fibrin and Antiphospholipid-Syndrome

The pathogenesis of the antiphospholipid syndrome (APS) is complex and involves the persistent presence of antiphospholipid antibodies (aPL) in the bloodstream causing a prothrombotic condition. aPL induce excessive activation of the endothelium, monocytes, and platelets in consort with aberrations in hemostasis/clotting, fibrinolytic system, and complement activation. Impaired fibrinolysis has been found in APS patients with thrombotic as well as obstetric manifestations. Increased levels of plasminogen activator inhibitor-1 and thrombin-activatable fibrinolysis inhibitor, together with the presence of aPL against annexin-2, tissue-type plasminogen activator, and plasminogen contribute to the compromised fibrinolytic activity in these patients. Furthermore, unfavorably altered fibrin morphology, less amenable to fibrinolysis, has been proposed as a novel prothrombotic mechanism in APS. This review aims to summarize the present knowledge of the mechanisms involved in impaired fibrinolysis in APS patients. We also present a case from clinical practice as an illustration of fibrinolysis impairment in APS patients from a real-life setting.

Topics: Antibodies, Antiphospholipid; Antiphospholipid Syndrome; Blood Coagulation; Female; Fibrin; Fibrinolysis; Humans; Pregnancy

To critically review the literature regarding inherited thrombophilia and recurrent fetal loss.. English-language literature review.. Women who experienced repeated pregnancy wastage.. Aspirin, glucocorticoids, heparin, and IV immunoglobulin for the prevention of miscarriage.. Live birth, miscarriage, preeclampsia, and pregnancy loss.. Recurrent fetal loss and other placental vascular pathologies of pregnancy have long been associated with antiphospholipid syndrome, an acquired autoimmune thrombophilic state. The number of known heritable thrombophilic disorders has grown rapidly in recent years with the identification of activated protein C resistance, factor V Leiden mutation, and hyperhomocysteinemia as major causes of thrombosis. Data accumulated over the past 2 years suggest that heritable thrombophilia is associated with an increased risk of fetal loss and preeclampsia. The present review discusses potential pathogenetic mechanisms for this association and evaluates reported therapeutic regimens for the prevention of fetal loss in women with thrombophilia.. Placental thrombosis may be the final common pathophysiologic pathway in most women with habitual abortions and repeated pregnancy wastage. Prophylactic antithrombotic therapy is indicated in women with heritable thrombophilia and antiphospholipid syndrome and probably is more effective than the previously used modalities of prednisone, aspirin, and IV immunoglobulin.

Topics: Abortion, Habitual; Antiphospholipid Syndrome; Antithrombin III Deficiency; Female; Fibrin; Humans; Hyperhomocysteinemia; Pregnancy; Protein C; Prothrombin; Thrombophilia

APS is associated with arterial and venous thrombosis. The unfavourable fibrin clot phenotype, including formation of dense and poorly lysable clots, has been reported in thrombotic APS. We investigated whether abnormal plasma clot properties are predictive of recurrent thromboembolism in APS.. We followed 126 consecutive patients with thrombotic APS and 105 control subjects, without APS, matched for thrombotic events. Plasma fibrin clot permeability (Ks), turbidity measurements and clot lysis time were evaluated ⩾5 months after a thrombotic event. The primary composite end point was symptomatic recurrent venous thromboembolism, ischaemic stroke and/or myocardial infarction.. During follow-up (median, 62 months; range 46-74 months; 1183.2 patient-years), the primary outcome was observed in 33 (26.2%) APS patients and 16 (15.2%) controls, including 25 (19.8%) and 14 (13.3%) subjects with recurrent venous thromboembolism, respectively. Reduced Ks and prolonged clot lysis time predicted recurrent thromboembolic events in APS patients [per 1 × 10-9 cm2: hazard ratio (HR) = 0.37; 95% CI: 0.24, 0.56; and per 10 min: HR = 1.20; 95% CI: 1.01, 1.40, respectively] and in controls (per 1×10-9 cm2: HR = 0.23; 95% CI: 0.11, 0.42; and per 10 min: HR = 1.51; 95% CI: 1.08, 2.16, respectively). A multivariate analysis showed that positive IgG and IgM anti-β2 glycoprotein I antibodies, withdrawal of anticoagulation, lower platelet count and reduced Ks predicted thromboembolic events in APS patients.. Formation of denser fibrin networks could be a novel risk factor for recurrent thromboembolism in APS, which highlights the importance of fibrin phenotype in thrombotic disorders.

Topics: Adult; Antiphospholipid Syndrome; Blood Coagulation; Female; Fibrin; Fibrin Clot Lysis Time; Follow-Up Studies; Humans; Incidence; Male; Middle Aged; Permeability; Poland; Prospective Studies; Recurrence; Thromboembolism; Time Factors

The prothrombotic fibrin clot phenotype has been reported in patients with thrombotic antiphospholipid syndrome (APS) and venous thromboembolism (VTE). Protein composition of plasma fibrin clots in APS has not been studied. We evaluated 23 patients with thrombotic APS, 19 with VTE alone, and 20 well-matched controls. A proteomic analysis of fibrin clots generated from citrated plasma was based on liquid chromatography-mass spectrometry. Plasma levels of thrombospondin-1 (TSP1), apolipoprotein(a), A-I, and B-100, complement components (C)3a, C5b-C9, histidine-rich glycoprotein (HRG), and prothrombin were evaluated using immunoenzymatic tests. In plasma fibrin clots of APS patients, compared with VTE subjects and controls, we identified decreased amounts of (pro)thrombin, antithrombin-III, apolipoprotein A-I, and HRG with no differences in plasma levels of antithrombin, prothrombin, along with lower plasma HRG and apolipoprotein A-I. In APS patients, plasma HRG positively correlated with amounts of clot-bound HRG, while apolipoprotein A-I was inversely associated with clot-bound levels of this protein. The most predominant proteins within the clots of APS patients were bone marrow proteoglycan, C5-C9, immunoglobulins, apolipoprotein B-100, platelet-derived proteins, and TSP1. Our study is the first to demonstrate differences in the protein composition of fibrin clots generated from plasma of thrombotic APS patients versus those with VTE alone.

Topics: Adult; Antiphospholipid Syndrome; Blood Coagulation; Blood Proteins; Case-Control Studies; Female; Fibrin; Humans; Male; Middle Aged; Proteome; Thrombosis; Venous Thromboembolism

Thrombosis and complement activation are pathogenic features of antiphospholipid syndrome (APS). Their molecular link is Plasma carboxypeptidase-B, also known as thrombin activatable fibrinolysis inhibitor (TAFIa), which plays a dual role: anti-fibrinolytic, by cleaving carboxyl-terminal lysine residues from partially degraded fibrin, and anti-inflammatory, by downregulating complement anaphylatoxins C3a and C5a.. To investigate the levels of TAFI (proenzyme) and TAFIa (active enzyme) in relation to complement activation, fibrin clot permeability and fibrinolytic function in clinical and immunological subsets of 52 APS patients and 15 controls.. TAFI (p<0.001), TAFIa (p<0.05) and complement factor C5a (p<0.001) were increased, while fibrin permeability (p<0.01) was decreased and clot lysis time (CLT) was prolonged (p<0.05) in APS patients compared to controls. Furthermore, TAFIa was increased (p<0.01) in samples from APS patients affected by arterial thrombosis compared to other APS-phenotypes. Positive associations were found between TAFI and age, fibrinogen and C5a, and between TAFIa and age, fibrinogen and thrombomodulin.. TAFI and TAFIa levels were increased in patients with APS as a potential response to complement activation. Interestingly, TAFI activation was associated with arterial thrombotic APS manifestations. Thus, TAFIa may be considered a novel biomarker for arterial thrombosis in APS.

Topics: Adult; Antiphospholipid Syndrome; Carboxypeptidase B2; Complement Activation; Complement C5a; Female; Fibrin; Humans; Male; Thromboplastin

A novel heterozygous variant, FGA c.169_180+2 del (designated fibrinogen Shanghai), was identified in a patient with dysfibrinogenemia with antiphospholipid antibody syndrome (APS) and recurrent venous thrombosis, and in his asymptomatic father. We aimed to reveal the functional implication of structural change caused by this variant.. Transcription analysis was performed with FGA minigene transfection assay to evaluate the impact of nucleosides deletion on mRNA editing. The fibrinogen isolated from propositus' plasma was used to characterise its functional defects. Fibrin polymerization and clot lysis experiments were performed by optical measurement of turbidity. Thrombin-catalysed fibrinopeptide release was analysed by the reversed-phase, high-performance liquid chromatography. The ultrastructures of fibrin clots were visualised by scanning electron microscopy.. FGA c.169_180+2 del led to an aberrant mRNA with exon 2 skipping and encoded an shortened Aα chain with 42 amino acids truncation at its N-terminal. The propositus' fibrinogen had an impaired release of fibrinopeptide A and abnormal polymerization with a significantly prolonged lag time, a slower maximum slope and reduced final turbidity. The fibrin clot formed with propositus' fibrinogen showed thicker fibres with looser network structure. Clot lysis was normal using the purified fibrinogen but was significantly impaired using the plasma sample from propositus, compared with that from his father.. Fibrinogen Shanghai results in N-terminal truncation of Aα chain, which does not interfere with synthesis, assembly or secretion of fibrinogen, but compromises fibrin polymerization and clot formation. APS at least partially contributes to the development of thrombosis in the propositus.

Topics: Afibrinogenemia; Antiphospholipid Syndrome; China; Fibrin; Fibrinogen; Humans; Male; Mutation; Venous Thrombosis; Young Adult

Although portal vein thrombosis in cirrhotic patients is frequently observed, the\ detailed process remains to be clarified, and the role of anticardiolipin antibody in the development of\ portal vein thrombosis has been controversial.. A 52-year-old man, who had been diagnosed with alcoholic cirrhosis of the liver, was\ admitted to our hospital suffering from dyspnea and ascites. Just after being diagnosed as having\ antiphospholipid antibody syndrome with lung thrombosis and delivering a positive result for the β\ 2-glycoprotein I-dependent anticardiolipin antibody, he sustained rupture of the esophageal varices\ with rapid development of portal vein thrombosis, which resolved under anticoagulant therapy. Two\ years later, he was admitted again on suspicion of thrombosis because of an elevation in the serum\ D-dimer level, and computed tomography showed portal and upper mesenteric vein thrombosis.\ Although immediate anticoagulant therapy resulted in complete recanalization, he suffered the same\ episode 2 months later, which occurred with re-elevation of the serum D-dimer level.. A positive finding of an anticardiolipin antibody in cirrhotic patients has been considered\ to be nonspecific and not related to the development of thrombus in the portal vein. This case,\ however, seems to indicate that cirrhotic patients with the β2-glycoprotein I-dependent\ anticardiolipin antibody should be regarded as being at high risk for portal vein thrombosis. Monitoring\ with the serum D-dimer was useful in detecting portal vein thrombosis in its early stage.

Topics: Antiphospholipid Syndrome; Fibrin; Fibrinogen; Humans; Liver Cirrhosis; Male; Middle Aged; Portal Vein; Tomography, X-Ray Computed; Venous Thrombosis

The antiphospholipid syndrome (APS) is defined by persistent antiphospholipid antibodies together with thrombosis and/or pregnancy morbidity. We investigated the tightness of fibrin clot and fibrinolytic function in plasma samples from APS patients compared with two control groups.. APS patients (n=49), healthy controls (HC) (n=19) and warfarin-treated nonAPS thrombosis controls (nonAPS-TC) (n=39) were investigated. Fibrin permeability was assessed as the permeability coefficient (Ks) by a flow measurement technique. Additionally, clot density and fibrinolytic function was analysed by a turbidimetric clotting and lysis assay. Fibrin structure was visualised using scanning electron microscopy. Finally, the number of cell-derived microparticles (MPs) in the samples were correlated to fibrin permeability. The Ks value was lower in samples from APS-patients compared to HC and nonAPS-TC (p<0.0001 for both) indicating a less permeable fibrin clot in APS patients. Scanning electron microscopy images confirmed compact fibrin with smaller intrinsic pores and thinner fibers in samples from APS patients as compared to HC. Prolonged fibrinolysis (clot lysis) times were present in the subgroup of APS patients with previous arterial thrombosis (n=15) as compared to HC and to nonAPS-TC (all p-values<0.05). In conclusion, tighter fibrin clots were formed in plasma from APS patients compared with healthy controls and warfarin treated patients with thrombosis of "nonAPS origin". This new observation presents a possible mechanism contributing to the thrombotic predisposition of APS patients. Impaired fibrinolysis, selectively present among APS patients with previous arterial thrombosis, may further aggravate the pro-thrombotic state in this APS subgroup.

Topics: Adult; Antiphospholipid Syndrome; Case-Control Studies; Female; Fibrin; Fibrinolysis; Humans; Male; Middle Aged; Thrombosis

We tested the hypothesis that plasma fibrin clot structure/function is unfavourably altered in patients with antiphospholipid syndrome (APS). Ex vivo plasma clot permeability, turbidity and susceptibility to lysis were determined in 126 consecutive patients with APS enrolled five months or more since thrombotic event vs 105 controls. Patients with both primary and secondary APS were characterised by 11% lower clot permeability (p<0.001), 4.8% shorter lag phase (p<0.001), 10% longer clot lysis time (p<0.001), and 4.7% higher maximum level of D-dimer released from clots (p=0.02) as compared to the controls. Scanning electron microscopy images confirmed denser fibrin networks composed of thinner fibres in APS. Clots from patients with "triple-antibody positivity" were formed after shorter lag phase (p=0.019) and were lysed at a slower rate (p=0.004) than in the remainder. Clots from APS patients who experienced stroke and/or myocardial infarction were 8% less permeable (p=0.01) and susceptible to lysis (10.4% longer clot lysis time [p=0.006] and 4.5% slower release of D-dimer from clots [p=0.01]) compared with those following venous thromboembolism alone. Multivariate analysis adjusted for potential confounders showed that in APS patients, lupus anticoagulant and "triple-positivity" were the independent predictors of clot permeability, while "triple-positivity" predicted lysis time. We conclude that APS is associated with prothrombotic plasma fibrin clot phenotype, with more pronounced abnormalities in arterial thrombosis. Molecular background for this novel prothrombotic mechanism in APS remains to be established.

Topics: Adult; Antiphospholipid Syndrome; Autoantibodies; Biomarkers; Blood Coagulation Tests; Case-Control Studies; Chi-Square Distribution; Female; Fibrin; Fibrin Fibrinogen Degradation Products; Humans; Linear Models; Male; Microscopy, Electron, Scanning; Middle Aged; Multivariate Analysis; Myocardial Infarction; Poland; Predictive Value of Tests; Prognosis; Risk Factors; Stroke; Thrombosis; Time Factors; Venous Thromboembolism

Antiphospholipid syndrome (APS) is defined by thrombosis, fetal loss, and the presence of antiphospholipid antibodies, including anti-β2-glycoprotein-1 autoantibodies (anti-β2GP1) that have a direct role in the pathogenesis of thrombosis in vivo. The cellular targets of the anti-β2GP1 autoantibody/β2GP1 complex in vivo were studied using a laser-induced thrombosis model of APS in a live mouse and human anti-β2GP1 autoantibodies affinity-purified from APS patients. Cell binding of fluorescently labeled β2GP1 and anti-β2GP1 autoantibodies revealed their colocalization on the platelet thrombus but not the endothelium. Anti-β2GP1 autoantibodies enhanced platelet activation, monitored by calcium mobilization, and endothelial activation, monitored by intercellular adhesion molecule-1 expression. When eptifibatide was infused to block platelet thrombus formation, enhanced fibrin generation and endothelial cell activation were eliminated. Thus, the anti-β2GP1 autoantibody/β2GP1 complex binds to the thrombus, enhancing platelet activation, and platelet secretion leads to enhanced endothelium activation and fibrin generation. These results lead to a paradigm shift away from the concept that binding of the anti-β2GP1 autoantibody/β2GP1 complex activates both endothelial cells and platelets toward one in which activation of platelets in response to anti-β2GP1 autoantibody/β2GP1 complex binding leads to subsequent enhanced endothelium activation and fibrin generation.

Topics: Animals; Antibodies, Antiphospholipid; Antiphospholipid Syndrome; Autoantibodies; beta 2-Glycoprotein I; Blood Platelets; Blotting, Western; Cell Membrane; Cells, Cultured; Disease Models, Animal; Endothelium; Fibrin; Fibrinogen; Humans; Intercellular Adhesion Molecule-1; Mice; Mice, Inbred C57BL; Platelet Activation; Thrombosis

Formation of denser fibrin networks displaying impaired lysability has been reported in subjects at an increased risk of atherosclerosis. Given recent data on prothrombotic fibrin clot phenotype reported in patients with antiphospholipid syndrome (APS), we tested the hypothesis that altered fibrin clot properties are associated with increased intima-media thickness (IMT) observed in PAPS.. We studied 30 consecutive patients with PAPS and 30 controls matched for age, sex and the type of previous thromboembolism. We assessed plasma fibrin clot permeability (Ks) and clot lysis time (CLT) with their potential determinants. The IMT was measured in 3 segments of the carotid arteries.. Patients with APS had 15.2% lower Ks (p=0.002) and 9.7% prolonged CLT (p=0.039) compared with controls. The IMT in the APS group was greater in the common carotid artery (5.7%; p=0.002), at the bifurcation (17.46%; p<0.001), and the internal artery (9.26%; p=0.015). Patients with triple positivity in the antiphospholipid antibody profile (n=9; 30%) had lower Ks and greater IMT (both, p<0.05), compared with those with single positivity (n=13; 43.3%). Multivariate analysis adjusted for potential confounders showed that in APS patients, oxidized low-density lipoproteins (p=0.019) were the only independent predictor of Ks, while thrombin activatable fibrinolysis inhibitor activity (p<0.001) predicted CLT. Plasminogen activator inhibitor-1 (PAI-1) was found to be the independent predictor of the IMT in the common carotid artery (p=0.004), and in the internal carotid artery (p<0.001).. Reduced Ks and susceptibility to lysis are associated with greater IMT in PAPS, which might contribute to the early atherosclerosis in this disease.

Topics: Adult; Antibodies, Antiphospholipid; Antiphospholipid Syndrome; Carotid Intima-Media Thickness; Female; Fibrin; Fibrin Clot Lysis Time; Fibrinolysis; Humans; Lipoproteins, LDL; Male; Middle Aged

This work was aimed at characterizing the interaction of β(2)-glycoprotein I (β(2)GPI), an abundant plasma protein of unknown function, with human thrombin, the final effector protease in the coagulation cascade.. The β(2)GPI-thrombin interaction was studied by surface plasmon resonance (SPR), fluorescence, and molecular modeling. The effect of β(2)GPI on the procoagulant (fibrin generation and platelet aggregation) and anticoagulant (protein C activation) functions of thrombin were investigated with turbidimetric, immunocytofluorimetric and enzymatic assays.. SPR and fluorescence data indicated that β(2)GPI tightly bound thrombin (K(d) = 34 nM) by interacting with both protease exosites, while leaving the active site accessible. This picture is fully consistent with the theoretical model of the β(2)GPI-thrombin complex. In particular, blockage of thrombin exosites with binders specific for exosite-1 (hirugen and HD1 aptamer) or exosite-2 (fibrinogen γ'-peptide and HD22 aptamer) impaired the β2 GPI-thrombin interaction. Identical results were obtained with thrombin mutants having one of the two exosites selectively compromised by mutation (Arg73Ala and Arg101Ala). Fluorescence measurements indicated that β(2)GPI did not affect the affinity of the enzyme for active site inhibitors, such as p-aminobenzamidine and the hirudin(1-47) domain, in agreement with the structural model. β(2)GPI dose-dependently prolonged the thrombin clotting time and ecarin clotting time in β(2)GPI-deficient plasma. β(2)GPI inhibited thrombin-induced platelet aggregation (IC50 = 0.36 μM) by impairing thrombin cleavage of protease-activated receptor 1 (PAR1) (IC50 = 0.32 μM), both on gel-filtered platelets and in whole blood. Strikingly, β(2) GPI did not affect thrombin-mediated generation of the anticoagulant protein C.. β(2) GPI functions as a physiologic anticoagulant by inhibiting the key procoagulant activities of thrombin without affecting its unique anticoagulant function.

Topics: Anticoagulants; Antiphospholipid Syndrome; Benzamidines; beta 2-Glycoprotein I; Blood Coagulation; Catalytic Domain; Chromatography, Gel; Coagulants; Enzyme Inhibitors; Fibrin; Flow Cytometry; Hemostasis; Hirudins; Humans; Hydrolysis; Inhibitory Concentration 50; Kinetics; Mutation; Nephelometry and Turbidimetry; Protein Binding; Receptor, PAR-1; Surface Plasmon Resonance; Thrombin

Anedoctal reports suggest that some thrombotic primary antiphospholipid antibody syndrome (PAPS) patients on oral anticoagulation require higher than average doses to achieve given targets international normalized ratios (INR).. To test the hypothesis of relative warfarin resistance in thrombotic PAPS and the effect of baseline IgG anticardiolipin antibodies, the cytochrome CYP2C9 and the vitamin K epoxide reductase (VKORC1) haplotypes we compared weekly warfarin consumption of 40 TPAPS (mean age 44 ± 16years) with that of 65 thrombotic patients with inherited thrombophilia (IT) (mean age 52 ± 18) at similar target INR 2.0-3.0 followed up between January-1994 and January 2003. To investigate an involvement of the epoxidation pathway in this difference and to assess enhanced residual fibrin turnover decarboxylated prothrombin (PIVKA-II) and D-dimers (DD) were cross-sectionally investigated in the same patients between March and May 2008.. CEX7 and VKORC1 polymorphisms explained 45.1% of the variability in warfarin consumption, whose age-adjusted mean weekly consumption was greater in PAPS than IT (27.62 vs 21.24 mg, p = 0.03). In PAPS baseline IgG aCL and VKORC1 predicted weekly warfarin consumption (p = 0.028 and p = 0.024). IgG β(2)GPI and warfarin dose independently predicted plasma PIVKA-II (p = 0.01 and p = 0.02). Age and sex adjusted DD was greater in PAPS than IT (132 ± 34 vs 83 ± 37 mg/dl, p = 0.03).. Thrombotic PAPS exhibit a degree of warfarin resistance partly accounted by antiphospholipid antibodies and are in a state of enhanced fibrin turnover despite oral anticoagulation that might have implications for re-thrombosis and atherosclerosis.

Topics: Administration, Oral; Adult; Antibodies, Antiphospholipid; Anticoagulants; Antiphospholipid Syndrome; Aryl Hydrocarbon Hydroxylases; Cytochrome P-450 CYP2C9; Dose-Response Relationship, Drug; Female; Fibrin; Humans; International Normalized Ratio; Male; Middle Aged; Mixed Function Oxygenases; Polymorphism, Single Nucleotide; Thrombosis; Vitamin K Epoxide Reductases; Warfarin

The present work was intended to study the process of fibrin formation and lysis and plasmin generation in a group of patients with recurrent miscarriage (RM), due to the presence of antiphospholipid antibodies (N = 10); as well as in women with RM without the antiphospholipid syndrome (APS) (N = 6), compared with those of a group of healthy women (N= 8). In the group of patients with APS, nine were positive for antibodies against cardiolipin (aCL), five for anti-beta2-glycoprotein I (anti-beta2GPI), four for both antibodies, and one for antibodies against prothrombin (aPT) and lupus anticoagulant (LA). Fibrin formation and lysis was followed by turbidity and plasmin generation using chromogenic substrate S2251. The polymerization curves from RM patients without APS and the LA patient showed an increased slope and maximum turbidity compared to those of the control group. The speed of lysis was higher in the LA patient (21 +/- 0) 10(-4) deltaOD/seg and the RM patients without APS (19.6 +/- 5.7) 10(-4) deltaDO/seg, compared to that of the control group (14.5 +/- 2.8) 10(-4) deltaDO/seg. Plasmin generation increased only in RM patients without APS (85 +/- 24%) against the control group (52 +/- 3%), p = 0.005. The changes observed in the fibrin polymerization and lysis process of women with RM without APS and LA seem to be related to their higher fibrinogen levels, while the increased plasmin generation was related to the patients' morbidity.

Topics: Abortion, Habitual; Adult; Antibodies, Anticardiolipin; Antibodies, Antiphospholipid; Antiphospholipid Syndrome; Autoantigens; beta 2-Glycoprotein I; Biopolymers; Blood Coagulation; Enzyme Activation; Female; Fibrin; Fibrinolysin; Fibrinolysis; Humans; Lupus Coagulation Inhibitor; Nephelometry and Turbidimetry; Plasminogen; Pregnancy; Streptokinase; Thrombin; Thrombophilia; Young Adult

Mesothelial/monocytic incidental cardiac excrescence (MICE) is a rare benign lesion composed of a mixture of histiocytes, mesothelial cells, fibrin, adipocytes and scattered inflammatory cells without a vascular network or supporting stroma. Its pathogenesis is controversial with some authors favoring an artifactual theory while others consider a reactive phenomenon. To date, only 41 cases of MICE have been reported in the literature. We describe an additional case of MICE in a 24-year-old female with antiphospholipid syndrome. A mobile hyperechogenic mass attached to the left ventricular surface of the aortic valve was documented by transthoracic echocardiography (TTE). The patient did have cardiac catheterization one month before the cardiac surgery. Histopathologic and immunohistochemical examination showed a lesion composed of histiocytes and mesothelial cells together with fibrin and scattered inflammatory cells. To our knowledge, this is the first case of MICE detected in a patient with antiphospholipid syndrome.

Topics: Antiphospholipid Syndrome; Aortic Valve; Biomarkers; Cardiac Surgical Procedures; Epithelium; Female; Fibrin; Heart Valve Diseases; Histiocytes; Humans; Immunohistochemistry; Treatment Outcome; Ultrasonography; Young Adult

A high incidence of thromboembolic events has been reported in patients with systemic lupus erythematosus (SLE). Phosphatidylserine (PS) is normally sequestered in the inner leaflet of cell membranes. Externalization of PS during cell activation is mediated by phospholipid scramblase 1 (PLSCR1) and has a central role in promoting blood coagulation. We investigated the underlying pathogenic status of thrombophilia in SLE by analyzing PLSCR1 expression on monocytes from patients with SLE.. Sixty patients with SLE were evaluated. Twenty-three patients had antiphospholipid syndrome (APS/SLE). Plasma D-dimer levels were measured as a marker of fibrin turnover. The cDNA encoding human PLSCR1 was cloned from the total RNA extract from monocytes, and independent clones were sequenced. PLSCR1 mRNA expression in CD14+ cells was determined by real-time polymerase chain reaction. PS exposure on CD14+ cell surface was analyzed by flow cytometry.. Elevated D-dimer levels were found in plasma from SLE patients. Three splice variants of PLSCR1 mRNA were identified in all subjects, and levels of full-length PLSCR1 mRNA were significantly increased in SLE compared to healthy controls (2.9 +/- 1.5 vs 1.3 +/- 0.4, respectively; p < 0.0001). Flow-cytometry analysis showed relative enhancement of PS exposure in the surface of CD14+ cells in SLE patients compared to healthy controls.. Novel PLSCR1 splice variants were identified. Monocytes in SLE patients had enhanced PLSCR1 mRNA expression, as well as increased fibrin turnover and cell-surface PS exposure, indicating that PLSCR1 may, in part, contribute to the prothrombotic tendency in SLE.

Topics: Adult; Aged; Antiphospholipid Syndrome; Cell Membrane; Exocytosis; Female; Fibrin; Fibrin Fibrinogen Degradation Products; Flow Cytometry; Gene Expression; Humans; Lupus Erythematosus, Systemic; Male; Middle Aged; Monocytes; Phosphatidylserines; Phospholipid Transfer Proteins; Protein Isoforms; RNA Splicing; RNA, Messenger; Young Adult

Antibodies to prothrombin (APTs) and to beta2-glycoprotein I are the major autoantibodies responsible for lupus anticoagulant (LAC) activity. APTs comprise antibodies against prothrombin alone as well as antibodies against phosphatidylserine/prothrombin complex (anti-PS/PT), the latter being highly associated with the antiphospholipid syndrome (APS). The effect of anti-PS/PT on thrombin generation has not been elucidated, and the paradoxical effect of LAC (an anticoagulant in vitro, but a procoagulant in vivo) remains an enigma. The purpose of this study was to investigate the effects of anti-PS/PT on thrombin generation and to examine the LAC paradox.. We evaluated 36 anti-PS/PT-positive APS patients and 127 healthy subjects. Markers of in vivo thrombin/fibrin generation, including prothrombin fragment F1+2, thrombin-antithrombin III complex, soluble fibrin monomer, D-dimer, and fibrin degradation products, were measured. Mouse monoclonal anti-PS/PT antibody 231D was established, and its effects on in vitro thrombin generation were investigated by chromogenic assay.. Significantly elevated levels of markers of thrombin/fibrin generation were observed in anti-PS/PT-positive patients, regardless of the presence or absence of anticardiolipin antibodies, as compared with healthy subjects. In the presence of low concentrations of human activated factor V (FVa), monoclonal antibody 231D increased thrombin generation in a dose-dependent manner. In contrast, when high concentrations of FVa were added, monoclonal antibody 231D decreased thrombin generation. Under a constant concentration of FVa, a high concentration of human FXa enhanced the effect of 231D.. The presence of anti-PS/PT greatly correlated with increased thrombin generation in APS patients. The in vitro effects of monoclonal antibody 231D on thrombin generation are "biaxial" according to the FVa/FXa balance. These data may serve as a clue to understanding the LAC paradox and the thrombogenic properties of anti-PS/PT.

Topics: Adolescent; Adult; Aged; Animals; Antibodies, Monoclonal; Antiphospholipid Syndrome; Autoantibodies; Biomarkers; Cells, Cultured; Female; Fibrin; Humans; Male; Mice; Mice, Inbred BALB C; Middle Aged; Phosphatidylserines; Prothrombin; Thrombin; Young Adult

Because both immunoglobulin G (IgG) and phospholipids interfere with fibrinolysis, their combined modulating effects were investigated in experimental models of three consecutive steps of the fibrinolytic process [diffusion of tissue-type plasminogen activator (tPA) into the clot, plasminogen activation on fibrin surface and fibrin dissolution by plasmin] using IgGs isolated from healthy subjects and from patients with antiphospholipid syndrome in combination with mixtures of synthetic dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylserine. In fibrin clots containing phospholipids the normal IgG enhanced the barrier function of the phospholipids with respect to the diffusion of tPA and plasminogen activation, but did not modify the lysis by plasmin. One of the examined antiphospholipid syndrome-IgGs also restricted the diffusion of tPA, but it accelerated the plasminogen activation on the fibrin surface and slowed down the lysis of fibrin by plasmin. Another antiphospholipid syndrome IgG, which did not affect significantly the tPA penetration into the fibrin gel, did not modify the plasminogen activation on its own, but it partially opposed the inhibiting effect of phospholipids on plasmin formation and accelerated the end-stage lysis of fibrin containing phospholipids. The IgGs from the two examined antiphospholipid syndrome patients did not show consistent deviation from the pattern of normal IgG effects on fibrinolysis in phospholipid environment. Thus, a high degree of heterogeneity with respect to the profibrinolytic or antifibrinolytic effects of the pathological IgGs can be expected in the antiphospholipid syndrome patient population, which may contribute to the variable thrombotic symptoms in this clinical syndrome.

Topics: Antibodies, Antiphospholipid; Antiphospholipid Syndrome; Case-Control Studies; Fibrin; Fibrinolysin; Fibrinolysis; Humans; Immunoglobulin G; Phospholipids; Tissue Plasminogen Activator

The annexin A2 (A2) heterotetramer, consisting of two copies of A2 and two copies of S100A10/p11, promotes fibrinolytic activity on the surface of vascular endothelial cells by assembling plasminogen and tissue plasminogen activator (tPA) and accelerating the generation of plasmin. In humans, overexpression of A2 by acute promyelocytic leukemia cells is associated with excessive fibrinolysis and hemorrhage, whereas anti-A2 autoantibodies appear to accentuate the risk of thrombosis in patients with anti-phospholipid syndrome. Complete deficiency of A2 in mice leads to a lack of tPA cofactor activity, accumulation of intravascular fibrin, and failure to clear arterial thrombi. Within the endothelial cell, p11 is required for Src kinase-mediated tyrosine phosphorylation of A2, which signals translocation of both proteins to the cell surface. Here we show that p11 is expressed at very low levels in the absence of A2 both in vitro and in vivo. We demonstrate further that unpartnered p11 becomes polyubiquitinated and degraded via a proteasome-dependent mechanism. A2 stabilizes intracellular p11 through direct binding, thus masking an autonomous p11 polyubiquitination signal that triggers proteasomal degradation. This interaction requires both the p11-binding N-terminal domain of A2 and the C-terminal domain of p11. This mechanism prevents accumulation of free p11 in the endothelial cell and suggests that regulation of tPA-dependent cell surface fibrinolytic activity is precisely tuned to the intracellular level of p11.

Topics: Animals; Annexin A2; Antiphospholipid Syndrome; Autoantibodies; Cell Line, Tumor; Endothelial Cells; Fibrin; Fibrinolysin; Fibrinolysis; Hemorrhage; Humans; Leukemia, Promyelocytic, Acute; Mice; Mice, Knockout; Oncogene Protein pp60(v-src); Proteasome Endopeptidase Complex; Protein Binding; Protein Transport; S100 Proteins; Thrombosis; Tissue Plasminogen Activator; Ubiquitin; Ubiquitination

Routinely available coagulation assays are not capable of detecting clinically defined hypercoagulable states. A number of global coagulation assays have been developed with the potential to evaluate hypercoagulability, which predisposes to the common clinical events of arterial and venous thromboembolism (VTE).. We hypothesized that the overall hemostatic potential (OHP) assay would show abnormal fibrin generation and lysis in patients with clinically defined hypercoagulable states.. We used the OHP assay as described by Blombäck and colleagues [1,2] in 161 clinically hypercoagulable patients with arterial or VTE, pregnancy complications or autoimmune disease. Eighty patients had associated antiphospholipid antibodies (APLA). Ninety-eight normal plasma donors were tested for comparison.. We derived three new assay parameters for correlation with hypercoagulable states: the maximum optical density, maximum slope, and delay in onset of fibrin generation. We found significantly different assay results for all patients' parameters examined when compared with controls, indicating both increased fibrin generation and reduced fibrinolysis in hypercoagulable patients. The findings were similar whether samples were collected in association with an acute thrombotic event or not. Estimated assay sensitivity for detection of a clinically defined hypercoagulable state was 96%.. The OHP assay is a simple, inexpensive global test that is useful for assessing patients with hypercoagulable states including APLA. OHP results are significantly abnormal in hypercoagulable groups compared with controls, indicating that both increased fibrin generation and reduced fibrinolysis contribute to hypercoagulable states. The assay may ultimately assist in tailoring clinical management to patients' individual requirements.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Antiphospholipid Syndrome; Blood Coagulation Tests; Case-Control Studies; Female; Fibrin; Fibrinolysis; Hemostasis; Humans; Male; Middle Aged; Pilot Projects; Predictive Value of Tests; Pregnancy; Pregnancy Complications, Hematologic; Reproducibility of Results; Sensitivity and Specificity; Thromboembolism; Thrombophilia; Time Factors; Venous Thrombosis

The combined presence of anti-phospholipid Ab (aPL) and thrombosis is recognized as the antiphospholipid syndrome (APS). The aPL represent a heterogeneous group of Ab that recognize various phospholipids (PL), PL-binding plasma proteins, and/or PL-protein complexes. Recently, we found the presence of antithrombin Ab in some APS patients and that some of these anti-thrombin Ab could inhibit thrombin inactivation by antithrombin. Considering that thrombin is homologous to plasmin, which dissolves fibrin, we hypothesize that some APS patients may have Ab that react with plasmin, and that some anti-plasmin Ab may interfere with the plasmin-mediated lysis of fibrin clots. To test this hypothesis, we searched for anti-plasmin Ab in APS patients and then studied those found for their effects on the fibrinolytic pathway. The results revealed that seven of 25 (28%) APS patients have IgG anti-plasmin Ab (using the mean OD plus 3 SD of 20 normal controls as the cutoff) and that six of six patient-derived IgG anti-thrombin mAb bind to plasmin with relative K(d) values ranging from 5.6 x 10(-8) to 1 x 10(-6) M. These K(d) values probably represent affinities in the higher ranges known for human IgG autoantibodies against protein autoantigens. Of these mAb, one could reduce the plasmin-mediated lysis of fibrin clots. These findings suggest that plasmin may be an important driving Ag for some aPL B cells in APS patients, and that the induced anti-plasmin Ab may act either directly, by binding to plasmin and inhibiting its fibrinolytic activity, or indirectly, by cross-reacting with other homologous proteins in the coagulation cascade to promote thrombosis.

Topics: Amino Acid Sequence; Antibodies, Monoclonal; Antiphospholipid Syndrome; Autoantibodies; Binding Sites, Antibody; Fibrin; Fibrinolysin; Fibrinolysis; Humans; Immunoglobulin G; Molecular Sequence Data; Plasminogen; Thrombosis

Antiphospholipid syndrome is characterized by recurrent pregnancy loss, thrombosis, and antiphospholipid antibodies. However, some women with clinical features of antiphospholipid syndrome test negative for antiphospholipid antibodies ("antiphospholipid-like syndrome"). Women with antiphospholipid and antiphospholipid-like syndromes have serum immunoglobulin G that harms murine pregnancy, suggesting that the mechanisms of fetal death may be similar in both groups. The objective of our study was to determine whether patients with antiphospholipid and antiphospholipid-like syndromes share pathophysiology by comparing the histology of gestational tissues from these groups.. Placenta and abortion specimens were obtained from 44 pregnancies in 26 women with antiphospholipid syndrome and 37 pregnancies in 21 women with antiphospholipid-like syndrome. Of these, 16 pregnancies with antiphospholipid syndrome and 8 with antiphospholipid-like syndrome were treated with a variety of medications intended to improve pregnancy outcome. Placentas from 31 elective pregnancy terminations and 40 pregnancies complicated by idiopathic preterm delivery served as an additional control group. Twenty histologic parameters were systematically assessed by a single investigator who was blinded to the clinical status of the specimens. Histopathologic findings were compared among groups using multivariate logistic regression analysis.. Antiphospholipid syndrome pregnancies included 15 spontaneous abortions, 13 fetal deaths, and 16 live births. Pregnancies in the antiphospholipid-like syndrome group resulted in 5 spontaneous abortions, 30 fetal deaths, and one live birth. Gestational tissues from antiphospholipid and antiphospholipid-like syndrome pregnancies were similar for every histologic feature tested. Decidua from women with both antiphospholipid and antiphospholipid-like syndromes had more necrosis, acute and chronic inflammation, and vascular thrombus compared to controls. Placental tissue from antiphospholipid and antiphospholipid-like syndrome pregnancies showed more infarction, intravascular fibrin deposition, syncytial knot formation, and fibrosis than controls. Histologic features were variable within groups. There were no histologic differences in tissues from live births and pregnancy losses, or in treated and untreated pregnancies.. Placental histopathology is similar in antiphospholipid and antiphospholipid-like syndrome pregnancies, suggesting that these disorders may share pathophysiology. Histologic findings in women with APS are non-specific and may not differentiate between women with APS and APS-like syndromes.

Topics: Abortion, Spontaneous; Adult; Antibodies, Antiphospholipid; Antiphospholipid Syndrome; Chorionic Villi; Decidua; Female; Fetal Death; Fibrin; Fibrosis; Humans; Inflammation; Logistic Models; Necrosis; Placenta; Pregnancy; Thrombosis; Trophoblasts

The main event in blood coagulation is the thrombincatalyzed conversion of fibrinogen into fibrin. This singular transformation of a soluble protein into an insoluble polymeric network occurs with faultless precision. Abnormalities of fibrin polymerization can lead to hemorragic and thrombotic disorders. Increased fibrinogen plasma concentration (Fg) and fibrin polymerization rate (FPR) could be additional risk factors associated with atherothrombosis in antiphospholipid syndrome (APS) and in systemic lupus erythematosus (SLE). Our objective was to investigate Fg and FPR in consecutive patients with APS and SLE. Thirty-nine patients and 31 age- and gender-matched healthy controls were studied. Sixteen patients had primary APS, 13 patients had SLE, and 10 patients had SLE plus APS. The mean of the FPR was significantly increased (0.2799 +/- 0.091) in patients with APS plus SLE as compared with the control group (0.2052 +/- 0.055) (p < 0.05). Fg was higher in APS plus SLE (3.15 g/L +/- 0.43) and in primary APS (3.03 g/L +/- 0.29) than in controls (2.87 g/L +/- 0.49). Our results demonstrated an increased FPR in patients with APS plus SLE. This phenomenon could be an additional risk factor for thrombosis in these autoimmune diseases.

Topics: Adult; Antiphospholipid Syndrome; Blood Coagulation; Female; Fibrin; Fibrinogen; Humans; Kinetics; Lupus Erythematosus, Systemic; Male; Reference Values

Immunoglobulin G (IgG) isolated from normal human blood plasma stabilizes the structure of perfused crosslinked fibrin and prolongs the time for its dissolution with plasmin, when the fibrin surface is exposed to 500 s(-1) shear rate flow. The IgG from patients suffering in antiphospholipid syndrome with thrombotic complications exerts even stronger antifibrinolytic effect. A patient, whose IgG does not affect the fibrin dissolution with plasmin, displays a bleeding tendency. The shear stress-induced disassembly of the fibrin clots containing IgGs with antifibrinolytic potency occurs at a much more advanced stage of fibrin digestion, as evidenced by the electrophoretic pattern of the ureatreated samples. The antifibrinolytic effects are also produced under static conditions and these are caused by the variable portion of the IgG molecules (fragment Fab), whereas the constant part (fragment Fc) has no inhibitory effect. The IgGs with antifibrinolytic properties do not affect directly the plasmin activity in amidolytic assay, but the IgGs from APS patients obliterate the competition of the fibrin and the peptidyl-p-nitroanilide for the protease in the same assay system suggesting interference of the IgGs with the plasmin action on the fibrin substrate. Thus, the correlation of the clinical symptoms with the effect of the isolated IgG on the dissolution of perfused fibrin clots supports a physiological and a pathological role of IgG in the fibrinolytic process related to the variability of the cross-reactions of immunoglobulins with fibrin, fibrin degradation products or fibrin-plasmin complexes.

Topics: Adult; Aged; Antibodies, Anticardiolipin; Antiphospholipid Syndrome; Autoantibodies; Case-Control Studies; Cross Reactions; Female; Fibrin; Fibrinolysin; Fibrinolysis; Humans; Immunoglobulin Fab Fragments; Immunoglobulin G; Kinetics; Male; Middle Aged; Thrombosis

A total of 260 consecutive patients, referred for hypercoagulable assessment, was included in this study. Four coagulation activation markers were utilized to assess these patients [enzyme-linked immunosorbent assays for soluble fibrin polymer (TpP), prothrombin fragment 1.2, thrombin-antithrombin complex, and D-dimer]. The mean levels of the activation markers directly correlated with the number of hypercoagulable abnormalities. The percentage of patients with increased TpP levels for each group was lower than the other activation markers. The findings indicate that activation markers reflect the number of underlying thrombophilic abnormalities. Our data suggest that there is a utility in performing a panel of coagulation activation markers to assess the thrombotic risk. The measurement of soluble fibrin polymer may be more reflective of an impending vascular event.

Topics: Activated Protein C Resistance; Adolescent; Adult; Aged; Aged, 80 and over; Antiphospholipid Syndrome; Antithrombin III; Antithrombin III Deficiency; Autoimmune Diseases; Biomarkers; Enzyme-Linked Immunosorbent Assay; Factor V; Female; Fibrin; Fibrin Fibrinogen Degradation Products; Humans; Hyperhomocysteinemia; Male; Middle Aged; Peptide Fragments; Peptide Hydrolases; Protein C Deficiency; Protein S Deficiency; Prothrombin; Risk; Solubility; Thrombophilia

We present three pregnancies in which massive perivillous fibrous deposition (MPVFD) and maternal floor infarction (MFI) occurred in patients with primary antiphospholipid antibody syndrome (PAPS) attending a recurrent miscarriage clinic, and who were treated with low dose aspirin and heparin. We hypothesise that PAPS may be a predisposing factor to the development of this condition. The increased prevalence of late pregnancy complications in PAPS patients with a history of early miscarriage suggests that aspirin and heparin therapy does not eradicate the underlying pathological process but merely reduces the severity. Therefore, untreated early pregnancy losses may be converted into treated pregnancies with late antenatal complications. Some patients with PAPS may therefore be prone to suffer either the previously reported complications of the uteroplacental vasculature, such as pre-eclampsia, and/or specific complications related to the environment of the intervillus space, such as MPVFD/MFI.

Topics: Abortion, Habitual; Adult; Antiphospholipid Syndrome; Chorionic Villi; Female; Fibrin; Humans; Infarction; Placenta; Pregnancy

Anti-beta 2-glycoprotein I antibodies bind to endothelial cells through beta 2-GPI. The antibodies are present in patients with systemic lupus erythematosus and antiphospholipid syndrome and are associated with the pathogenesis of the disease. Anti-endothelial cell antibodies that react with constitutive antigens on ECs are present in patients with vasculiditis and other diseases. Both types of antibodies can activate ECs. Frequent findings in APLS and vasculitis are fibrin deposits and thromboembolic phenomena. These indicate that the coagulation system is activated. However, the mechanism of activation is not clear. ECs generate tissue factor upon stimulation with various substances. In the present study we report that monoclonal anti-beta 2-GPI antibodies and AECAs, derived from a patient with primary APLS and a patient with Takayasu's arteritis, respectively, induce a potent tissue factor in ECs. The production of TF activity, TF antigen and TF mRNA is dose and time dependent. The TF activity was induced also by F(ab)2 but not by Fc fragments and was abolished completely by pre-incubation with ant-TF antibodies. The TF that is induced in ECs by AECAs with and without beta 2-GPI specificity may activate the coagulation and thereby play a major role in the pathogenesis of fibrin deposition and thrombus formation in diseases that are associated with the presence of these antibodies.

Topics: Antibodies; Antigens; Antiphospholipid Syndrome; Apolipoproteins; beta 2-Glycoprotein I; Binding Sites, Antibody; Cells, Cultured; Endothelium, Vascular; Fibrin; Glycoproteins; Humans; Immunoglobulin Fab Fragments; Immunoglobulin Fc Fragments; Lupus Erythematosus, Systemic; Membrane Glycoproteins; RNA, Messenger; Takayasu Arteritis; Thromboembolism; Thromboplastin; Vasculitis

We describe the first case of catastrophic antiphospholipid antibody syndrome (APS) in a patient with progressive systemic sclerosis (SSc). After initial presentation with digital gangrene the patient developed rapidly progressive multiorgan failure and died within 19 hours. Postmortem examination revealed extensive multiorgan arterial microthrombi of days' to months' duration. This suggests that a subclinical state of thrombosis existed before onset of catastrophic APS. Given the poor prognosis of established catastrophic APS there is a need for a means to detect subclinical thrombosis and treat "at risk" patients before clinically apparent thrombosis occurs.

Topics: Adult; Antiphospholipid Syndrome; Brain; Fatal Outcome; Female; Fibrin; Histocytochemistry; Humans; Lupus Erythematosus, Systemic; Mitral Valve