Antithrombin: a new look at the actions of a serine protease inhibitor

The natural anticoagulant protein S; hemostatic functions and deficiency

Protein S (PS) is a vital endogenous anticoagulant. It plays a crucial role in regulating coagulation by acting as a cofactor for the activated protein C (APC) and tissue factor pathway inhibitor (TFPI) pathways. Additionally, it possesses direct anticoagulant properties by impeding the intrinsic tenase and prothrombinase complexes. Protein S oversees the coagulation process in both the initiation and propagation stages through these roles. The significance of protein S in regulating blood clotting can be inferred from the significant correlation between deficits in protein S and an elevated susceptibility to venous thrombosis. This is likely because activated protein C and tissue factor pathway inhibitor exhibit low efficacy as anticoagulants when no cofactors exist. The precise biochemical mechanisms underlying the roles of protein S cofactors have yet to be fully elucidated. Nevertheless, recent scientific breakthroughs have significantly enhanced comprehension findings for these functions. The diagnosis of protein S deficiency, both from a technical and genetic standpoint, is still a subject of debate due to the complex structural characteristics of the condition. This paper will provide an in-depth review of the molecular structure of protein S and its hemostatic effects. Furthermore, we shall address the insufficiency of protein S and its methods of diagnosis and treatment.

Do we need more guidance on thrombophilia testing? Challenges and special considerations

INTRODUCTION

Thrombophilia testing (TT) is a laboratory procedure designed to detect the risk factors involved in the pathogenesis of vascular occlusions. The role of TT is also controversial because it has a limited impact on the choice and duration of antithrombotic treatments.

AREAS COVERED

We reviewed, by examining MEDLINE up to October 2023. Accepted and not accepted thrombophilia markers are discussed along with the appropriateness or not of prescribing TT in several conditions such as: provoked and unprovoked venous thromboembolism (VTE), women who are planning a pregnancy whose relatives had VTE or have a hereditary thrombophilia, before assumption of estro-progestins, after multiple pregnant loss, arterial thrombosis, retinal vein occlusion, and splanchnic vein thrombosis.

EXPERT OPINION

TT is not essential in the management of VTE, but it may be useful for limiting adverse events in case of thrombophilia. We expose our criticism of items afforded by other guidelines by presenting our opinion based on both the scientific evidence and clinical practice. We also deal with common mistakes in prescribing and interpretations of TT hoping to purpose an educational approach on this topic. Finally, we emphasize the creation of the expert in hemostasis and thrombosis who should be present in every hospital.

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.

Salivary Chemical Barrier Proteins in Oral Squamous Cell Carcinoma-Alterations in the Defense Mechanism of the Oral Cavity

Oral squamous cell carcinoma (OSCC) is one of the most frequent types of head and neck cancer. Despite the genetic and environmental risk factors, OSCC is also associated with microbial infections and/or dysbiosis. The secreted saliva serves as the chemical barrier of the oral cavity and, since OSCC can alter the protein composition of saliva, our aim was to analyze the effect of OSCC on the salivary chemical barrier proteins. Publicly available datasets regarding the analysis of salivary proteins from patients with OSCC and controls were collected and examined in order to identify differentially expressed chemical barrier proteins. Network analysis and gene ontology (GO) classification of the differentially expressed chemical barrier proteins were performed as well. One hundred and twenty-seven proteins showing different expression pattern between the OSCC and control groups were found. Protein-protein interaction networks of up- and down-regulated proteins were constructed and analyzed. The main hub proteins (IL-6, IL-1B, IL-8, TNF, APOA1, APOA2, APOB, APOC3, APOE, and HP) were identified and the enriched GO terms were examined. Our study highlighted the importance of the chemical barrier of saliva in the development of OSCC.

Galectin-3 as a Marker for Increased Thrombogenicity in COVID-19

Galectin-3 is a beta-galactoside-binding lectin involved in inflammation and lung fibrosis and postulated to enhance thrombosis. In COVID-19, it is considered to be a prognostic marker of severity. The aim of this study was to evaluate whether galectin-3 is associated with thrombogenicity in COVID-19. Patients with moderate-to-severe COVID-19 (COVpos; n = 55) and patients with acute respiratory diseases, but without COVID-19 (COVneg; n = 35), were included in the study. We measured the amount of galectin-3, as well as other platelet and coagulation markers, and correlated galectin-3 levels with these markers of thrombogenicity and with the SOFA Score values. We found that galectin-3 levels, as well as von Willebrand Factor (vWF), antithrombin and tissue plasminogen activator levels, were higher in the COVpos than they were in the COVneg cohort. Galectin-3 correlated positively with vWF, antithrombin and D-dimer in the COVpos cohort, but not in the COVneg cohort. Moreover, galactin-3 correlated also with clinical disease severity, as measured by the SOFA Score. In patients with acute respiratory diseases, galectin-3 can be considered as a marker not only for disease severity, but also for increased hypercoagulability. Whether galectin-3 might be a useful therapeutic target in COVID-19 needs to be assessed in future studies.

Five Challenging Cases of Hereditary Antithrombin Deficiency Characterized by Thrombosis or Complicated Pregnancy

Hereditary antithrombin deficiency (ATD) is a rare autosomal dominant condition (estimated prevalence 1:500-1:5000). Most ATD patients have AT activity levels 40-60% of normal. We present treatments for venous thromboembolism (VTE) in five cases of hereditary ATD. Four patients had a family history of ATD, and one had a de novo mutation. The majority of patients had a VTE while on prophylactic anticoagulation. AT concentrate augmentation was added in these cases to treat the VTE and for prophylaxis against further episodes. Two patients had significant bleeding events, one had permanent physical sequelae. Two of the patients were pregnant. VTE is a common cause of morbidity and mortality during pregnancy. Although low molecular weight heparins are the drugs of choice during pregnancy, this treatment was inadequate in one patient (developed VTE on therapy). These cases emphasize the need to screen for ATD in young patients (<55 years) presenting with VTE. AT augmentation therapy may be necessary in patients inadequately treated with conventional anticoagulants. Careful monitoring and individualized care are needed in ATD patients, especially those with demonstrated bleeding tendencies.

The relationship between antithrombin administration and inflammation during veno-venous ECMO

Veno-venous Extracorporeal Membrane Oxygenation (ECMO) is used in the most severe cases of respiratory failure and further exacerbates the patients’ inflammatory status. Antithrombin is supplemented during ECMO for its anticoagulant effects, but it also deploys anti-inflammatory properties. In this pre-specified ancillary study of the GATRA trial [NCT03208270] we aimed to evaluate the relationship between antithrombin and inflammation during ECMO. Forty-six patients were included in the study, 23 were randomized to receive antithrombin to maintain a level of 80–120% (study group) and 23 were randomized not to be supplemented (control group). Anticoagulation was provided in both groups with heparin infusion. Six cytokines were measured at 5 timepoints from prior to ECMO start to 7 days after ECMO removal. Cytokines decreased during the study but overall were not very different in the two groups. Testing the interaction between the study group and timepoints suggests that the administration of antithrombin led to a more rapid decrease over time of IL-6, IL-1β, TNF-⍺ and Pro-ADM. Plasma levels of antithrombin (either endogenous or exogenous) were negatively associated with all cytokines. Inflammation decreases during ECMO but a causal effect of antithrombin administration on the reduction of inflammation (and its clinical relevance) must be confirmed by appropriately powered studies.

Chemical Barrier Proteins in Human Body Fluids

Chemical barriers are composed of those sites of the human body where potential pathogens can contact the host cells. A chemical barrier is made up by different proteins that are part of the antimicrobial and immunomodulatory protein/peptide (AMP) family. Proteins of the AMP family exert antibacterial, antiviral, and/or antifungal activity and can modulate the immune system. Besides these proteins, a wide range of proteases and protease inhibitors can also be found in the chemical barriers maintaining a proteolytic balance in the host and/or the pathogens. In this review, we aimed to identify the chemical barrier components in nine human body fluids. The interaction networks of the chemical barrier proteins in each examined body fluid were generated as well.

Molecular analysis of vascular gene expression

A State of the Art lecture entitled "Molecular Analysis of Vascular Gene Expression" was presented at the ISTH Congress in 2021. Endothelial cells (ECs) form a critical interface between the blood and underlying tissue environment, serving as a reactive barrier to maintain tissue homeostasis. ECs play an important role in not only coagulation, but also in the response to inflammation by connecting these two processes in the host defense against pathogens. Furthermore, ECs tailor their behavior to the needs of the microenvironment in which they reside, resulting in a broad display of EC phenotypes. While this heterogeneity has been acknowledged for decades, the contributing molecular mechanisms have only recently started to emerge due to technological advances. These include high-throughput sequencing combined with methods to isolate ECs directly from their native tissue environment, as well as sequencing samples at a high cellular resolution. In addition, the newest technologies simultaneously quantitate and visualize a multitude of RNA transcripts directly in tissue sections, thus providing spatial information. Understanding how ECs function in (patho)physiological conditions is crucial to develop new therapeutics as many diseases can directly affect the endothelium. Of particular relevance for thrombotic disorders, EC dysfunction can lead to a procoagulant, proinflammatory phenotype with increased vascular permeability that can result in coagulopathy and tissue damage, as seen in a number of infectious diseases, including sepsis and coronavirus disease 2019. In light of the current pandemic, we will summarize relevant new data on the latter topic presented during the 2021 ISTH Congress.

The effect of hyperoxia on the hemostasiological status of severely burned patients

The state of the hemostasis system was studied in 9 patients of the middle age group (44 ± 9.94 years) who received thermal trauma on an area of more than 32% (49.4 ± 18.3) of the body surface, accompanied by the development of burn shock. The standard therapy for burn injury was supplemented with HBO sessions. Treatment with hyperbaric oxygen was carried out in pressure chambers BLKS-307, BLKS-307/1. The state of the coagulation, anticoagulant and fibrinolytic links of the hemostasis system, as well as the viscoelastic properties of the blood, were assessed immediately before the HBO session and immediately after it. The total number of comparison pairs was 45. Under the influence of HBO therapy, there was an increase in the activity of antithrombin III (ATIII), protein C (PrS) and a decrease in the viscoelastic properties of blood (p <0.05). Positive deviations in the values of ATIII, Pr C, von Willebrand factor, APTT, prothrombin and thrombin time, fibrinogen, factor XIII, XIIa-dependent fibrinolysis, D-dimers and thromboelastography parameters were revealed. The maximum frequency of their occurrence was recorded for ATIII (95%), the minimum - for the D-dimer (62%). After HBO procedures, undesirable deviations of the hemostatic system parameters were also noted. They were chaotic, were compensated by an increase in the activity of physiological anticoagulants and were not accompanied by complications of a thrombogenic nature. Thus, conducting HBO therapy sessions in the acute period of burn disease increases the activity of physiological anticoagulants and stabilizes the viscoelastic properties of blood. There is a high frequency of occurrence of positive effects of hyperoxia on the components of the hemostasis system. The identification of its undesirable effects indicates the need to monitor the state of the hemostasis system during HBO procedures.

Platelet-Therapeutics to Improve Tissue Regeneration and Wound Healing-Physiological Background and Methods of Preparation

Besides their function in primary hemostasis, platelets are critically involved in the physiological steps leading to wound healing and tissue repair. For this purpose, platelets have a complex set of receptors allowing the recognition, binding, and manipulation of extracellular structures and the detection of pathogens and tissue damage. Intracellular vesicles contain a huge set of mediators that can be released to the extracellular space to coordinate the action of platelets as other cell types for tissue repair. Therapeutically, the most frequent use of platelets is the intravenous application of platelet concentrates in case of thrombocytopenia or thrombocytopathy. However, there is increasing evidence that the local application of platelet-rich concentrates and platelet-rich fibrin can improve wound healing and tissue repair in various settings in medicine and dentistry. For the therapeutic use of platelets in wound healing, several preparations are available in clinical practice. In the present study we discuss the physiology and the cellular mechanisms of platelets in hemostasis and wound repair, the methods used for the preparation of platelet-rich concentrates and platelet-rich fibrin, and highlight some examples of the therapeutic use in medicine and dentistry.

When antithrombin substitution strikes back

Commercially available products used for antithrombin supplementation, for example, in extracorporeal life support, may contain latent antithrombin, a hyper-stable strongly procoagulative and anti-angiogenic residue. Latent antithrombin is associated with severe thrombosis in the critically ill. In the manufacturing process of fractionated antithrombin from plasma, heat treatment, citrate, and freeze drying speed up the transformation of native antithrombin to latent antithrombin. Manufacturers are not required to assess and report the latent antithrombin content of their products. When reported, the latent antithrombin fractions in their product range from <1% to 40% of total antithrombin compared with <3% in the healthy adult and less in children. The aims of this work were (1) to convey increased awareness to clinicians who may experience defaulted, expected effect after antithrombin supplementation in, for example, heparin anticoagulation during extracorporeal life support and (2) to urge manufacturers to assess and disclose latent antithrombin content in their products.

Role of Thrombin in Central Nervous System Injury and Disease

Thrombin is a Na+-activated allosteric serine protease of the chymotrypsin family involved in coagulation, inflammation, cell protection, and apoptosis. Increasingly, the role of thrombin in the brain has been explored. Low concentrations of thrombin are neuroprotective, while high concentrations exert pathological effects. However, greater attention regarding the involvement of thrombin in normal and pathological processes in the central nervous system is warranted. In this review, we explore the mechanisms of thrombin action, localization, and functions in the central nervous system and describe the involvement of thrombin in stroke and intracerebral hemorrhage, neurodegenerative diseases, epilepsy, traumatic brain injury, and primary central nervous system tumors. We aim to comprehensively characterize the role of thrombin in neurological disease and injury.

Predictive Utility of Antithrombin III in Acute Kidney Injury in Living-Donor Liver Transplantation: A Retrospective Observational Cohort Study

INTRODUCTION

This study was performed to determine the association between the serum level of antithrombin III (ATIII) level and the risk of acute kidney injury (AKI) in patients undergoing living-donor liver transplantation (LDLT).

PATIENTS AND METHODS

A total of 591 patients undergoing LDLT were retrospectively investigated and 14 patients were excluded because of a history of kidney dysfunction or missing data; 577 patients were finally enrolled in the study. The study population was divided into normal and low ATIII groups. Data on all laboratory variables, including ATIII, were collected on the day before surgery.

RESULTS

After LDLT, 143 patients developed AKI (24.8%). A lower ATIII was independently associated with postoperative AKI along with preoperative (diabetes mellitus) and intraoperative (mean heart rate, hourly urine output) factors. Based on the standard cutoff for normal ATIII (<70%), the probability of AKI was 2.8-fold higher in the low ATIII group than in the normal ATIII group. In addition, patients with low ATIII received blood transfusion products during the operation and underwent longer duration mechanical ventilation.

CONCLUSIONS

Preoperative ATIII measurement will help improve risk stratification for postoperative AKI development in patients undergoing LDLT.

Clot activators and anticoagulant additives for blood collection. A critical review on behalf of COLABIOCLI WG-PRE-LATAM

In the clinical laboratory, knowledge of and the correct use of clot activators and anticoagulant additives are critical to preserve and maintain samples in optimal conditions prior to analysis. In 2017, the Latin America Confederation of Clinical Biochemistry (COLABIOCLI) commissioned the Latin American Working Group for Preanalytical Phase (WG-PRE-LATAM) to study preanalytical variability and establish guidelines for preanalytical procedures to be applied by clinical laboratories and health care professionals. The aim of this critical review, on behalf of COLABIOCLI WG-PRE-LATAM, is to provide information to understand the mechanisms of the interactions and reactions that occur between blood and clot activators and anticoagulant additives inside evacuated tubes used for laboratory testing. Clot activators - glass, silica, kaolin, bentonite, and diatomaceous earth - work by surface dependent mechanism whereas extrinsic biomolecules - thrombin, snake venoms, ellagic acid, and thromboplastin - start in vitro coagulation when added to blood. Few manufacturers of evacuated tubes state the type and concentration of clot activators used in their products. With respect to anticoagulant additives, sodium citrate and oxalate complex free calcium and ethylenediaminetetraacetic acid chelates calcium. Heparin potentiates antithrombin and hirudin binds to active thrombin, inactivating the thrombin irreversibly. Blood collection tubes have improved continually over the years, from the glass tubes containing clot activators or anticoagulant additives that were prepared by laboratory personnel to the current standardized evacuated systems that permit more precise blood/additive ratios. Each clot activator and anticoagulant additive demonstrates specific functionality, and both manufacturers of tubes and laboratory professional strive to provide suitable interference-free sample matrices for laboratory testing. Both manufacturers of in vitro diagnostic devices and laboratory professionals need to understand all aspects of venous blood sampling so that they do not underestimate the impact of tube additives on laboratory testing.

Anticoagulant and signaling functions of antithrombin

Antithrombin (AT) is a major plasma glycoprotein of the serpin superfamily that regulates the proteolytic activity of the procoagulant proteases of both intrinsic and extrinsic pathways. Two important structural features that participate in the regulatory function of AT include a mobile reactive center loop that binds to active site of coagulation proteases, trapping them in the form of inactive covalent complexes, and a basic D-helix that binds to therapeutic heparins and heparan sulfate proteoglycans (HSPGs) on vascular endothelial cells. The binding of D-helix of AT by therapeutic heparins promotes the reactivity of the serpin with coagulation proteases by several orders of magnitude by both a conformational activation of the serpin and a template (bridging) mechanism. In addition to its essential anticoagulant function, AT elicits a potent anti-inflammatory signaling response when it binds to distinct vascular endothelial cell HSPGs, thereby inducing prostacyclin synthesis. Syndecans-4 has been found as a specific membrane-bound HSPG receptor on endothelial cells that relays the signaling effect of AT to the relevant second messenger molecules in the signal transduction pathways inside the cell. However, following cleavage by coagulation proteases and/or by spontaneous conversion to a latent form, AT loses both its anti-inflammatory activity and high-affinity interaction with heparin and HSPGs. Interestingly, these low-affinity heparin conformers of AT elicit potent proapoptotic and antiangiogenic activities by also binding to specific HSPGs by unknown mechanisms. This review article will summarize current knowledge about mechanisms through which different conformers of AT exert their serine protease inhibitory and intracellular signaling functions in these biological pathways.

Antithrombin Deficiency in Trauma and Surgical Critical Care

Antithrombin deficiency (ATD) was described in 1965 by Olav Egeberg as the first known inherited form of thrombophilia. Today, it is understood that ATDs can be congenital or acquired, leading to qualitative, quantitative, or mixed abnormalities in antithrombin (AT). All ATDs ultimately hinder AT's ability to serve as an endogenous anticoagulant and antiinflammatory agent. As a result, ATD patients possess higher risk for thromboembolism and can develop recurrent venous and arterial thromboses. Because heparin relies on AT to augment its physiologic function, patients with ATD often exhibit profound heparin resistance. Although rare as a genetic disorder, acquired forms of ATD are seen with surprising frequency in critically ill patients. This review discusses ATD in the context of surgical critical care with specific relevance to trauma, thermal burns, cardiothoracic surgery, and sepsis.

Cleavage of proteoglycans, plasma proteins and the platelet-derived growth factor receptor in the hemorrhagic process induced by snake venom metalloproteinases

Envenoming by viperid snakes results in a complex pattern of tissue damage, including hemorrhage, which in severe cases may lead to permanent sequelae. Snake venom metalloproteinases (SVMPs) are main players in this pathogenesis, acting synergistically upon different mammalian proteomes. Hemorrhagic Factor 3 (HF3), a P-III class SVMP from Bothrops jararaca, induces severe local hemorrhage at pmol doses in a murine model. Our hypothesis is that in a complex scenario of tissue damage, HF3 triggers proteolytic cascades by acting on a partially known substrate repertoire. Here, we focused on the hypothesis that different proteoglycans, plasma proteins, and the platelet derived growth factor receptor (PDGFR) could be involved in the HF3-induced hemorrhagic process. In surface plasmon resonance assays, various proteoglycans were demonstrated to interact with HF3, and their incubation with HF3 showed degradation or limited proteolysis. Likewise, Western blot analysis showed in vivo degradation of biglycan, decorin, glypican, lumican and syndecan in the HF3-induced hemorrhagic process. Moreover, antithrombin III, complement components C3 and C4, factor II and plasminogen were cleaved in vitro by HF3. Notably, HF3 cleaved PDGFR (alpha and beta) and PDGF in vitro, while both receptor forms were detected as cleaved in vivo in the hemorrhagic process induced by HF3. These findings outline the multifactorial character of SVMP-induced tissue damage, including the transient activation of tissue proteinases, and underscore for the first time that endothelial glycocalyx proteoglycans and PDGFR are targets of SVMPs in the disruption of microvasculature integrity and generation of hemorrhage.

Plasmodium falciparum histidine rich protein HRPII inhibits the anti-inflammatory function of antithrombin

BACKGROUND

It has been reported that histidine-rich protein II (HRPII), secreted by the malaria parasite, Plasmodium falciparum (Pf), inhibits the heparin-dependent anticoagulant activity of antithrombin (AT) in vitro and in plasma-based assay systems.

OBJECTIVE

The objective of this study was to test the hypothesis that HRPII may also interact with the AT-binding vascular glycosaminoglycans (GAGs), thereby inhibiting the anti-inflammatory signaling function of the serpin.

METHODS

We expressed HRPII in bacteria, purified it to homogeneity and studied its effect on endothelial cell signaling in the absence and presence of AT employing established signaling assays.

RESULTS

We demonstrate that a low concentration of HRPII potently disrupts the barrier permeability function of endothelial cells. Moreover, HRPII competitively inhibits the protective effect of AT by a concentration-dependent manner. Similarly, AT inhibits the pro-inflammatory activity of HRPII by a concentration-dependent manner. The siRNA knockdown of 3-O-sulfotransferase 1 (3-OST-1), the enzyme responsible for the essential 3-O-sulfation of the AT-binding GAGs, downregulates the pro-inflammatory function of HRPII in endothelial cells, supporting the hypothesis that HRPII competitively inhibits the interaction of AT with 3-OS containing vascular GAGs. Histidine-rich protein II elicits its barrier-disruptive effect by the Src-dependent phosphorylation of vascular endothelial (VE)-cadherin and AT counteracts this effect. We further demonstrate that inorganic polyphosphates bind HRPII with a high affinity to amplify the pro-inflammatory signaling function of HRPII in both cellular and in vivo permeability models.

CONCLUSION

We postulate that Pf-derived HRPII and polyphosphate can contribute to the pathogenesis of malaria infection by downregulating the AT-dependent anti-inflammatory and anticoagulant pathways.

Comprehensive Proteomic Profiling of Pressure Ulcers in Patients with Spinal Cord Injury Identifies a Specific Protein Pattern of Pathology

Objective: Severe pressure ulcers (PUs) do not respond to conservative wound therapy and need surgical repair. To better understand the pathogenesis and to advance on new therapeutic options, we focused on the proteomic analysis of PU, which offers substantial opportunities to identify significant changes in protein abundance during the course of PU formation in an unbiased manner. Approach: To better define the protein pattern of this pathology, we performed a proteomic approach in which we compare severe PU tissue from spinal cord injury (SCI) patients with control tissue from the same patients. Results: We found 76 proteins with difference in abundance. Of these, 10 proteins were verified as proteins that define the pathology: antithrombin-III, alpha-1-antitrypsin, kininogen-1, alpha-2-macroglobulin, fibronectin, apolipoprotein A-I, collagen alpha-1 (XII) chain, haptoglobin, apolipoprotein B-100, and complement factor B. Innovation: This is the first study to analyze differential abundance protein of PU tissue from SCI patients using high-throughput protein identification and quantification by tandem mass tags followed by liquid chromatography tandem mass spectrometry. Conclusion: Differential abundance proteins are mainly involved in tissue regeneration. These proteins might be considered as future therapeutic options to enhance the physiological response and permit cellular repair of damaged tissue.

Hemostasis in elderly patients with human immunodeficiency virus (HIV) infection-Cross-sectional study

Introduction: Aging and chronic HIV infection are clinical conditions that share the states of inflammation and hypercoagulability. The life expectancy of the world population has increased in the last decades, bringing as complications the occurrence of diseases that undergoing metabolic, bone, cardiological, vascular and neurological alterations. HIV-infected patients experience these changes early and are living longer due to the success of antiretroviral therapy. The objectives of this study was to evaluate some changes in the plasma hemostatic profile of 115 HIV-reactive elderly individuals over 60 years old in the chronic phase of infection, and compare with 88 healthy uninfected elderly individuals. Plasma determinations of D-dimers, Fibrinogen, von Willebrand Factor, Antithrombin, Prothrombin Time, Activated Partial Thromboplastin Time, and platelet count were performed. In the HIV-reactive group, these variables were analyzed according to viral load, protease inhibitor use and CD4⁺ T lymphocyte values. After adjusted values for age and sex, the results showed higher levels of Antithrombin (103%; 88%, p = 0.0001) and Prothrombin Time activities (92.4%; 88.2%, p = 0.019) in the HIV group compared to the control group. We observed higher values of Fibrinogen in protease inhibitor users in both the male (p = 0.043) and female (p = 0.004) groups, and in the female HIV group with detected viral load (p = 0.015). The male HIV group with a CD4⁺ count> 400 cells / mm³ presented higher von Willebrand Factor values (p = 0.036). D-Dimers had higher values in the older age groups (p = 0.003; p = 0.042, respectively). Conclusion: Our results suggest that the elderly with chronic HIV infection with few comorbidities had a better hemostatic profile than negative control group, reflecting the success of treatment. Protease inhibitor use and age punctually altered this profile.

Glycocalyx Degradation in Ischemia-Reperfusion Injury

The glycocalyx is a layer coating the luminal surface of vascular endothelial cells. It is vital for endothelial function as it participates in microvascular reactivity, endothelium interaction with blood constituents, and vascular permeability. Structural and functional damage to glycocalyx occurs in various disease states. A prominent clinical situation characterized by glycocalyx derangement is ischemia-reperfusion (I/R) of the whole body as well as during selective I/R to organs such as the kidney, heart, lung, or liver. Degradation of the glycocalyx is now considered a cornerstone in I/R-related endothelial dysfunction, which further impairs local microcirculation with a feed-forward loop of organ damage, due to vasoconstriction, leukocyte adherence, and activation of the immune response. Glycocalyx damage during I/R is evidenced by rising plasma levels of its principal constituents, heparan sulfate and syndecan-1. By contrast, the concentrations of these compounds in the circulation decrease after successful protective interventions in I/R, suggesting their use as surrogate biomarkers of endothelial integrity. In light of the importance of the glycocalyx in preserving endothelial cell integrity and its involvement in pathologic conditions, several promising therapeutic strategies to restore the damaged glycocalyx and to attenuate its deleterious consequences have been suggested. This review focuses on alterations of glycocalyx during I/R injury in general (to vital organs in particular), and on maneuvers aimed at glycocalyx recovery during I/R injury.

Significance of plasma fibrinogen level and antithrombin activity in sepsis: A multicenter cohort study using a cubic spline model

INTRODUCTION

Sepsis leads to coagulopathy by the activation of inflammatory mediators and vascular endothelial cell injury. A number of biomarkers are used to evaluate coagulopathy on sepsis. Fibrinogen and antithrombin activity have been reported as biomarkers of coagulopathy; however, the utility of these two markers has not been well established. This study aimed to evaluate the detailed association between these two markers and clinical outcomes in sepsis patients.

MATERIALS AND METHODS

This was a post hoc analysis of a multicenter, prospective cohort study conducted in 59 intensive care units throughout Japan from January 2016 to March 2017. We included 1103 adult patients with severe sepsis based on the Sepsis-2 criteria. The associations between the coagulation markers and in-hospital mortality were examined using linear and non-linear logistic regression analyses. We also evaluated the associations between the coagulation markers and disseminated intravascular coagulation (DIC) scores. The International Society on Thrombosis and Haemostasis overt DIC score was calculated after subtracting the fibrinogen component.

RESULTS

The decreased levels of the fibrinogen and antithrombin activity were significantly associated with an increase in mortality (P = 0.011 and 0.002, respectively). In addition, cubic spline regression demonstrated that mortality sharply increased at a fibrinogen level of approximately <200 mg/dL and at an antithrombin activity of approximately <50%. Similarly, the decreased levels of the two markers non-linearly correlated with the elevation of DIC score.

CONCLUSIONS

The fibrinogen level and antithrombin activity should be reconsidered as unique biomarkers for sepsis and sepsis-induced DIC.

Antithrombin supplementation during extracorporeal membrane oxygenation: study protocol for a pilot randomized clinical trial

BACKGROUND

Normal levels of plasma antithrombin (AT) activity might decrease heparin requirements to achieve an adequate level of anticoagulation during treatment with extracorporeal membrane oxygenation (ECMO). Acquired AT deficiency during ECMO is common, but formal recommendations on target, timing, and rate of AT supplementation are lacking. Thus, we conceived a pilot trial to evaluate the feasibility and safety of prolonged AT supplementation in patients requiring veno-venous ECMO for respiratory failure.

METHODS

Grifols Antithrombin Research Awards (GATRA) is a prospective, randomized, single blinded, multicenter, controlled two-arm trial. Patients undergoing veno-venous ECMO will be randomized to either receive AT supplementation to maintain a functional AT level between 80 and 120% (AT supplementation group) or not (control group) for the entire ECMO course. In both study groups, anticoagulation will be provided with unfractionated heparin following a standardized protocol. The primary endpoint will be the dose of heparin required to maintain the ratio of activated partial thromboplastin time between 1.5 and 2. Secondary endpoints will be the adequacy of anticoagulation and the incidence of hemorrhagic and thrombotic complications.

DISCUSSION

GATRA is a pilot trial that will test the efficacy of a protocol of AT supplementation in decreasing the heparin dose and improving anticoagulation adequacy during ECMO. If positive, it might provide the basis for a future larger trial aimed at verifying the impact of AT supplementation on a composite outcome endpoint including hemorrhagic events, transfusion requirements, and mortality.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03208270 . Registered on 5 July 2017.

Advance in the Management of Sepsis-Induced Coagulopathy and Disseminated Intravascular Coagulation

Coagulopathy commonly occurs in sepsis as a critical host response to infection that can progress to disseminated intravascular coagulation (DIC) with an increased mortality. Recent studies have further defined factors responsible for the thromboinflammatory response and intravascular thrombosis, including neutrophil extracellular traps, extracellular vesicles, damage-associated molecular patterns, and endothelial glycocalyx shedding. Diagnosing DIC facilitates sepsis management, and is associated with improved outcomes. Although the International Society on Thrombosis and Haemostasis (ISTH) has proposed criteria for diagnosing overt DIC, these criteria are not suitable for early detection. Accordingly, the ISTH DIC Scientific Standardization Committee has proposed a new category termed "sepsis-induced coagulopathy (SIC)" to facilitate earlier diagnosis of DIC and potentially more rapid interventions in these critically ill patients. Therapy of SIC includes both treatment of the underlying infection and correcting the coagulopathy, with most therapeutic approaches focusing on anticoagulant therapy. Recently, a phase III trial of recombinant thrombomodulin was performed in coagulopathic patients. Although the 28-day mortality was improved by 2.6% (absolute difference), it did not reach statistical significance. However, in patients who met entry criteria for SIC at baseline, the mortality difference was approximately 5% without increased risk of bleeding. In this review, we discuss current advances in managing SIC and DIC.

Comparison of Antithrombin III and Pentoxifylline Treatments in Gram Negative Sepsis Patients Developing Disseminated Intravascular Coagulation

Objective:

The aim of this study was to evaluate the effects of antithrombin III (AT III) and pentoxifylline treatments on the gram negative septic patients with disseminated intravascular coagulation (DIC).

Method:

For six days after plasma AT III activity dropped lower than 80% in Gram-patients who developed DIC were treated with AT III (90-120 IU/kg/day in 6 hours) or pentoxifylline (1.5 mg/kg/h in 6 hours) Fibrinogen, FDP, D-dimer, complete blood count, AT III activity, and DIC scores were calculated and recorded.

Results:

The coagulation tests, AT III activity and FDP started to improve from the second day of treatment with both treatments (p<0.05). D-Dimer started to decrease on the second day of treatment with pentoxifylline (p<0.001) and fourth day of AT III treatment (p<0.05). Fibrinogen levels decreased on the second day of pentoxifylline treatment (p<0.05) and on the last day of AT III treatment (p<0.001). DIC scores started to decrease on the last day of treatment with AT III treatment (p<0.001) and on the third day of treatment with pentoxifylline (p<0.05).

Conclusion:

Both ATIII and pentoxifylline treatments had positive effects on fibrinogen, FDP, D-Dimer, AT III activity and DIC scores in patients with Gram-negative sepsis who developed DIC.

Antithrombotic properties of hemofilter coated with polymer having a hydrophilic blood-contacting layer

OBJECTIVE:

Extracorporeal circulation devices are coated with a biocompatible polymer coating agent (BPCA) that has a hydrophilic blood-contacting layer, but hemofilters are not. We aimed to investigate the antithrombotic properties of a BPCA-coated hemofilter.

METHODS:

Four experiments using BPCA-coated circuits and non-coated hemofilters and four experiments using BPCA-coated circuits and BPCA-coated hemofilters were performed with whole human blood and compared by measuring the circuit pressure every 5 min, antithrombin activity every 40 min, and thrombin-antithrombin complex every 40 min, for a total of 240 min of recirculation.

RESULTS:

The mean time required for the pressure at the inlet of the hemofilter to increase sharply was longer in BPCA-coated than in non-coated hemofilters (66 ± 11 min vs 25 ± 9 min, p < 0.01). The mean antithrombin activity value at 200 and 240 min of recirculation was significantly higher in the experiments with BPCA-coated versus non-coated hemofilters (43.3 ± 2.87 vs 33.3 ± 5.74, p = 0.04; 42.8 ± 3.59 vs 31.0 ± 5.35, p = 0.01, respectively); the antithrombin activity values at the other time points were not significantly different. Furthermore, all thrombin-antithrombin complex values in experiments with the BPCA-coated hemofilters achieved overrange at 80 min of recirculation, whereas those with the non-coated hemofilter achieved overrange at 40 min.

CONCLUSION:

This study suggests that BPCA-coated hemofilters can inhibit antithrombin consumption, contributing to antithrombotic effects in extracorporeal circulation circuits.

Optimal Antithrombin Activity Threshold for Initiating Antithrombin Supplementation in Patients With Sepsis-Induced Disseminated Intravascular Coagulation: A Multicenter Retrospective Observational Study

Low-dose antithrombin supplementation therapy (1500 IU/d for 3 days) improves outcomes in patients with sepsis-induced disseminated intravascular coagulation (DIC). This retrospective study evaluated the optimal antithrombin activity threshold to initiate supplementation, and the effects of supplementation therapy in 1033 patients with sepsis-induced DIC whose antithrombin activity levels were measured upon admission to 42 intensive care units across Japan. Of the 509 patients who had received antithrombin supplementation therapy, in-hospital mortality was significantly reduced only in patients with very low antithrombin activity (≤43%; bottom quartile; adjusted hazard ratio: 0.603; 95% confidence interval: 0.368-0.988; P = .045). Similar associations were not observed in patients with low, moderate, or normal antithrombin activity levels. Supplementation therapy did not correlate with the incidence of bleeding requiring transfusion. The adjusted hazard ratios for in-hospital mortality increased gradually with antithrombin activity only when initial activity levels were very low to normal but plateaued thereafter. We conclude that antithrombin supplementation therapy in patients with sepsis-induced DIC and very low antithrombin activity may improve survival without increasing the risk of bleeding.

Concomitant Versus Individual Administration of Antithrombin and Thrombomodulin for Sepsis-Induced Disseminated Intravascular Coagulation: A Nationwide Japanese Registry Study

Background:

Antithrombin and recombinant human thrombomodulin (rhTM) are individually reported to improve survival in sepsis-induced disseminated intravascular coagulation (DIC). However, continuing controversy exists as to which agent is superior and whether concomitant therapy is superior to individual administration.

Methods:

This post hoc analysis included adult patients with sepsis-induced DIC from a nationwide multicenter registry database in Japan. We categorized patients into 4 groups: patients who received (1) individual administration of antithrombin, (2) individual administration of rhTM, (3) both, and (4) neither. In-hospital mortality was compared between every 2 groups among the 4 groups by Cox proportional hazards model adjusted with propensity scores.

Results:

In total, 1432 patients with sepsis-induced DIC were included. Although both antithrombin and rhTM were associated better outcome compared with no anticoagulants, mortality benefits were similar between each individual anticoagulant. Similarly, no significant difference in mortality was detected between individual administrations and concomitant therapy.

Conclusion:

Antithrombin and rhTM might have comparable efficacy in reducing mortality in patients with sepsis; however, concomitant therapy appeared to offer no additional survival benefit.

Antithrombin Ⅲ is a Novel Predictor for Contrast Induced Nephropathy After Coronary Angiography

BACKGROUND/AIMS

Antithrombin Ⅲ (AT Ⅲ) is an important endogenous anticoagulant and has strong anti-inflammatory properties. Low ATⅢ activity is considered to be a predictor of poor outcomes in several conditions, including acute kidney injury after cardiac surgery. However, the association between the ATⅢ level and the occurrence of contrast induced nephropathy (CIN) has not been elucidated. In this study, our aim was to identify the potential predictive value of ATⅢ for CIN.

METHODS

We enrolled a total of 460 patients who underwent coronary angiography (CAG) from January 2015 to December 2016 in coronary care units (CCU). ATⅢ activity in plasma collected before CAG was measured and <75% was considered low activity according to reference values. A cross-sectional study on CIN after CAG was conducted and the risk factors were analyzed. CIN was diagnosed according to the KDIGO guideline.

RESULTS

Of these 460 patients undergoing CAG, 125 (27.17%) progressed to CIN. The incidence of CIN was significantly higher in patients with low ATⅢ activity compared to patients with normal ATⅢ activity (Pearson's chi-squared test P=0.002). As ATⅢ activity declined, the prevalence of CIN progressively increased, with the highest value (58.8%) in patients with an ATⅢ activity <60%. Moreover, the ATⅢ activity was significantly lower in CIN patients than in non-CIN patients (84.43±16.3% vs. 92.14±13.94%, P<0.001). After multivariable analysis, ATⅢ activity <75% remained a significant independent predictor of CIN (OR 2.207,95%CI [1.29-3.777]; P=0.004) as well as baseline serum creatinine (OR 1.009,95%CI [1.001-1.016]; P=0.026).

CONCLUSIONS

Patients with low ATⅢ activity had a higher risk of developing CIN after CAG. The initial ATⅢ activity may be a novel independent predictor for CIN.

A summary of the Japan septic disseminated intravascular coagulation study

Over the past few decades, the large, international, randomized controlled trials of anticoagulant therapies for patients with sepsis have not yielded any improvement in mortality rates. However, in Japan, anticoagulant therapies are administered for sepsis patients with disseminated intravascular coagulation (DIC), but not for sepsis patients without DIC. Furthermore, epidemiological data regarding sepsis in Japan are scarce. Therefore, a nationwide multicenter retrospective observational study, the Japan Septic Disseminated Intravascular Coagulation (JSEPTIC DIC) study, was undertaken. The JSEPTIC DIC study enrolled 42 intensive care units and included 3,195 patients with sepsis. The results of the JSEPTIC DIC study indicated the following: (i) anticoagulant therapy may be effective in sepsis-induced DIC patients at high risk for death, (ii) recombinant human soluble thrombomodulin administration and antithrombin supplementation are associated with survival benefits in patients with sepsis-induced DIC.

Management of disseminated intravascular coagulation: current insights on antithrombin and thrombomodulin treatments

Sepsis and septic shock are frequently complicated by disseminated intravascular coagulation (DIC), which decreases the survival rate of patients with sepsis. In the past, large international randomized controlled trials (RCTs) using physiological anticoagulants for sepsis-induced DIC were not performed; however, RCTs have been conducted for sepsis and/or septic shock. In these trials, physiological anticoagulants did not show any beneficial effects compared with placebo for the treatment of sepsis and/or septic shock. In Japan, DIC treatments using antithrombin (AT) and/or recombinant human soluble thrombomodulin (rhTM) are common for patients with sepsis-induced DIC. Recently, large propensity score analyses demonstrated that AT and rhTM improved survival in patients with sepsis-induced DIC. Furthermore, post hoc analyses and meta-analyses that selected patients with sepsis-induced DIC from the previous large international RCTs indicated that physiological anticoagulants improved survival without increasing the associated sepsis-induced DIC bleeding. DIC treatments, such as AT and rhTM, may demonstrate beneficial effects when they are targeted at patients with sepsis-induced DIC only.

Classic thrombophilic gene variants

Thrombophilia is defined as a condition predisposing to the development of venous thromboembolism (VTE) on the basis of a hypercoagu-lable state. Over the past decades, great advances in the pathogenesis of VTE have been made and nowadays it is well established that a thrombophilic state may be associated with acquired and/or inherited factors. The rare loss-of-function mutations of the genes encoding natural anticoagulant proteins (i. e. protein C, protein S and antithrombin) and the more common gain-of-function polymorphisms factor V Leiden and prothrombin G20210A are the main genetic determinants of thrombophilia. In addition, non-O blood group has been consistently demonstrated to be the most frequent inherited marker of an increased risk of VTE. The mechanism role of these inherited thrombophilia markers will be discussed in this narrative review.

How I treat heterozygous hereditary antithrombin deficiency in pregnancy

Untreated hereditary antithrombin deficiency in pregnancy is associated with maternal venous thromboembolism (VTE) and possibly with fetal loss. Thromboprophylaxis during pregnancy is recommended, but dosages remain controversial. Our objective was to perform a retrospective assessment of thrombotic events and pregnancy outcomes in women with hereditary antithrombin deficiency managed according to a standard protocol. Pregnancies in individuals with hereditary antithrombin deficiency were identified from a hospital database. Women with no prior VTE received enoxaparin 40 mg daily until 16 weeks gestation and thereafter 40 mg twice daily. Women with prior VTE received intermediate dose enoxaparin (1 mg/kg) once daily, increased to twice daily at 16 weeks and anti-Xa monitored dosing. Thromboprophylaxis was stopped at initiation of labour or 12 hours prior to caesarean and 50 IU/kg antithrombin concentrate given. Thromboprophylaxis was restarted after delivery. Eighteen pregnancies in 11 women with antithrombin deficiency were identified. Seventeen pregnancies (94%) were successful. Median gestation was 39 weeks (range 30–41) and median birth-weight was 2,995 g (910–4,120 g),but 6/17 infants (35%) were small for gestational age (p=0.01). Estimated blood loss at delivery was median 375 ml (200–600 ml). Four pregnancies were complicated by VTE; one newly presented with a thrombotic event, two patients were not taking thromboprophylaxis and one occurred despite thromboprophylaxis. Two novel mutations(p.Leu317Ser and p.His33GInfsX32) are described. In conclusion, in antithrombin deficiency the use of low-molecular-weight heparin in pregnancy and puerperium with antithrombin concentrate predelivery was associated with successful pregnancy outcome; rates of VTE appear to be lower than previously reported, but remain elevated

SerpinC1/Antithrombin III in kidney-related diseases

The gene SerpinC1 encodes a serine protease inhibitor named antithrombin III (ATIII). This protease demonstrates both anticoagulant and anti-inflammatory action. ATIII is the most important coagulation factor inhibitor, and even minor changes in ATIII can significantly alter the risk of thromboembolism. ATIII can also suppress inflammation via a coagulation-dependent or -independent effect. Moreover, apart from ATIII deficiency, ATIII and its gene SerpinC1 may also be related to many diseases (e.g. hypertension, kidney diseases). The present review summarizes how ATIII affects the progress of kidney disease and its mechanism. Further studies are required to investigate how ATIII affects renal function and the treatment.

Women with homozygous AT deficiency type II heparin-binding site (HBS) are at high risk of pregnancy loss and pregnancy complications

Data regarding outcome and therapy of pregnancies in patients with homozygous antithrombin (AT) deficiency are very rare. We conducted a retrospective, descriptive investigation with emphasis on the obstetric history of eight women with homozygous AT deficiency heparin-binding site (HBS), who had at least one pregnancy. The aim of the study was to get a better insight into the outcome and identify suitable management procedures of pregnancy in this rare disease. All patients suffered from homozygous AT deficiency caused by the mutation c.391C>T p.Leu131Phe in the AT gene (SERPINC1). The women reported in total 23 pregnancies; one pregnancy was excluded because of induced abortion. We found that only seven out of the 22 analyzed pregnancies ended with a live infant, all of them were born preterm. Among the 15 negative outcomes, seven were early pregnancy losses and eight were intrauterine fetal deaths. We found no clear association between treatment protocols and outcome. Eight pregnancies were not treated at all; all of them ended with pregnancy loss. We conclude that homozygous AT deficiency HBS, a form of severe thrombophilia, is associated with high risk of pregnancy loss and preterm delivery. Rigorous anticoagulation and/or replacement of AT during pregnancy may improve the outcome.

Importance of post-translational modifications on the function of key haemostatic proteins

Post-translational modifications (PTMs) such as glycosylation and phosphorylation play an important role on the function of haemostatic proteins and are critical in the setting of disease. Such secondary level changes to haemostatic proteins have wide ranging effects on their ability to interact with other proteins. This review aimed to summarize the knowledge of the common PTMs associated with haemostatic proteins and the implications of such modifications on protein function. Haemostatic proteins that represent the main focus for studies specific to PTMs are von Willebrand factor, tissue factor, factor VIII, antithrombin and fibrinogen. These proteins are susceptible to PTMs by glycosylation, phosphorylation, sulphation, citrullination and nitration, respectively, with a significant impact on their function. During synthesis, vWF must undergo extensive PTMs, with N-linked glycosylation being the most common. Increased phosphorylation of tissue factor results in increased affinity for platelets to the vessel endothelium. Citrullination of antithrombin leads to an increased anticoagulant function of this protein and therefore an anticoagulant state that inhibits clot formation. On the contrary, nitration of fibrinogen has been shown to result in a prothrombotic state, whilst sulphation is required for the normal function of Factor VIII. From this review, it is evident that PTMs of haemostatic proteins as a change in protein structure at a secondary level greatly influences the behaviour of the protein at a tertiary level.

Pigment epithelium-derived factor (PEDF): a novel trophoblast-derived factor limiting feto-placental angiogenesis in late pregnancy

The rapidly expanding feto-placental vasculature needs tight control by paracrine and endocrine mechanisms. Here, we focused on paracrine influence by trophoblast, the placental epithelium. We aimed to identify differences in regulation of feto-placental angiogenesis in early versus late pregnancy. To this end, the effect of conditioned media (CM) from early and late pregnancy human trophoblast was tested on network formation, migration and proliferation of human feto-placental endothelial cells. Only CM of late pregnancy trophoblast reduced network formation and migration. Screening of trophoblast transcriptome for anti-angiogenic candidates identified pigment epithelium-derived factor (PEDF) with higher expression and protein secretion in late pregnancy trophoblast. Addition of a PEDF-neutralizing antibody restored the anti-angiogenic effect of CM from late pregnancy trophoblast. Notably, human recombinant PEDF reduced network formation only in combination with VEGF. Also in the CAM assay, the combination of PEDF with VEGF reduced branching of vessels below control levels. Analysis of phosphorylation of ERK1/2 and FAK, two key players in VEGF-induced proliferation and migration, revealed that PEDF altered VEGF signaling, while PEDF alone did not affect phosphorylation of ERK1/2 and FAK. These data suggest that the trophoblast-derived anti-angiogenic molecule PEDF is involved in restricting growth and expansion of the feto-placental endothelium predominantly in late pregnancy and targets to modulate the intracellular effect of VEGF.

Antithrombin for the prevention of intraventricular hemorrhage in very preterm infants

BACKGROUND

Preterm birth remains the major risk factor for the development of intraventricular hemorrhage, an injury that occurs in 25% of very low birth weight infants. Intraventricular hemorrhage is thought to be venous in origin and intrinsic thromboses in the germinal matrix are likely to play a triggering role. Antithrombin, a glycoprotein synthesized in the liver, is the major plasma inhibitor of thrombin thus modulating blood coagulation. Very low birth weight newborn infants have low levels of antithrombin and the risk of developing intraventricular hemorrhage is increased by the presence of hypercoagulability in the first hours of life. The administration of anticoagulants such as antithrombin may offset the increased risk of developing intraventricular hemorrhage. Anticoagulants may also reduce the risk of developing parenchymal venous infarct, a condition known to complicate intraventricular hemorrhage.

OBJECTIVES

To assess whether the prophylactic administration of antithrombin (started within the first 24 hours after birth) reduces the incidence of germinal matrix-intraventricular hemorrhage in very preterm neonates when compared to placebo, no treatment, or heparin.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library 2015), MEDLINE (1996 to 22 November 2015), EMBASE (1980 to 22 November 2015), and CINAHL (1982 to 22 November 2015). No language restrictions were applied. We searched the abstracts of the major congresses in the field (Perinatal Society of Australia and New Zealand and Pediatric Academic Societies) from 2000 to 2015.

SELECTION CRITERIA

Randomised controlled trials, quasi-randomised controlled trials and cluster trials comparing the administration of early, i.e. within the first 24 hours of life, antithrombin in very preterm infants (gestational age < 32 weeks, any birth weight).

DATA COLLECTION AND ANALYSIS

For each of the included trials, two authors independently extracted data (e.g. number of participants, birth weight, gestational age, antithrombin formulation (plasma-derived or recombinant), mode of administration, and duration of therapy, etc.) and assessed the risk of bias (e.g. adequacy of randomization, blinding, completeness of follow-up). The primary outcomes considered in this review are intraventricular hemorrhage and severe intraventricular hemorrhage.

MAIN RESULTS

Two randomized controlled trials, for a total of 182 infants, met the inclusion criteria of this review. Both trials compared antithrombin with placebo. We found no significant differences in the rates of intraventricular hemorrhage (typical RR 1.30, CI 95% 0.87 to 1.93, typical RD 0.09, 95% CI -0.05 to 0.23; 2 studies, 175 infants; I² = 18% for RR and I² = 42% for RD) and severe intraventricular hemorrhage (typical RR 1.04, CI 95% 0.55 to 1.94; typical RD 0.01, 95% CI -0.11 to 0.12; 2 studies, 175 infants; I² = 0% for RR and I² = 0% for RD). Among secondary outcomes, we found no significant differences in terms of neonatal mortality (typical RR 2.00, CI 95% 0.62 to 6.45; typical RD 0.04, 95% CI -0.03 to 0.12; 2 studies, 182 infants; I² = 46% for RR and I² = 61% for RD) and in the other specified outcomes, such as bronchopulmonary dysplasia. The quality of the evidence supporting these findings is limited due to the imprecision of the estimates.

AUTHORS' CONCLUSIONS

The administration of antithrombin seems not to reduce the incidence and severity of intraventricular hemorrhage in very preterm infants. Limited evidence is available on other clinically relevant outcomes. Given the imprecision of the estimate, the results of this systematic review are consistent with either a benefit or a detrimental effect of antithrombin and do not provide a definitive answer to the review question.

[Experience in treating portal thromboses in patients with chronic myeloproliferative diseases]

Patients with myeloproliferative diseases (MPD) are noted to be at high risk for portal thromboses. This problem gives rise to disability if it is untimely treated or resistant to therapy. The paper gives the experience of the Outpatient Department of the Hematology Research Center, Ministry of Health of the Russian Federation, in using antithrombin III in MPD patients (3 patients with primary myelofibrosis, 3 with essential thrombocythemia) and acute and subacute portal vein thromboses resistant to therapy with direct anticoagulants. In all 5 cases, the use of antithrombin III in combination with low-molecular-weight heparin showed a positive clinical effect as rapid relief of pain syndrome and comparatively early (3-week to 1.5-2-month) recanalization of thrombosed vessels. Three clinical cases are described in detail.

Antithrombin: anti-inflammatory properties and clinical applications

Many humoral and cellular components participate in bidirectional communication between the coagulation and inflammation pathways. Natural anticoagulant proteins, including antithrombin (AT), tissue factor pathway inhibitor, and protein C, suppress proinflammatory mediators. Conversely, inflammation blunts anticoagulant activity and, when uncontrolled, promotes systemic inflammation-induced coagulation, such as those that occur in disseminated intravascular coagulation and severe sepsis. This review discusses the mechanisms of action and clinical use of AT concentrate in critically ill patients and in the settings of perioperative anticoagulation management for surgery and obstetrics. AT is a serine protease inhibitor with broad anticoagulant activity and potent anti-inflammatory properties. In clinical conditions associated with hereditary or acquired AT deficiency, administration of AT concentrate has been shown to restore proper haemostasis and attenuate inflammation. Of note, AT modulates inflammatory responses not only by inhibiting thrombin and other clotting factors that induce cytokine activity and leukocyte-endothelial cell interaction, but also by coagulation-independent effects, including direct interaction with cellular mediators of inflammation. An increasing body of evidence suggests that AT concentrate may be a potential therapeutic agent in certain clinical settings associated with inflammation. In addition to the well-known anticoagulation properties of AT for the treatment of hereditary AT deficiency, AT also possesses noteworthy anti-inflammatory properties that could be valuable in treating acquired AT deficiency, which often result in thrombotic states associated with an inflammatory component.