Inhibitor development in mild haemophilia after a major surgery for periampullary cancer (Whipple's procedure) in an elderly man

Around the world, with the availability of factor concentrates, patients with haemophilia have undergone major and minor surgeries. Inhibitor development in early postoperative period leading to inadequate factor recovery and ongoing bleeding is a nightmare for both operating surgeon as well as haematologists. We describe a case of an elderly man with mild haemophilia A, who was diagnosed with pancreatic carcinoma and underwent Whipple's procedure. After an uneventful procedure, he developed high-titre inhibitors and bleeding a week after surgery posing major challenges in his management. The case highlights the importance of experienced surgeons, trained haematologists, regular monitoring of factor assay/inhibitors, adequate factor and bypassing-agent support while performing such procedures.

Perspectives on the Optimal Genetically Engineered Pig in 2018 for Initial Clinical Trials of Kidney or Heart Xenotransplantation

For a clinical trial today, what might realistically be the optimal pig among those currently available? Deletion of expression of the 3 pig carbohydrate antigens, against which humans have natural (preformed) antibodies (triple-knockout pigs), should form the basis of any clinical trial. However, because both complement and coagulation can be activated in the absence of antibody, the expression of human complement- and coagulation-regulatory proteins is likely to be important in protecting the graft further. Any genetic manipulation that might reduce inflammation of the graft, for example, expression of hemeoxygenase-1 or A20, may also be beneficial to the long-term survival of the graft. The transgene for human CD47 is likely to have a suppressive effect on monocyte/macrophage and T-cell activity. Furthermore, deletion of xenoantigen expression and expression of a human complement-regulatory protein are both associated with a reduced T-cell response. Although there are several other genetic manipulations that may reduce the T-cell response further, it seems likely that exogenous immunosuppressive therapy, particularly if it includes costimulation blockade, will be sufficient. We would therefore suggest that, with our present knowledge and capabilities, the optimal pig might be a triple-knockout pig that expressed 1 or more human complement-regulatory proteins, 1 or more human coagulation-regulatory proteins, a human anti-inflammatory transgene, and CD47. Absent or minimal antibody binding is important, but we suggest that the additional insertion of protective human transgenes will be beneficial, and may be essential.

Identification of factor inhibitors by diagnostic haemostasis laboratories

We have assessed the proficiency of diagnostic haemostasis facilities to correctly identify coagulation factor abnormalities and inhibitors. Forty-two laboratories participating in the external Quality Assurance Program (QAP) conducted by the RCPA agreed to participate and were each sent a set of eight sample (each 3x1ml) for evaluation. They were asked to blind test these samples for the presence or absence of inhibitors, and wher identified, to perform further analysis (including specific inhibitor analysis). In order to make the exercise more challenging, in addition to true factor inhibitors, samples were provided that reflected potential pre-analytical variables that might arise and complicate inhibitor detection or lead to false inhibitor identification. In brief, the sample set comprised a true high level factor (F)V inhibitor, a true moderate level FVIII inhibitor (but sample was defibrinogenated),a true lupus anticoagulant (LA),a normal (but slightly aged) plasma sample, a normal serum sample, a normal EDTA sample, an oral anticoagulant/vitamin K deficiency sample, and a gross heparin (∼10U/ml) contaminated sample. Sixty-three percent of participants correctly identified the true FV inhibitor as such, although the reported range varied greatly [10 to >250 Bethesda units (BU/ml)] and 46% correctly identi fied the true FVIII inhibitor, despite the complication of the sample presentation, although the reported range also varied (7 to 64 BU/ml). Some laboratories either failed to identify the inhibitor present, or misidentified the inhibitor type. The LA, the oral anticoagulant/vitamin K deficiency, the normal serum sample, and the normal (aged) sample were also correctly identified by most laboratories, as was the absence of specific factor inhibitors in these samples. However, a small subset of laboratories incorrectly identified the presence of specific factor inhibitors in some of these samples. The heparin sample was also correctly identified by most (68%) laboratories. In contrast, the normal EDTA sample was misidentified as a FV and/or FVIII inhibitor by most (68%) laboratories, and only one laboratory correctly identified this as an EDTA sample. Thus, we conclude that although laboratories are able, in most cases, to identify the presence of true factor inhibitors, there is a large variation in identified inhibitor levels and there are also some significant errors in identification (i.e. false negatives and misidentifications). In addition, there is a significant false positive error rate where some laboratories will identify the presence of specific factor inhibitors where no such inhibitor exists (i.e. false positives).

Complement Interactions with Blood Cells, Endothelial Cells and Microvesicles in Thrombotic and Inflammatory Conditions

The complement system is activated in the vasculature during thrombotic and inflammatory conditions. Activation may be associated with chronic inflammation on the endothelial surface leading to complement deposition. Complement mutations allow uninhibited complement activation to occur on platelets, neutrophils, monocytes, and aggregates thereof, as well as on red blood cells and endothelial cells. Furthermore, complement activation on the cells leads to the shedding of cell derived-microvesicles that may express complement and tissue factor thus promoting inflammation and thrombosis. Complement deposition on red blood cells triggers hemolysis and the release of red blood cell-derived microvesicles that are prothrombotic. Microvesicles are small membrane vesicles ranging from 0.1 to 1 μm, shed by cells during activation, injury and/or apoptosis that express components of the parent cell. Microvesicles are released during inflammatory and vascular conditions. The repertoire of inflammatory markers on endothelial cell-derived microvesicles shed during inflammation is large and includes complement. These circulating microvesicles may reflect the ongoing inflammatory process but may also contribute to its propagation. This overview will describe complement activation on blood and endothelial cells and the release of microvesicles from these cells during hemolytic uremic syndrome, thrombotic thrombocytopenic purpura and vasculitis, clinical conditions associated with enhanced thrombosis and inflammation.

Serum anti-60S ribosomal protein L29 antibody as a novel prognostic marker for unresectable pancreatic cancer

BACKGROUND/AIMS

Recently, we found the presence of anti-60S ribosomal protein L29 antibody (anti-RPL29) in human sera, inhibiting the proliferation of pancreatic cancer cells in vitro. We aimed to estimate the association of serum anti- RPL29 levels with clinical features in patients affected with unresectable pancreatic cancer.

METHODS

We retrospectively reviewed 105 patients with unresectable pancreatic cancer. Serum anti-RPL29 levels were measured by the indirect enzyme-linked immunosorbent assay. The cut-off was represented by the 95th percentile in 62 healthy volunteers.

RESULTS

Median survival time (MST) was 11.1 months in 49 patients showing serum anti-RPL29 level >cut-off and 7.4 months in 56 patients showing serum anti-RPL29 level ≤ cutoff. In locally advanced disease, MST was 17.9 months in 22 patients showing serum anti-RPL29 level >cut-off and 10.0 months in 19 patients showing serum anti-RPL29 level ≤ cutoff. In metastatic disease, MST was 8.7 months in 27 patients showing serum anti-RPL29 level >cut-off and 5.9 months in 37 patients showing serum anti-RPL29 level ≤ cut-off. In the multivariate Cox proportional hazard model, serum anti- RPL29 level >cut-off, abdominal or back pain, performance status, and metastatic disease were identified as independent prognostic factors.

CONCLUSION

Serum anti-RPL29 levels may be a novel candidate for a prognostic marker for unresectable pancreatic cancer.

The Lectin Pathway of Complement and Biocompatibility

In modern health technologies the use of biomaterials in the form of stents, haemodialysis tubes, artificial implants, bypass circuits etc. is rapidly expanding. The exposure of synthetic, foreign surfaces to the blood and tissue of the host, calls for strict biocompatibility in respect to contact activation, the coagulation system and the complement system. The complement system is an important part of the initial immune response and consists of fluid phase molecules in the blood stream. Three different activation pathways can initiate the complement system, the lectin, the classical and the alternative pathway, all converging in an amplification loop of the cascade system and downstream reactions. Thus, when exposed to foreign substances complement components will be activated and lead to a powerful inflammatory response. Biosurface induced complement activation is a recognised issue that has been broadly documented. However, the specific role of lectin pathway and the pattern recognition molecules initiating the pathway has only been transiently investigated. Here we review the current data on the field.

Hemostatic factors, innate immunity and malignancy

Genetics-based studies have established the critical importance of tumor cell-associated tissue factor, circulating and endothelial cell-associated regulators of thrombin function and multiple thrombin substrates in metastasis. There appear to be multiple pathways by which procoagulants influence tumor biology, but the capacity of hemostatic factors to regulate innate immune function is at least one emerging theme. Several reports have shown that the platelet/fibrin(ogen) axis supports metastasis by limiting natural killer cellmediated lysis of newly-localized micrometastases. Furthermore, there is increasingly compelling evidence that hemostatic and innate immune system interactions also support very early events in cancer development. Analyses of the role of fibrin(ogen) in inflammation-driven colon cancer established a major role for this provisional matrix protein in early tumor development. A seminal property of fibrin(ogen) driving tumor formation in this context is the capacity to support local leukocyte activation events through engagement of the leukocyte integrin α(M)β(2). More recent studies have also suggested that hemostatic factors can, in at least some settings, program the malignant phenotype in tumor cells. Platelet-derived TGF-β1 and other platelet products were reported to trigger a more invasive and prometastatic epithelial-mesenchymal-like transition in embolic tumor cells. These findings support the intriguing concept that tumor cell functional properties can continue to evolve, even beyond the primary tumor site, in response to tumor cell-hemostatic factor interactions in the bloodstream. Taken together, there is strong evidence that the hemostatic system plays a multifaceted role in cancer pathogenesis and that therapies targeting selected hemostatic factors may present a powerful means to impede tumor development and metastasis.

Role of regulatory T cells in tolerance to coagulation factors

The immune response to coagulation factors VIII or IX, in particular formation of inhibitory antibodies, complicates treatment of hemophilia. Therefore, a number of recent studies in animal models have explored novel approaches toward induction of immune tolerance in protein or gene replacement therapy. Strong evidence has emerged that regulatory T cells (Treg) are an important component of the mechanism by which tolerance is maintained and inhibitor formation, a T help dependent response, is prevented. Limited data in patients also support this concept. In particular, CD4+ CD25+ FoxP3+ Treg, whether naturally occurring or induced, have been invoked in suppression of antibody and of cytotoxic T lymphocyte responses to the therapeutic clotting factor. This review summarizes the data on this emerging concept of Treg-mediated regulation of the immune response in treatment of hemophilia, strategies and mechanisms of Treg induction and function, and the implications for development of immune tolerance protocols.

Harmful molecular mechanisms in sepsis

Sepsis and sepsis-associated multi-organ failure are major challenges for scientists and clinicians and are a tremendous burden for health-care systems. Despite extensive basic research and clinical studies, the pathophysiology of sepsis is still poorly understood. We are now beginning to understand that sepsis is a heterogeneous, dynamic syndrome caused by imbalances in the 'inflammatory network'. In this Review, we highlight recent insights into the molecular interactions that occur during sepsis and attempt to unravel the nature of the dysregulated immune response during sepsis.

The role of hemocytes in the immunity of the spider Acanthoscurria gomesiana

Invertebrates protect themselves against microbial infection through cellular and humoral immune defenses. Since the available information on the immune system of spiders is scarce, the main goal of the present study was to investigate the role of hemocytes and antimicrobial peptides (AMPs) in defense against microbes of spider Acanthoscurria gomesiana. We previously described the purification and characterization of two AMPs from the hemocytes of naïve spider A. gomesiana, gomesin and acanthoscurrin. Here we show that 57% of the hemocytes store both gomesin and acanthoscurrin, either in the same or in different granules. Progomesin labeling in hemocyte granules indicates that gomesin is addressed to those organelles as a propeptide. In vivo and in vitro experiments showed that lipopolysaccharide (LPS) and yeast caused the hemocytes to migrate. Once they have reached the infection site, hemocytes may secrete coagulation cascade components and AMPs to cell-free hemolymph. Furthermore, our results suggest that phagocytosis is not the major defense mechanism activated after microbial challenge. Therefore, the main reactions involved in the spider immune defense might be coagulation and AMP secretion.

Coagulation disorders and inhibitors of coagulation in children from Mansoura, Egypt

Disorders of coagulation in children often prove challenging to the medical care team. The aims of this study were to assess the spectrum and prevalence of coagulation disorders among children attending Mansoura University Children Hospital (MUCH), Mansoura, Egypt. A total of 105 pediatric patients were referred to MUCH. They were divided into two groups: congenital coagulation disorders (75 cases, age 45.36 +/- 48.59 months), and acquired coagulation disorders (30 cases, age 56.13 +/- 61.61 months). All patients were subjected to thorough history taking including the nature of bleeding, family, past history, mode of inheritance, and detailed physical findings. Hemostatic tests included: platelet count, bleeding time (BT), prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT). Specific tests in the congenital group include assay of coagulation factors according to each disorder, Von Willebrand factor assay, ristocetin aggregation test, APTT mixing study for detection of inhibitors in complicated hemophilia cases, F VIII C to VWAg ratio with cut off 0.7 for detection of carriers in some hemophilia A families. Congenital disorders constituted 71.4% of the studied cases vs. 28.6% for acquired disorders. Hemophilia A (42.85%), hemophilia B (14.28%) and liver diseases (14.28%) represented the majority of the studied cases. Mild and moderate cases of hemophilia A and B are more frequent than severe cases in both types. Male sex is more frequent than female in the congenital group (94.7 vs. 5.3%, P < 0.001). Direct correlation existed between factor level assay and severity of hemophilia (r = 0.73, P = 0.006). Three mothers and one sister were identified as carrier out of four families. Anti-clotting factors inhibitor was detected in 18.2% of patients with hemophilia A and in 9.1% with hemophilia B. In conclusion, our study found that hemophilias are the most prevalent congenital coagulation disorders among children. Attention must be given for detection of hemophilia carriers and inhibitors of clotting factors.

An overview of the history, clinical practice concerns, comparative studies and strategies to optimize therapy of bypassing agents

Despite significant advances in the treatment of haemophilia, including availability of recombinant coagulation factor replacement products and the use of prophylactic infusion regimens, the segment of haemophilic patients who develop inhibitory antibodies remain at higher risk for morbidity and mortality associated with recurrent or uncontrolled bleeding events. Bypassing agents represent the mainstay of treatment and prevention of bleeding. The most commonly used of the currently available therapeutic agents are a plasma-based therapy, factor eight inhibitor bypassing activity, vapour heated, and a recombinant therapy, NovoSeven (recombinant activated factor VIIa). A substantial body of literature exists to document efficacy and adverse event profiles for these two products. There is, however, a paucity of data arising from adequately powered prospective trials to determine optimal treatment and dosing in various clinical situations. Certain clinical circumstances, patient profiles, individual responses, or provider predilection may lead to preferential use of one of these products over the other; however, the continued presence of both agents in the therapeutic armamentarium remains critically important to this fragile population. The historical use, clinical practice concerns, published comparative studies and methods for optimization of these two bypassing agents are reviewed.

Some antiphospholipid antibodies recognize conformational epitopes shared by beta2-glycoprotein I and the homologous catalytic domains of several serine proteases

OBJECTIVE

To test the hypothesis that some antiphospholipid antibodies (aPL) in patients with the antiphospholipid syndrome (APS) recognize a conformational epitope shared by beta2-glycoprotein I (beta2GPI; the major autoantigen for the antiphospholipid antibodies) and the homologous catalytic domains of several serine proteases (such as thrombin, activated protein C [APC], and plasmin) involved in hemostasis.

METHODS

We generated 4 new IgG monoclonal aPL (2 screened against beta2GPI, 1 against thrombin, and 1 against protein C) from 2 APS patients. The monoclonal antibodies (mAb) were analyzed for binding to beta2GPI, thrombin, APC, and plasmin, as well as for anticardiolipin antibody (aCL) activity. To demonstrate a shared epitope between beta2GPI and a serine protease, 1 mAb was studied by cross-inhibition analysis.

RESULTS

Both of the IgG anti-beta2GPI mAb bound to thrombin, APC, and plasmin. On the other hand, the 1 anti-thrombin mAb and the 1 anti-protein C mAb also bound to beta2GPI. Moreover, the binding of 1 cross-reactive mAb to beta2GPI was inhibited by alpha-thrombin (which contains only the catalytic domain of thrombin). All 4 mAb displayed aCL activity.

CONCLUSION

Taken together with the findings that some aCL bind to several serine proteases that participate in hemostasis and share homologous catalytic domains, these data demonstrate that some aCL in APS patients recognize one or more conformational epitopes shared by beta2GPI and the catalytic domains of disease-relevant serine proteases.

Stability, sterility, coagulation, and immunologic studies of salmon coagulation proteins with potential use for mammalian wound healing and cell engineering

Fibrin sealants made by polymerization of fibrinogen activated by the protease thrombin have many applications in hemostasis and wound healing. In treatments of acute injury or surgical wounds, concentrated fibrin preparations mimic the initial matrix that normally prevents bleeding and acts as a scaffold for cells that initiate tissue repair. However risks of infectious disease, immunogenic reaction, and the high cost of purified human or other mammalian blood proteins limit widespread use of these materials. Purified coagulation proteins from Atlantic salmon represent a potentially safer, equally effective, and less costly alternative in part because of the low ambient temperature of these farmed animals and the absence of endogenous agents known to be infectious in mammalian hosts. This study reports rheologic measurements of lyophilized salmon fibrinogen and thrombin that demonstrate stability to prolonged storage and gamma irradiation sufficient to reduce viral loads by over five orders of magnitude. Coagulation and immunologic studies in rats and rabbits treated intraperitoneally with salmon fibrin show no deleterious effects on coagulation profiles and no cross reactivity with host fibrinogen or thrombin. The results support the potential of salmon fibrin as an alternative to mammalian proteins in clinical applications.

Molecular Basis for Invertebrate Innate Immune Recognition of (1→3)-β- D-Glucan as A Pathogen-Associated Molecular Pattern

Innate immunity responds to various pathogen-associated molecular patterns (PAMPs) to evaluate the biological nature of foreign materials by using limited numbers of receptors. Analyses of interactions between PAMPs and its receptors are essential to understand the molecular basis regarding how we discriminate self and non-self materials. Upon infection of horseshoe crabs, an arthropod species, rapid hemolymph coagulation is induced to engulf invading microorganisms by a cascade-type reaction. The reaction is very sensitive to lipopolysaccharide and (1-->3)-beta-D-glucans on Gram-negative bacteria and fungi, respectively, and hence is utilized as assay reagents that detect and quantitate these PAMPs with a name of "limulus test." In this mini-review, recognition of (1-->3)-beta-D-glucans by a unique serine protease zymogen factor G of horseshoe crab is described. Molecular dissection and detailed kinetic analyses have revealed that multivalent binding to polymers of a simple target structure is one of the principles that allows stable and specific recognition of PAMPs by pattern recognition receptors in innate immunity.

Coagulation Defects

The present understanding of the coagulation process emphasizes the final common pathway and the proteolytic systems that result in the degradation of formed clots and the prevention of unwanted clot formations, as well as a variety of defense systems that include tissue repair, autoimmune processes, arteriosclerosis, tumor growth, the spread of metastases, and defense systems against micro-organisms. This article discusses diagnosis and management of some of the most common bleeding disorders. The goals are to provide a simple guide on how best to manage patients afflicted with congenital or acquired clotting abnormalities during the perioperative period, present a brief overview of the methods of testing and monitoring the coagulation defects, and discuss the appropriate pharmacologic or blood component therapies for each disease.

Current opinion on inhibitor treatment options

Inhibitor development in patients with hemophilia complicates hemostatic management. Currently, high doses of factor concentrates are used to override low-titer, low-responding inhibitors during acute bleeding episodes. Bypassing agents, such as the activated prothrombin complex concentrate (aPCC), Factor Eight Inhibitor Bypassing Activity, Anti-Inhibitor Coagulant Complex, Vapor Heated (FEIBA; Baxter AG, Vienna, Austria), and activated recombinant factor VII (rFVIIa; NovoSeven, Novo Nordisk A/S, Bagsvaerd, Denmark), are commonly used to treat acute bleeding episodes in patients with high-titer, high-responding inhibitors, whereas long-term therapeutic options include inhibitor eradication using immune tolerance induction. Neither FEIBA nor rFVIIa can be monitored with a laboratory assay, making it difficult to establish optimal dosages. Comparative studies evaluating the efficacy of FEIBA and rFVIIa for bleed control have been sparse, prompting investigators to initiate crossover comparison studies to assess the efficacy and cost of aPCC and rFVIIa in the treatment of joint hemorrhages. Both the cost of therapy and the outcome of therapy will need to be considered in the development of future hemostatic agents for patients with inhibitors.

Coagulation and sepsis

Sepsis is a complex disease and coagulation derangements are part of this context. The inflammatory storm is ultimately responsible for coagulation derangements. It is characterized by exacerbated coagulation, impaired anticoagulation and decreased fibrin removal. These derangements are implicated in the generation of microcirculation thrombosis, with deposition of microclots and obstruction of circulation, impairing blood flow and contributing to tissue hypoperfusion and consequently, organ dysfunction. This review will address the main issues regarding coagulation disorders in the context of sepsis.

Acquired coagulation inhibitor-associated bleeding disorders: an update

Acquired blood coagulation inhibitors are circulating immunoglobulins that neutralize the activity of a specific coagulation protein or accelerate its clearance from the plasma, thus causing a bleeding tendency. In this review, we focus on the nonhemophilic inhibitors of coagulation, i.e. the autoantibodies occurring in individuals without a pre-existent coagulation defect, reporting the most recent advances in the pathophysiology, diagnosis and treatment of these rare acquired bleeding disorders.

A prospective study of the prevalence of heparin-induced antibodies and other associated thromboembolic risk factors in pediatric patients undergoing hemodialysis

Heparin, which is used at high doses in hemodialysis patients, may induce antibodies favoring thromboembolic complications. We prospectively investigated the prevalence of heparin-induced platelet-reactive antibodies in a cohort of 38 pediatric hemodialysis patients, by means of heparin/platelet factor 4 (H/PF4) ELISA and heparin-induced platelet activation assay (HIPA). We also assessed other acquired and congenital hypercoagulable states. Heparin-induced antibodies were detected in 13 and 21% of patients with HIPA and ELISA, respectively. Anti-H/PF4 antibodies were negatively correlated with the number of hemodialysis sessions. These antibodies disappeared after a median time of 6 months despite continuing heparin treatment. The prevalence of antiphospholipid antibodies was 21% (anticardiolipin 10.5%, anti-beta2GPI 13%, and lupus anticoagulant 5%). Blood levels of homocysteine, factor VIII, and fibrinogen were significantly higher and factor II levels were significantly lower in hemodialysis patients than in controls, whereas factor VII, factor IX, and natural coagulation inhibitor levels were similar in patients and controls. Overall, 26 of 38 patients had at least one biomarker of hypercoagulability, but only 1 patient, without anti-H/PF4 antibodies, presented with thrombosis. In conclusion, heparin induces the transient production of anti-H/PF4 antibodies in children undergoing hemodialysis, but other abnormalities probably contribute to hypercoagulability. These findings may help to improve the diagnosis and management of thrombotic events in hemodialysis patients.

Two-way interactions between inflammation and coagulation

Activation of inflammatory and coagulation pathways is important in the pathogenesis of vascular disease. There is ample evidence that extensive cross-talk between these two systems exists, whereby inflammation not only leads to activation of coagulation, but coagulation also markedly affects inflammatory activity. The main interfaces linking coagulation and inflammation are the tissue factor pathway, thrombin, the protein C system and the fibrinolytic (or plasminogen-plasmin) system. Proinflammatory cytokines and chemokines can affect all these coagulation mechanisms, and vice versa, activated coagulation proteases and physiological anticoagulants or components of the plasminogen-plasmin system can modulate inflammation by specific cell receptors. The intricate relationship between inflammation and coagulation may not only be relevant for vascular thrombotic disease but also has major consequences in the pathogenesis of microvascular failure and subsequent multiple organ failure in the setting of severe infection. This review focuses on the present understanding of the bidirectional relationship between inflammation and coagulation.

Prevalence of hepatitis C virus infection and HCV genotypes among hemophiliacs in the State of Bahia, Northeastern Brazil: analysis of serological and virological parameters

The objective of the present study was to analyze HCV serological and virological parameters from hemophiliacs in the State of Bahia. Anti-HCV was investigated by ELISA in a cohort of 268 hemophiliacs A/B who were followed-up in a reference unit for hemotherapy in the State of Bahia. HCV viremia and genotypes were also determined from a subset of 66 anti-HCV seropositive hemophiliacs. Seroprevalence among hemophiliacs was 42.2% (95% CI 36.5-48.1) and was significantly higher (p<0.05) according to age > or =10 years, presence of factor VIII/IX inhibitory antibodies and other infection markers. None of the hemophiliacs less than 5 years of age were anti-HCV seropositive. Viremia was detectable in 77.3% (51/66). HCV genotype 1 (74%) was the most prevalent followed by genotype 3 (22%) and genotype 2 (4%). Our results indicate that HCV prevalence is still high among hemophiliacs, although HCV transmission was not observed in young hemophiliacs.

Autoantibodies against the endothelial receptor of protein C are associated with acute myocardial infarction in young women

BACKGROUND

Acute myocardial infarction (AMI) is rare among young women. The search for unknown risk factors is warranted. Endothelial protein C receptor (EPCR) is largely present at the endothelial surface of large arteries. No studies about association of anti-EPCR autoantibodies (anti-EPCR) with AMI are available.

METHODS

Plasma IgA, IgM and IgG anti-EPCR levels were measured by enzyme-linked immunosorbent assay in 165 women younger than 45 years who survived a first AMI and 165 healthy women, matched by age and geographical origin.

RESULTS

Using the 90th percentile of IgA anti-EPCR in the control group, IgA anti-EPCR were independently associated with AMI after adjustment for cardiovascular risk factors (OR 5.1; 95% CI 1.7-15.6; P = 0.004). The risk apparently conferred by IgA anti-EPCR increased dose-dependently (P for trend =0.0002). IgM anti-EPCR were less consistently associated with AMI: a significant increase in the risk was found when women above the 90th percentile were compared with those in the lowest quartile (OR 3.6; 95% CI 1.2-11.5; P = 0.03). IgG anti-EPCR were similar in patients and controls. A total of 145 patients underwent coronary arteriography. IgA or IgM anti-EPCR were not different among patients with different degrees of atherosclerotic lesion (anova, P = 0.77 and 0.24, respectively).

CONCLUSIONS

High levels of IgA and, to a lesser extent, IgM anti-EPCR, are associated with AMI in young women.

Biomaterial-associated thrombosis: roles of coagulation factors, complement, platelets and leukocytes

Our failure to produce truly non-thrombogenic materials may reflect a failure to fully understand the mechanisms of biomaterial-associated thrombosis. The community has focused on minimizing coagulation or minimizing platelet adhesion and activation. We have infrequently considered the interactions between the two although we are generally familiar with these interactions. However, we have rarely considered in the context of biomaterial-associated thrombosis the other major players in blood: complement and leukocytes. Biomaterials are known agonists of complement and leukocyte activation, but this is frequently studied only in the context of inflammation. For us, thrombosis is a special case of inflammation. Here we summarize current perspectives on all four of these components in thrombosis and with biomaterials and cardiovascular devices. We also briefly highlight a few features of biomaterial-associated thrombosis that are not often considered in the biomaterials literature: The importance of tissue factor and the extrinsic coagulation system. Complement activation as a prelude to platelet activation and its role in thrombosis. The role of leukocytes in thrombin formation. The differing time scales of these contributions.

Factors affecting choice of hemostatic agent for the hemophilia patient with an inhibitor antibody

Achieving adequate hemostasis in patients with hemophilia and high-titer inhibitor antibodies remains a challenge despite the development of plasma-derived and recombinant therapies to bypass the inhibitory effect. A group of hemophilia treaters met to examine the factors that influence physician choices among the very costly and cumbersome available therapies. Specific knowledge deficits in need of prospective research were identified with respect to the rational treatment of inhibitor patients.

FEIBAR safety profile in multiple modes of clinical and home-therapy application

The development of neutralizing antibodies to factor VIII or IX therapeutic concentrates remains the most serious and challenging complication in the management of patients with haemophilia A and B. FEIBA, Anti-Inhibitor Coagulant Complex, is an activated prothrombin complex concentrate that has been used to treat patients with such complications for almost 30 years. The mechanism of action of FEIBA has been proposed to involve simultaneous FVIII/FIX inhibitor bypassing action in the common, intrinsic and extrinsic coagulation pathways. FEIBA is derived from human plasma that undergoes stringent viral screening followed by significant viral inactivation and removal. To date, there have been no confirmed reports of transmission of hepatitis A, B or C, or of human immunodeficiency viruses associated with the use of the current, vapour-heat-treated FEIBA concentrate. The incidence of thrombotic adverse events recorded in the Baxter pharmacovigilance database for the 10-year postmarket period (1990-99) was approximately 4 : 100,000 infusions of FEIBA. Almost all documented thrombotic events with FEIBA occurred with doses that exceeded dosing recommendations, and known risk factors for cardiovascular disease were evident in more than 80% of the patients involved. Overall, clinical data have shown FEIBA to be safe and well-tolerated for use in a wide variety of clinical settings, including treatment of bleeding episodes, management of surgical procedures, home therapy, long-term prophylaxis, and prophylaxis during immune tolerance induction, when used according to dosing guidelines.

The Use of Antibodies to Coagulation Factors for Anticoagulant Therapy

Current treatments for preventing thrombotic diseases are associated with a significant risk of bleeding. Improved anticoagulant agents are therefore still required. The specificity and pharmacokinetics properties of monoclonal antibodies to coagulation factors allow novel anticoagulation approaches. Treatment with human antibodies or humanized mouse monoclonal antibodies should avoid unacceptable side effects due to immune response to the drug. Such antibodies were developed against three coagulation factor: Tissue factor (TF), Factor IX (FIX) and Factor VIII (FVIII). A fully humanized antibody was successfully derived from a mouse monoclonal antibodies to TF. In vivo studies with monoclonal antibodies to TF demonstrated efficient antithrombotic activity. Anti-TF antibodies may also prove useful in cardiovascular disorders and cancer, given the role of TF in these diseases. Mouse and human monoclonal antibodies to FIX were also efficient to prevent thrombosis in animal models of venous and arterial thrombosis and in stroke. A humanized anti-FIX antibody was tested in phase I study in healthy volunteers. The pharmacokinetics of the antibody were determined by the rapid formation of stable complexes with newly synthesised FIX. Human anti-FVIII antibodies inhibiting only partially FVIII activity were recently described. Investigations in mice have established that treatment with such anti-FVIII antibodies is efficient to prevent deep vein thrombosis. Given the low concentration of FVIII in plasma and the long half-life of antibody, treatment with anti-FVIII antibody could be very convenient, allowing one administration every month. Altogether, monoclonal antibodies to coagulation factor appear as promising novel antithrombotic drugs.

Activated protein C induces endothelial cell proliferation by mitogen-activated protein kinase activation in vitro and angiogenesis in vivo

Activated protein C (APC), a natural anticoagulant, has recently been demonstrated to activate the mitogen-activated protein kinase (MAPK) pathway in endothelial cells in vitro. Because the MAPK pathway is implicated in endothelial cell proliferation, it is possible that APC induces endothelial cell proliferation, thereby causing angiogenesis. We examined this possibility in the present study. APC activated the MAPK pathway, increased DNA synthesis, and induced proliferation in cultured human umbilical vein endothelial cells dependent on its serine protease activity. Antibody against the endothelial protein C receptor (EPCR) inhibited these events. Early activation of the MAPK pathway was inhibited by an antibody against protease-activated receptor-1, whereas neither late and complete activation of the MAPK pathway nor endothelial cell proliferation were inhibited by this antibody. APC activated endothelial nitric oxide synthase (eNOS) via phosphatidylinositol 3-kinase-dependent phosphorylation, followed by activation of protein kinase G, suggesting that APC bound to EPCR might activate the endothelial MAPK pathway by a mechanism similar to that of VEGF. APC induced morphogenetic changes resembling tube-like structures of endothelial cells, whereas DIP-APC did not. When applied topically to the mouse cornea, APC clearly induced angiogenesis in wild-type mice, but not in eNOS knockout mice. These in vitro events induced by APC might at least partly explain the angiogenic activity in vivo. This angiogenic activity of APC might contribute to maintain proper microcirculation in addition to its antithrombotic activity.

Hemophilic arthropathy

The most common clinical manifestation of hemophilia is arthropathy secondary to recurrent hemarthroses and chronic synovitis. Joint-surface erosions secondary to chronic synovitis often occur in early childhood and progress to advanced arthropathy by late adolescence. The knee, elbow, ankle, hip, and shoulder are the most commonly involved joints. Management of hemophilic arthropathy has advanced with the development of purified clotting factor concentrates and procedures to prevent chronic synovitis. Radiosynovectomy using beta particle-emitting radiocolloids has been effective in dramatically reducing the frequency of hemarthroses and resolving chronic synovitis. The most common surgical procedures used to manage hemophilic arthropathy are synovectomy, joint debridement, fusion, and joint arthroplasty. Late infection and arthrofibrosis complicate joint arthroplasty more often in these patients than in patients with other forms of arthritis. The high incidence of late infection may relate to frequent intravenous self-infusion of clotting factor combined with immune suppression. Despite the medical and surgical complexities of hemophilic arthropathy, orthopaedic procedures have a high incidence of patient satisfaction.

Advances in clotting factor treatment for congenital hemorrhagic disorders

During the last 50 years, clotting factor replacement has evolved from the use of frozen plasma in the 1950s, through the serendipitous discovery of cryoprecipitate in the 1960s and the development of purified clotting factors in the 1970s and 1980s, to the era of recombinant clotting factors beginning in the 1990s. The dawn of the new millennium has seen the refinement of recombinant factor (rF) VIII with enhanced safety via the elimination of plasma-derived culture media or product stabilizers. During the last decade of the 20th century, a cure for hemophilia through gene therapy became a possibility. This was, in part, facilitated by availability of large (dogs) and small (mice) animal models for hemophilia A and B. Although this review will focus primarily on clotting factor replacement, the reader may refer to recent discourse on gene therapy for hemophilia.

Common polymorphisms in the glyoxalase-1 gene and their association with pro-thrombotic factors

Advanced glycation endproducts (AGEs) form at an accelerated rate in diabetes and contribute to the development of macrovascular disease. Their precursors are detoxified by the glyoxalase system. Perturbations of the glyoxalase-1 gene may alter AGEs' interactions and affect pro-thrombotic factors. We screened the glyoxalase-1 gene for mutations and measured pro-thrombotic markers in 537 subjects from 89 healthy probands. Common single nucleotide polymorphisms (SNPs) were identified at positions -7 (C to T) and 20203 (C to A) from the translation start site. These SNPs were in Hardy-Weinberg equilibrium (CC=105, CA=266, AA=148; p>0.05; CC=126, CT=279, TT=114; p>0.05, respectively) and in linkage disequilibrium (D=27%, p<0.01), with mutant allele frequencies of 48% and 52% respectively. A significant association was found between SNPs at position 20203 and PAI-1 antigen concentrations and -7 and factor XIII A2B2 complex (p=0.001 and p=0.042). After Bonferroni correction a significant association remained between the SNP at 20203 and PAI-1 concentrations (p=0.005), and after adjustment for pedigree the association accounted for 1.3% of its heritability (p=0.04). No significant associations were found for SNP -7 T to C and factor VII activity, tPa concentrations, fibrinogen concentrations or factor XIII concentrations and SNP 20203 C to A and factor VII concentrations, PAI-1 concentrations, tPa concentrations or fibrinogen concentrations. Common variants in the glyoxalase-1 gene are associated with some pro-thrombotic factors, account for part of their heritability in healthy pedigrees and may alter susceptibility to macrovascular complications.

Coagulation, inflammation, and the risk of neonatal white matter damage

Indicators of coagulation activation are sometimes increased in the blood of newborns and adults who have a systemic inflammatory response. These coagulation factors have the ability to exacerbate inflammation, which in turn can promote coagulation. Therapies directed solely at coagulation factors and therapies directed solely at inflammation factors have not proved effective in reducing mortality in adults with a systemic inflammatory response syndrome and multi-organ dysfunction (SIRS/MOD). On the other hand, the only therapy that has reduced mortality in SIRS/MOD is activated protein C, which has both anti-coagulation and anti-inflammatory effects. This and other observations support the view that activated coagulation factors enhance inflammation. Since newborns at risk of cerebral white matter damage and cerebral palsy are more likely than their peers to have a systemic inflammatory response, which is sometimes accompanied by elevated blood levels of coagulation factors, we suggest that activated coagulation factors contribute to the occurrence of cerebral white matter damage by exacerbating inflammatory phenomena, rather than by occluding cerebral blood vessels.

Activated protein C inhibits bronchial hyperresponsiveness and Th2 cytokine expression in mice

Asthma is one of the most common diseases and is characterized by airway obstruction, airway inflammation, and increased airway responsiveness. Glucocorticoids are very effective in treatment, but their long-term use is associated with several side effects, so that new anti-inflammatory drugs are in development. Activated protein C (APC) is a serine protease with potent anti-inflammatory effects. This study evaluated the effect of inhaled APC on airway inflammation and hyperresponsiveness in a murine asthma model. Asthma was induced in BALB/c mice by exposure to chicken egg ovalbumin (OVA), and the effect of inhaled APC was assessed by administering prior to OVA exposure. Inhalation of APC significantly inhibited the expression of T helper 2 (Th2) cytokines, immunoglobulin E (IgE), eosinophilic inflammation, and hyperresponsiveness. APC also significantly suppressed the expression of Th2 cytokines and IgE from lymphocytes isolated from OVA-sensitized/challenged animals. In addition, binding of signal transducer and activator of transcription 6 (STAT6) and nuclear factor kappa B (NF-kappa B) oligonucleotides to lung nuclear proteins was significantly reduced in mice treated with inhaled APC. In brief, the exogenous supplementation of APC inhibits the immunologic and inflammatory responses induced by Th2 cytokines in a mouse model of asthma and may represent a novel anti-inflammatory treatment.

[Coagulopathy with autoantibodies to blood-clotting factors: overview and laboratory diagnosis]

The acquired inhibitors of blood clotting-factors are immunoglobulins that directly inhibit clotting factors or accelerate their clearance from circulation. The majority of inhibitors are directed against factor VIII, which arises spontaneously in healthy elderly, postpartum women, patients with autoimmune disorders or malignancy, and those with various underlying disorders. The most common initial symptom is bleeding into the skin or muscles spontaneously or caused by minor trauma, which sometimes extends to cause severe anemia. Those with acquired hemophilia may not receive a first consultation by a hematologist, resulting in delayed laboratory diagnosis. The activated partial thromboplastin time (APTT) of the hemophilia patient's plasma is prolonged, and is not corrected by mixing with normal plasma for 2 hours. The mixing test provides suggestive evidence of a factor VIII inhibitor, but can not distinguish lupus anticoagulant. Although the factor VIII activity of plasma is remarkably low, the activities of other intrinsic clotting factors can also be reduced apparently in the one-stage assay. A quantitative inhibitor measurement assay is required to confirm that the inhibitor acts specifically on factor VIII.