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Venous air embolism, which may complicate medical and surgical procedures, activates complement and triggers thromboinflammation. In lepirudin-anticoagulated human whole blood, we examined the effect of air bubbles on complement and its role in thromboinflammation. Whole blood from 16 donors was incubated with air bubbles without or with inhibitors of C3, C5, C5aR1, or CD14. Complement activation, hemostasis, and cytokine release were measured using ELISA and quantitative PCR. Compared with no air, incubating blood with air bubbles increased, on average, C3a 6.5-fold, C3bc 6-fold, C3bBbP 3.7-fold, C5a 4.6-fold, terminal complement complex sC5b9 3.6-fold, prothrombin fragments 1+2 (PTF1+2) 25-fold, tissue factor mRNA (TF-mRNA) 26-fold, microparticle tissue factor 6.1-fold, β-thromboglobulin 26-fold (all p < 0.05), and 25 cytokines 11-fold (range, 1.5-78-fold; all p < 0.0001). C3 inhibition attenuated complement and reduced PTF1+2 2-fold, TF-mRNA 5.4-fold, microparticle tissue factor 2-fold, and the 25 cytokines 2.7-fold (range, 1.4-4.9-fold; all p < 0.05). C5 inhibition reduced PTF1+2 2-fold and TF-mRNA 12-fold (all p < 0.05). C5 or CD14 inhibition alone reduced three cytokines, including IL-1β ( p = 0.02 and p = 0.03). Combined C3 and CD14 inhibition reduced all cytokines 3.9-fold (range, 1.3-9.5-fold; p < 0.003) and was most pronounced for IL-1β (3.2- versus 6.4-fold), IL-6 (2.5- versus 9.3-fold), IL-8 (4.9- versus 8.6-fold), and IFN-γ (5- versus 9.5-fold). Antifoam activated complement and was avoided. PTF1+2 was generated in whole blood but not in plasma. In summary, air bubbles activated complement and triggered a C3-driven thromboinflammation. C3 inhibition reduced all mediators, whereas C5 inhibition reduced only TF-mRNA. Combined C5 and CD14 inhibition reduced IL-1β release. These data have implications for future mechanistic studies and possible pharmacological interventions in patients with air embolism., (Copyright © 2021 by The Authors.)

Beyond hemostasis, platelets actively participate in immune cell recruitment and host defense, yet their potential in the resolution of inflammatory processes remains unknown. Here, we demonstrate that platelets are recruited into the lung together with neutrophils during the onset of inflammation and alongside regulatory T (T reg) cells during the resolution phase. This partnering dichotomy is regulated by differential adhesion molecule expression during resolution. Mechanistically, intravascular platelets form aggregates with T reg cells, a prerequisite for their recruitment into the lung. This interaction relies on platelet activation by sCD40L and platelet P-selectin binding to PSGL-1 on T reg cells. Physical platelet-T reg cell interactions are necessary to modulate the transcriptome and instruct T reg cells to release the anti-inflammatory mediators IL-10 and TGFβ. Notably, the presence of platelet-T reg cell aggregates in the lung was also required for macrophage transcriptional reprogramming, polarization toward an anti-inflammatory phenotype, and effective resolution of pulmonary inflammation. Thus, platelets partner with successive immune cell subsets to orchestrate both the initiation and resolution of inflammation., Competing Interests: Disclosures: J. Dalli reported "other" from Resolomics Limited outside the submitted work. A. Zarbock reported grants from Deutsche Forschungsgemeinschaft during the conduct of the study. No other disclosures were reported., (© 2021 Rossaint et al.)

PTX3 is a soluble pattern recognition molecule (PRM) belonging to the humoral innate immune system, rapidly produced at inflammatory sites by phagocytes and stromal cells in response to infection or tissue injury. PTX3 interacts with microbial moieties and selected pathogens, with molecules of the complement and hemostatic systems, and with extracellular matrix (ECM) components. In wound sites, PTX3 interacts with fibrin and plasminogen and favors a timely removal of fibrin-rich ECM for an efficient tissue repair. Idiopathic Pulmonary Fibrosis (IPF) is a chronic and progressive interstitial lung disease of unknown origin, associated with excessive ECM deposition affecting tissue architecture, with irreversible loss of lung function and impact on the patient's life quality. Maccarinelli et al. recently demonstrated a protective role of PTX3 using the bleomycin (BLM)-induced experimental model of lung fibrosis, in line with the reported role of PTX3 in tissue repair. However, the mechanisms and therapeutic potential of PTX3 in IPF remained to be investigated. Herein, we provide new insights on the possible role of PTX3 in the development of IPF and BLM-induced lung fibrosis. In mice, PTX3-deficiency was associated with worsening of the disease and with impaired fibrin removal and subsequently increased collagen deposition. In IPF patients, microarray data indicated a down-regulation of PTX3 expression, thus suggesting a potential rational underlying the development of disease. Therefore, we provide new insights for considering PTX3 as a possible target molecule underlying therapeutic intervention in IPF., Competing Interests: AM and BB are inventors of patents on pentraxin-3 and obtain royalties on related reagents. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Doni, Mantovani, Bottazzi and Russo.)

Chronic graft-versus-host disease (cGvHD) is an immune mediated late complication of allogeneic hematopoietic stem cell transplantation (alloHSCT). Discovery of adequate biomarkers could identify high-risk patients and provide an effective pre-emptive intervention or early modification of therapeutic strategy, thus reducing prevalence and severity of the disease among long-term survivors of alloHSCT. Inflammation, endothelial injury, and endothelial dysfunction are involved in cGvHD development. Altered levels of acute phase reactants have shown a strong correlation with the activity of several immune mediated disorders and are routinely used in clinical practice. Since elevated von Willebrand factor (VWF) and factor VIII (FVIII) levels have been described as acute phase reactants that may indicate endothelial dysfunction and inflammation in different settings, including chronic autoimmune diseases, they could serve as potential candidate biomarkers of cGvHD. In this review we focused on reported data regarding VWF and FVIII as well as other markers of inflammation and endothelial dysfunction, evaluating their potential role in cGvHD., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Lelas, Greinix, Wolff, Eissner, Pavletic and Pulanic.)

Computational models of various facets of hemostasis and thrombosis have increased substantially in the last decade. These models have the potential to make predictions that can uncover new mechanisms within the complex dynamics of thrombus formation. However, these predictions are only as good as the data and assumptions they are built upon, and therefore model building requires intimate coupling with experiments. The objective of this article is to guide the reader through how a computational model is built and how it can inform and be refined by experiments. This is accomplished by answering six questions facing the model builder: (1) Why make a model? (2) What kind of model should be built? (3) How is the model built? (4) Is the model a "good" model? (5) Do we believe the model? (6) Is the model useful? These questions are answered in the context of a model of thrombus formation that has been successfully applied to understanding the interplay between blood flow, platelet deposition, and coagulation and in identifying potential modifiers of thrombin generation in hemophilia A., Competing Interests: K.B.N. reports grants from National Institutes of Health, during the conduct of the study. D.M.M. reports grants from Army Research Office, during the conduct of the study., (The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/).)

Hemostasis is a complex wound-healing process involving numerous mechanical and biochemical mechanisms and influenced by many factors including platelets, coagulation factors, and endothelial components. Slight alterations in these mechanisms can lead to either prothrombotic or bleeding consequences, and such hemostatic imbalances can lead to significant clinical consequences with resultant morbidity and mortality. An ideal hemostasis assay would not only address all the unique processes involved in clot formation and resolution but also take place under flow conditions to account for endothelial involvement. Global assays do exist; however, these assays are not flow based. Flow-based assays have been limited secondary to their large blood volume requirements and low throughput, limiting potential clinical applications. Microfluidic-based assays address the aforementioned limitations of both global and flow-based assays by utilizing standardized devices that require low blood volumes, offer reproducible analysis, and have functionality under a range of shear stresses and flow conditions. While still largely confined to the preclinical space, here we aim to discuss these novel technologies and potential clinical implications, particularly in comparison to the current, commercially available point-of-care assays., Competing Interests: W.A.L. reports grants from NIH, during the conduct of the study, and nonfinancial support from Sanguina, Inc, outside the submitted work., (Thieme. All rights reserved.)

The cross-talk between the inflammatory complement system and hemostasis is becoming increasingly recognized. The interaction between complement C1q, initiation molecule of the classical pathway, and von Willebrand factor (vWF), initiator molecule of primary hemostasis, has been shown to induce platelet rolling and adhesion in vitro . As vWF disorders result in prolonged bleeding, a lack of C1q as binding partner for vWF might also lead to an impaired hemostasis. Therefore, this study aimed to investigate the in vivo relevance of C1q-dependent binding of vWF in hemostasis. For this purpose, we analyzed parameters of primary and secondary hemostasis and performed bleeding experiments in wild type (WT) and C1q-deficient ( C1qa -/- ) mice, with reconstitution experiments of C1q in the latter. Bleeding tendency was examined by quantification of bleeding time and blood loss. First, we found that complete blood counts and plasma vWF levels do not differ between C1qa -/- mice and WT mice. Moreover, platelet aggregation tests indicated that the platelets of both strains of mice are functional. Second, while the prothrombin time was comparable between both groups, the activated partial thromboplastin time was shorter in C1qa -/- mice. In contrast, tail bleeding times of C1qa -/- mice were prolonged accompanied by an increased blood loss. Upon reconstitution of C1qa -/- mice with C1q, parameters of increased bleeding could be reversed. In conclusion, our data indicate that C1q, a molecule of the first-line of immune defense, actively participates in primary hemostasis by promoting arrest of bleeding. This observation might be of relevance for the understanding of thromboembolic complications in inflammatory disorders, where excess of C1q deposition is observed., (Copyright © 2020 Donat, Kölm, Csorba, Tuncer, Tsakiris and Trendelenburg.)

The complement system, originally classified as part of innate immunity, is a tightly self-regulated system consisting of liquid phase, cell surface, and intracellular proteins. In the blood circulation, the complement system, platelets, coagulation system, and fibrinolysis system form a close and complex network. They activate and regulate each other and jointly mediate immune monitoring and tissue homeostasis. The dysregulation of each cascade system results in clinical manifestations and the progression of different diseases, such as sepsis, atypical hemolytic uremic syndrome, C3 glomerulonephritis, systemic lupus erythematosus, or ischemia-reperfusion injury. In this review, we summarize the crosstalk between the complement system, platelets, and coagulation, provide integrative insights into how complement dysfunction leads to hemopathic progression, and further discuss the therapeutic relevance of complement in hemolytic and thrombotic diseases., (Copyright © 2020 Luo, Hu, Wang, Zipfel and Hu.)

In recent years, accumulating evidence has indicated that platelets continuously repair vascular damage at sites of inflammation and/or infection. Studies in mouse models of inflammation have highlighted the fact that the mechanisms underlying bleeding prevention by platelets in inflamed organs can substantially differ from those supporting primary hemostasis following tail tip transection or thrombus formation in models of thrombosis. As a consequence, exploration of the hemostatic function of platelets in inflammation, as well as assessment of the risk of inflammation-induced bleeding associated with a platelet deficit and/or the use of anti-thrombotic drugs, require the use of dedicated experimental models. In the present review, we present the pros and cons of the cutaneous reversed passive Arthus reaction, a model of inflammation which has been instrumental in studying how inflammation causes vascular injury and how platelets continuously intervene to repair it. The limitations and common issues encountered when working with mouse models of inflammation for investigating platelet functions in inflammation are also discussed.

Traumatic-induced coagulopathy (TIC) is often associated with significant bleeding, transfusion requirements, inflammation, morbidity, and mortality. This review considers TIC as a systems failure, not as a single-event manifestation of trauma. After briefly reviewing the meaning of TIC and the bewildering array of fibrinolysis phenotypes, we will discuss the role of platelets and fibrinogen in coagulopathy. Next, we will review the different TIC hypotheses and drill down to a single mechanistic domain comprising (1) thrombin's differential binding to thrombomodulin, (2) the expression of annexin II-S100A10 complex, and (3) the functional integrity of the endothelial glycocalyx. This triad forms the basis of the "switch" hypothesis of TIC. We will next address the potential limitations of current practice in treating a coagulation or fibrinolytic defect, and the next defect, and so on down the line, which often leads to what U.S. surgeon William C. Shoemaker considered "an uncoordinated and sometimes contradictory therapeutic outcome." The treat-as-you-go approach using sequential, single-target treatments appears to be a by-product of decades of highly reductionist thinking and research. Lastly, we will present a unified systems hypothesis of TIC involving three pillars of physiology: the central nervous system (CNS)-cardiovascular system, the endothelial glycocalyx, and mitochondrial integrity. If CNS control of ventriculoarterial coupling is maintained close to unity following trauma, we hypothesize that the endothelium will be protected, mitochondrial energetics will be maintained, and TIC (and inflammation) will be minimized. The Systems Hypothesis of Trauma (SHOT) also helps to answer why certain groups of severely bleeding trauma patients are still dying despite receiving the best care. Currently, no drug therapy exists that targets the whole system., Competing Interests: Dr. Geoffrey Dobson is the sole inventor of the ALM concept for cardioplegia, surgery, infection, and trauma. All other authors have no conflicts to declare., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Monitoring of the hemostasis status is essential for therapeutic anticoagulants, undergoing surgery, cardiovascular diseases, etc. Although the clinical values of conventional blood coagulation tests have been well demonstrated, these devices have limitations such as large and expensive equipment, excessive sample volumes, long turnaround times, and difficulty in miniaturization for point-of-care use. Here, we present a novel strategy to evaluate blood hemostasis using the single-port Love-mode surface acoustic wave (SLSAW) sensor. The SLSAW sensor was designed as a plug-and-play-type unit for disposable use and operated under the harmonic resonant mode to produce frequency response to the blood coagulation cascade. Compared with a quartz crystal microbalance, Lamb wave, and film bulk acoustic resonator, the frequency shift of SLSAW was significantly increased, ranging from approximately 8960 to 10 368 kHz, which indicated enhancement of the signal-to-noise ratio. To demonstrate the feasibility of the SLSAW, studies were carried out to examine the effects of temperature and clotting reagents on coagulation times and kinetics. Activated partial thromboplastin times of plasma were validated by comparing with SYSMEX CA-7000 with the correlation ( R 2 ) as 0.996. In terms of coagulation kinetics, reaction time, clot formation time, maximum frequency shift, and clot formation rate of whole blood correlated well with corresponding parameters of the standard thromboelastography (TEG) analyzer ( R 2 = 0.9942, 0.9868, 0.9712, and 0.9939, respectively). The SLSAW sensor, with the advantages of low cost, small size, little sample consumption (1 μL), disposable use, and simple operation, is a promising tool for point-of-care diagnosis of hemostasis.

Dan-hong injection (DHI) is extracted from Salvia miltiorrhiza (SM) and Carthamus tinctorius (CT) and is widely used for the treatment of cardiovascular diseases. Our previous results showed DHI could improve hemorheology in rats. Since complex cellular interactions such as inflammation and oxidative stress are believed to be implicated in the pathogenesis of cardiovascular events, investigation of such pathological factors will contribute substantially to the understanding of the features and mechanisms of DHI. Therefore, in this study we used a rat model of blood stasis to explore the overall effects of DHI by detecting twenty three indexes, which were related to inflammation, immune response, vascular endothelial function, myocardial energy metabolism, oxidative stress, platelet aggregation, liver and renal function. Meanwhile, the interaction between SM and CT was discussed by comparing the effects of each single herb. DHI could significantly decrease the serum contents of IL-1β, TNF-α, IL-6, IL-8, IgM, IgG, IgA, MPO, hs-CRP, MDA, LDH, CK-MB, PAF, ALP and Cr, while elevate NO, SOD, TP and UA levels, indicating that DHI could inhibit inflammation and platelet aggregation, thereby relieving immune response and peroxidation, protecting vascular endothelial and organ function, and then prevent and treat cardiovascular diseases. In terms of compatibility, SM and CT showed complementary effects on markers of inflammatory and oxidative status, vascular endothelial damage and myocardial energy metabolism. On the other hand, they counteracted each other and SM reduced the side effects of creatinine caused by CT. This study contributes to comprehensively understand the pharmacodynamics effects and mechanism of DHI., (Copyright © 2019 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Despite the improved therapeutic advances in the management of acute promyelocytic leukemia (APL), a significant early mortality during induction, also referred to as early death (ED), remains an obstacle for further improvement in outcome. Hemorrhagic complications are the most common cause of morbidity and mortality. Perturbed hemostatic dysfunction is present as the result of abnormalities in both the coagulation and the fibrinolytic systems. The activation of coagulation is distinct from the classical disseminated intravascular coagulation. Multiple abnormalities in the fibrinolytic system have recently been identified. The most significant change is increased production of tissue plasminogen activator (tPA) and its receptor annexin A2 by the APL promyelocytes. Among the hemorrhagic complications, intracranial hemorrhage predominates. The pathogenesis of this catastrophic event is elucidated by new evidence of adverse effect of tissue plasminogen activator (tPA) on the brain, including both the plasmin-dependent and plasmin-independent pathways. In order to address the hemorrhagic complications, a thorough understanding of the hemostatic dysfunction is essential. In this article, our current concept of the abnormal hemostasis in APL is reviewed. The failure to reduce the early death rate, despite the introduction of effective therapy, will also be discussed., Competing Interests: None., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Circulating cell-derived microparticles (MPs) exhibit procoagulant activity and have been investigated for a possible role in some human pathologies. However, their potential role in hemostasis has been neglected and often denied. This review brings to attention a specific body of direct clinical evidence supporting an important but distinctive role of MPs in hemostasis. Evidence for a role of MPs in hemostasis includes: (1) two congenital bleeding disorders attributed to impaired release of MPs; (2) two recent studies of trauma patients relating naturally elevated endogenous MPs at admission to reduced transfusion requirements and better outcomes; (3) a study of coronary surgery patients showing that elevated MP before surgery reduces transfusion requirements during surgery; and (4) a clinical study of patients with immune thrombocytopenia demonstrating that those with high circulating MP have reduced bleeding compared to patients with similar platelet counts but lower MP levels. Mechanisms involving potentiating the contact factor pathway are thought to play a key role and are probably synergistic with polyphosphate released from activated platelets at sites of endothelial injury. Hemostatic defect of patients with deficient MP-mediated coagulation resembles deficiency of FXI (hemophilia C), distinct from hemophilia A or B, so can be termed type C hemostasis. A better understanding of this proposed hemostatic pathway may lead to improved methods for controlling excessive bleeding in surgery, trauma, and other clinical settings., Competing Interests: Dr. Jy reports grants from RxMP Therapeutics, Inc., during the conduct of the study, as well as owning 5% equity of RxMP Therapeutics; grants from Wallace H Coulter Foundation, outside the submitted work. In addition, Dr. Jy has a patent, US patent #8,105,632, licensed to RxMP Therapeutics, and a second patent, US Patent #9,155,764, also licensed to RxMP Therapeutics. Dr. Ahn reports grants from RxMP Therapeutics, Inc, during the conduct of the study, as well as owning 10% equity of RxMP Therapeutics; grants from Wallace H. Coulter Foundation, outside the submitted work. In addition, Dr. Ahn has a patent, US Patent #8,105,632, licensed to RxMP Therapeutics, and a second patent, US Patent #9,155,764, also licensed to RxMP Therapeutics. Mr. Horstman reports having a patent, US Patent #8,105,632, licensed to RxMP Therapeutics, and a second patent, US Patent #9,155,764, also licensed to RxMP Therapeutics. Mr. McCauley has nothing to disclose., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

This study aimed to provide a preliminary evaluation of the analytical performance of the new Roche COBAS T 711: fully automated coagulation analyzer, which uses both liquid and lyophilized reagent cassettes. The analytical assessment included analysis of imprecision and linearity of prothrombin time (PT), activated partial thromboplastin time (APTT), and fibrinogen on COBAS T 711: analyzer. Test results of 120 routine plasma samples were also compared with those obtained using two other coagulation analyzers (Instrumentation Laboratory ACL TOP 700 and Stago STA-R MAX). The accuracy, imprecision, and comparability of manual and automatic lyophilized material resuspension were also evaluated using 200 routine plasma samples. Overall, automatic resuspension was found to be more precise than, and equally accurate as, manual reconstitution, with coefficient of variations (CV%) three- to sixfold lower compared with manual reconstitution. The analytical imprecision was found to be excellent, as attested by total CV% of 0.7% for PT, 1.7 to 1.8% for APTT, and 1.9 to 3.2% for fibrinogen. Linearity was excellent over a clinically significant range of PT, APTT, and fibrinogen values, displaying correlation coefficients comprised between 0.994 and 0.999. Methods comparison studies revealed that results of PT, APTT, and fibrinogen on COBAS T 711: are globally aligned with those obtained using identical plasma samples on IL ACL TOP 700 and Stago STA-R MAX, displaying correlation coefficients of 0.97 for PT, 0.81 and 0.88 for APTT, 0.90 and 0.94 for fibrinogen, respectively. In conclusion, the results of this preliminary evaluation demonstrate that PT, APTT, and fibrinogen on COBAS T 711: coagulation analyzer displays excellent performance for routine use in clinical laboratories., Competing Interests: None., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

The authors provide a narrative review of mainstream hemostasis analyzers. The review is presented in two parts. In the first part, the authors give voice to several internationally representative manufacturers of mainstream hemostasis analyzers. They ask these manufacturers to (1) answer a series of survey questions that may otherwise reflect common questions asked by users or potential users of their equipment, (2) provide a bullet list of their main focus areas, and (3) provide other information in regard to their instrumentation. The authors then offer their own personal perspective of the benefits of various aspects of such equipment, as well as a sampling of some hemostasis tests as currently available, or potentially in progress. It is hoped that this snapshot of mainstream hemostasis diagnostics and coagulation testing drives positive future changes that will ultimately provide the best outcomes for laboratories performing hemostasis assays and the patients they help diagnose and manage., Competing Interests: The authors have no conflicts of interest to disclose. Manufacturers were consulted in regard to the proposed content of this review, and provided the major portion of the information in Part I of this review. Manufacturers did not otherwise direct or influence this review, in particular Part II, which authentically reflects the authors' personal viewpoints, based on their personal experience and knowledge of the literature. The opinions expressed here are those of the authors, and are not necessarily those of the University Hospital of Verona or of New South Wales Health Pathology., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

There is a clinical need for pragmatic approaches to measure integrated hemostatic reactions in whole blood rapidly, using small volumes of blood. The authors have applied T2 magnetic resonance (T2MR) to assess coagulation reactions based on partitioning of red blood cells and proteins that occurs during fibrin formation and platelet-mediated clot contraction. T2MR is amenable to measuring clotting times, individual coagulation factors, and platelet function. T2MR also revealed a novel "hypercoagulable" signature characterized by fibrin clots almost insusceptible to fibrinolysis that surround tessellated arrays of polyhedral erythrocytes ("third peak"). This signature, which develops under conditions associated with intense clot formation in vitro, may help identify patients at risk of developing thrombosis and for monitoring antithrombotic therapies in the future., Competing Interests: Disclosure The authors report no conflicts of interest in this work., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

The involvement of the hemostatic system in immune-mediated inflammation is widely reported. Many coagulation factors play a role in the pathogenesis of autoimmune diseases, such as systemic vasculitis and systemic lupus erythematosus. Hemostatic disorders are also involved in asthma and chronic spontaneous urticaria (CSU). Factor XIIa (FXIIa) was one of the first coagulation factors implicated in inducing both humoral and cellular responses and is therefore considered a prime new therapeutic target in immune-mediated inflammation. The involvement of coagulation factors, such as tissue factor and fibrinogen, in the pathogenesis of asthma has been reported. The finding of platelet activation in asthma also indicates a link between bronchial inflammation and hemostasis. The pathogenesis of mast cell degranulation and CSU was also shown to be associated with the activation of hemostatic factors such as fibrinogen and FXIIa. Increased plasma levels of D-dimer have been widely reported as a biological marker for the duration and severity of CSU. In addition, endothelial-induced cell activation by the kallikrein-high molecular weight complex and the release of heat shock protein 90 was shown to be involved in mast cell degranulation disorders. In this narrative review, the authors aim to summarize the role of hemostasis in inflammation, asthma, and CSU by focusing on the increasing information linking hemostatic factors and immune-mediated disorders., Competing Interests: Disclosure The authors report no conflicts of interest in this work., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Acute-phase reactants indicate inflammation and are increasingly used in veterinary medicine to indicate and to monitor progression of disease. Hemostasis and inflammation have interconnected pathophysiologic pathways and influence each other on different levels. This study established observed normal ranges for acute-phase reactants and for coagulation and thromboelastographic (TEG) parameters in 49 dromedary camels ( Camelus dromedarius) and assessed the response to chronic and acute inflammation. Chronically infected animals suffering from lymph abscessation due to Corynebacterium spp. had significantly higher concentrations of the acute-phase reactants haptoglobin ( P < 0.005) and fibrinogen ( P < 0.013) and an increased clot strength characterized by an increase of the TEG parameters MA ( P < 0.039), representing the maximum amplitude of the clot strengths, and G, the global clot strength ( P < 0.022), compared to healthy animals. When the acute-phase and hemostatic responses of 10 males receiving a gonadotropin-releasing hormone vaccine and of 9 males that were surgically castrated over 7 days were studied, haptoglobin proved to be a minor positive acute-phase protein, with moderate levels in healthy animals. It increased significantly after both vaccination and castration and remained elevated 7 days postinsult. The negative reactant iron significantly decreased over the 7-day period after castration, whereas a similar decrease following vaccination lasted less than 3 days. Fibrinogen reacted as a positive, minor reactant, with a significant increase and a peak on days 3-5, with higher values seen after castration. Prothrombin time showed a slight shortening at days 5-7, and the TEG parameters MA and G showed significantly increased values, similar to fibrinogen. The acute-phase protein serum amyloid A showed poor repeatability, suggesting that the assay was not reliable.

While platelets have long been known to be essential for maintaining hemostasis in the vasculature, their role in tissue repair, inflammation and innate and adaptive immunity is a more recent science. The ability of platelets to attach to the vessel wall, form aggregates and promote fibrin formation, key elements of blood clotting, has been said to both favor and dampen inflammation, to fight infection and to assure an adequate immune response. To fulfill their different roles platelets often synchronize with leukocytes and cells of the immune system. But just as the molecular pathways of platelets in preventing blood loss can lead to arterial thrombosis and stroke if occurring in an uncontrolled manner, the failure to control inflammation can lead to sepsis and inadequate platelet function and can aggravate many major illnesses. This review is aimed to present a global picture of multifaceted platelet biology and platelet involvement in selected non-hemostatic events.

Hypobaric hypoxia (HH) during airline travel induces several (patho-) physiological reactions in the human body. Whereas severe hypoxia is investigated thoroughly, very little is known about effects of moderate or short-term hypoxia, e.g. during airline flights. The aim of the present study was to analyse changes in serum protein expression and activation of signalling cascades in human volunteers staying for 30 min in a simulated altitude equivalent to airline travel. After approval of the local ethics committee, 10 participants were exposed to moderate hypoxia (simulation of 2400 m or 8000 ft for 30 min) in a hypobaric pressure chamber. Before and after hypobaric hypoxia, serum was drawn, centrifuged, and analysed by two-dimensional gel electrophoresis (2-DIGE) and matrix-assisted laser desorption/ionization followed by time-of-flight mass spectrometry (MALDI-TOF). Biological functions of regulated proteins were identified using functional network analysis (GeneMania ® , STRING ® , and Perseus ® software). In participants, oxygen saturation decreased from 98.1 ± 1.3% to 89.2 ± 1.8% during HH. Expression of 14 spots (i.e., 10 proteins: ALB, PGK1, APOE, GAPDH, C1QA, C1QB, CAT, CA1, F2, and CLU) was significantly altered. Bioinformatic analysis revealed an association of the altered proteins with the signalling cascades "regulation of haemostasis" (four proteins), "metabolism" (five proteins), and "leukocyte mediated immune response" (five proteins). Even though hypobaric hypoxia was short and moderate (comparable to an airliner flight), analysis of protein expression in human subjects revealed an association to immune response, protein metabolism, and haemostasis., Competing Interests: The authors declare no conflicts of interest.

Besides their undiscussed role in hemostasis and thrombosis, platelets are also key effector cells capable of assisting and modulating inflammatory reactions and immune responses. Platelets play a sentinel role in immune surveillance by recognizing danger signals from pathogens and cell damage through the expression of toll-like receptors (TLRs) on its surface and internal compartments. Platelets express all 10 TLRs transcripts and its signalosome, including adaptor proteins and transcription factors. The activation of these receptors in platelets triggers hemostatic and inflammatory responses which participate in the host's response to bacterial and viral infections, linking thrombosis with infection and immunity. Among the responses elicited by the activation of platelet TLRs are platelet adhesion and aggregation, formation of mixed platelet-leukocyte aggregates, expression and secretion of cytokines and quemokines, and thrombin generation. TLRs also are expressed in megakaryocytes, and their activation regulates not only platelet biogenesis, but also pro-inflammatory and antiviral responses. This review will focus on work that has shown the role of platelet TLRs, mainly in thromboinflammatory responses elicited by platelets and megakaryocytes.

Expanding evidence indicates multiple interactions between the hemostatic system and innate immunity, and the coagulation and complement cascades. Here we show in a tissue factor (TF)-dependent model of flow restriction-induced venous thrombosis that complement factors make distinct contributions to platelet activation and fibrin deposition. Complement factor 3 (C3) deficiency causes prolonged bleeding, reduced thrombus incidence, thrombus size, fibrin and platelet deposition in the ligated inferior vena cava, and diminished platelet activation in vitro. Initial fibrin deposition at the vessel wall over 6 hours in this model was dependent on protein disulfide isomerase (PDI) and TF expression by myeloid cells, but did not require neutrophil extracellular trap formation involving peptidyl arginine deiminase 4. In contrast to C3 -/- mice, C5-deficient mice had no apparent defect in platelet activation in vitro, and vessel wall platelet deposition and initial hemostasis in vivo. However, fibrin formation, the exposure of negatively charged phosphatidylserine (PS) on adherent leukocytes, and clot burden after 48 hours were significantly reduced in C5 -/- mice compared with wild-type controls. These results delineate that C3 plays specific roles in platelet activation independent of formation of the terminal complement complex and provide in vivo evidence for contributions of complement-dependent membrane perturbations to prothrombotic TF activation on myeloid cells., (© 2017 by The American Society of Hematology.)

Venous thrombosis (VT) is the third most common cause of cardiovascular death worldwide. Complications from VT and pulmonary embolism are the leading cause of lost disability-adjusted life years. Risks include genetic (e.g., non-O blood group, activated protein C resistance, hyperprothrombinemia) and acquired (e.g., age, surgery, cancer, pregnancy, immobilisation, female hormone use) factors. Pathophysiologic mechanisms that promote VT are incompletely understood, but involve abnormalities in blood coagulability, vessel function, and flow (so-called Virchow's Triad). Epidemiologic studies of humans, animal models, and biochemical and biophysical investigations have revealed contributions from extrinsic, intrinsic, and common pathways of coagulation, endothelial cells, leukocytes, red blood cells, platelets, cell-derived microvesicles, stasis-induced changes in vascular cells, and blood rheology. Knowledge of these mechanisms may yield new therapeutic targets. Characterisation of mechanisms that mediate VT formation and stability, particularly in aging, are needed to advance understanding of VT.

While hemostasis is the physiological process that prevents blood loss after vessel injury, thrombosis is often portrayed as a pathologic event involving blood coagulation and platelet aggregation eventually leading to vascular occlusion and tissue damage. However, recent work suggests that thrombosis can also be a physiological process, termed immunothrombosis, initiated by the innate immune system providing a first line of defense to locally control infection. Fibrin forms the structural basis of immunothrombotic clots and its assembly involves the concerted action of coagulation factors, platelets and leukocytes. Here, we summarize the cellular and molecular events that initiate fibrin formation during the innate immune response and discuss how aberrant activation of these pathways fosters pathologies associated with thrombosis, including disseminated intravascular coagulation and atherothrombosis., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Introduction: Discrepancies have been previously reported for one-stage clotting and chromogenic assays for FVIII activity analysis. Inter-laboratory variations in instruments, method of clot detection, assay set-up, reference standard calibration, reagent source and reagent composition all contribute to assay variability., Aim: To characterise multilaboratory assay variability in measuring ADYNOVATE, OBIZUR and ADVATE FVIII activity in human plasma and survey multinational FVIII activity assay preferences., Methods: As samples from patients treated with either of the FVIII products are not available in the quantities required for a systematic collaborative study, haemophilia A plasma was spiked in vitro with either ADYNOVATE (PEGylated rFVIII), OBIZUR [Porcine Sequence Antihaemophilic Factor (Recombinant)] or ADVATE at high (0.80 IU or U mL -1 ), medium (0.20 IU or U mL -1 ) and low (0.05 IU or U mL -1 ) FVIII concentrations, based on labelled potencies. Clinical laboratories used their routine FVIII activity assay to determine FVIII activity of each product. Thirty-five data sets using one-stage clotting assay and 11 sets using chromogenic assay were obtained., Results: A vast majority of laboratories (98%) prefer and rely on the one-stage clotting assay. Mean recoveries across all concentrations were 113%, 120% and 127% for ADYNOVATE, OBIZUR and ADVATE respectively. Assay variation was comparable between ADVATE, ADYNOVATE and OBIZUR with inter-laboratory percent coefficients of variation (%CV) ranging from 11 to 22%. Mean chromogenic assay results were 116%, 51% and 113% for ADYNOVATE, OBIZUR and ADVATE respectively. Inter-laboratory CV's were similar for ADYNOVATE, OBIZUR and ADVATE., Conclusions: One-stage clotting assays can and will be used with sufficient accuracy and precision for the measurement of ADYNOVATE, OBIZUR and ADVATE in plasma samples from subjects with haemophilia A. Chromogenic assay underestimates OBIZUR potency, particularly at lower concentrations., (© 2016 Baxalta Innovations GmbH. Haemophilia Published by John Wiley & Sons Ltd.)

As our knowledge of the structure and functions of fibrinogen and fibrin has increased tremendously, several key findings have given some people a superficial impression that the biological and clinical significance of these clotting proteins may be less than earlier thought. Most strikingly, studies of fibrinogen knockout mice demonstrated that many of these mice survive to weaning and beyond, suggesting that fibrin(ogen) may not be entirely necessary. Humans with afibrinogenemia also survive. Furthermore, in recent years, the major emphasis in the treatment of arterial thrombosis has been on inhibition of platelets, rather than fibrin. In contrast to the initially apparent conclusions from these results, it has become increasingly clear that fibrin is essential for hemostasis; is a key factor in thrombosis; and plays an important biological role in infection, inflammation, immunology, and wound healing. In addition, fibrinogen replacement therapy has become a preferred, major treatment for severe bleeding in trauma and surgery. Finally, fibrin is a unique biomaterial and is used as a sealant or glue, a matrix for cells, a scaffold for tissue engineering, and a carrier and/or a vector for targeted drug delivery., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Platelet-derived mediators, either in an autocrine or paracrine mode of action, regulate systemic and vascular inflammation as well as contribute to innate immune defense and also to regenerative mechanisms. This review reevaluates the impact of inflammatory mediators such as CXC-chemokine-Ligands, their receptors in modulating platelet functions and platelet survival, thereby influencing inflammatory or regenerative processes. We further explore the contribution of cyclophilin A and C-reactive protein in regulating thrombotic and hemostatic attributes of platelets. Moreover, we emphasize on the role of platelets as active components bridging the innate and adaptive immune responses, toll-like receptors on platelets, platelet interactions with the complement system, and platelet-derived thrombocidins exhibiting direct antimicrobial properties. As highlighted in this review, the multifaceted aspects of platelets and platelet-derived factors encourage further investigations in this intriguing and expansive but largely uncharted area of research in platelet biology., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Platelets are megakaryocyte-derived cellular fragments, which lack a nucleus and are the smallest circulating cells and are classically known to have a major role in supporting hemostasis. Apart from this well-established role, it is now becoming evident that platelets are also capable of conveying other important functions, such as during infection and inflammation. This paper will outline these nonhemostatic functions in two major sections termed "Platelets versus pathogens" and "Platelet-target cell communication". Platelets actively contribute to protection against invading pathogens and are capable of regulating immune functions in various target cells, all through sophisticated and efficient mechanisms. These relatively novel features will be highlighted, illustrating the multifunctional role of platelets in inflammation., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Unlabelled: ESSENTIALS: An IgA paraprotein with anti-thrombin activity was not associated with a severe bleeding phenotype. This observation challenges the paradigm that anticoagulant therapy necessarily increases bleeding risk. Characterization of the antibody showed that it specifically binds to thrombin exosite I. A therapeutic drug with the properties of this antibody might be an antithrombotic that doesn't cause bleeding., Background: We report the case of a 54-year-old female who presented with a traumatic subdural hemorrhage. Coagulation tests were markedly prolonged due to the presence of an anti-thrombin IgA paraprotein at 3 g L(-1) . The patient made a complete recovery and has had no abnormal bleeding during a 7-year follow-up, despite the persistence of the paraprotein., Objectives: To determine how the paraprotein prolonged clotting tests by defining its target and its epitope., Methods: The paraprotein was purified and added to normal pooled plasma for in vitro clotting assays. Binding studies were conducted to determine the affinity of the IgA for thrombin. The Fab was isolated and crystallized with thrombin., Results: The purified IgA was sufficient to confer the patient's in vitro coagulation profile in normal pooled plasma, and was found to bind specifically and with high affinity to thrombin. A crystal structure of the Fab fragment in complex with thrombin revealed an exosite I interaction involving CDRH3 of the antibody., Conclusions: Although the patient originally presented with a subdural bleed, the hematoma resolved without intervention, and no other bleeding event occurred during the subsequent 7 years. During this period, the patient's IgA paraprotein levels have remained constant at 3 g L(-1) , suggesting that the presence of a high-affinity, exosite I-directed antibody is consistent with normal hemostasis. A therapeutic derivative of this antibody might therefore permit antithrombotic dose escalation without an associated increase in the risk of bleeding., (© 2015 The Authors. Journal of Thrombosis and Haemostasis published by Wiley Periodicals, Inc. on behalf of International Society on Thrombosis and Haemostasis.)

As the development of a hypercoagulable state in the setting of disseminated intravascular coagulation (DIC) induces localized infection, therapy for DIC should be evaluated according to the findings of examinations for both severe sepsis and DIC. DIC is classified into the following types: "bleeding type," "organ failure type," "asymptomatic type," and "complication type." The "bleeding type" and "organ failure type" are considered to reflect the "plasmin inhibitor (PI) deficiency type" and "antithrombin (AT) deficiency type," respectively. In order to improve the diagnosis of DIC, in particular limitations in global coagulation tests, the Japanese Society of Thrombosis and Hemostasis recently proposed tentative diagnostic criteria for DIC using hemostatic molecular markers and AT. The recommendations for treatment of DIC, especially the use of AT concentrates, recombinant activated protein C and thrombomodulin, vary among several guidelines for the management of DIC. These agents inhibit the effects of key proteases in activating coagulation and consequently exert an anti-inflammatory effect on DIC. Hence, it is necessary to extensively evaluate these agents in well-conducted clinical trials.

Unlabelled: Tissue factor (TF) is expressed in the heart where it is required for haemostasis. High levels of TF are also expressed in atherosclerotic plaques and likely contribute to atherothrombosis after plaque rupture. Indeed, risk factors for atherothrombosis, such as diabetes, hypercholesterolaemia, smoking and hypertension, are associated with increased TF expression in circulating monocytes, microparticles and plasma. Several therapies that reduce atherothrombosis, such as statins, ACE inhibitors, beta-blockers and anti-platelet drugs, are associated with reduced TF expression. In addition to its haemostatic and pro-thrombotic functions, the TF : FVIIa complex and downstream coagulation proteases activate cells by cleavage of protease-activated receptors (PARs). In mice, deficiencies in either PAR-1 or PAR-2 reduce cardiac remodelling and heart failure after ischaemia-reperfusion injury. This suggests that inhibition of coagulation proteases and PARs may be protective in heart attack patients. In contrast, the TF/thrombin/PAR-1 pathway is beneficial in a mouse model of Coxsackievirus B3-induced viral myocarditis. We found that stimulation of PAR-1 increases the innate immune response by enhancing TLR3-dependent IFN-β expression. Therefore, inhibition of the TF/thrombin/PAR-1 pathway in patients with viral myocarditis could have detrimental effects., Conclusion: The TF : FVIIa complex has both protective and pathological roles in the heart.

The paper analyzes the results of a survey of 37 patients with acute ulcerative gastroduodenal hemorrhage. During endoscopy found that 7 patients the cause of bleeding was gastric ulcer, duodenal ulcer in 27 and 3 concomitant ulcer. Hemostasis was evaluated by J. Forrest and the severity of blood loss was assessed by the A.A. Shalimov: with blood loss was mild in 11 patients, the average degree--12 and with severe--14. In all patients on admission in the peripheral blood were studied state of cellular, humoral and cytokine profile: CD3+, CD4+, CD8+, CD4+/CD8 + and CD19+, FI, FF, CEC, IgA, M, G, TNF-α, IFN-γ, IL-1, IL-2, IL-4, IL-6, IL-8 and IL-10. In general patients with on admission revealed significant changes in the immune and cytokine status. In cellular immunity occurs immunosuppression. Disturbances in humoral immunity manifests itself in increased levels of lymphocytes in blood loss and hardships of all multi-directional changes in the concentration of immunoglobulins depending on the amount of blood loss. When there is an imbalance in cytokine status, the depth of which depends on the degree of blood loss.

Shortly after myocardial infarction, various circulating leukocyte subsets accumulate in the heart. Leukocyte recruitment is highly coordinated and relies on cell production in the bone marrow, mobilization to the blood, and chemokine-mediated infiltration to the destination tissue. Neutrophils, which are phagocytic and inflammatory, are among the first leukocytes to accumulate in large numbers. Within a day, neutrophils disappear and are replaced by a subset of monocytes that further contribute to inflammation and phagocytosis. After a few days, monocyte-derived reparative macrophages accrue, quell inflammation, and foster angiogenesis and tissue remodelling. Studies suggest a well-balanced response comprising these three waves is essential to optimal infarct healing.

The initiation of thrombus formation at sites of vascular injury to secure haemostasis after tissue trauma requires the interaction of surface-exposed von Willebrand factor (VWF) with its primary platelet receptor, the glycoprotein (GP) Ib-IX-V complex. As an insoluble component of the extracellular matrix (ECM) of endothelial cells, VWF can directly initiate platelet adhesion. Circulating plasma VWF en-hances matrix VWF activity by binding to structures that become exposed to flowing blood, notably collagen type I and III in deeper layers of the vessel along with microfibrillar collagen type VI in the subendothelium. Moreover, plasma VWF is required to support platelet-to-platelet adhesion - i. e. aggregation - which promotes thrombus growth and consolidation. For these reasons, understanding how plasma VWF interaction with platelet receptors is regulated, particularly any distinctive features of GPIb binding to soluble as opposed to immobilized VWF, is of paramount importance in vascular biology. This brief review will highlight knowledge acquired and key problems that remain to be solved to elucidate fully the role of VWF in normal haemostasis and pathological thrombosis.

Clinically relevant clotting abnormalities in cancer patients are referred to as Trousseau's syndrome. While thrombotic complications such as venous thromboembolism are most frequent in every day's practice, cancer patients may also experience severe bleeding symptoms due to complex systemic coagulopathies, including disseminated intravascular coagulation, haemolytic thrombotic microangiopathy, and hyperfibrinolysis. The pathophysiology of Trousseau's syndrome involves all aspects of Virchow's triad, but previous basic research has mainly focused on the cellular and molecular mechanisms underlying blood hypercoagulability in solid cancers and haematological malignancies. In this regard, over-expression of tissue factor (TF), the principal initiator of the extrinsic coagulation pathway, by primary tumour cells and increased shedding of TF-bearing plasma microparticles are critical to both thrombus formation and cancer progression. However, novel findings on intrinsic contact activation in vivo, such as the release of polyphosphates or DNA by activated platelets and neutrophils, respectively, have pointed to additional pathways in the complex pathophysiology of Trousseau's syndrome.

The paradigm that platelet aggregation, which contributes to bleeding arrest and also to thrombovascular disorders, initiates after signaling-induced platelet activation has been refuted in past recent years. Platelets can form aggregates independently of activation when soluble von Willebrand factor (VWF) is present and the shear rate exceeds a certain threshold where active A1 domains become exposed in soluble VWF multimers and can bind to platelet glycoprotein Ib. Subsequently - fostering each other - VWF can self-assemble into large nets combining with platelets into large conglomerates, which are entirely reversible when they enter a flow region with shear rates below the threshold. In addition the threshold changes from approximately 20 000 s⁻¹ in wall parallel flow to approximately 10 000 s⁻¹ in stagnation point flow. VWF containing ultra-large multimers - as when just released from endothelial storage sites - has been shown to have the highest binding potential to platelets and to each other, thus facilitating rapid platelet accrual to sites of vessel injury and exposed subendothelial structures, i.e. collagen. The VWF nets as well as the platelet-VWF conglomerates are controlled by the cleaving protease ADAMTS13 within minutes under high shear flow. Therewith the hemostatic potential is delivered where needed and the thrombogenic potential is highly controlled twofold: by flow and enzymatic proteolytic cleavage.

Patients with diabetes are at increased risk of cardiovascular morbidity and mortality. While arteriosclerotic lesions have long been recognized as the underlying cause more recent studies suggest that alterations of the blood are also critically involved. Following plaque rupture, adherence of platelets is followed by the formation of a cross-linked fibrin clot. Patients with diabetes exhibit a prothrombotic milieu consisting of hyper reactive platelets, a tight and rigid clot structure which is due to up-regulation of coagulation factors and prolongation of clot lysis. Metabolic alterations as well as inflammatory processes, which are up-regulated in diabetes, are thought to be the main underlying causes. More recently, the complement cascade has emerged as a potential new player in this context with several complement components directly influencing both platelet function and coagulation. This review provides an overview concerning the changes that lead to alterations of platelet function and clot structure in diabetes.

Improvements in the control of haemorrhage after trauma have resulted in the survival of many people who would otherwise have died from the initial loss of blood. However, the danger is not over once bleeding has been arrested and blood pressure restored. Two-thirds of patients who die following major trauma now do so as a result of causes other than exsanguination. Trauma evokes a systemic reaction that includes an acute, non-specific, immune response associated, paradoxically, with reduced resistance to infection. The result is damage to multiple organs caused by the initial cascade of inflammation aggravated by subsequent sepsis to which the body has become susceptible. This Series examines the biological mechanisms and clinical implications of the cascade of events caused by large-scale trauma that leads to multiorgan failure and death, despite the stemming of blood loss. Furthermore, the stark and robust epidemiological finding--namely, that age has a profound influence on the chances of surviving trauma irrespective of the nature and severity of the injury--will be explored. Advances in our understanding of the inflammatory response to trauma, the impact of ageing on this response, and how this information has led to new and emerging treatments aimed at combating immune dysregulation and reduced immunity after injury will also be discussed.

This review collects evidence about immune and inflammatory functions of platelets from a clinician's point of view. A focus on clinically relevant immune functions aims at stimulating further research, because the complexity of platelet immunity is incompletely understood and not yet translated into patient care. Platelets promote chronic inflammatory reactions (e.g. in atherosclerosis), modulate acute inflammatory disorders such as sepsis and other infections (participating in the host defense against pathogens), and contribute to exacerbations of autoimmune conditions (like asthma or arthritis). It would hence be obsolete to restrict a description of platelet functions to thrombosis and haemostasis--platelets clearly are the most abundant cells with immune functions in the circulation.

Platelets are small circulating anucleate cells that are of crucial importance in haemostasis. Over the last decade, it has become increasingly clear that platelets play an important role in inflammation and can influence both innate and adaptive immunity. Sepsis is a potentially lethal condition caused by detrimental host response to an invading pathogen. Dysbalanced immune response and activation of the coagulation system during sepsis are fundamental events leading to sepsis complications and organ failure. Platelets, being major effector cells in both haemostasis and inflammation, are involved in sepsis pathogenesis and contribute to sepsis complications. Platelets catalyse the development of hyperinflammation, disseminated intravascular coagulation and microthrombosis, and subsequently contribute to multiple organ failure. Inappropriate accumulation and activity of platelets are key events in the development of sepsis-related complications such as acute lung injury and acute kidney injury. Platelet activation readouts could serve as biomarkers for early sepsis recognition; inhibition of platelets in septic patients seems like an important target for immune-modulating therapy and appears promising based on animal models and retrospective human studies.

Background: The clinical phenotype of individuals with acquired factor V (A-FV) inhibitors varies from asymptomatic (non-B group) to life-threatening bleeding (B group), but the mechanism(s) underlying this variation in hemorrhagic phenotype are poorly understood., Objective: To investigate coagulation mechanistically in a range of patients with A-FV antibodies., Methods and Results: Ten cases of A-FV inhibitors in the non-B (n = 5) and B groups (n = 5) were studied. Thrombin generation assays in these plasmas revealed little thrombin generation, despite similar FV activity levels in both groups. However, prothrombin time-based clot waveform analysis revealed that the clot times were significantly prolonged and the maximum velocity and acceleration of coagulation were lower in the B group than in the non-B group, suggesting that this technique might be useful for predicting and monitoring hemorrhagic symptoms. A-FV inhibitors from the non-B group recognized predominantly the FV heavy chain, whereas those from the B group recognized the light chain. Purified anti-FV autoantibodies (autoAbs) from the B group inhibited FV binding to phospholipid by 60-90%, whereas there was little effect on this reaction in the non-B group. In addition, anti-FV autoAbs from the non-B group impaired the activated protein C (APC) cofactor activity of FV in FVIIIa inactivation mechanisms, and delayed APC-catalyzed cleavage of FVa at Arg306, but not at Arg506, indicating the presence of APC resistance in the non-B group., Conclusions: The results suggest that the different hemorrhagic phenotypes in A-FV inhibitors depend on the specific epitope of anti-FV autoAbs, and appear to be associated with an imbalance of procoagulant and anticoagulant function., (© 2014 International Society on Thrombosis and Haemostasis.)

Circumstantial evidence suggests that the innate immune system and coagulation system share a common evolutionary origin, which explains the extensive crosstalk between inflammatory cytokines and coagulation factors, with many components being important for both systems. This crosstalk has been extensively studied in sepsis, an acute state of high-grade inflammation. However, rheumatoid arthritis (RA) as well as many other autoimmune diseases can also be considered as a prothrombotic state. More and more studies show that autoimmune diseases, including RA, are a risk factor for cardiovascular disease, and also for venous thromboembolic events, such as pulmonary embolism and deep vein thrombosis. Inflammation and its effect on the haemostatic system is probably the link between these diseases. This viewpoint gives an update of the current literature on thromboembolic risk in RA, but also documents important knowledge gaps. This viewpoint will therefore help to focus on further research topics to improve diagnostic and therapeutic options which may relieve both the proinflammatory and the prothrombotic burden of autoimmune diseases.

The complement system is important part of our innate immune system and interacts directly with the hemostatic system. Disorders of complement activation or dysregulation resulting in excess complement generation, such as Paroxysmal Nocturnal Hemoglobinuria (PNH), atypical Hemolytic uremic Syndrome (aHUS) and antiphospholipid syndrome (APLS) have been associated with significant thrombophilia. Terminal Complement (C5b-9) deposition on endothelial and tumor cell membranes has also been reported in a variety of cancer. Recent developments in complement inhibition have given us new insights into the mechanism of thrombosis in these disorders., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Influenza viruses cause acute respiratory infections, which are highly contagious and occur as seasonal epidemic and sporadic pandemic outbreaks. Innate immune response is activated shortly after infection with influenza A viruses (IAV), affording effective protection of the host. However, this response should be tightly regulated, as insufficient inflammation may result in virus escape from immunosurveillance. In contrast, excessive inflammation may result in bystander lung tissue damage, loss of respiratory capacity, and deterioration of the clinical outcome of IAV infections. In this review, we give a comprehensive overview of the innate immune response to IAV infection and summarize the most important findings on how the host can inappropriately respond to influenza.

Background: We previously reported that a humanized anti-factor IXa/X bispecific antibody, hBS23, mimics the function of FVIII even in the presence of FVIII inhibitors, and has preventive hemostatic activity against bleeding in an animal model of acquired hemophilia A. After further molecular engineering of hBS23, we recently identified an improved humanized bispecific antibody, ACE910, for clinical investigation., Objectives: To elucidate the in vivo hemostatic potency of ACE910 by examining its effect against ongoing bleeds, and to determine its pharmacokinetic parameters for discussion of its potency for prophylactic use., Methods: A nonhuman primate model of acquired hemophilia A was established by injecting anti-primate FVIII neutralizing antibody. When bleeds emerged following an artificial bleed-inducing procedure, either ACE910 or recombinant porcine FVIII (rpoFVIII) was intravenously administered. rpoFVIII was additionally administered twice daily on the following 2 days. Bleeding symptoms were monitored for 3 days. A pharmacokinetic study and multiple-dosing simulations of ACE910 were also performed., Results: A single bolus of 1 or 3 mg kg⁻¹ ACE910 showed hemostatic activity comparable to that of 10 U kg⁻¹ (twice daily) rpoFVIII against ongoing bleeds. The determined ACE910 pharmacokinetic parameters included a long half-life (3 weeks) and high subcutaneous bioavailability (nearly 100%). The simulation results based on pharmacokinetic parameters indicated that the above hemostatic level could be maintained with once-weekly subcutaneous administration of ACE910, suggesting the possibility of more effective prophylaxis., Conclusions: ACE910 may offer an alternative on-demand treatment option for patients with hemophilia A, as well as user-friendly and aggressive routine supplementation.

Here, we developed a clinically translatable platelet gene therapy approach for hemophilia B. Platelet-targeted FIX (2bF9) expression was introduced by transplantation of hematopoietic stem cells (HSCs) transduced with 2bF9 lentivirus (LV). Sustained therapeutic levels of platelet-FIX expression were obtained in FIX(null) mice that received 2bF9 LV-transduced HSCs. Approximately 6-39% of the platelets expressed FIX in the transduced recipients, which was sufficient to rescue the bleeding diathesis in FIX(null) mice in tail clipping models. Sequential bone marrow transplantation demonstrated that platelet-FIX expression in the secondary recipients was sustained, leading to phenotypic correction. Notably, none of the transduced recipients developed anti-FIX antibodies after platelet gene therapy. Only one of the nine recipients developed a low titer of inhibitory antibodies (1.6 BU/ml) after challenge with rhFIX. These data suggest that platelet gene therapy can not only restore hemostasis but also induce immune tolerance in hemophilia B mice, indicating that this approach may be a promising strategy for gene therapy of hemophilia B in humans.