Antithrombin Acts as a Negative Acute Phase Protein as Established with Studies on HepG2 Cells and in Baboons

Thrombotic triad in microgravity

Thrombotic disease may be an underdiagnosed condition of prolonged exposure to microgravity and yet the underlying factors remain poorly defined. Recently, an internal jugular vein thrombosis was diagnosed in a low-risk female astronaut after an approximately 7-week space mission. Six of the additional 10 crew members demonstrated jugular venous flow risk factors, such as suspicious stagnation or retroversion. Fortunately, all were asymptomatic. Observations in space as well as clinical and in vitro microgravity studies on Earth, where experiments are designed to recapitulate the conditions of space, suggest effects on blood flow stasis, coagulation, and vascular function. In this article, the related literature on thrombotic disease in space is reviewed, with consideration of these elements of Virchow's triad.

The Effects of Mammary Gland ATIII Overexpression on the General Health of Dairy Goats and Their Anti-Inflammatory Response to LPS Stimulation

Antithrombin III is an important anticoagulant factor with anti-inflammatory properties. However, few studies have explored its anti-inflammatory actions in ATIII overexpressed transgenic animals. In this study, the dairy goats with mammary overexpression of ATIII were used to investigate their general health, milk quality and particularly their response to inflammatory challenge. The results showed that transgenic goats have a normal phenotype regarding their physiological and biochemical parameters, including whole blood cells, serum protein levels, total cholesterol, urea nitrogen, uric acid, and total bilirubin, compared to the WT. In addition, the quality of milk also improved in transgenic animals compared to the WT, as indicated by the increased milk fat and dry matter content and the reduced somatic cell numbers. Under the stimulation of an LPS injection, the transgenic goats had elevated contents of IGA, IGM and superoxide dismutase SOD, and had reduced proinflammatory cytokine release, including IL-6, TNF-α and IFN-β. A 16S rDNA sequencing analysis also showed that the transgenic animals had a similar compositions of gut microbiota to the WT goats under the stimulation of LPS injections. Mammary gland ATIII overexpression in dairy goats is a safe process, and it did not jeopardize the general health of the transgenic animals; moreover, the compositions of their gut microbiota also improved with the milk quality. The LPS stimulation study suggests that the increased ATIII expression may directly or indirectly suppress the inflammatory response to increase the resistance of transgenic animals to pathogen invasion. This will be explored in future studies.

Antithrombin Activity and Association with Risk of Thrombosis and Mortality in Patients with Cancer

Venous and arterial thromboembolism (VTE/ATE) are common complications in cancer patients. Antithrombin deficiency is a risk factor for thrombosis in the general population, but its connection to risk of cancer-associated thrombosis is unclear. We investigated the association of antithrombin activity levels with risk of cancer-associated VTE/ATE and all-cause mortality in an observational cohort study including patients with cancer, the Vienna Cancer and Thrombosis Study. In total, 1127 patients were included (45% female, median age: 62 years). Amongst these subjects, 110 (9.7%) patients were diagnosed with VTE, 32 (2.8%) with ATE, and 563 (49.9%) died. Antithrombin was not associated with a risk of VTE (subdistribution hazard ratio (SHR): 1.00 per 1% increase in antithrombin level; 95% CI: 0.99-1.01) or ATE (SHR: 1.00; 95% CI: 0.98-1.03). However, antithrombin showed a u-shaped association with the risk of all-cause death, i.e., patients with very low but also very high levels had poorer overall survival. In the subgroup of patients with brain tumors, higher antithrombin levels were associated with ATE risk (SHR: 1.02 per 1% increase; 95% CI: 1.00-1.04) and mortality (HR: 1.01 per 1% increase; 95% CI: 1.00-1.02). Both high and low antithrombin activity was associated with the risk of death. However, no association with cancer-associated VTE and ATE across all cancer types was found, with the exception of in brain tumors.

Procoagulant and anticoagulant plasma indicators in diabetic dogs showing increased antithrombin III levels in canine diabetes mellitus

Background

Diabetes mellitus (DM) often leads to dangerous thromboembolic complications in humans. DM is also a relatively common endocrinopathy of dogs. There is scarce information regarding procoagulant and anticoagulant plasma indicators in this disease. The aim of the study was to evaluate the levels of the selected plasma haemostatic parameters in dogs suffering from diabetes. The study group consisted of 20 dogs meeting all the inclusion criteria, with fasting glycaemia exceeding 11.1 mmol/l. The control group consisted of 15 healthy dogs presented for routine examination. An evaluation of the prothrombin time (PT); and fibrinogen, D-dimer and antithrombin III (ATIII) levels was performed.

Results

Except for ATIII activity, the haemostatic parameter differences were not statistically significant. High values of ATIII activity were observed in 90% of diabetic dogs. On average, the values amounted to 166.6% and were 31.4% higher than those in the control group. The ATIII activity in the diabetic group was significantly higher than that in the control group (p = 0.0004).

Conclusions

Here, we report elevated levels of ATIII in diabetic dogs. This finding may suggest the protective role of ATIII against potential thrombotic events. However, the exact role of ATIII in dog diabetes remains unclear.

Protective effects of 17β-oestradiol on coagulation and systemic inflammation after total occlusion of the descending aorta in male rats

OBJECTIVES

The surgical treatment for diseases of the descending aorta is related to a high mortality rate because of the activation of a systemic inflammatory process due to ischaemia and reperfusion (I/R) injury. Activation of coagulation can contribute to the inflammatory process, resulting in microcirculatory damage and multiple organ failure. Our goal was to evaluate the role of prophylactic intravenous 17β-oestradiol (E2) in coagulation, the inflammatory response and hepatic injury after occlusion of the descendent proximal aorta in male rats.

METHODS

Wistar male rats were randomized and allocated to 3 groups (n = 8 per group): sham, surgically manipulated; IR, animals subjected to I/R; and E2, animals treated with E2 (280 µg/kg, intravenously) before I/R. I/R was induced by insertion of a 2-Fr Fogarty arterial embolectomy catheter in the descending aorta, which was occluded for 20 min, followed by a reperfusion period of 2 h. Serological markers, platelet aggregation, hepatic vascular flow, systemic and liver inflammatory response and apoptosis were analysed. The coagulation process was evaluated by thromboelastometry.

RESULTS

The aortic occlusion led to a reduction in plasma fibrinogen concentration in parallel with increased clotting time, greater clot firmness and reduced lysis. E2 treatment was able to increase fibrinogen, prevent the increase in clotting time and normalize clot firmness, but it exerted only a mild effect on clot lysis. Platelet aggregation was increased by IR, and E2 treatment was able to reduce it. There was a reduction in flow percentage in the IR group that was not prevented by E2. In parallel, higher aggregate formation was observed in the vessels of the IR group of animals. There was increased systemic release of interleukin-1-β, interleukin-6 and interleukin-10 in the IR group, which was reduced in the treated animals.

CONCLUSIONS

The current results suggest that pretreatment with E2 before an ischaemic period induced by occlusion of the proximal descending aorta is effective in preventing alterations in coagulation and systemic inflammation due to I/R injury.

Decreased antithrombin activity and inflammation in cats

OBJECTIVES

The objective of this study was to determine if inflammatory markers are associated with antithrombin activity in cats.

METHODS

For a retrospective population of 231 cats admitted to a referral hospital, antithrombin activity was classified as decreased (n = 77), intermediate (n = 97) or in the upper quartile (n = 57). Odds ratios (ORs) were calculated for an association between decreased or upper quartile activity and hypoalbuminemia, hyperfibrinogenemia, band neutrophilia and toxic change. Multiple logistic regression was performed to determine if an association between band neutrophilia and decreased antithrombin activity was independent of decreased hepatic synthesis, consumptive coagulopathy or protein loss.

RESULTS

Cats with decreased antithrombin activity were more likely than cats with intermediate-to-upper quartile activity to have band neutrophilia (OR 2.85, P = 0.0050), hypoalbuminemia (OR 12.1, P <0.0001) or toxic neutrophils (OR 4.47, P <0.0001). Cats with antithrombin activity in the upper quartile were less likely than those with intermediate-to-low activity to have hypoalbuminemia (OR 0.31, P = 0.0023) or toxic neutrophils (OR 0.44, P = 0.033). In a regression model that included other mechanisms for decreased antithrombin, band neutrophilia remained associated with decreased antithrombin activity (adjusted OR 2.62, P = 0.013).

CONCLUSIONS AND RELEVANCE

Contrary to previous studies suggesting antithrombin is a feline positive acute phase protein, this study demonstrates an association between decreased antithrombin activity and inflammation. Further studies are needed to determine the mechanistic basis of this association.

Acute Kidney Injury in Decompensated Cirrhosis Is Associated With Both Hypo-coagulable and Hyper-coagulable Features

BACKGROUND AND AIMS

Recent evidence suggests that acute kidney injury (AKI) is the main predictor of postparacentesis bleeding in patients with cirrhosis. To assess the factors responsible for bleeding tendency in AKI, we performed a prospective study comparing all three aspects of hemostasis (platelets, coagulation, and fibrinolysis) in patients with decompensated cirrhosis with and without AKI.

APPROACH AND RESULTS

Primary hemostasis assessment included platelet aggregation and secretion (platelet function markers) and von Willebrand factor. Secondary hemostasis assessment included pro-coagulant (factor VIII and factor XIII) and anti-coagulant (protein C, protein S, and antithrombin) factors and thrombin generation. Tertiary hemostasis assessment included fibrinolytic factors and plasmin-antiplasmin complex. Eighty patients with decompensated cirrhosis were recruited (40 each with and without AKI). Severity of cirrhosis and platelet count were comparable between groups. Median serum creatinine was 1.8 mg/dL and 0.8 mg/dL in patients with and without AKI, respectively. At baseline, patients with cirrhosis and AKI had lower platelet aggregation and secretion, indicative of impaired platelet function (increased bleeding tendency), without differences in von Willebrand factor. Regarding coagulation factors, factor VIII was higher, whereas protein C, protein S, and antithrombin were all lower, which, together with increased thrombin generation, indicate hypercoagulability. In contrast, factor XIII was lower in AKI (increased bleeding tendency). Finally, while both hypofibrinolytic and hyperfibrinolytic changes were present in AKI, a higher plasmin-antiplasmin complex indicated a hyperfibrinolytic state. After AKI resolution (n = 23 of 40), platelet function and coagulation improved to levels observed in patients with cirrhosis patients without AKI; however, fibrinolysis remained hyperactivated.

CONCLUSIONS

In patients with decompensated cirrhosis, AKI is associated with both hypocoagulable and hypercoagulable features that can potentially increase the risk of both bleeding and thrombosis.

A link between inflammation and thrombosis in atherosclerotic cardiovascular diseases: Clinical and therapeutic implications

The association between thrombosis and acute coronary syndromes is well established. Inflammation and activation of innate and adaptive immunity are another important factor implicated in atherosclerosis. However, the exact interactions between thrombosis and inflammation in atherosclerosis are less well understood. Accumulating data suggest a firm interaction between these two key pathophysiologic processes. Pro-inflammatory cytokines, such as tumor necrosis factor α, interleukin-6 and interleukin-1, have been implicated in the thrombotic cascade following plaque rupture and myocardial infarction. Furthermore, cell adhesion molecules accelerate not only atheromatosis but also thrombosis formation while activated platelets are able to trigger leukocyte adhesion and accumulation. Additionally, tissue factor, thrombin, and activated coagulation factors induce the release of pro-inflammatory cytokines such as prostaglandin and C reactive protein, which may further induce von Willebrand factor secretion. Treatments targeting immune activation (i.e. interleukin-1 inhibitors, colchicine, statins, etc.) may also beneficially modulate platelet activation while common anti-thrombotic therapies appear to attenuate the inflammatory process. Taken together in the context of cardiovascular diseases, thrombosis and inflammation should be studied and managed as a common entity under the concept of thrombo-inflammation.

Comparative Proteomic Analysis of Serum from Pigs Experimentally Infected with Trichinella spiralis, Trichinella britovi, and Trichinella pseudospiralis

Although the available proteomic studies have made it possible to identify and characterize Trichinella stage-specific proteins reacting with infected host-specific antibodies, the vast majority of these studies do not provide any information about changes in the global proteomic serum profile of Trichinella-infested individuals. In view of the above, the present study aimed to examine the protein expression profile of serum obtained at 13 and 60 days postinfection (d.p.i.) from three groups of pigs experimentally infected with Trichinella spiralis, Trichinella britovi, and Trichinella pseudospiralis and from uninfected, control pigs by two-dimensional gel electrophoresis (2-DE) followed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The comparative proteomic analysis of the T. spiralis group vs. the control group revealed 5 differently expressed spots at both 13 and 60 d.p.i. Experimental infection with T. britovi induced significant expression changes in 3 protein spots at 13 d.p.i. and in 6 protein spots at 60 d.p.i. in comparison with the control group. Paired analyses between the group infected with T. pseudospiralis and the uninfected control group revealed 6 differently changed spots at 13 d.p.i. and 2 differently changed spots at 60 d.p.i. Among these 27 spots, 15 were successfully identified. Depending on the Trichinella species triggering the infection and the time point of serum collection, they were IgM heavy-chain constant region, antithrombin III-precursor, immunoglobulin gamma-chain, clusterin, homeobox protein Mohawk, apolipoprotein E precursor, serum amyloid P-component precursor, Ig lambda chains, complement C3 isoform X1, and apolipoprotein A-I. Our results demonstrate that various Trichinella species and different phases of the invasion produce a distinct, characteristic proteomic pattern in the serum of experimentally infected pigs.

Disseminated Intravascular Coagulation: An Update on Pathogenesis, Diagnosis, and Therapeutic Strategies

Disseminated intravascular coagulation (DIC) is an acquired clinicobiological syndrome characterized by widespread activation of coagulation leading to fibrin deposition in the vasculature, organ dysfunction, consumption of clotting factors and platelets, and life-threatening hemorrhage. Disseminated intravascular coagulation is provoked by several underlying disorders (sepsis, cancer, trauma, and pregnancy complicated with eclampsia or other calamities). Treatment of the underlying disease and elimination of the trigger mechanism are the cornerstone therapeutic approaches. Therapeutic strategies specific for DIC aim to control activation of blood coagulation and bleeding risk. The clinical trials using DIC as entry criterion are limited. Large randomized, phase III clinical trials have investigated the efficacy of antithrombin (AT), activated protein C (APC), tissue factor pathway inhibitor (TFPI), and thrombomodulin (TM) in patients with sepsis, but the diagnosis of DIC was not part of the inclusion criteria. Treatment with APC reduced 28-day mortality of patients with severe sepsis, including patients retrospectively assigned to a subgroup with sepsis-associated DIC. Treatment with APC did not have any positive effects in other patient groups. The APC treatment increased the bleeding risk in patients with sepsis, which led to the withdrawal of this drug from the market. Treatment with AT failed to reduce 28-day mortality in patients with severe sepsis, but a retrospective subgroup analysis suggested possible efficacy in patients with DIC. Clinical studies with recombinant TFPI or TM have been carried out showing promising results. The efficacy and safety of other anticoagulants (ie, unfractionated heparin, low-molecular-weight heparin) or transfusion of platelet concentrates or clotting factor concentrates have not been objectively assessed.

Adipokines at the crossroad between obesity and cardiovascular disease

Obesity, and especially excessive visceral adipose tissue accumulation, is considered as a low-grade inflammatory state that is responsible for adipocyte dysfunction and associated metabolic disorders. Adipose tissue displays endocrine functions by releasing pro- or antiinflammatory bioactive molecules named adipokines. An altered expression of these molecules, provoked by obesity or adipocyte dysregulation, contributes to major metabolic diseases such as insulin resistance and type 2 diabetes mellitus that are important risk factors for cardiovascular disease. However, obesity is also characterised by the expansion of perivascular adipose tissue that acts locally via diffusion of adipokines into the vascular wall. Local inflammation within blood vessels induced by adipokines contributes to the onset of endothelial dysfunction, atherosclerosis and thrombosis, but also to vascular remodelling and hypertension. A fast expansion of obesity is expected in the near future, which will rapidly increase the incidence of these cardiovascular diseases. The focus of this review is to summarise the link between metabolic and cardiovascular disease and discuss current treatment approaches, limitations and future perspectives for more targeted therapies.

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.

PAMPs and DAMPs as triggers for DIC

Thrombosis is generally considered harmful because it compromises the blood supply to organs. However, recent studies have suggested that thrombosis under certain circumstances plays a major physiological role in early immune defense against invading pathogens. This defensive role of thrombosis is now referred to as immunothrombosis. Activated monocytes and neutrophils are two major inducers of immunothrombosis. Monocytes and neutrophils are activated when they detect pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). Detection of PAMPs and DAMPs triggers tissue factor expression on monocytes and neutrophil extracellular trap (NET) release by neutrophils, promoting immunothrombosis. Although tissue factor-mediated and NET-mediated immunothrombosis plays a role in early host defense against bacterial dissemination, uncontrolled immunothrombosis may lead to disseminated intravascular coagulation.

Antithrombin III, but not C1 esterase inhibitor reduces inflammatory response in lipopolysaccharide-stimulated human monocytes in an ex-vivo whole blood setting

In order to examine the immunomodulatory effects of antithrombin III (AT-III) and C1 esterase inhibitor (C1-INH) in human monocytes, we investigated the intracellular expression of interleukin (IL)-6, IL-8, and tumor necrosis factor (TNF)-α in an ex-vivo laboratory study in a whole blood setting. Heparinized whole blood samples from 23 healthy male and female volunteers (mean age: 27±7years) were pre-incubated with clinically relevant concentrations of AT-III (n=11) and C1-INH (n=12), then stimulated with 0.2 ng/mL lipopolysaccharide (LPS) for 3h. After phenotyping CD14⁺ monocytes, intracellular expression of IL-6, IL-8, and TNF-α was assessed using flow cytometry. In addition, 12 whole blood samples (AT-III and C1-INH, n=6 each) were examined using hirudin for anticoagulation; all samples were processed in the same way. To exclude cytotoxicity effects, 7-amino-actinomycin D and Nonidet P40 staining were used to investigate probes. This study is the first to demonstrate the influence of C1-INH and AT-III on the monocytic inflammatory response in a whole blood setting, which mimics the optimal physiological setting. Cells treated with AT-III exhibited significant downregulation of the proportion of gated CD14⁺ monocytes for IL-6 and IL-8, in a dose-dependent manner; downregulation for TNF-α did not reach statistical significance. There were no significant effects on mean fluorescence intensity (MFI). In contrast, C1-INH did not significantly reduce the proportion of gated CD14⁺ monocytes or the MFI regarding IL-6, TNF-α, and IL-8. When using hirudin for anticoagulation, no difference in the anti-inflammatory properties of AT-III and C1-INH in monocytes occurs. Taken together, in contrast to TNF-α, IL-6 and IL-8 were significantly downregulated in monocytes in an ex-vivo setting of human whole blood when treated with AT-III. This finding implicates monocytes as an important point of action regarding the anti-inflammatory properties of AT-III in sepsis. C1-INH was unable to attenuate the monocytic response, which supports the hypothesis that other cellular components in whole blood (e.g., neutrophils) might be responsible for the known effects of C1-INH in inflammation.

Severe sepsis, coagulation, and fibrinolysis: dead end or one way?

It was suggested more than 30 yrs ago that inhibition of the clotting cascade by natural anticoagulants could decrease the high mortality observed in patients suffering from severe sepsis and septic shock. Unfortunately, this therapeutic "paradigm" has led to a dead end, illustrated by the failure of all randomized trials and the recent withdrawal of recombinant activated protein C. Should we now definitely give up trying to treat septic coagulation disturbances or is there any therapeutic alternative?

Viscoelastic and aggregometric point-of-care testing in patients with septic shock - cross-links between inflammation and haemostasis

BACKGROUND

In the pathogenesis of sepsis, inflammation-induced changes in coagulation play a pivotal role.

METHODS

In total, 90 patients (30 patients with septic shock, 30 surgical patients following major abdominal surgery and 30 healthy volunteers) were enrolled. Blood samples from patients with septic shock were collected at the time of sepsis diagnosis as well as 24 h, 4 days, 7 days, 14 days and 28 days later. Samples from surgical patients with a post-surgical inflammatory response were collected three times (before surgery, immediately after surgery and 24 h after surgery) and once from healthy volunteers. Thromboelastometry (ROTEM (®) ), as well as whole blood impedance aggregometry (Multiplate(®) ) were performed. Additionally, plasma concentrations of interleukin-6 and tumour necrosis factor-alpha were measured using enzyme-linked immunosorbent assay kits.

RESULTS

Thromboelastometry lysis index was shown to be a reliable biomarker for septic shock. Furthermore, in septic patients with overt disseminated intravascular coagulation, thromboelastometry revealed signs indicating a hypocoagulable status, whereas patients without overt disseminated intravascular coagulation were found to be hypercoagulable. Platelet aggregation capability, as assessed by whole blood impedance aggregometry, was significantly reduced in septic patients with overt disseminated intravascular coagulation, whereas it was comparable with healthy volunteers and in septic patients without overt disseminated intravascular coagulation.

CONCLUSION

Viscoelastic and aggregometric point-of-care testing was shown to be potentially useful for bedside diagnosis of sepsis. Moreover, viscoelastic and aggregometric point-of-care testing was able to determine the phase of septic coagulopathy (hypercoagulability vs. hypocoagulability) and therefore identified patients at high risk for overt disseminated intravascular coagulation.

A novel serpin with antithrombin-like activity in Branchiostoma japonicum: implications for the presence of a primitive coagulation system

Serine protease inhibitors, or serpins, are a group of widely distributed proteins with similar structures that use conformational change to inhibit proteases. Antithrombin (AT) is a member of the serine protease inhibitor superfamily and a major coagulation inhibitor in all vertebrates, but its evolutionary origin remains elusive. In this study we isolated for the first time a cDNA encoding an antithrombin homolog, BjATl, from the protochordate Branchiostoma japonicum. The deduced protein BjATl consisted of 338 amino acids sharing 36.7% to 41.1% identity to known vertebrate ATs. BjATl contains a potential N-linked glycosylation site, two potential heparin binding sites and the reactive center loop with the absolutely conserved sequence Gly-Arg-Ser; all of these are features characteristic of ATs. All three phylogenetic trees constructed using Neighbor-Joining, Maximum-Likelihood and Bayesian-Inference methods also placed BjATl together with ATs. Moreover, BjATl expressed in yeast cells was able to inhibit bovine thrombin activity by forming a SDS-stable BjATl-thrombin complex. It also displays a concentration-dependent inhibition of thrombin that is accelerated by heparin. Furthermore, BjATl was predominantly expressed in the hepatic caecum and hind-gut, agreeing with the expression pattern of AT in mammalian species. All these data clearly demonstrate that BjATl is an ortholog of vertebrate ATs, suggesting that a primitive coagulation system emerged in the protochordate.

Discovery of candidate serum proteomic and metabolomic biomarkers in ankylosing spondylitis

Ankylosing Spondylitis (AS) is a common inflammatory rheumatic disease with a predilection for the axial skeleton, affecting 0.2% of the population. Current diagnostic criteria rely on a composite of clinical and radiological changes, with a mean time to diagnosis of 5 to 10 years. In this study we employed nano liquid-chromatography mass spectrometry analysis to detect and quantify proteins and small compounds including endogenous peptides and metabolites in serum from 18 AS patients and nine healthy individuals. We identified a total of 316 proteins in serum, of which 22 showed significant up- or down-regulation (p < 0.05) in AS patients. Receiver operating characteristic analysis of combined levels of serum amyloid P component and inter-α-trypsin inhibitor heavy chain 1 revealed high diagnostic value for Ankylosing Spondylitis (area under the curve = 0.98). We also depleted individual sera of proteins to analyze endogenous peptides and metabolic compounds. We detected more than 7000 molecular features in patients and healthy individuals. Quantitative MS analysis revealed compound profiles that correlate with the clinical assessment of disease activity. One molecular feature identified as a Vitamin D3 metabolite—(23S,25R)-25-hydroxyvitamin D3 26,23-peroxylactone—was down-regulated in AS. The ratio of this vitamin D metabolite versus vitamin D binding protein serum levels was also altered in AS as compared with controls. These changes may contribute to pathological skeletal changes in AS. Our study is the first example of an integration of proteomic and metabolomic techniques to find new biomarker candidates for the diagnosis of Ankylosing Spondylitis.

Plasminogen activator inhibitor-1 (PAI-1): a key factor linking fibrinolysis and age-related subclinical and clinical conditions

INTRODUCTION

The close relationship existing between aging and thrombosis has growingly been studied in this last decade. The age-related development of a prothrombotic imbalance in the fibrinolysis homeostasis has been hypothesized as the basis of this increased cardiovascular and cerebrovascular risk. Fibrinolysis is the result of the interactions among multiple plasminogen activators and inhibitors constituting the enzymatic cascade, and ultimately leading to the degradation of fibrin. The plasminogen activator system plays a key role in a wide range of physiological and pathological processes.

METHODS

Narrative review.

RESULTS

Plasminogen activator inhibitor-1 (PAI-1) is a member of the superfamily of serine-protease inhibitors (or serpins), and the principal inhibitor of both the tissue-type and the urokinase-type plasminogen activator, the two plasminogen activators able to activate plasminogen. Current evidence describing the central role played by PAI-1 in a number of age-related subclinical (i.e., inflammation, atherosclerosis, insulin resistance) and clinical (i.e., obesity, comorbidities, Werner syndrome) conditions is presented.

CONCLUSIONS

Despite some controversial and unclear issues, PAI-1 represents an extremely promising marker that may become a biological parameter to be progressively considered in the prognostic evaluation, in the disease monitoring, and as treatment target of age-related conditions in the future.

Ambient particulate matter accelerates coagulation via an IL-6-dependent pathway

The mechanisms by which exposure to particulate matter increases the risk of cardiovascular events are not known. Recent human and animal data suggest that particulate matter may induce alterations in hemostatic factors. In this study we determined the mechanisms by which particulate matter might accelerate thrombosis. We found that mice treated with a dose of well characterized particulate matter of less than 10 microM in diameter exhibited a shortened bleeding time, decreased prothrombin and partial thromboplastin times (decreased plasma clotting times), increased levels of fibrinogen, and increased activity of factor II, VIII, and X. This prothrombotic tendency was associated with increased generation of intravascular thrombin, an acceleration of arterial thrombosis, and an increase in bronchoalveolar fluid concentration of the prothrombotic cytokine IL-6. Knockout mice lacking IL-6 were protected against particulate matter-induced intravascular thrombin formation and the acceleration of arterial thrombosis. Depletion of macrophages by the intratracheal administration of liposomal clodronate attenuated particulate matter-induced IL-6 production and the resultant prothrombotic tendency. Our findings suggest that exposure to particulate matter triggers IL-6 production by alveolar macrophages, resulting in reduced clotting times, intravascular thrombin formation, and accelerated arterial thrombosis. These results provide a potential mechanism linking ambient particulate matter exposure and thrombotic events.

Global tests of haemostasis in critically ill patients with severe sepsis syndrome compared to controls

Haemostatic changes in septic patients are complex, with both procoagulant and anticoagulant changes. Thirty-eight patients with severe sepsis and 32 controls were investigated by coagulation screens, individual factor assays, calibrated automated thrombography (CAT), whole blood low-dose-tissue factor activated (LD-TFA) Rotem and LD-TFA waveform analysis. Thirty-six of 38 patients had an abnormal coagulation screen. The mean levels of factors II, V (P < 0.05), VII, X, XI and XII, antithrombin and protein C (P < 0.01) was decreased in sepsis compared with controls. The mean factor VIII and fibrinogen level (P < 0.001) was increased. CAT in platelet rich and poor plasma showed a prolonged lag time (P < 0.02), decreased peak thrombin (P < 0.02) and delayed time to peak thrombin (P < 0.001) in sepsis patients, however, the endogenous thrombin potential was equivalent in sepsis and controls. In LD-TFA Rotem, septic patients had delayed clot times (P = 0.04) but an increased maximum velocity of clot formation (P < 0.01) and area under the clot elasticity curve (P < 0.01). LD-TFA waveform analysis showed a delayed onset time but an increased rate of clot formation (P < 0.005). In conclusion, global tests of haemostasis suggest that in this patient group, activation of haemostasis is delayed but once initiated thrombin generation and clot formation are normal or enhanced.

Hemostasis and aging

Many changes in the vasculature, hemostasis and endothelium, including alterations of platelets, coagulation and fibrinolytic factors, occur during aging. While the increasing hypercoagulability observed with aging may account for the higher incidence of thrombotic cardiovascular disorders in the elderly, the lack of genetic protective factors against thrombosis in healthy centenarians suggests that little is yet known about the age-associated changes of hemostasis. The complex inter-relationships between inherited and acquired factors influencing the hemostatic system during aging are discussed in this review.

High-dose antithrombin III in the treatment of severe sepsis in patients with a high risk of death: efficacy and safety

OBJECTIVE

To explore if patients with severe sepsis and with a predicted high risk of death (according to the Simplified Acute Physiology Score II) might have a treatment benefit from high-dose antithrombin III.

DESIGN

Subgroup analysis of a randomized, placebo-controlled, double-blind, prospective phase III study.

SETTING

Unifactorial and multifactorial reanalysis of prospectively defined populations from the KyberSept trial.

PATIENTS

We studied 1,008 patients (43.6% of the overall intention-to-treat population, n = 2,314) with a predicted mortality rate of 30-60% at study entry as defined by the Simplified Acute Physiology Score II.

INTERVENTIONS

Patients were randomized in a 1:1 fashion to receive either high-dose antithrombin III (30,000 IU intravenously over the period of 4 days) or placebo.

MEASUREMENTS AND MAIN RESULTS

In a Kaplan-Meier analysis of patients with a predicted mortality of 30-60%, the survival time when followed up for 90 days after admission was increased in the high-dose antithrombin III group compared with placebo (p = .04). If heparin was avoided during the 4-day treatment phase with high-dose antithrombin III (n = 140) or placebo (n = 162), the treatment effect appeared to be even more pronounced: 28-day mortality rate, 35.7% vs. 44.4% (risk ratio, 0.804; 95% confidence interval, 0.607-1.064); 56-day mortality rate, 39.9% vs. 52.2% (risk ratio, 0.764; 95% confidence interval, 0.593-0.984); 90-day mortality rate, 42.8% vs. 55.1% (risk ratio, 0.776; 95% confidence interval, 0.614-0.986). Like in the overall population, the percentage with any bleeding was increased in patients receiving high-dose antithrombin III compared with placebo. Survival rates were in favor of high-dose antithrombin III in patients both with and without bleeding complications.

CONCLUSIONS

Treatment with high-dose antithrombin III may increase survival time up to 90 days in patients with severe sepsis and high risk of death. This benefit may even be stronger when concomitant heparin is avoided.

Presence and localization of antithrombin and its regulation after acute lipopolysaccharide exposure in amphioxus, with implications for the origin of vertebrate liver

Antithrombin (AT), which is mainly synthesized in the liver, is an acute-phase plasma protein in mammalian species. Here, we demonstrated that sheep anti-human AT antibody cross-reacted with the humoral fluids in amphioxus Branchiostoma belcheri tsingtauense as well as human serum. The concentration of AT in the humoral fluids in amphioxus decreased slightly at first and then increased after the acute challenge with lipopolysaccharide, while the level of total proteins remained unchanged. These suggest the presence of the same acute-phase response pattern in amphioxus, as observed in some mammalian species. Immunohistochemically, AT was localized in the hepatic diverticulum. It is clear that the hepatic diverticulum in amphioxus is homologous to the vertebrate liver with respect to AT synthesis. This lends support to the hypothesis originally suggested by Müller that the vertebrate liver evolved from the hepatic diverticulum of an amphioxus-like ancestor during early chordate evolution.

Disseminated Intravascular Coagulation in Sepsis

Disseminated intravascular coagulation is a frequent complication of sepsis. Coagulation activation, inhibition of fibrinolysis, and consumption of coagulation inhibitors lead to a procoagulant state resulting in inadequate fibrin removal and fibrin deposition in the microvasculature. As a consequence, microvascular thrombosis contributes to promotion of organ dysfunction. Recently, three randomized, double-blind, placebo-controlled trials investigated the efficacy of antithrombin, activated protein C (APC), and tissue factor pathway inhibitor, respectively, in sepsis patients. A significant reduction in mortality was demonstrated in the APC trial. In this article, we first discuss the physiology of coagulation and fibrinolysis activation. Then, the pathophysiology of coagulation activation, consumption of coagulation inhibitors, and the inhibition of fibrinolysis leading to a procoagulant state are described in more detail. Moreover, therapeutic concepts as well as the three randomized, double-blind, placebo-controlled studies are discussed.

DAP12 (KARAP) amplifies inflammation and increases mortality from endotoxemia and septic peritonitis

DAP12 (KARAP) is a transmembrane signaling adaptor for a family of innate immunoreceptors that have been shown to activate granulocytes and monocytes/macrophages, amplifying production of inflammatory cytokines. Contrasting with these data, recent studies suggest that DAP12 signaling has an inhibitory role in the macrophage response to microbial products (Hamerman, J.A., N.K. Tchao, C.A. Lowell, and L.L. Lanier. 2005. Nat. Immunol. 6:579–586). To determine the in vivo role for DAP12 signaling in inflammation, we measured the response of wild-type (WT) and DAP12^−/− mice to septic shock. We show that DAP12^−/− mice have improved survival from both endotoxemia and cecal ligation and puncture–induced septic shock. As compared with WT mice, DAP12^−/− mice have decreased plasma cytokine levels and a decreased acute phase response during sepsis, but no defect in the recruitment of cells or bacterial control. In cells isolated after sepsis and stimulated ex vivo, DAP12 signaling augments lipopolysaccharide-mediated cytokine production. These data demonstrate that, during sepsis, DAP12 signaling augments the response to microbial products, amplifying inflammation and contributing to mortality.

Azithromycin inhibits interleukin-6 but not fibrinogen production in hepatocytes infected with cytomegalovirus and chlamydia pneumoniae

Chlamydia pneumoniae and cytomegalovirus (CMV) have been associated with the development of atherosclerosis. Inflammatory stimuli initiate the biosynthesis of fibrinogen, interleukin (IL)-6 and plasminogen activator inhibitor (PAI)-1 in the liver. Chronic infection may perpetuate the inflammatory status. We hypothesized that infection of human hepatocytes with the intracellular pathogens C pneumoniae and CMV accelerates biosynthesis of fibrinogen, IL-6, and PAI-1 but that this biosynthesis can be reduced with the use of azithromycin. HepG2 human hepatocytes were infected with C pneumoniae and CMV in vitro in the presence of 0, 0.016, 0.125, or 1 microg/mL azithromycin. We measured IL-6, PAI-1, and fibrinogen after 24, 48, 72, and 96 hours. C pneumoniae-infected hepatocytes produce IL-6 (2667 +/- 309 pg/mL vs 137 +/- 120 pg/mL in uninfected cells after 96 hours. Incubation with 0.016 microg/mL azithromycin decreased IL-6 levels to a mean of 1516 +/- 402 pg/mL, and incubation with 0.125 and 1 microg/mL azithromycin decreased IL-6 to 871 +/- 364 and 752 +/- 403 pg/mL, respectively. C pneumoniae-induced IL-6 production was time- and dose-dependent. The interaction of C pneumoniae with azithromycin treatment was significant, indicating an inhibitory effect of azithromycin on C pneumoniae-induced IL-6 production. CMV infection did not lead to IL-6 production by hepatocytes. C pneumoniae and CMV infection did not induce any changes in PAI-1 production. Fibrinogen production was increased by CMV infection after 72 hours (838 +/- 88 ng/mL; P <.01) and after 96 hours by infection with both C pneumoniae and CMV (765 +/- 100 and 846 +/- 123 ng/mL, respectively; P <.05). Azithromycin did not suppress CMV- or C pneumoniae-induced fibrinogen production. Moreover, we could not confirm an antiinflammatory effect of azithromycin in experiments with cross-titrations of azithromycin against either IL-1 or IL-6 (P >.05). Azithromycin reduces C pneumoniae-induced IL-6 production, but not fibrinogen production, by human hepatocytes. This is a result of the antimicrobial properties of azithromycin and not a direct antiinflammatory effect.

Interactions between coagulation and inflammation

The coagulation system evolved as a mechanism to limit the loss of vital elements from the internal milieu following mechanical injury to the circulatory system. The innate immune system developed as a rapid response system to detect and clear microbial invaders that have breached the integument of multicellular organisms. The coagulation and innate immunity systems coevolved from a common ancestral substrate early in eukaryotic development, and these 2 systems retain a highly integrated and coregulated circuitry of signals and control elements that defend the host following tissue injury and microbial invasion. Advances in the understanding of the molecular mechanisms that control clotting and inflammation have led to the successful development of recombinant human activated protein C for the treatment of human septic shock. Optimal use of this and other anticoagulant agents in sepsis will necessitate further basic research into the critical linkage between coagulation and innate immunity.

Influence of modest endotoxemia on postoperative antithrombin deficiency and circulating secretory immunoglobulin a levels

OBJECTIVE

To evaluate the influence of modest endotoxemia on postoperative antithrombin deficiency and cholestasis.

SUMMARY BACKGROUND DATA

It has not been determined whether endotoxin translocation in small amounts is a physiological phenomenon or whether it is a potential health hazard.

METHODS

Blood endotoxin, antithrombin III (ATIII), secretory immunoglobulin A (sIgA), which was selected as a marker of cholestasis, C-reactive protein (CRP), and alpha-1-antitrypsin (AAT) concentrations were measured from the 20 patients undergoing curative gastrectomy for gastric cancer preoperatively and postoperatively. Portal and systemic blood samples were taken for the analysis of endotoxin and interleukin-6 (IL-6) concentrations during surgery in these patients.

RESULTS

Although plasma endotoxin levels showed a significant increase during surgery, we did not find a correlation with ATIII, sIgA, CRP, and IL-6 levels. Systemic blood endotoxin levels during surgery correlated with a postoperative rise of serum AAT levels. Plasma ATIII levels transiently decreased on the first and third postoperative day, and sIgA levels were shown to increase on the seventh postoperative day. There was a weak relationship between the extent of postoperative endotoxemia and a reduction in ATIII concentrations.

CONCLUSIONS

The influence of modest endotoxemia on postoperative antithrombin deficiency and cholestasis was limited, and increased translocational endotoxemia during abdominal surgery may be a physiological phenomenon to trigger off an acute-phase protein response.

Recombinant antithrombin attenuates pulmonary inflammation following smoke inhalation and pneumonia in sheep

OBJECTIVE

The interaction between coagulation and inflammation has become one of the major topics in critical care medicine. In the present study, we investigated the effect of posttreatment of sepsis with recombinant human antithrombin.

DESIGN

Experimental laboratory in a university hospital.

SETTING

University laboratory.

SUBJECTS

Female merino ewes (n = 16).

INTERVENTIONS

After 1 wk of recovery from the surgical preparation, a tracheotomy was performed followed by insufflation of 48 breaths of cotton smoke (<40 degrees C). Afterward, a stock solution of live (5 x 10(11) colony-forming units) was instilled in the both lung lobes through a bronchoscope. All sheep were mechanically ventilated employing 100% oxygen. An infusion of recombinant human antithrombin (100 units x kg(-1) x 24 hrs(-1), intravenously; n = 6) or saline (n = 6) was started 1 hr after injury. Sham control animals (n = 4) were surgically prepared but not insufflated with smoke and bacteria. Lung histologic changes were evaluated by a scoring system.

MEASUREMENTS AND MAIN RESULTS

The infusion of recombinant human antithrombin maintained the baseline antithrombin activity throughout the study; in the saline-treated group, antithrombin activity decreased significantly. The lung wet/dry weight ratio and the histology score (combined scores for congestion, edema, inflammation, and hemorrhage) were significantly increased by the insult, but recombinant human antithrombin attenuated these responses. More than 30% of both bronchi and bronchioles were obstructed by cast formation after smoke inhalation and pneumonia. The cast was composed of epithelial cells, neutrophils, mucus, and fibrin. The obstruction was significantly improved by recombinant human antithrombin infusion. Arterial pressure and urine output were also attenuated in recombinant human antithrombin-treated animals. The increases in plasma nitrate/nitrite concentrations and pulmonary shunt fraction after the injury were not attenuated by recombinant human antithrombin.

CONCLUSION

Posttreatment by recombinant human antithrombin was effective in treating acute lung injury after smoke inhalation and pneumonia in sheep. We hypothesize that the decrease in antithrombin activity during sepsis might induce severe airway obstruction and that supplementation with antithrombin inhibits this decrease.

A perturbation of antithrombin-III and protein C coupling associates with an increase of anti-beta2-glycoprotein I antibody in non-antiphospholipid antibody syndrome cerebral ischemia

Anti-beta -glycoprotein I antibody (abetaGPI) has been recognized in raising the risk of cerebral ischemia in patients with antiphospholipid antibody syndrome (APS), especially by protein C (PC) axis perturbation. Although a high potential is also seen in non-APS patients, the mechanism is substantially unknown. In the present study, we examined the effect of abetaGPI on PC and antithrombin-III (AT-III) activity in non-APS patients with non-cardiac cerebral ischemia (NCCI). A total of 111 NCCI patients and 30 healthy controls were enrolled. They were free of APS manifestation, and their anticardiolipin antibody and lupus anticoagulant tests were within normal range. There were 14.4% patients found to have an abnormal increase of blood abetaGPI. The PC, AT-III, albumin, aminotransferases, creatinine, prothrombin time and activated partial thromboplastin time did not differ between our patients and controls, or patients with or without increased abetaGPI. However, a marked decrease of the PC/AT-III ratio was found in patients with increased abetaGPI. The correlation between PC and AT-III activity was highly significant in patients with an increase of abetaGPI (P = 0.001), only marginal in controls (P = 0.042), and was insignificant in patients with a normal abetaGPI (P = 0.277). The abetaGPI did not correlate to PC or AT-III activity in either patients or controls. These findings suggest that high PC/AT-III coupling may relate to NCCI in non-APS patients associated with an increase of abetaGPI. This coupling effect seems not to be caused by abetaGPI directly.

The anti-inflammatory actions of antithrombin--a review

Leukocyte-endothelial cell interaction and microvascular perfusion failure are characteristic deteriorations of the microcirculation in endotoxaemia and are known to play a crucial role in the development of septic multiple organ dysfunction. Recent studies have indicated that antithrombin III treatment is capable of significantly ameliorating these microcirculatory disorders. Endothelial cells have important anticoagulant systems, including the heparan sulfate-antithrombin system. Antithrombin III stimulates prostacyclin generation in endothelial cells by interacting with heparan sulfate of endothelial cells and inhibits cytokine and tissue factor production in endothelial cells and monocytes. Similar mechanisms may be involved in cellular actions of antithrombin III causing desensitization of chemoattractant receptors of leukocytes by activating the heparan sulfate proteoglycan, syndecan-4. Thus, antithrombin III might be among the useful agents for treating coagulation abnormalities associated with sepsis or other inflammation because it inhibits not only coagulation but also downregulation of anticoagulant activities of endothelial cells and affects leukocyte activation.

Antithrombin, heparin, and heparan sulfate

OBJECTIVES

To review the experimental and clinical evidence that antithrombin has multiple mechanisms for both its anticoagulant and anti-inflammatory properties. The interaction between antithrombin and specific polysulfated, acidic oligosaccharide moieties found on heparin and related proteoglycan molecules within the circulation and on endothelial surfaces will also be examined.

DATA SOURCES

Review of the literature relating to antithrombin published during the past 25 yrs.

DATA SUMMARY

Antithrombin is the most abundant endogenous anticoagulant circulating in human plasma. This serine protease inhibitor participates in the regulation of clotting in both physiologic and pathologic states. Reduced antithrombin activity in the early phases of sepsis contributes to a procoagulant state with excess activation of the innate immune response. Antithrombin binds to specific pentasaccharides expressed on heparin, glycosaminoglycans, and related proteoglycans within the circulation and along endothelial surfaces. The functions of neutrophils, monocytes, and endothelial cells are altered as a result of their interaction with antithrombin. These effects are mediated by the enzyme inhibitory action of antithrombin and its ability to function as a ligand for antithrombin receptors on cell surfaces. In addition, antithrombin exerts anti-inflammatory properties by both prostacyclin-dependent and prostacyclin-independent actions; heparin interferes with these anti-inflammatory properties. The role of antithrombin in sepsis, its therapeutic utility in severe sepsis, and its combination with heparin remain the subject of considerable debate. The results of a recent phase 3 clinical trials with high-dose antithrombin in sepsis suggested a beneficial effect in patients who did not concomitantly receive heparin, thereby generating new challenges in the understanding of interactions between antithrombin and heparin or heparin-like proteoglycans.

CONCLUSIONS

Antithrombin has complex interactions with host coagulopathic and systemic inflammatory responses under physiologic conditions and in sepsis. The impact of these interactions in critically ill patients and the therapeutic implications of administration of antithrombin, and various doses and types of heparin in such patients, need further clarification.

[Coagulation activation with intraportal islets of Langerhans transplantation in swine]

STUDY AIM

Intraportal islet allograft appears to be one of the promising treatments for type I diabetes. However, many limiting factors persist. An activation of the coagulation cascade upon contact with islets, has been reported recently in vitro and could play a crucial role in a non specific inflammatory reaction and favour the specific immune reaction. The aim of this experimental study was to confirm in vivo this activation of the coagulation cascade.

MATERIAL AND METHODS

An allogenic islets preparation or a material control (inert microbeads) was injected intraportally, in Large White pigs (n = 26), associated with or without an anticoagulant treatment (heparin). Systemic markers of haemostasis were measured in pigs for 72 hours following injection of the studied material.

RESULTS

The thrombin-antithrombin complex increased and platelet count decreased in groups receiving preparation of islets, both indicators of an activation of the coagulation cascade. This activation was proportional to the injected volume and was partially attenuated by heparin. No activation was observed in pigs receiving the material control.

CONCLUSION

The activation of the coagulation cascade and the non specific inflammatory reaction could be one of the obstacles to the success of the islet allografts. The use of anticoagulant and anti-inflammatory molecules could potentially allow an improvement of the present results of islet allograft.

Protein C replacement in severe meningococcemia: rationale and clinical experience

Severe meningococcemia, which is associated with hemodynamic instability, purpura fulminans and disseminated intravascular coagulation, still has a high mortality rate, and patients who survive are often left invalids because of amputations and organ failure. Clinical studies have shown that levels of protein C are markedly decreased in patients with severe meningococcemia and that the extent of the decrease correlates with a negative clinical outcome. There is a growing body of data demonstrating that activated protein C, in addition to being an anticoagulant, is also a physiologically relevant modulator of the inflammatory response. The dual function of protein C may be relevant to the treatment of individuals with severe meningococcal sepsis. In the present review we give a basic overview of the protein C pathway and its anticoagulant activity, and we summarize experimental data showing that activated protein C replacement therapy clearly reduces the mortality rate for fulminant meningococcemia.

Antithrombin inhibits lipopolysaccharide-induced tissue factor and interleukin-6 production by mononuclear cells, human umbilical vein endothelial cells, and whole blood

OBJECTIVE

To investigate the effects of antithrombin on lipopolysaccharide (LPS)-induced tissue factor and interleukin-6 (IL-6) production in three different in vitro cellular systems: whole blood, human umbilical vein endothelial cells, and mononuclear cells.

DESIGN AND SETTING

Laboratory in vitro study of the effects of antithrombin on procoagulant activity and cytokine release by LPS-stimulated endothelial and peripheral blood cells.

SUBJECTS

In vitro whole blood, isolated human umbilical vein endothelial cell, and mononuclear cell cultures.

INTERVENTIONS

Addition of antithrombin to LPS-treated whole blood, human umbilical vein endothelial cells, and mononuclear cells.

MEASUREMENT AND MAIN RESULTS

Citrated whole blood, isolated human umbilical vein endothelial cells, or mononuclear cells were stimulated with LPS for 4-6 hrs in the presence or absence of antithrombin. Tissue factor activity was estimated by a tissue factor-dependent clotting or chromogenic assay and IL-6 was measured by specific ELISA. Antithrombin was found to inhibit tissue factor and IL-6 production in all three systems in a dose-dependent manner (0-40 IU/mL). Flow-through fractions of immunoadsorbed antithrombin concentrate were found to be ineffective. Five different batches of the same antithrombin concentrate were tested and the inhibitory activity was found to be consistent throughout all batches. Up to 40 microM of recombinant hirudin, a specific thrombin inhibitor, did not inhibit the production of tissue factor or IL-6 in either of the three cell systems, suggesting that the observed inhibition by antithrombin was not due solely to its ability to inhibit thrombin.

CONCLUSIONS

Apart from the inhibition of thrombin and other activated clotting factors, antithrombin may also down-regulate the cellular expression of proinflammatory cytokines. Consequently, antithrombin concentrates may have value in the treatment of sepsis-induced disseminated intravascular coagulation.

Tissue factor pathway inhibitor (TFPI) in disseminated intravascular coagulation: low levels of the activated factor X-TFPI complex

Tissue factor pathway inhibitor (TFPI) fractions and coagulation markers were determined in 26 patients with disseminated intravascular coagulation (DIC). Thrombin-antithrombin complex and fibrin monomer values were markedly elevated in all patients (P < 0.01). The median TFPI activity level (2.1 nmol/l) was lower than in normal controls (2.6 nmol/l; P < 0.01). The median free TFPI level was within the normal reference range, but seven patients had levels above and nine patients had levels below normal range. The median activated factor X (FXa)-TFPI complex level in patients (0.13 nmol/l) was lower than in controls (0.18 nmol/l; P < 0.01). Only one patient had a FXa-TFPI complex level above the normal range, while eight patients had levels below. In conclusion, TFPI activity, free TFPI antigen and FXa-TFPI complex levels vary considerably in DIC. Activation of coagulation may increase TFPI levels, as reported by other workers and supported by a positive correlation between tissue factor and free TFPI in the present material. A negative correlation between fibrin monomer and free TFPI (r = -0.46, P = 0.019) might indicate that hyperactive coagulation leads to consumption of TFPI. Subnormal FXa-TFPI levels in DIC, possibly caused by consumption, may imply a reduced capacity to inactivate the triggering factor VIIa-tissue factor complex.

Clinical trial results with antithrombin III in sepsis

OBJECTIVE

To present and discuss the rationale and results of clinical trials using antithrombin (AT) supplementation in patients with sepsis.

DATA SOURCES/STUDY SELECTION

Review of all controlled (open or double-blind) studies of patients with severe sepsis or septic shock who were treated with AT concentrates to obtain better control of coagulation activation and inflammation.

DATA EXTRACTION

AT is a major inhibitor of the coagulation cascade. Recent experimental studies have also shown that it can modulate the inflammatory reactions that occur during sepsis. An early and prolonged decrease in AT activity is well documented during sepsis-induced disseminated intravascular coagulation and during the systemic inflammatory response. Thus, supplementation with AT concentrates has been proposed as a potential therapy in sepsis patients.

DATA SYNTHESIS

Numerous uncontrolled studies of AT supplementation in sepsis patients have been reported in the last 20 yrs. Since 1993, four placebo-controlled randomized studies have been performed in France, Germany, Northwestern Europe, and Italy. Three of these studies were subjected to a meta-analysis of 122 patients. Results showed a nonsignificant 22% reduction in the 30-day all-cause mortality and a reduction in the length of stay in the intensive care unit in the AT treated group. The Italian study of 120 patients demonstrated that the overall mortality was similar in the placebo and treated groups. However, post hoc analysis according to the Cox regression model showed that in patients with septic shock, AT supplementation significantly decreased the risk of death.

CONCLUSIONS

Together, these studies are consistent with the positive effect seen with AT supplementation in patients with severe sepsis. A multicenter phase III trial is currently in progress to definitively document its effect on mortality.

Recombinant human antithrombin III improves survival and attenuates inflammatory responses in baboons lethally challenged with Escherichia coli

Plasma-derived antithrombin III (ATIII) prevents the lethal effects of Escherichia coli infusion in baboons, but the mechanisms behind this effect are not clear. In the present study, we evaluated the effects of recombinant human ATIII (rhATIII) on the clinical course and the inflammatory cytokine and coagulation responses in baboons challenged with lethal dose of E coli. Animals in the treatment group (n = 5) received high doses of rhATIII starting 1 hour before an E colichallenge. Those in the control group were administered saline. Survival was significantly improved in the treatment group (P = .002). Both groups had similar hemodynamic responses to E coli challenge but different coagulation and inflammatory responses. The rhATIII group had an accelerated increase of thrombin-ATIII complexes and significantly less fibrinogen consumption compared to controls. In addition, the rhATIII group had much less severe thrombotic pathology on autopsy and virtually no fibrinolytic response to E coli challenge. Furthermore, the rhATIII group had a significantly attenuated inflammatory response as evidenced by marked reduction of the release of various cytokines. We conclude that the early administration of high doses of rhATIII improves the outcome in baboons lethally challenged with E coli, probably due to the combined anticoagulation and anti-inflammatory effects of this therapy.

Inflammation-induced systemic proteolysis of inter-alpha-inhibitor in plasma from patients with sepsis

Inter-alpha-inhibitor (IalphaI) is a human plasma serine proteinase inhibitor. It contains one light peptide chain called bikunin that exerts antiproteinase activity and other antiinflammatory functions. Bikunin is covalently linked to two heavy chains that, after tissular diffusion, stabilize the extracellular matrix. Owing to its negative acute-phase reactant character and its susceptibility to proteolysis, IalphaI has been implicated in the pathophysiology of sepsis. Moreover, IalphaI has been shown to exert a protective effect on a pig model of endotoxic shock. Twenty patients admitted to the intensive care unit (ICU) for a septic syndrome were included in the present study. IalphaI and antithrombin III (ATIII) levels were measured on admission. Sequential measurements of IalphaI could be done in 4 patients. We demonstrate that IalphaI levels are significantly decreased in plasma samples collected on admission from patients with sepsis (59 +/- 32 mg/L vs 241 +/- 70 mg/L; P < .0001). This decrease was greater in severe sepsis and septic shock than in sepsis. Death was not predictable from initiol IalphaI levels. In 2 patients with a favorable course, IalphaI values regularly increased during the ICU stay. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by immunoblot analysis and microsequencing, we characterized IalphaI-related components in plasma from several patients; they obviously arise from IalphaI through proteolytic cleavage. Thus, systemic proteolysis and decreased biosynthesis both contribute to the fall in the plasma level of IalphaI. Because IalphaI is very sensitive to proteolysis by polymorphonuclear granulocytes (PMNs) that are stimulated during sepsis, we suggest that IalphaI plasma level would be a useful marker for neutrophil proteinase activity. ATIII, as well as IalphaI, is considered a negative acute phase protein. Because in vitro ATIII is less susceptible than IalphaI to proteolysis by PMNs and because their relative levels weakly correlated, we suggest that an unspecific systemic proteolysis is not significantly involved in the ATIII deficiency occurring in sepsis.