Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0409974 (lupus)
 22,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Microparticles (MPs) resulting from vesiculation of platelets and other blood cells have been extensively documented in vitro and have been found in increased numbers in several vascular diseases, but little is known about MPs of endothelial origin. The aim of this study was to analyze morphological, immunological, and functional characteristics of MPs derived from human umbilical vein endothelial cells (HUVECs) stimulated by TNF, and to investigate whether these MPs are detectable in healthy individuals and in patients with a prothrombotic coagulation abnormality. Electron microscopy evidenced bleb formation on the membrane of TNF-stimulated HUVECs, leading to increased numbers of MPs released in the supernatant. These endothelial microparticles (EMPs) expressed the same antigenic determinants as the corresponding cell surface, both in resting and activated conditions. MPs derived from TNF-stimulated cells induced coagulation in vitro, via a tissue factor/factor VII-dependent pathway. The expression of E-selectin, ICAM-1, alphavbeta3, and PECAM-1 suggests that MPs have an adhesion potential in addition to their procoagulant activity. In patients, labeling with alphavbeta3 was selected to discriminate EMPs from those of other origins. We provide evidence that endothelial-derived MPs are detectable in normal human blood and are increased in patients with a coagulation abnormality characterized by the presence of lupus anticoagulant. Thus, MPs can be induced by TNF in vitro, and may participate in vivo in the dissemination of proadhesive and procoagulant activities in thrombotic disorders.
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PMID:In vitro generation of endothelial microparticles and possible prothrombotic activity in patients with lupus anticoagulant. 1039 3

Antiphospholipid antibodies (aPL) may stimulate tissue factor (TF) expression in cultured endothelial cells and monocytes, but there are discrepancies as to the expression of TF in the patients with antiphospholipid syndrome (APS). By using reverse transcription and polymerase chain reaction amplification, we have analysed TF mRNA accumulation in freshly isolated mononuclear blood cells (MBC) of 14 patients with primary APS (PAPS) and six normal controls. TF mRNA accumulation was low or absent in uncultured MBC from all normal controls, but was elevated in uncultured MBC from nine of the patients as well as in normal MBC incubated with 100 ng/ml lipopolysaccharide (LPS). Mean levels of TF mRNA, as measured by densitometry, were higher in MBC from patients (N = 14) than in those from controls (N = 6, P = 0.009), and in MBC from patients with a history of thrombosis (N = 9) than in those from patients without thrombosis (N = 5, P = 0.02). Uncultured MBC of patients with thrombosis accumulated TF mRNA at similar levels to LPS-treated normal MBC. Increased levels of TF mRNA were found in eight of ten patients with conventional aPL (ie, anti-cardiolipin antibodies [aCL] and/or lupus anticoagulant [LA]) and little if any accumulation of TF mRNA was observed in three of four patients without aPL at the time of study. These data strongly suggest that circulating monocytes of many patients with PAPS are subjected to an up-regulated TF expression that may well explain their prothrombotic state. Although the presence or absence of TF mRNA in MBC was associated with, respectively, the presence or absence of conventional aPL in 11 of the 14 patients studied, our study cannot exclude the involvement of factors other than aCL or LA in inducing TF expression.
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PMID:Increased levels of tissue factor mRNA in mononuclear blood cells of patients with primary antiphospholipid syndrome. 1061 37

To evaluate the relationship between the tissue factor (TF) pathway and lupus anticoagulant (LA), in the present study, we measured the plasma levels of TF antigen and TF pathway inhibitor (TFPI) antigen in patients positive for LA. Plasma TF and TFPI levels in LA-positive patients were significantly higher than levels in healthy volunteers (p < 0.01). In LA-positive patients, there were no significant differences in plasma TF and TFPI levels between patients with and without thrombosis. In patients with thrombosis, there was no significant difference in the plasma TF level between LA-positive and LA-negative patients; however, the plasma TFPI level in LA-positive patients was significantly lower than that in LA-negative patients (p < 0.01). We also examined the TF pathway in human umbilical venous endothelial cells (HUVEC) incubated with plasma of LA-positive patients, LA-negative patients, and healthy volunteers. TF activity was significantly higher (p < .05) in HUVECs incubated with the plasma of LA-positive patients than in cells incubated with the plasma of the other two groups (p < .01). However, there was no significant difference in TFPI antigen levels among the media of HUVECs incubated with the plasma of all groups. The viability of HUVEC incubated with the plasma of LA-positive patients with thromboses, LA-positive patients without thromboses, and LA-negative patients with thromboses were significantly lower than that of HUVECs incubated with the plasma of healthy volunteers (p < .01). These findings suggest that abnormalities of the TF pathway plays an important role in the mechanism of hypercoagulability in LA-positive patients. LA may affect vascular endothelial cells causing thrombogenesis.
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PMID:Aberrations of the tissue factor pathway in patients positive for lupus anticoagulant. 1072 76

Anti-beta2-Glycoprotein I (beta2GPI) autoantibodies are the prominent laboratory feature of Hughes syndrome. By prolonging some coagulation tests in the presence of exogenous phospholipids (PL), they behave as classical Lupus Anticoagulants (LA). We investigated the effect of 3 affinity-purified anti-beta2GPI IgG preparations from patients with Hughes syndrome on fibrin polymerization and fibrinolysis of normal plasma, measured by comparing the optical densities of assay mixtures in the presence of the autoantibodies or normal IgG. The presence of anti-beta2GPI IgG in diluted Russell Viper Venom Time (dRVVT) assays, carried out using a PL dilution of 1:8 or 1:64, resulted in a delay in the onset of polymerization by 30-40 and 60-70s, respectively. Fibrin polymerization was complete after 250s for both anti-beta2GPI IgG and normal IgG. The inhibitory effect of the anti-beta2GPI antibodies was not observed in the presence of excess PL, as expected for LA. Anti-beta2GPI IgG increased the plateau level of polymerization when dRVVT was performed in the presence of 1.5 nM recombinant tissue plasminogen activator, but did not impair the fibrinolytic process, which was almost complete after 250 min. The autoantibodies did not delay the onset of fibrin polymerization in tests carried out using recombinant tissue factor. On the contrary, the autoantibodies enhanced polymerization in prothrombin time assays, and accelerated it in tissue thromboplastin inhibition tests, with no effect on fibrinolysis. These data provide evidence that anti-beta2GPI LA may act as either anticoagulants or procoagulants in different in vitro coagulation tests.
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PMID:Effect of anti-beta2glycoprotein I Lupus Anticoagulants on fibrin polymerization and fibrinolysis. 1095 74

Because of the variable responsiveness of thromboplastins to lupus anticoagulants (LA), concerns have been raised about the validity of the prothrombin time-International Normalized Ratio (PT-INR) in monitoring oral anticoagulant treatment in patients with the antiphospholipid syndrome (APS) and LA. To date, few studies have been performed, numbers of patients investigated are relatively small and results are conflicting. We report on a multicentre study organized to investigate further this clinically relevant issue. Each of nine thrombosis centres was asked to collect plasma samples from patients with APS who were on oral anticoagulants (cases) and patients without APS who were on oral anticoagulants (controls). Nine thromboplastins (three human recombinant, one from human placenta and five from rabbit brain) were calibrated at the co-ordinating centre according to World Health Organization guidelines. Measurements of the INR and factor X amidolytic activity for all frozen plasmas were performed centrally. The numbers of patients investigated were 58 cases and 57 controls. Between-reagent variability of the INR was higher in cases [coefficient of variation (CV) = 12.4%] than in controls (CV = 6.7%), but this was because of one of the thromboplastins only (Thromborel R, human recombinant), which measured considerably higher INR values than the others in cases but not in controls. In conclusion, our data indicate that LA interference on the PT-INR measured with the majority of commercial thromboplastins is not enough to cause concern if insensitive thromboplastins, properly calibrated to assign them an instrument-specific International Sensitivity Index are used. New thromboplastins, especially those made of relipidated tissue factor, should be checked for their responsiveness to LA before they are used to monitor oral anticoagulant treatment in patients with APS.
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PMID:Laboratory control of oral anticoagulant treatment by the INR system in patients with the antiphospholipid syndrome and lupus anticoagulant. Results of a collaborative study involving nine commercial thromboplastins. 1173 53

In patients with lupus anticoagulants (LA), acquired resistance to activated protein C (APC) is difficult to demonstrate with clot-based assays due to the presence of the anticoagulant. Via the conversion of a fluorogenic substrate (thrombinography), we monitored the complete process of thrombin formation and decay and its delimitation by the protein C system in eight consecutive LA-patients without anticoagulant therapy and non-carriers of the V Leiden polymorphism. Thrombin generation was triggered in platelet-poor and platelet-rich plasma by recalcification in the presence of a low concentration of tissue factor. In 7 out of 8 patients we observed a long lag-time before the thrombin burst (LA effect) together with a marked inability of APC to diminish the thrombin activity. The lag-phase was however prolonged to some degree by APC. The effects were more outspoken in the presence of phospholipids from patients' platelets than with added phospholipids. Thrombinography thus demonstrates APC resistance in LA-patients despite the occurrence of long lag-times (clotting times). The amount of thrombin activity generated in the presence of APC could be a better indicator of the thrombotic risk than the moment at which the thrombin burst starts.
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PMID:Thrombinography shows acquired resistance to activated protein C in patients with lupus anticoagulants. 1257 97

The association of antiphospholipid (aPL) antibodies with thrombosis in patients with antiphospholipid syndrome (APS) is well documented in humans and in animal studies. However, the mechanisms by which aPL antibodies induce thrombosis are the subject of much current study. It has been suggested that aPL may activate endothelial cells (ECs), thus creating a hypercoagulable state that precedes and contributes to thrombosis in patients with APS. Several studies have shown that aPL upregulate ECs' adhesion molecules (CAMs): intercellular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin (E-sel) or induce tissue factor (TF) in monocytes in vitro. Similarly, the incubation of EC with antibodies reacting with beta2glycoprotein I (beta2GPI) has been shown to induce EC activation with concomitant upregulation of CAMs, IL-6 production and alteration of prostaglandin metabolism. Our group has shown that aPL-mediated upregulation of adhesion molecules on ECs correlates with an increased adhesion of leukocytes to endothelium in the microcirculation of mouse cremaster muscle, a n indication of EC activation in vivo, andwith enhanced thrombosis in vivo. In another series of studies, investigators have shown that upregulation of expression of adhesion molecules by some murine monoclonal anti-beta2glycoprotein I (anti-beta2GPI) antibodies correlated with fetal resorption in mice in vivo. More recently, one study showed that the anti-hypercholesterolaemic drug fluvastatin inhibited the aPL-mediated enhanced adhesion of monocytes to ECs in vitro. Data from our laboratories indicate that fluvastatin also reverses thrombus formation and activation of EC induced by aPL in an in vivo mouse model. As additional support for the hypothesis that aPL antibodies activate ECs and may create an hypercoagulable state in APS patients, two recent studies indicated that levels of soluble ICAM-1 and VCAM-1 were significantly increased in the plasma of patients with APS and recurrent thrombosis. Furthermore, studies utilizing knockout mice and specific monoclonal anti-VCAM-1 antibodies have demonstrated that expression of ICAM-1, P-selectin, E-selectin and VCAM-1 are important in in vivo aPL-mediated thrombosis and EC activation in mice. Recent data suggests that aPL antibodies also induce expression of TF not only in monocytes but in ECs. Hence, the interference of aPL with the TF mechanism may be another important mechanism by which these antibodies create a hypercoagulable state and prone patients to thrombosis. Specifically, how aPL alters EC activation state and the molecular and intracellular mechanisms involved have not yet been defined. APL may interact with specific cell surface receptors (proteins and/or lipids) induce signals that have consequences downstream, and that ultimately will result in upregulation of cell surface proteins (i.e., CAMs and TF) and subsequently induce EC activation. In that regard, our group recently showed that aPL-mediated upregulation of adhesion molecules in ECs is preceded by activation of the nuclear factor kappa B (NFkappaB). Other intracellular mechanisms triggered by aPL are not completely understood and are the subject of current investigation. In conclusion, studies suggest that activation of ECs by aPL is an important mechanism that may precede thrombus formation in patients with APS. Hence, the interplay between aPL antibodies and ECs is important inthe pathogenesis of thrombosis in APS.
Lupus 2003
PMID:Probing antiphospholipid-mediated thrombosis: the interplay between anticardiolipin antibodies and endothelial cells. 1289 95

The antiphospholipid syndrome (APS) is characterized by the presence of antiphospholipid antibodies (aPL) in patients with thromboembolic complications. In APS, most aPL are autoantibodies to beta2-glycoprotein I and prothrombin, which play a major role in the APS pathogenesis. Nevertheless, antibodies with the same antigen specificity are also found in aPL patients with leprosy, in whom thromboembolic complications are uncommon. The in vivo upregulation of the tissue factor (TF) pathway and the imbalance of cytokines have been proposed as potential mechanisms of thrombosis in the APS. We measured the circulating levels of TF, interleukin 6 (IL-6), IL-6 receptor (sIL-6R), tumor necrosis factor (TNF-alpha) and interferon gamma (IFN-gamma) in 83 patients with autoimmune aPL (42 with and 41 without clinical features of definite primary APS), 48 leprosy patients (33 with aPL) and 48 normal controls. There was a trend (P = 0.06) to higher median sTF in patients with autoimmune aPL (139 pg/mL) compared with leprosy patients (103.5 pg/mL) and controls (123 pg/mL). In addition, the frequency of raised sTF levels (> 187 pg/mL) was significantly higher in the group with autoimmune aPL [22.9% (APS 21.4%, non-APS 24.4%)] but not in leprosy (10.4%) compared with controls (4.2%). Elevated levels of IL-6 and TNF-alpha and a trend to lower IFN-gamma were found in patients with definite APS. Leprosy patients with aPL, however, had increased TNF-alpha and IFN-gamma but normal IL-6 levels. Levels of sIL-6R did not differ between controls and either patients with autoimmune aPL or leprosy. The different cytokine profiles as well as differences in circulating levels of TF might contribute to the high thrombotic risk found in patients with autoimmune aPL but not in leprosy related aPL patients.
Lupus 2005
PMID:Circulating levels of tissue factor and proinflammatory cytokines in patients with primary antiphospholipid syndrome or leprosy related antiphospholipid antibodies. 1575 17

Many patients with lupus anticoagulants (LA) are treated with oral anticoagulation and monitored using the international normalised ratio (INR) derived from the prothrombin time (PT). Recent reports have produced conflicting conclusions about the extent to which LA interferes with PT determination. The degree of anticoagulation may be overestimated in a patient whose LA affects the PT. A number of reports conclude that specific thromboplastin reagents containing recombinant tissue factor are sensitive to the presence of LAs and should not be used to monitor oral anticoagulant therapy in these patients. These studies were performed on orally anticoagulated patients. The present retrospective study on 400 patients with LAs who were not receiving therapeutic anticoagulation was performed to ascertain the frequency of prolonged PT in these patients when using Innovin recombinant thromboplastin. Only 17 (4.3%) out of 400 had prolonged PT in the presence of LA. As this is a low prevalence, and not all patients with LAs will require anticoagulant therapy, it is concluded that baseline INR determination should be used to highlight the need to monitor individual patients with LA-insensitive reagents. As the use of moderate-intensity oral anticoagulation for patients with LAs and previous thrombosis is receiving wider acceptance, an informed approach to anticoagulant monitoring will reduce the possibility of under-anticoagulating patients receiving this therapy.
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PMID:Low frequency of elevated prothrombin times in patients with lupus anticoagulants when using a recombinant thromboplastin reagent: implications for dosing and monitoring of oral anticoagulant therapy. 1581 6

The association of thrombosis and gestational morbidity with antiphospholipid antibodies is termed antiphospholipid syndrome (APS). Annexin 2 (A2) is a profibrinolytic endothelial cell surface receptor that binds plasminogen, its tissue activator (tPA), and beta(2)-glycoprotein I (beta2GPI), the main antigen for antiphospholipid antibodies. Here, we evaluate A2 as a target antigen in APS. Serum samples from 434 individuals (206 patients with systemic lupus erythematosus without thrombosis, 62 with APS, 21 with nonautoimmune thrombosis, and 145 healthy individuals) were analyzed by enzyme-linked immunosorbent assay (ELISA) and immunoblot for antiphospholipid and A2 antibodies. Anti-A2 antibodies (titer > 3 SDs) were significantly more prevalent in patients with APS (22.6%; venous, 17.5%; arterial, 34.3%; and mixed thrombosis, 40.4%) than in healthy individuals (2.1%, P < .001), patients with nonautoimmune thrombosis (0%, P = .017), or patients with lupus without thrombosis (6.3%, P < .001). Anti-A2 IgG enhanced the expression of tissue factor on endothelial cells (6.4-fold +/- 0.13-fold SE), blocked A2-supported plasmin generation in a tPA-dependent generation assay (19%-71%) independently of beta2GPI, and inhibited cell surface plasmin generation on human umbilical vein endothelial cells (HUVECs) by 34% to 83%. We propose that anti-A2 antibodies contribute to the prothrombotic diathesis in antiphospholipid syndrome.
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PMID:Autoantibodies against the fibrinolytic receptor, annexin 2, in antiphospholipid syndrome. 1649 10


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