Anticoagulant modulation of inflammation in severe sepsis

Deranged Balance of Hemostasis and Fibrinolysis in Disseminated Intravascular Coagulation: Assessment and Relevance in Different Clinical Settings

The disruption of hemostasis/fibrinolysis balance leads to disseminated intravascular coagulation, manifested clinically by bleeding or thrombosis, and multiorgan failure. This study reviews hemostatic assessment and therapeutic strategies that restore this balance in critically ill patients.

Fibrinaloid Microclots and Atrial Fibrillation

Atrial fibrillation (AF) is a comorbidity of a variety of other chronic, inflammatory diseases for which fibrinaloid microclots are a known accompaniment (and in some cases, a cause, with a mechanistic basis). Clots are, of course, a well-known consequence of atrial fibrillation. We here ask the question whether the fibrinaloid microclots seen in plasma or serum may in fact also be a cause of (or contributor to) the development of AF. We consider known 'risk factors' for AF, and in particular, exogenous stimuli such as infection and air pollution by particulates, both of which are known to cause AF. The external accompaniments of both bacterial (lipopolysaccharide and lipoteichoic acids) and viral (SARS-CoV-2 spike protein) infections are known to stimulate fibrinaloid microclots when added in vitro, and fibrinaloid microclots, as with other amyloid proteins, can be cytotoxic, both by inducing hypoxia/reperfusion and by other means. Strokes and thromboembolisms are also common consequences of AF. Consequently, taking a systems approach, we review the considerable evidence in detail, which leads us to suggest that it is likely that microclots may well have an aetiological role in the development of AF. This has significant mechanistic and therapeutic implications.

Assessment of soluble thrombomodulin and soluble endoglin as endothelial dysfunction biomarkers in seriously ill surgical septic patients: correlation with organ dysfunction and disease severity

BACKGROUND

Sepsis, a complex condition characterized by dysregulated immune response and organ dysfunction, is a leading cause of mortality in ICU patients. Current diagnostic and prognostic approaches primarily rely on non-specific biomarkers and illness severity scores, despite early endothelial activation being a key feature of sepsis. This study aimed to evaluate the levels of soluble thrombomodulin and soluble endoglin in seriously ill surgical septic patients and explore their association with organ dysfunction and disease severity.

METHODOLOGY

A case control study was conducted from March 2022 to November 2022, involving seriously ill septic surgical patients. Baseline clinical and laboratory data were collected within 24 h of admission to the Surgical Intensive Care Unit. This included information such as age, sex, hemodynamic parameters, blood chemistry, SOFA score, qSOFA score, and APACHE-II score. A proforma was filled out to record these details. The outcome of each patient was noted at the time of discharge.

RESULTS

The study found significantly elevated levels of soluble thrombomodulin and soluble endoglin in seriously ill surgical septic patients. The RTqPCR analysis revealed a positive correlation between soluble thrombomodulin and soluble endoglin levels with the qSOFA score, as well as, there was a positive association between RTqPCR soluble thrombomodulin and the SOFA score. These findings indicate a correlation between these biomarkers and organ dysfunction and disease severity.

CONCLUSION

The study concludes that elevated levels of soluble thrombomodulin and soluble endoglin can serve as endothelial biomarkers for early diagnosis and prognostication in seriously ill surgical septic patients.

Extracellular histones trigger oxidative stress-dependent induction of the NF-kB/CAM pathway via TLR4 in endothelial cells

Extracellular histones have been reported to aggravate different pathophysiological processes by increasing vascular permeability, coagulopathy, and inflammation. In the present study, we elucidate how extracellular histones (10–100 µg/mL) concentration dependently increase cytosolic reactive oxygen species (ROS) production using human umbilical vein endothelial cells (HUVECs). Furthermore, we identify cyclooxygenase (COX) and NADPH oxidase (NOX) activity as sources of ROS production in extracellular histone-treated HUVEC. This COX/NOX-mediated ROS production is also involved in enhanced NF-kB activity and cell adhesion molecules (VCAM1 and ICAM1) expression in histone-treated HUVEC. Finally, by using different toll-like receptor (TLR) antagonists, we demonstrate the role of TLR4 in CAMs overexpression triggered by extracellular histones in endothelial cells. In conclusion, our data suggest that through TLR4 signaling, extracellular histones increase endothelial cell activation, a mechanism involving increased COX- and NOX-mediated ROS. These findings increase our understanding on how extracellular histones enhance systemic inflammatory responses in diseases in which histone release occurs as part of the pathological processes.

Effect of anticoagulant and platelet inhibition on the risk of bacteremia among patients with acute pyelonephritis: a retrospective cohort study

Background

An increasing number of patients are being prescribed anticoagulants and platelet inhibitors (antithrombotic treatment). Basic research has suggested an association between antithrombotic treatment and bacteremia during kidney infection. Here, we investigated the association between antithrombotic treatment, bacteremia and acute kidney injury in patients with acute pyelonephritis.

Methods

A retrospective cohort study was conducted in a large university hospital in Sweden. Data were retrieved from electronic medical records for adult patients with acute pyelonephritis in 2016. The main outcome was bacteremia and secondary outcome acute kidney injury. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated through multiple logistic regression. Treatment with different groups of antithrombotic agents were compared to no antithrombotic treatment.

Results

1814 patients with acute pyelonephritis were included, in whom bacteremia developed in 336 (18.5%). Low-molecular-weight heparin (LMWH) at prophylactic doses was associated with a lower risk of bacteremia, compared to no antithrombotic treatment (OR 0.5; 95% CI 0.3–0.7). Other antithrombotic treatments were not associated with a risk of bacteremia. Additionally, patients with prophylactic doses of LMWH had a lower risk of acute kidney injury (OR 0.5; 95% CI 0.3–0.8).

Conclusions

We found no association between antithrombotic treatment and an increased risk of bacteremia during acute pyelonephritis. Conversely, patients with prophylactic doses of LMWH had a slightly reduced risk of bacteremia. LMWH at prophylactic doses was also associated with a lower risk of acute kidney injury. Our results suggest that it is safe to continue antithrombotic treatment during acute pyelonephritis, in regards to bacteremia and acute kidney injury risk.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07474-4.

Phenotype-oriented anticoagulant therapy for sepsis: still a work in progress

Coagulation disorders ranging from subtle changes in coagulation parameters to fatal disseminated intravascular coagulation (DIC) are common in septic patients. Coagulation activation is considered to be one of the most important factors contributing to multiple organ dysfunction syndrome (MODS) in sepsis. Anticoagulant therapy is, therefore, necessary to prevent MODS, but eligibility criteria remain controversial. Sepsis is a highly heterogeneous syndrome, which could explain the negative results of clinical studies on the treatment of sepsis. Recently, sepsis has been subdivided into several phenotypes with different therapeutic outcomes. At present, septic patients with dysfunctional coagulation expressed as increased D-dimer and fibrin/fibrinogen degradation products (FDPs) are considered to be candidates for anticoagulant therapy. In this review, we aimed to describe the features of different septic phenotypes. We also discuss factors that contribute to controversies in this area, and challenges in defining which septic phenotypes are good candidates for anticoagulant therapy.

Assessment of clinical characteristics and treatment outcomes of pediatric patients with intracardiac thrombosis: a single-center experience

The prevalence of intracardiac thrombus (ICT) is gradually increasing, though it is rare among children. Data related to the occurrence of ICT among children are limited, and treatment recommendations have been made utilizing adult guidelines. The primary objective of this study is to determine associated factors, management, and outcomes of intracardiac thrombosis in children. Between January 2013 and January 2020, patients diagnosed with ICT at the Pediatric Hematology-Oncology and Pediatric Cardiology departments in our hospital were included in the study. Demographic characteristics, clinical and laboratory findings, treatment protocols, and outcomes were analyzed retrospectively. The median age at diagnosis was 10.5 months (2 days to 14.5 years), and the median follow-up period was 6.5 months (1 month to 3.1 years). The most common primary diagnoses of the patients, in order of frequency, were heart disease (n: 8), metabolic disease (n: 3), prematurity and RDS (n: 3), burns (n: 2), pneumonia (n: 2), and asphyxia (n: 2). CVC was present in 19/23 of the patients. The reasons for CVC insertion were the need for plasmapheresis in one patient with a diagnosis of HUS and the need for well tolerated vascular access because of long-term hospitalization in others. LMWH was administered to all patients as first-line therapy. Complete response was achieved in 19 (79%) of 24 patients and 4 patients (16.6%) were unresponsive to medical treatment. It was found out that the thrombus location, type, sepsis, and hemoculture positivity, as well as the presence of CVC, had no impact on treatment response (chi-square P = 0.16, 0.12, 0.3, 0.49, 0.56). Moreover, no correlation was determined between thrombus size and treatment response (Mann Whitney U test P = 0.47). The mortality rate was determined to be 12.5% (3/24). Spontaneous occurrence of ICT is rare in childhood, without any underlying primary disease or associated factor. The presence of CVC, sepsis, and heart disease are factors associated with ICT. The success rate is increased with medical treatment. There was no significant difference in treatment response between the newborn and 1 month to 18-year-old patient group. It has been demonstrated that thrombus size, type, localization; sepsis, and hemoculture positivity had no impact on the treatment response.

The Effect of Various Types of Anticoagulant Therapy on the Reduction of Mortality in COVID-19

Coronavirus disease 2019 (COVID-19) is a viral infection that, in severe course, leads to the development of a cytokine storm, systemic inflammatory response and coagulopathy. Unlike other sepsis-associated disseminated intravascular coagulopathy, COVID-19 induced coagulopathy is realized mainly in thrombosis. Researchers around the world are currently developing adequate diagnostic, monitoring and anticoagulant therapy approaches to safely and effectively manage patients with severe COVID-19. The need to develop laboratory monitoring is due to the fact that 20% of patients have changes in hemostasis indicators, while in patients with a severe form of the disease, they are present in 100% of cases. In case of deaths from COVID-19, there is an increase in the concentration of D-dimer and fibrinogen degradation products. Thus, the severity of hemostasis disorders has an important prognostic value. Anticoagulant therapy is included in the list of all recommendations as an effective means of reducing mortality from COVID-19. The questions of the recommended groups and doses of anticoagulant drugs are still open. The approach to the choice of an anticoagulant should be based not only on risk factors, characteristics of the course of the disease, anamnesis, but also on the wishes of the patient during long-term therapy at the post-hospital stage.

The Role of HSP70 in the Protective Effects of NVP-AUY922 on Multiple Organ Dysfunction Syndrome in Endotoxemic Rats

Sepsis is defined as a life-threatening organ dysfunction syndrome with high morbidity and mortality caused by bacterial infection. The major characteristics of sepsis are systemic inflammatory responses accompanied with elevated oxidative stress, leading to multiple organ dysfunction syndrome (MODS), and disseminated intravascular coagulation (DIC). As a molecular chaperon to repair unfolded proteins, heat shock protein 70 (HSP70) maintains cellular homeostasis and shows protective effects on inflammatory damage. HSP 90 inhibitors were reported to exert anti-inflammatory effects via activation of the heat shock factor-1 (HSF-1), leading to induction of HSP70. We evaluated the beneficial effect of HSP 90 inhibitor NVP-AUY 922 (NVP) on multiple organ dysfunction syndrome induced by lipopolysaccharide (LPS) and further explored the underlying mechanism. NVP (5 mg/kg, i.p.) was administered 20 h prior to LPS initiation (LPS 30 mg/kg, i.v. infusion for 4 h) in male Wistar rats. Results demonstrated that pretreatment with NVP significantly increased survival rate and prevented hypotension at 6 h after LPS injection. Plasma levels of ALT, CRE and LDH as well as IL-1β and TNF-α were significantly reduced by NVP at 6 h after LPS challenge. The induction of inducible NO synthase in the liver, lung and heart and NF-κB p-p65 and caspase 3 protein expression in the heart were also attenuated by NVP. In addition, NVP markedly induced HSP70 and HO-1 proteins in the liver, lung and heart after LPS injection. These results indicated that NVP possessed the anti-inflammatory and antioxidant effects on LPS-induced acute inflammation, which might be associated with HSP70 and HO-1, leading to prevent MODS in sepsis. NVP might be considered as a novel therapeutic strategy in the prevention of sepsis-induced MODS.

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.

Catheter-directed thrombolysis to treat acute pulmonary thrombosis in a patient with COVID-19 pneumonia

We describe a case of a patient who presented to the emergency department with severe shortness of breath and was diagnosed with mild COVID-19 pneumonia and concomitant intermediate-high risk saddle pulmonary thromboembolism. Additionally, the patient had sustained a significant head injury 2 days prior due to a syncopal episode. The patient was treated successfully with catheter-directed thrombolysis (CDT). The case highlights the importance of considering thromboembolic complications in COVID-19 infection, independent of the severity of the associated pneumonia. The case also demonstrates the potential benefit of CDT in treating COVID-19-related thromboembolism.

SEDAR-SEMICYUC consensus recommendations on the management of haemostasis disorders in severely ill patients with COVID-19 infection

The infection by the coronavirus SARS-CoV-2, which causes the disease called COVID-19, mainly causes alterations in the respiratory system. In severely ill patients, the disease often evolves into an acute respiratory distress syndrome that can predispose patients to a state of hypercoagulability, with thrombosis at both venous and arterial levels. This predisposition presents a multifactorial physiopathology, related to hypoxia as well as to the severe inflammatory process linked to this pathology, including the additional thrombotic factors present in many of the patients.

In view of the need to optimise the management of hypercoagulability, the working groups of the Scientific Societies of Anaesthesiology-Resuscitation and Pain Therapy (SEDAR) and of Intensive, Critical Care Medicine and Coronary Units (SEMICYUC) have developed a consensus to establish guidelines for actions to be taken against alterations in haemostasis observed in severely ill patients with COVID-19. These recommendations include prophylaxis of venous thromboembolic disease in these patients, and in the peripartum, management of patients on long-term antiplatelet or anticoagulant treatment, bleeding complications in the course of the disease, and the interpretation of general alterations in haemostasis.

SEDAR-SEMICYUC consensus recommendations on the management of haemostasis disorders in severely ill patients with COVID-19 infection

The infection by the coronavirus SARS-CoV-2, which causes the disease called COVID-19, mainly causes alterations in the respiratory system. In severely ill patients, the disease often evolves into an acute respiratory distress syndrome that can predispose patients to a state of hypercoagulability, with thrombosis at both venous and arterial levels. This predisposition presents a multifactorial physiopathology, related to hypoxia as well as to the severe inflammatory process linked to this pathology, including the additional thrombotic factors present in many of the patients. In view of the need to optimise the management of hypercoagulability, the working groups of the Scientific Societies of Anaesthesiology-Resuscitation and Pain Therapy (SEDAR) and of Intensive, Critical Care Medicine and Coronary Units (SEMICYUC) have developed a consensus to establish guidelines for actions to be taken against alterations in haemostasis observed in severely ill patients with COVID-19. These recommendations include prophylaxis of venous thromboembolic disease in these patients, and in the peripartum, management of patients on long-term antiplatelet or anticoagulant treatment, bleeding complications in the course of the disease, and the interpretation of general alterations in haemostasis.

Pathogenesis and Treatment Strategies of COVID-19-Related Hypercoagulant and Thrombotic Complications

The new type of pneumonia caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is endemic worldwide, and many countries cannot be spared, becoming a global health concern. The disease was named COVID-19 by the World Health Organization (WHO) on January 30, 2020, when the WHO declared the Chinese outbreak of COVID-19 to be a public health emergency of international concern. The clinical features of COVID-19 include dry cough, fever, diarrhea, vomiting, and myalgia. Similar to SARS-CoV and MERS-CoV, nearly 20% of patients experienced various fatal complications, including acute kidney injury and acute respiratory distress syndrome caused by cytokine storm. Furthermore, systemic cytokine storm induced vascular endothelial injury, which extensively mediates hypercoagulability in blood vessels and disseminated intravascular coagulation. The autopsy pathology of COVID-19 confirmed the above. This article briefly summarizes the mechanism of hypercoagulability and thrombotic complications of severe COVID-19 and proposes that blood hypercoagulability and intravascular microthrombosis are the development nodes of severe COVID-19. Therefore, anticoagulation and anti-inflammatory therapy can be used as important treatment strategies for severe COVID-19.

The cytokine storm of COVID-19: a spotlight on prevention and protection

INTRODUCTION

The cytokine release syndrome (CRS) of COVID-19 is associated with the development of critical illness requiring multi-organ support. Further research is required to halt progression of multi-organ injury induced by hyper-inflammation.

AREAS COVERED

PubMed/MEDLINE^TM databases were accessed between May 9^th-June 9^th, 2020, to review the latest perspectives on the treatment and pathogenesis of CRS.

EXPERT OPINION

Over-activity of chemotaxis triggers a macrophage activation syndrome (MAS) resulting in the release of pro-inflammatory cytokines. IL-6 and TNF- α are at the forefront of hyper-inflammation. The inflammatory cascade induces endothelial activation and capillary leak, leading to circulatory collapse and shock. As endothelial dysfunction persists, there is activation of the clotting cascade and microvascular obstruction. Continued endothelial activation results in multi-organ failure, regardless of pulmonary tissue damage. We propose that targeting the endothelium may interrupt this cycle. Immuno-modulating therapies have been suggested, however, further data is necessary to confirm that they do not jeopardize adaptive immunity. Inhibition of IL-6 and the Janus Kinase, signal transducer and activator of transcription proteins pathway (JAK/STAT), are favorable targets. Remote ischemic conditioning (RIC) reduces the inflammation of sepsis in animal models and should be considered as a low risk intervention, in combination with cardiovascular protection.

The interplay between host haemostatic systems and Leptospira spp. infections

Hemostasis is a defence mechanism that protects the integrity of the vascular system and is comprised of the coagulation cascade, fibrinolysis, platelet aggregation, and vascular endothelium. Besides the primary function in preserving the vascular integrity, the haemostatic system cooperates with immune and inflammatory processes to eliminate invading pathogens during microbial infections. Under pathological manifestations, hemostasis must therefore interact in a coordinated manner with inflammatory responses and immune reactions. Several pathogens can modulate these host-derived countermeasures by specifically targeting certain haemostatic components for their own benefit. Thus, the ability to modulate host defence systems has to be considered as an essential bacterial virulence mechanism. Complications that bacterial pathogens can induce are therefore often the consequence of evoked host responses. A comprehensive understanding of the molecular mechanisms triggered in infectious processes may help to develop prophylactic methods and novel therapies for the patients suffering from a particular infectious disease. This review aims to provide a critical updated compiling of recent studies on how the pathogenic Leptospira can interact with and manipulate the host haemostatic systems and the consequences for leptospirosis pathogenesis.

Understanding Infection-Induced Thrombosis: Lessons Learned From Animal Models

Thrombosis is a common consequence of infection that is associated with poor patient outcome. Nevertheless, the mechanisms by which infection-associated thrombosis is induced, maintained and resolved are poorly understood, as is the contribution thrombosis makes to host control of infection and pathogen spread. The key difference between infection-associated thrombosis and thrombosis in other circumstances is a stronger inflammation-mediated component caused by the presence of the pathogen and its products. This inflammation triggers the activation of platelets, which may accompany damage to the endothelium, resulting in fibrin deposition and thrombus formation. This process is often referred to as thrombo-inflammation. Strikingly, despite its clinical importance and despite thrombi being induced to many different pathogens, it is still unclear whether the mechanisms underlying this process are conserved and how we can best understand this process. This review summarizes thrombosis in a variety of models, including single antigen models such as LPS, and infection models using viruses and bacteria. We provide a specific focus on Salmonella Typhimurium infection as a useful model to address all stages of thrombosis during infection. We highlight how this model has helped us identify how thrombosis can appear in different organs at different times and thrombi be detected for weeks after infection in one site, yet largely be resolved within 24 h in another. Furthermore, we discuss the observation that thrombi induced to Salmonella Typhimurium are largely devoid of bacteria. Finally, we discuss the value of different therapeutic approaches to target thrombosis, the potential importance of timing in their administration and the necessity to maintain normal hemostasis after treatment. Improvements in our understanding of these processes can be used to better target infection-mediated mechanisms of thrombosis.

Crosstalk between Platelet and Bacteria: A Therapeutic Prospect

Platelets are typically recognized for their roles in the maintenance of hemostasis and vascular wall repair to reduce blood loss. Beyond hemostasis, platelets also play a critical role in pathophysiological conditions like atherosclerosis, stroke, thrombosis, and infections. During infection, platelets interact directly and indirectly with bacteria through a wide range of cellular and molecular mechanisms. Platelet surface receptors such as GPIbα, FcγRIIA, GPIIbIIIa, and TLRs, etc. facilitate direct interaction with bacterial cells. Besides, the indirect interaction between platelet and bacteria involves host plasma proteins such as von Willebrand Factor (vWF), fibronectin, IgG, and fibrinogen. Bacterial cells induce platelet activation, aggregation, and thrombus formation in the microvasculature. The activated platelets induce the Neutrophil Extracellular Traps (NETs) formation, which further contribute to thrombosis. Thus, platelets are extensively anticipated as vital immune modulator cells during infection, which may further lead to cardiovascular complications. In this review, we cover the interaction mechanisms between platelets and bacteria that may lead to the development of thrombotic disorders. Platelet receptors and other host molecules involved in such interactions can be used to develop new therapeutic strategies to combat against infection-induced cardiovascular complications. In addition, we highlight other receptor and enzyme targets that may further reduce infection-induced platelet activation and various pathological conditions.

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.

C-Reactive Protein Predicts Risk of Venous Thromboembolism in Pediatric Musculoskeletal Infection

BACKGROUND

The rate of venous thromboembolism in children with musculoskeletal infections (MSKIs) is markedly elevated compared with hospitalized children in general. Predictive biomarkers to identify high-risk patients are needed to prevent the significant morbidity and rare mortality associated with thrombotic complications. We hypothesize that overactivation of the acute phase response is associated with the development of pathologic thrombi and we aim to determine whether elevations in C-reactive protein (CRP) are associated with increased rates of thrombosis in pediatric patients with MSKI.

METHODS

A retrospective cohort study measuring CRP in pediatric MSKI patients with or without thrombotic complications.

RESULTS

The magnitude and duration of elevation in CRP values correlated with the severity of infection and the development of pathologic thrombosis. In multivariable logistic regression, every 20 mg/L increase in peak CRP was associated with a 29% increased risk of thrombosis (P<0.001). Peak and total CRP were strong predictors of thrombosis with area under the receiver-operator curves of 0.90 and 0.92, respectively.

CONCLUSIONS

Future prospective studies are warranted to further define the discriminatory power of CRP in predicting infection-provoked thrombosis. Pharmacologic prophylaxis and increased surveillance should be strongly considered in patients with MSKI, particularly those with disseminated disease and marked elevation of CRP.

LEVEL OF EVIDENCE

Level III.

Complement component consumption in sepsis correlates better with hemostatic system parameters than with inflammatory biomarkers

INTRODUCTION

The aim of this study was to investigate the role of C3 and C4 complement components in prediction of sepsis outcome. The secondary aim was to determine relationship between complement components and other inflammatory parameters, and parameters of hemostasis.

METHODS

One-hundred-thirty-seven patients with sepsis (Sepsis-3 criteria) were included in the study. Routine laboratory markers, predictive APACHEII and SOFA scores, concentrations of C3 and C4, activated partial thromboplastin time (aPTT), prothrombin time (PT), thrombin time (TT), fibrinogen, antithrombin (AT), protein C (PC), protein S (PS), endogenous thrombin potential (ETP), thrombomodulin, and D-dimer were available. Concentrations of C3 and C4 were correlated with the disease outcome, predictive scores, inflammatory markers and parameters of hemostasis. Statistical analysis was performed using the non-parametric approach and significance was set at p < 0.05.

RESULTS

A significant depletion of the complement was observed in non-survivors (AUCROC_C3 = 0.692, p_C3 < 0.001,AUCROC_C4 = 0.672, p_C4 = 0.001). There was a significant negative correlation of C3and C4with APACHEII and SOFA (C3-APACHEII ρ = -0.364, p = 0.011, C3-SOFA ρ = -0.460, p < 0.001), aPTT (ρ = -0.407, p < 0.001), PT (ρ = -0.408, p < 0.001), and D-dimer (ρ = -0.274, p = 0.001). A significant positive correlation was observed with natural anticoagulants (C3-AT ρ = 0.493, p < 0.001; C3-PC ρ = 0.450, p < 0.001; C3-PS ρ = 0.345, p < 0.001), fibrinogen (ρ = 0.481, p < 0.001),and ETP (ρ = 0.384, p < 0.001). C3 and C4 correlated significantly only with CRP (ρ = 0.207, p = 0.015), while no significant correlations with procalcitonin and WBC were detected. Results were similar for C4 and C3, although C3 presented higher correlation coefficients.

CONCLUSION

In septic patients with poorer outcome, a significant depletion of the complement system was observed. Concentrations of complement components demonstrated stronger correlations with coagulation parameters than with inflammatory biomarkers.

Development of a Physiologically Based Pharmacokinetic Modelling Approach to Predict the Pharmacokinetics of Vancomycin in Critically Ill Septic Patients

BACKGROUND AND OBJECTIVES

Sepsis is characterised by an excessive release of inflammatory mediators substantially affecting body composition and physiology, which can be further affected by intensive care management. Consequently, drug pharmacokinetics can be substantially altered. This study aimed to extend a whole-body physiologically based pharmacokinetic (PBPK) model for healthy adults based on disease-related physiological changes of critically ill septic patients and to evaluate the accuracy of this PBPK model using vancomycin as a clinically relevant drug.

METHODS

The literature was searched for relevant information on physiological changes in critically ill patients with sepsis, severe sepsis and septic shock. Consolidated information was incorporated into a validated PBPK vancomycin model for healthy adults. In addition, the model was further individualised based on patient data from a study including ten septic patients treated with intravenous vancomycin. Models were evaluated comparing predicted concentrations with observed patient concentration-time data.

RESULTS

The literature-based PBPK model correctly predicted pharmacokinetic changes and observed plasma concentrations especially for the distribution phase as a result of a consideration of interstitial water accumulation. Incorporation of disease-related changes improved the model prediction from 55 to 88% within a threshold of 30% variability of predicted vs. observed concentrations. In particular, the consideration of individualised creatinine clearance data, which were highly variable in this patient population, had an influence on model performance.

CONCLUSION

PBPK modelling incorporating literature data and individual patient data is able to correctly predict vancomycin pharmacokinetics in septic patients. This study therefore provides essential key parameters for further development of PBPK models and dose optimisation strategies in critically ill patients with sepsis.

Mechanisms and Targeted Therapies for Pseudomonas aeruginosa Lung Infection

Pseudomonas aeruginosa is a complex gram-negative facultative anaerobe replete with a variety of arsenals to activate, modify, and destroy host defense mechanisms. The microbe is a common cause of nosocomial infections and an antibiotic-resistant priority pathogen. In the lung, P. aeruginosa disrupts upper and lower airway homeostasis by damaging the epithelium and evading innate and adaptive immune responses. The biology of these interactions is essential to understand P. aeruginosa pathogenesis. P. aeruginosa interacts directly with host cells via flagella, pili, lipoproteins, lipopolysaccharides, and the type III secretion system localized in the outer membrane. P. aeruginosa quorum-sensing molecules regulate the release of soluble factors that enhance the spread of infection. These characteristics of P. aeruginosa differentially affect lung epithelial, innate, and adaptive immune cells involved in the production of mediators and the recruitment of additional immune cell subsets. Pathogen interactions with individual host cells and in the context of host acute lung infection are discussed to reveal pathways that may be targeted therapeutically.

Serum histones as biomarkers of the severity of heatstroke in dogs

Heatstroke is associated with systemic inflammatory response syndrome, leading to multiple organ dysfunction and death. Currently, there is no specific treatment decreasing hyperthermia-induced inflammatory/hemostatic derangements. Emerging studies indicate that histones leaking from damaged cells into the extracellular space are toxic, pro-inflammatory, and pro-thrombotic. We therefore hypothesize that serum histones (sHs) are elevated during heatstroke and are associated with the severity of the disease. Sixteen dogs with heatstroke and seven healthy controls were included in the study. Median serum histones (sHs) upon admission in dogs with heatstroke were significantly higher (P = 0.043) compared to that in seven controls (13.2 vs. 7.3 ng/mL, respectively). sHs level was significantly higher among non-survivors and among dogs with severe hemostatic derangement (P = 0.049, median 21.4 ng/mL vs. median 8.16 ng/mL and P = 0.038, 19.0 vs. 7.0 ng/mL, respectively). There were significant positive correlation between sHs and urea (r = 0.8, P = 0.02); total CO2 (r = 0.661, P = 0.05); CK (r = 0.678, P = 0.04); and prothrombin time (PT) 12 h post presentation (r = 0.888, P = 0.04). The significant positive correlation between sHs and other heatstroke severity biomarkers, and significant increase among severely affected dogs, implies its role in inflammation/oxidation/coagulation during heatstroke. sHs, unlike other prognostic and severity biomarkers in heatstroke, can be pharmacologically manipulated, offering a potential therapeutic target.

Fibrinogen and D-dimer levels elevate in advanced hepatocellular carcinoma: High pretreatment fibrinogen levels predict poor outcomes

AIM

Plasma fibrinogen and D-dimer have been reported to predict survival in several types of malignancies. The aim of this study is to investigate their predictive value in patients with hepatocellular carcinoma (HCC).

METHODS

We retrospectively analyzed plasma fibrinogen and D-dimer levels from 252 subjects: control (n = 20), hepatitis (n = 20), cirrhosis (n = 20), and HCC (n = 192) subjects. The clinical involvement and prognostic value of fibrinogen and D-dimer was analyzed in HCC subjects. To confirm the effects of tumor on hypercoagulability and fibrinolysis, fibrinogen and D-dimer levels were measured in nude mice following HCC inoculation.

RESULTS

Fibrinogen decreased and D-dimer increased in cirrhosis subjects relative to other groups. In HCC subjects, elevated fibrinogen and D-dimer levels were significantly associated with adverse tumor features (increased size, stage, and grade) and systemic inflammation. Patients with HCC with either elevated fibrinogen or D-dimer levels had significantly higher 3-year tumor recurrence rates (65% vs. 41%, P < 0.001 for fibrinogen; 67% vs. 40%, P = 0.011 for D-dimer) and significantly lower 3-year overall survival rates (57% vs. 79%, P < 0.001 for fibrinogen; 56% vs. 80%, P = 0.001 for D-dimer). After multivariate analysis, elevated fibrinogen levels remained an independent predictor of poor prognosis in HCC patients. Finally, elevated levels of fibrinogen and D-dimer were confirmed in nude mice following tumor inoculation.

CONCLUSION

The fibrinogen and D-dimer levels, elevating after carcinogenesis, may serve as simple but effective predictors of adverse tumor profiles and outcomes in HCC.

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.

Coagulation Profile in Patients with Different Etiologies for Cushing Syndrome: A Prospective Observational Study

Previous studies reported a higher prevalence of venous-thromboembolic events among patients with Cushing disease (CD) compared to those with ACTH-independent Cushing syndrome (CS) from adrenal sources. The objective of the current study was to evaluate the coagulation profile of patients with CS from different etiologies. A prospective observational study was conducted at a clinical research center. The study included adult patients admitted for evaluation of suspected CS (n=85), that were divided into 3 groups: CD (n=22), ACTH-independent CS from an adrenal tumor/hyperplasia (adrenal CS, n=21), and a control group consisting of subjects with negative screening for CS (rule-out CS, n=42). Coagulation profiles were drawn before and 8.5±4.3 months after surgery (trans-sphenoidal or adrenalectomy, n=18), and included fibrinogen, Factor VIII (FVIII), von Willebrand factor antigen (vWF:Ag), plasminogen activator inhibitor-1 (PAI-1), antithrombin III (ATIII), Protein C (PC), Protein S (PS), α2-antiplasmin (α2AP), and aPTT measurements. Patients with CD had higher baseline mean cortisol levels, ATIII activity and vWF:Ag levels compared with adrenal CS. Differences in ATIII activity and vWF:Ag levels remained even after controlling for BMI, and ATIII after also controlling for 24-h urinary free cortisol collections. Our study showed for the first time the differences in coagulation profiles between various etiologies of CS. We assume that the higher cortisol burden among CD patients may explain the differences found in the coagulation profile as well as the higher risk for VTE compared with primary adrenal CS patients.

Association Between Hematologic and Inflammatory Markers and 31 Thrombotic and Hemorrhagic Events in Berlin Heart Excor Patients

Bleeding and thrombotic events remain a significant cause of morbidity in pediatric patients supported with ventricular assist devices (VADs). The objective of this study is to identify the association between markers of anticoagulation and bleeding and thrombosis events during Berlin Heart ExCor support. A retrospective, single-center analysis of 9 patients supported with the Berlin Heart ExCor was performed. Inflammatory and anticoagulation parameters including C-reactive protein, fibrinogen, partial thromboplastin time (PTT), and platelet count were measured at 48 and 24 h before and after bleeding or thrombosis events. Patients served as their own controls, and the same parameters were measured during a control period where subjects did not experience either event. All patients received the anticoagulation regimen proposed by Berlin Heart. A total of 31 bleeding or thrombotic events were identified and matched to 18 control events. Patient with predominantly thrombotic events tended to weigh less than those with bleeding events (Δ7.7 kg, p < 0.001). PTT levels were higher before and after bleeding (Δ17.36, p = 0.002) and thrombosis (Δ8.75, p < 0.001) events relative to control. Heparin dose decreased after a thrombosis event (Δ-5.67, p = 0.097), and this decrease was significantly different from control (p = 0.032). Non-collinearity between heparin dose and PTT should prompt further inflammatory and hematological investigation. In addition, heavier patients were more prone to bleeding complications. The role of inflammation in the development of thrombus or hemorrhages in the pediatric VAD population needs to be studied further.

Dual inhibition of thrombin and activated factor X attenuates disseminated intravascular coagulation and protects organ function in a baboon model of severe Gram-negative sepsis

Background

Inhibition of procoagulant pathways may improve outcome in sepsis. We examined whether a dual short-acting thrombin (factor II) and factor X (FX)a inhibitor (SATI) ameliorates sepsis-induced disseminated intravascular coagulation (DIC) and is organ-protective.

Methods

Escherichia coli were infused for 2 h in 22 anesthetized baboons. The control (CO) group (n = 8) received sterile isotonic solution only. In the treatment groups, SATI was administered starting 15 minutes after the end of the bacterial exposure. In the low-dose group (LD-SATI, n = 8), SATI was infused with 75 μg/kg/h for the first hour, followed by 23 μg/kg/h until the end of the study. In the high-dose SATI group (HD-SATI, n = 6), 225 μg/kg/h was administered for the first hour followed by continuous infusion of 69 μg/kg/h until termination of the study.

Results

Sepsis-induced DIC was attenuated, as reflected by lower peak thrombin-antithrombin complexes (threefold) and D-dimer levels (twofold) in both SATI groups compared to the CO. This coincided with strongly improved cell/organ protection assessed by decreased levels of lactate dehydrogenase (threefold), creatinine (twofold), aspartate aminotransferase (threefold), and amylase (twofold) compared to the CO group. Anuria, which started at 8 h in the CO group, was prevented in both SATI groups. Peak interleukin-6 release at 12 h was prevented in the treatment groups. In both SATI groups, fewer catecholamines were necessary and no bleeding complications were observed.

Conclusions

Dual inhibition of thrombin and FXa preserved activation of coagulation, protected organ function and ameliorated inflammation in severe Gram-negative sepsis in baboons. SATI could be a novel therapeutic agent against sepsis-induced DIC.

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.

Antithrombin III improved neutrophil extracellular traps in lung after the onset of endotoxemia

BACKGROUND

Coagulation and inflammation are closely linked during acute inflammatory conditions, such as sepsis. Antithrombin (AT) is an anticoagulant that also has anti-inflammatory activities. The effects of therapeutically administering AT III after the onset of endotoxemia or sepsis were not clear. Here, we studied the effects of administering AT III after inducing lethal endotoxemia in mice.

METHODS

Mice were injected intraperitoneally with lipopolysaccharide (LPS) to induce endotoxemia. AT III was administered 3 h later. We assessed survival and the severity of endotoxemia and quantified plasma cytokine levels and biochemical markers of liver and kidney function. In the lungs, we examined neutrophil accumulation, neutrophil extracellular traps, alveolar wall thickness, and chemokine (C-X-C motif) ligand 1 (cxcl-1), cxcl-2, and high mobility group box 1 expression.

RESULTS

Administering AT III reduced the severity and mortality of LPS-induced endotoxemia as indicated by 24-h survival of 84% of the mice that received LPS + AT III and only 53% of mice given LPS alone (P < 0.05). AT III treatment attenuated several changes induced in the lungs by endotoxemia including cxcl-2 mRNA expression, high mobility group box 1 protein expression, neutrophil accumulation, alveolar septal thickening, and neutrophil extracellular trap formation. AT III did not decrease plasma cytokine levels or plasma urea nitrogen levels that were upregulated as a result of LPS-induced endotoxemia.

CONCLUSIONS

Administration of AT III after the onset of endotoxemia improved outcomes in a mouse model. The attenuation of lung inflammation may have a large impact on mortality and morbidity. Because lung inflammation increases the likelihood of mortality from sepsis, AT III could be a useful agent in septic patients.

Angiopoietin-2 mediates thrombin-induced monocyte adhesion and endothelial permeability

Essentials Mechanism of thrombin-induced inflammation is not fully understood. Thrombin induced monocyte adhesion and barrier loss require Angiopoietin-2 (Ang-2). Ang-2 mediates vessel leakage and monocyte adhesion through SHP-2/p38MAPK pathway. Calcium dependent SHP2/p38MAPK activation regulates Ang-2 expression through a feedback loop.

SUMMARY

Background Thrombin imparts an inflammatory phenotype to the endothelium by promoting increased monocyte adhesion and vascular permeability. However, the molecular players that govern these events are incompletely understood. Objective The aim of this study was to determine whether Angiopoietin-2 (Ang-2) has a role, if any, in regulating inflammatory signals initiated by thrombin. Methods Assessment of vascular leakage by Miles assay was performed by intra-dermal injection on the foot paw. Surface levels of intercellular adhesion molecule-1 (ICAM-1) were determined by flow cytometry. Overexpression, knockdown and phosphorylation of proteins were determined by Western blotting. Results In time-course experiments, thrombin-stimulated Ang-2 up-regulation, peaked prior to the expression of adhesion molecule ICAM-1 in human umbilical vein-derived endothelial cells (HUVECs). Knockdown of Ang-2 blocked both thrombin-induced monocyte adhesion and ICAM-1 expression. In addition, Ang-2(-/-) mice displayed defective vascular leakage when treated with thrombin. Introducing Ang-2 protein in Ang-2(-/-) mice failed to recover a wild-type phenotype. Mechanistically, Ang-2 appears to regulate the thrombin-activated calcium spike that is required for tyrosine phosphatase SHP2 and p38 MAPK activation. Further, down-regulation of SHP2 attenuated both thrombin-induced Ang-2 expression and monocyte adhesion. Down-regulation of the adaptor protein Gab1, a co-activator of SHP2, as well as overexpression of the Gab1 mutant incapable of interacting with SHP2 (YFGab1), inhibited thrombin-mediated effects, including downstream activation of p38 MAPK, which in turn was required for Ang-2 expression. Conclusions The data establish an essential role of the Gab1/SHP2/p38MAPK signaling pathway and Ang-2 in regulating thrombin-induced monocyte adhesion and vascular leakage.

Platelets and coagulation in infection

Disseminated intravascular coagulation (DIC) is a frequent complication in sepsis that is associated with worse outcomes and higher mortality in patients. In addition to the uncontrolled generation of thrombi throughout the patient's vasculature, DIC often consumes large quantities of clotting factors leaving the patient susceptible to hemorrhaging. Owing to these complications, patients often receive anticoagulants to treat the uncontrolled clotting, often with mixed outcomes. This lack of success with the current array of anticoagulants can be partly explained by the fact that during sepsis clotting is often initiated by the immune system. Systemic inflammation has the capacity to activate and amplify coagulation and, as such, potential therapies for the treatment of sepsis-associated DIC need to address the interaction between inflammation and coagulation. Recent studies have suggested that platelets and neutrophil extracellular traps (NETs) are the key mediators of infection-induced coagulation. This review explores current anticoagulant therapies and discusses the development of future therapies to target platelet and NET-mediated coagulation.

Efficacy and Bleeding Risk of Antithrombin Supplementation in Patients With Septic Disseminated Intravascular Coagulation: A Third Survey

INTRODUCTION

Although recent studies have reported the efficacy of antithrombin (AT) supplementation for sepsis-associated disseminated intravascular coagulation (DIC), the factors that influence AT's effect have not been sufficiently studied. The purpose of this survey was to identify factors that modulate the effects and the adverse effects of AT.

METHODS

We performed a multi-institutional survey. The data from 159 patients with septic DIC with AT ≤70% and who had undergone AT supplementation were analyzed. The patients' demographic characteristics, including the infection site, baseline sepsis-related organ failure assessment (SOFA) score, baseline DIC score, and baseline AT activity, were analyzed in relation to the 28-day mortality. Bleeding-related adverse events were also examined.

RESULTS

Overall, 116 patients survived and 43 did not (28-day mortality: 27.0%). A logistic regression analysis revealed that the baseline SOFA score (odds ratio [OR]: 0.816, P = .001), coadministration of recombinant thrombomodulin (rTM; OR: 3.989, P = .006), and respiratory tract infection (OR: 0.129, P = .000) were significantly associated with the survival. Survivors exhibited a higher peak AT activity than nonsurvivors (85.1% vs 65.0%, P = .027). Bleeding events were observed in 4.13% (major bleeding: 1.65%) of the patients, and the coadministration of rTM did not increase the risk of bleeding (with rTM: 4.11% vs without rTM: 4.17%). Heparin was concomitantly used in 22 (18.2%) cases, and its use nonsignificantly increased the bleeding risk (with heparins: 9.09% vs without heparins: 3.03%; P = .224).

CONCLUSION

The coadministration of rTM may improve survival without increasing the risk of bleeding in patients with sepsis-associated DIC treated with AT.

Factor XI Deficiency Alters the Cytokine Response and Activation of Contact Proteases during Polymicrobial Sepsis in Mice

Sepsis, a systemic inflammatory response to infection, is often accompanied by abnormalities of blood coagulation. Prior work with a mouse model of sepsis induced by cecal ligation and puncture (CLP) suggested that the protease factor XIa contributed to disseminated intravascular coagulation (DIC) and to the cytokine response during sepsis. We investigated the importance of factor XI to cytokine and coagulation responses during the first 24 hours after CLP. Compared to wild type littermates, factor XI-deficient (FXI^-/-) mice had a survival advantage after CLP, with smaller increases in plasma levels of TNF-α and IL-10 and delayed IL-1β and IL-6 responses. Plasma levels of serum amyloid P, an acute phase protein, were increased in wild type mice 24 hours post-CLP, but not in FXI^-/- mice, supporting the impression of a reduced inflammatory response in the absence of factor XI. Surprisingly, there was little evidence of DIC in mice of either genotype. Plasma levels of the contact factors factor XII and prekallikrein were reduced in WT mice after CLP, consistent with induction of contact activation. However, factor XII and PK levels were not reduced in FXI^-/- animals, indicating factor XI deficiency blunted contact activation. Intravenous infusion of polyphosphate into WT mice also induced changes in factor XII, but had much less effect in FXI deficient mice. In vitro analysis revealed that factor XIa activates factor XII, and that this reaction is enhanced by polyanions such polyphosphate and nucleic acids. These data suggest that factor XI deficiency confers a survival advantage in the CLP sepsis model by altering the cytokine response to infection and blunting activation of the contact (kallikrein-kinin) system. The findings support the hypothesis that factor XI functions as a bidirectional interface between contact activation and thrombin generation, allowing the two processes to influence each other.

Aberrant coagulation causes a hyper-inflammatory response in severe influenza pneumonia

Influenza A virus (IAV) infects the respiratory tract in humans and causes significant morbidity and mortality worldwide each year. Aggressive inflammation, known as a cytokine storm, is thought to cause most of the damage in the lungs during IAV infection. Dysfunctional coagulation is a common complication in pathogenic influenza, manifested by lung endothelial activation, vascular leak, disseminated intravascular coagulation and pulmonary microembolism. Importantly, emerging evidence shows that an uncontrolled coagulation system, including both the cellular (endothelial cells and platelets) and protein (coagulation factors, anticoagulants and fibrinolysis proteases) components, contributes to the pathogenesis of influenza by augmenting viral replication and immune pathogenesis. In this review, we focus on the underlying mechanisms of the dysfunctional coagulatory response in the pathogenesis of IAV.

Antithrombin in the treatment of burn trauma

Antithrombin (AT) is a natural anticoagulant with anti-inflammatory properties that has demonstrated value in sepsis, disseminated intravascular coagulation and in burn and inhalation injury. With high doses, AT may decrease blood loss during eschar excision, reducing blood transfusion requirements. There are no human randomized, placebo-controlled studies, which have tested the true benefit of this agent in these conditions. Two main forms of AT are either plasma-derived AT (phAT) and recombinant AT (rhAT). Major ovine studies in burn and smoke inhalation injury have utilized rhAT. There have been no studies which have either translated the basic rhAT research in burn trauma, or determined the tolerance and pharmacokinetics of rhAT concentrate infusions in burn patients. Advantages of rhAT infusions are no risk of blood borne diseases and lower cost. However, the majority of human burn patient studies have been conducted utilizing phAT. Recent Japanese clinical trials have started using phAT in abdominal sepsis successfully. This review examines the properties of both phAT and rhAT, and analyzes studies in which they have been utilized. We believe that it is time to embark on a randomized placebo-controlled multi-center trial to establish the role of AT in both civilian and military patients with burn trauma.