text.

Objective:

Bacterial DNA (CpG DNA) persists in tissues and blood under pathological conditions that are associated with enhanced intravascular coagulation. Toll-like receptor 9 recognizes CpG DNA and elicits innate and adoptive immunity, yet the impact of CpG DNA on coagulation has not been studied. In this study, we investigated the effects of CpG DNA on the expression and activity of tissue factor, a key initiator of coagulation and tissue factor pathway inhibitor in human coronary artery endothelial cells and on coagulation in mice.

Design:

Controlled in vitro and in vivo studies.

Setting:

University research laboratory.

Subjects:

Cultured human coronary artery endothelial cell, wild-type mice, and TLR9-deficient mice.

Interventions:

Human coronary artery endothelial cell was challenged with CpG DNA, and tissue factor and tissue factor pathway inhibitor expression and activity were assessed. In mice, the effects of CpG DNA on bleeding time and plasma levels of thrombin-antithrombin complexes and tissue factor were measured.

Measurements and Main Results:

We found that CpG DNA, but not eukaryotic DNA, evoked marked nuclear factor-κB-mediated increases in tissue factor expression at both messenger RNA and protein levels, as well as in tissue factor activity. Conversely, CpG DNA significantly reduced tissue factor pathway inhibitor transcription, secretion, and activity. Inhibition of Toll-like receptor 9 with a telomere-derived Toll-like receptor 9 inhibitory oligonucleotide or transient Toll-like receptor 9 knockdown with small interfering RNA attenuated human coronary artery endothelial cell responses to CpG DNA. In wild-type mice, CpG DNA shortened the bleeding time parallel with dramatic increases in plasma thrombin-antithrombin complex and tissue factor levels. Pretreatment with inhibitory oligonucleotide or anti-tissue factor antibody or genetic deletion of TLR9 prevented these changes, whereas depleting monocytes with clodronate resulted in a modest partial inhibition.

Conclusions:

Our findings demonstrate that bacterial DNA through Toll-like receptor 9 shifted the balance of tissue factor and tissue factor pathway inhibitor toward procoagulant phenotype in human coronary artery endothelial cells and activated blood coagulation in mice. Our study identifies Toll-like receptor 9 inhibitory oligonucleotides as potential therapeutic agents for the prevention of coagulation in pathologies where bacterial DNA may abundantly be present.

Diagnostic and prognostic utility of tissue factor for severe sepsis and sepsis-induced acute lung injury

BACKGROUND

Tissue factor (TF) and tissue factor pathway inhibitor (TFPI) play a central role in the endothelial permeability regulation and dysfunction, which is associated with the development of sepsis and acute lung injury/acute respiratory distress syndrome (ALI/ARDS). The aim of this study is to assess the diagnostic and prognostic values of TF and TFPI in patients with sepsis and sepsis-induced ARDS.

METHODS

A total of 62 patients with sepsis, 167 patients with severe sepsis and 32 healthy volunteers were enrolled in this prospective observational study. TF and TFPI levels were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Patients with sepsis-induced ARDS showed significantly higher median levels of TF compared with patients without ARDS (1425.5 (1019.9 to 2595.2) pg/ml vs 916.2 (724.1 to 1618.2) pg/ml, P < 0.001), and compared with sepsis patients (943.5 (786.4 to 992.4) pg/ml, P < 0.001) on the day of admission. However, there was no significant difference between sepsis patients and healthy subjects, or between septic shock and non-septic shock patients (P > 0.05). The AUC of TF for the diagnosis of sepsis-induced ARDS was 0.749 (95% confidence interval (CI) 0.675-0.822). Plasma TF levels in the non-survivors of severe sepsis were significantly higher than those of survivors (1618.6 (1017.1 to 2900.8) pg/ml vs. 979.9 (757.2 to 1645.5) pg/ml, P < 0.001), and multivariate logistic regression showed the plasma value of TF was the independent predictor for 30-day mortality in patients with severe sepsis (P = 0.0022, odds ratio (OR) = 1.41, 95% CI 1.24-1.69). The AUC of TF for predicting 30-day mortality in severe sepsis patients was 0.718 (95% CI 0.641-0.794). However, there was no significant difference in the plasma TFPI values among the healthy control, sepsis and severe sepsis groups (P > 0.05).

CONCLUSIONS

Our data showed that tissue factor is a valuable diagnostic biomarker for the diagnosis of sepsis-induced ARDS. Moreover, tissue factor is a strong prognostic marker for short-term mortality in severe sepsis and sepsis-induced ARDS patients.

Crosstalk between the coagulation and complement systems in sepsis

Sepsis is a potent activator of the hemostatic and complement systems. While local activation of these proteolytic cascades contributes to the host defense, their uncontrolled systemic activation has major tissue damaging effects that lead to multiple organ failure and death. We have extensively studied the activation of complement and coagulation cascades in experimental sepsis using baboons challenged with live bacteria, such as Gram-negative Escherichia coli or Gram-positive Staphylococcus aureus and Bacillus anthracis, or with the bacterial product peptidoglycan. We observed that these challenges rapidly induce disseminated intravascular coagulation and robust complement activation. We applied a potent C3 convertase inhibitor, compstatin, which prevented sepsis-induced complement activation, reduced thrombocytopenia, decreased the coagulopathic responses, and preserving the endothelial anticoagulant properties. Overall, our work demonstrates that live bacteria and bacterial products activate the complement and coagulation cascades, and that blocking formation of complement activation products, especially during the organ failure stage of severe sepsis could be a potentially important therapeutic strategy.

Genetic variation in the tissue factor gene is associated with clinical outcome in severe sepsis patients

INTRODUCTION

Activation of inflammation and coagulation was closely related and mutually interdependent in sepsis. Tissue factor (TF) and its endogenous inhibitor, tissue factor pathway inhibitor (TFPI) was the main regulators of the initiation of coagulation process. Altered plasma levels of TF and TFPI have been related to worse outcome in sepsis. The objective of this study was to investigate whether single nucleotide polymorphisms (SNPs) in the TF and TFPI genes were associated with risk and outcome for patients with severe sepsis.

METHODS

Seventeen SNPs in TF and TFPI were genotyped in samples of sepsis (n =577) and severe sepsis patients (n =476), and tested for association in this case-control collection. We then investigated correlation between the associated SNPs and the mRNA expression, and protein level of the corresponding gene. The mRNA levels of TF were determined using real-time quantitative reverse transcription-polymerase chain reaction and the soluble plasma levels of TF were measured using enzyme linked immunosorbent assay (ELISA) method.

RESULTS

Association analysis revealed that three TF SNPs in perfect linkage disequilibrium, rs1361600, rs3917615 and rs958587, were significantly associated with outcome of severe sepsis. G allele frequency of rs1361600 in survivor patients was significantly higher than that in nonsurvivor severe sepsis patients (P =4.91 × 10(-5), odds ratio (OR) =0.48, 95% confidence interval (CI) 0.33 to 0.69). The association remained significant after adjustment for covariates in multiple logistic regression analysis and for multiple comparisons. Lipopolysaccharide-induced TF-mRNA expression levels in peripheral blood mononuclear cells from subjects carrying rs1361600 AG and GG genotypes, were significantly lower than those subjects carrying AA genotype (P =0.0012). Moreover, severe sepsis patients of GG and GA genotypes showed lower serum levels of TF than patients with AA genotype (P adj =0.02). The plasma levels of TF were also associated with outcome of severe sepsis patients (P adj =0.01). However, genotype and allele analyses did not show any significant difference between sepsis and severe sepsis patients.

CONCLUSIONS

Our findings indicate that common genetic variation in TF was significantly associated with outcome of severe sepsis in Chinese Han population.

Mild induced hypothermia: effects on sepsis-related coagulopathy--results from a randomized controlled trial

INTRODUCTION

Coagulopathy associates with poor outcome in sepsis. Mild induced hypothermia has been proposed as treatment in sepsis but it is not known whether this intervention worsens functional coagulopathy.

MATERIALS AND METHODS

Interim analysis data from an ongoing randomized controlled trial; The Cooling And Surviving Septic shock (CASS) study. Patients suffering severe sepsis/septic shock are allocated to either mild induced hypothermia (cooling to 32-34°C for 24hours) or control (uncontrolled temperature).

TRIAL REGISTRATION

NCT01455116. Thrombelastography (TEG) is performed three times during the first day after study enrollment in all patients. Reaction time (R), maximum amplitude (MA) and patients' characteristics are here reported.

RESULTS

One hundred patients (control n=50 and intervention n=50; male n=59; median age 68years) with complete TEG during follow-up were included. At enrollment, 3%, 38%, and 59% had a hypocoagulable, normocoagulable, and hypercoagulable TEG clot strength (MA), respectively. In the hypothermia group, functional coagulopathy improved during the hypothermia phase, measured by R and MA, in patients with hypercoagulation as well as in patients with hypocoagulation (correlation between ΔR and initial R: rho=-0.60, p<0.0001 and correlation between ΔMA and initial MA: rho=-0.50, p=0.0002). Similar results were not observed in the control group neither for R (rho=-0.03, p=0.8247) nor MA (rho=-0.15, p=0.3115).

CONCLUSION

Mild induced hypothermia did seem to improve functional coagulopathy in septic patients. This improvement of functional coagulopathy parameters during the hypothermia intervention persisted after rewarming. Randomized trials are warranted to determine whether the positive effect on sepsis-related coagulopathy can be transformed to improved survival.

The 'procoagulopathy' of trauma: too much, too late?

PURPOSE OF REVIEW

Although early acute traumatic coagulopathy has received much recent attention, the procoagulopathy that often follows appears less appreciated. Thromboembolic disease following trauma is common and lethal, but very effective prophylactic strategies are available. These strategies are variably implemented because of the difficulty in quantifying the magnitude of procoagulopathy in individual patients.

RECENT FINDINGS

The principal mechanisms of the procoagulopathy of trauma include inflammation and disseminated intravascular coagulation, tissue factor and thrombin dysregulation, and circulating microparticles and phospholipids. Quantification of these factors may allow better risk assessment in individual patients, but as yet none of these tests is in routine practice. Viscoelastic measurement of developing clot strength identifies a procoagulant state in many trauma patients, and may be a guide to the best choice of the many options for thromboembolic prophylaxis.

SUMMARY

The logical next step following from the improved pathophysiological understanding of the procoagulopathy of trauma should be a simultaneous clinical trial of procoagulopathy diagnosis and thromboembolic prophylaxis.

Acute lung injury and fibrosis in a baboon model of Escherichia coli sepsis

Sepsis-induced inflammation of the lung leads to acute respiratory distress syndrome (ARDS), which may trigger persistent fibrosis. The pathology of ARDS is complex and poorly understood, and the therapeutic approaches are limited. We used a baboon model of Escherichia coli sepsis that mimics the complexity of human disease to study the pathophysiology of ARDS. We performed extensive biochemical, histological, and functional analyses to characterize the disease progression and the long-term effects of sepsis on the lung structure and function. Similar to humans, sepsis-induced ARDS in baboons displays an early inflammatory exudative phase, with extensive necrosis. This is followed by a regenerative phase dominated by proliferation of type 2 epithelial cells, expression of epithelial-to-mesenchymal transition markers, myofibroblast migration and proliferation, and collagen synthesis. Baboons that survived sepsis showed persistent inflammation and collagen deposition 6-27 months after the acute episodes. Long-term survivors had almost double the amount of collagen in the lung as compared with age-matched control animals. Immunostaining for procollagens showed persistent active collagen synthesis within the fibroblastic foci and interalveolar septa. Fibroblasts expressed markers of transforming growth factor-β and platelet-derived growth factor signaling, suggesting their potential role as mediators of myofibroblast migration and proliferation, and collagen deposition. In parallel, up-regulation of the inhibitors of extracellular proteases supports a deregulated matrix remodeling that may contribute to fibrosis. The primate model of sepsis-induced ARDS mimics the disease progression in humans, including chronic inflammation and long-lasting fibrosis. This model helps our understanding of the pathophysiology of fibrosis and the testing of new therapies.

Comparison of the inhibitory activities of human tissue factor pathway inhibitor (TFPI)α and TFPIβ

BACKGROUND

Tissue factor pathway inhibitor (TFPI) is an alternatively spliced protein with two isoforms, TFPIα and TFPIβ, which differ in their C-terminal structure and cellular localization. Detailed characterization of their inhibitory activity is needed to define potentially unique inhibitory roles in tissue factor (TF)-mediated thrombotic and inflammatory disease, and to understand how pharmaceuticals targeted to different structural regions of the TFPI isoforms alter hemostasis in hemophilia patients.

METHODS

The TF inhibitory activity of TFPIβ localized to the surface of CHO cells was compared with that of soluble TFPIα by the use of in vitro and in vivo assays.

RESULTS

In TF-factor VIIa-mediated FXa generation assays, TFPIβ was a slightly better inhibitor than TFPIα, which was approximately three-fold better than TFPI-160, a soluble, altered form of TFPI similar to TFPIβ. In direct FXa inhibitory assays, TFPIβ had an IC50 2.5-fold lower than that of TFPIα and 56-fold lower than that of TFPI-160. TFPIβ inhibited TF-mediated CHO cell migration though Matrigel, whereas TFPIα and TFPI-160 were poor inhibitors, demonstrating that TFPIβ effectively blocks TF-initiated signaling events during cellular migration through matrices that are not permeable to soluble forms of TFPI. Furthermore, TFPIβ inhibited TF-dependent CHO cell infiltration into lung tissue following tail vein injection into SCID mice, and blocked the development of consumptive coagulopathy.

CONCLUSIONS

TFPIβ is a slightly better inhibitor of TF procoagulant activity than TFPIα. As a surface-associated protein, TFPIβ is a much better inhibitor of TF-mediated cellular migration than soluble TFPIα, and may specifically act in the inhibition of TF-mediated signaling events on inflamed endothelium and/or monocytes.

Plasmin-dependent proteolysis of tissue factor pathway inhibitor in a mouse model of endotoxemia

BACKGROUND

The development of a procoagulant state in sepsis, owing to aberrant expression of tissue factor (TF) and a sharp decrease in the level of its major inhibitor, TF pathway inhibitor (TFPI), could lead to microthrombotic organ failure. The mechanism for the decline in TFPI activity in the lung could involve plasmin-mediated cleavage of the inhibitor.

OBJECTIVE

To investigate the effect of plasmin generation on lung-associated TFPI activity, in normal conditions and during infusion of endotoxin (lipopolysaccharide [LPS]) in mice.

METHODS

Plasmin generation and TFPI activity were assayed in the lungs of mice deficient in tissue-type plasminogen (Plg) activator (t-PA) or Plg, at 2 h after LPS or saline injection.

RESULTS

The sharp loss of lung-associated TFPI activity at 2 h after LPS challenge paralleled the abrupt increase in plasmin generation. TFPI activity was significantly retained in both t-PA(-/-) and Plg(-/-) mice, which are unable to generate plasmin.

CONCLUSION

The increased plasmin generation during the early stages of sepsis could cleave/inactivate TFPI and thus lead to thrombotic complications.

Pathophysiology, staging and therapy of severe sepsis in baboon models

We review our baboon models of Escherichia coli sepsis that mimic, respectively, the shock/disseminated intravascular coagulation (DIC) and organ failure variants of severe sepsis, and analyse the pathophysiologic processes that are unique to each. The multi-stage, multi-factorial characteristics of severe sepsis develop as a result of the initial insult, which - depending on its intensity - activates components of the intravascular compartment leading to overwhelming shock/DIC; or initiates a sequence of events involving both the intra- and extravascular (tissues) compartments that lead to organ failure. In the latter case, the disorder passes through two stages: an initial inflammatory/coagulopathic intravascular first stage triggered by E. coli, followed by an extravascular second stage, involving components unique to each organ and triggered by ischemia/reperfusion (oxidative stress and histone release). Although a myriad of overlapping cellular and molecular components are involved, it is the context in which these components are brought into play that determine whether shock/DIC or organ failure predominate. For example, inflammatory and thrombotic responses amplified by thrombin in the first case whereas similar responses are amplified by complement activation products in the second. Rather than blocking specific mediators, we found that attenuation of the thrombin and complement amplification pathways can effectively reverse the shock/DIC and organ failure exhibited by the LD(100) and LD(50) E. coli models of severe sepsis, respectively. Translation of these concepts to successful intervention in the respective baboon models of E. coli sepsis and the application to their clinical counterparts is described.

Low levels of tissue factor lead to alveolar haemorrhage, potentiating murine acute lung injury and oxidative stress

BACKGROUND

Systemic blockade of tissue factor (TF) attenuates acute lung injury (ALI) in animal models of sepsis but the effects of global TF deficiency are unknown. We used mice with complete knockout of mouse TF and low levels (∼1%) of human TF (LTF mice) to test the hypothesis that global TF deficiency attenuates lung inflammation in direct lung injury.

METHODS

LTF mice were treated with 10 μg of lipopolysaccharide (LPS) or vehicle administered by direct intratracheal injection and studied at 24 h.

RESULTS

Contrary to our hypothesis, LTF mice had increased lung inflammation and injury as measured by bronchoalveolar lavage cell count (3.4×10(5) wild-type (WT) LPS vs 3.3×10(5) LTF LPS, p=0.947) and protein (493 μg/ml WT LPS vs 1014 μg/ml LTF LPS, p=0.006), proinflammatory cytokines (TNF-α, IL-10, IL-12, p<0.035 WT LPS vs LTF LPS) and histology compared with WT mice. LTF mice also had increased haemorrhage and free haemoglobin in the airspace accompanied by increased oxidant stress as measured by lipid peroxidation products (F(2) isoprostanes and isofurans).

CONCLUSIONS

These findings indicate that global TF deficiency does not confer protection in a direct lung injury model. Rather, TF deficiency causes increased intra-alveolar haemorrhage following LPS leading to increased lipid peroxidation. Strategies to globally inhibit TF may be deleterious in patients with ALI.

The reciprocal relationship between inflammation and coagulation

Inflammation and coagulation constitute two host defense systems with complementary roles in eliminating invading pathogens, limiting tissue damage, and restoring homeostasis. Extensive cross talk exists between these 2 systems, whereby inflammation leads to activation of coagulation, and coagulation considerably affects inflammatory activity. Infection leads to the production of proinflammatory cytokines that, in turn, stimulate the production of tissue factor. Activation of the coagulation system and ensuing thrombin generation are dependent on the expression of tissue factor. Conversely, activated coagulation proteases may affect specific receptors on inflammatory cells and endothelial cells and thereby modulate the inflammatory response. Activation of coagulation with the simultaneous down-regulation of endothelial-bound anticoagulant mechanisms and endogenous fibrinolysis characterizes the pathophysiology of sepsis. The mechanisms by which these highly complex and codependent defense strategies are linked together both in health and disease is the focus of this review.

Tissue factor pathway inhibitor: structure-function

TFPI is a multivalent, Kunitz-type proteinase inhibitor, which, due to alternative mRNA splicing, is transcribed in three isoforms: TFPIalpha, TFPIdelta, and glycosyl phosphatidyl inositol (GPI)-anchored TFPIbeta. The microvascular endothelium is thought to be the principal source of TFPI and TFPIalpha is the predominant isoform expressed in humans. TFPIalpha, apparently attached to the surface of the endothelium in an indirect GPI-anchor-dependent fashion, represents the greatest in vivo reservoir of TFPI. The Kunitz-2 domain of TFPI is responsible for factor Xa inhibition and the Kunitz-1 domain is responsible for factor Xa-dependent inhibition of the factor VIIa/tissue factor catalytic complex. The anticoagulant activity of TFPI in one-stage coagulation assays is due mainly to its inhibition of factor Xa through a process that is enhanced by protein S and dependent upon the Kunitz-3 and carboxyterminal domains of full-length TFPIalpha. Carboxyterminal truncated forms of TFPI as well as TFPIalpha in plasma, however, inhibit factor VIIa/tissue factor in two-stage assay systems. Studies in gene-disrupted mice demonstrate the physiological importance of TFPI.

Novel protein ADTRP regulates TFPI expression and function in human endothelial cells in normal conditions and in response to androgen

Thrombosis and cardiovascular disease (CVD) represent major causes of morbidity and mortality. Low androgen correlates with higher incidence of CVD/thrombosis. Tissue Factor Pathway Inhibitor (TFPI) is the major inhibitor of tissue factor-factor VIIa (TF-FVIIa)-dependent FXa generation. Because endothelial cell (EC) dysfunction leading to vascular disease correlates with low EC-associated TFPI, we sought to identify mechanisms that regulate the natural expression of TFPI. Data mining of NCBI's GEO microarrays revealed strong coexpression between TFPI and the uncharacterized protein encoded by C6ORF105, which is predicted to be multispan, palmitoylated and androgen-responsive. We demonstrate that this protein regulates both the native and androgen-enhanced TFPI expression and activity in cultured ECs, and we named it androgen-dependent TFPI-regulating protein (ADTRP). We confirm ADTRP expression and colocalization with TFPI and caveolin-1 in ECs. ADTRP-shRNA reduces, while over-expression of ADTRP enhances, TFPI mRNA and activity and the colocalization of TF-FVIIa-FXa-TFPI with caveolin-1. Imaging and Triton X-114-extraction confirm TFPI and ADTRP association with lipid rafts/caveolae. Dihydrotestosterone up-regulates TFPI and ADTRP expression, and increases FXa inhibition by TFPI in an ADTRP- and caveolin-1-dependent manner. We conclude that the ADTRP-dependent up-regulation of TFPI expression and activity by androgen represents a novel mechanism of increasing the anticoagulant protection of the endothelium.

Recombinant tissue factor pathway inhibitor in severe community-acquired pneumonia: a randomized trial

RATIONALE

Severe community-acquired pneumonia (sCAP) is a leading cause of death worldwide. Adjunctive therapies for sCAP are needed to further improve outcome. A systemic inhibitor of coagulation, tifacogin (recombinant human tissue factor pathway inhibitor) seemed to provide mortality benefit in the sCAP subgroup of a previous sepsis trial.

OBJECTIVES

Evaluate the impact of adjunctive tifacogin on mortality in patients with sCAP.

METHODS

A multicenter, randomized, placebo-controlled, double-blind, three-arm study was conducted from July 2005 to June 2008 at 188 centers in North and South America, Europe, South Africa, Asia, Australia, and New Zealand. Adults with sCAP were randomized to receive a continuous intravenous infusion of tifacogin 0.025 mg/kg/h, tifacogin 0.075 mg/kg/h, or matching placebo over 96 hours.

MEASUREMENTS AND MAIN RESULTS

Severity-adjusted 28-day all-cause mortality. Of 2,138 randomized patients, 946, 238, and 918 received tifacogin 0.025 mg/kg/h, tifacogin 0.075 mg/kg/h, and placebo, respectively. Tifacogin 0.075 mg/kg/h was discontinued after the first interim analysis according to prespecified futility criterion. The 28-day all-cause mortality rates were similar between the 0.025 mg/kg/h (18%) and placebo groups (17.9%) (P = 0.56). Greater reduction in prothrombin fragment 1+2 and thrombin antithrombin complexes levels relative to baseline throughout the first 96 hours was found with tifacogin 0.025 mg/kg/h than with placebo. The incidence of adverse events and serious adverse events were comparable between the tifacogin 0.025 mg/kg/h and placebo groups.

CONCLUSIONS

Tifacogin showed no mortality benefit in patients with sCAP despite evidence of biologic activity.

Tissue factor pathway inhibitor and bacterial infection

See also van den Boogaard FE, Brands X, Schultz MJ, Levi M, Roelofs JJTH, van 't Veer C, van der Poll T. Recombinant human tissue factor pathway inhibitor exerts anticoagulant, anti-inflammatory and antimicrobial effects in murine pneumococcal pneumonia. This issue, pp 122-32.