The relationship between plasma and placental tissue factor, and tissue factor pathway inhibitors in severe pre-eclampsia patients

Objective

To investigate the mechanism underlying the hypercoagulable state in severe pre-eclampsia.

Methods

Plasma tissue factor (TF) and tissue factor pathway inhibitor (TFPI) expression from pre-eclampsia patients and healthy pregnant controls were determined by ELISA. Placental TF and TFPI gene and protein expression were detected by quantitative RT-PCR, immunohistochemistry, and Western analysis.

Results

The plasma TF level in the pre-eclampsia group was significantly higher than the control group (p < 0.01), and surprisingly, the plasma TFPI-1 and TFPI-2 in the pre-eclampsia group were significantly lower (p < 0.01). Placental TF gene and protein expression levels in the pre-eclampsia group was significantly higher than the control group, while TFPI-1 and TFPI-2 levels were significantly lower (p < 0.05). Lastly, a significant correlation was found between plasma and placental TF protein levels in the pre-eclampsia group (p < 0.01).

Conclusion

Higher expression and/or release of TF from the placenta may contribute towards a pathological hypercoagulable state in pre-eclampsia patients.     

Markers of haemostasis and angiogenesis in placentae from gestational vascular complications: Impairment of mechanisms involved in maintaining intervillous blood flow

Introduction

Preeclampsia (PE) and fetal growth restriction (FGR) are multifactorial diseases, whose pathogenesis is largely unknown. A significant relationship between haemostasis and angiogenesis in placentae from uneventful pregnancies was previously shown.

Materials and Methods

RNA expression of haemostasis (TF, TFPI, TFPI-2, PAI-2, Anx V, TM) and angiogenesis (Ang-1, Ang-2, PlGF, VEGF) markers in placentae from PE (n = 12), PE+FGR (n = 17) and FGR (n = 20) in respect of placentae from uncomplicated pregnancies (n = 21) were investigated.

Results

Placentae from complicated pregnancies showed a significant lower expression (p ≤ 0.05 Mann-Whitney U test) of TF, TFPI, TFPI-2, Anx V, PAI-2 than those from in uncomplicated ones. VEGF and PlGF were not different in the considered groups; Ang-1 and Ang-2 were significantly higher (p ≤ 0.05 Mann-Whitney U test) in the PE group.Correlations between factors involved in haemostasis and those involved in angiogenesis, observed in placentae from uneventful pregnancies are lacking in those from complicated ones.

Conclusions

Haemostasis factors are reduced in placentae from complicated pregnancies. The relationship between haemostasis and angiogenesis observed in uncomplicated pregnancies is impaired in PE and FGR.     

Plasma factor and inhibitor composition contributes to thrombin generation dynamics in patients with acute or previous cerebrovascular events

Introduction

More than 80% of cerebrovascular events are ischemic and largely thromboembolic by nature. We evaluated whether plasma factor composition and thrombin generation dynamics might be a contributor to the thrombotic phenotype of ischemic cerebrovascular events.

Materials and Methods

We studied (1) 100 patients with acute ischemic stroke (n = 50) or transient ischemic attack (TIA) (n = 50) within the first 24 hours from symptom onset, and (2) 100 individuals 1 to 4 years following ischemic stroke (n = 50) or TIA (n = 50). The tissue factor pathway to thrombin generation was simulated with a mathematical model using plasma levels of clotting factors (F)II, V, VII, VIII, IX, X, antithrombin and free tissue factor pathway inhibitor (TFPI).

Results

The plasma levels of free TFPI, FII, FVIII, and FX were higher, while antithrombin was lower, in the acute patients compared to the previous event group (all p ≤ 0.02). Thrombin generation during acute events was enhanced, with an 11% faster maximum rate, a 15% higher maximum level and a 26% larger total production (all p < 0.01). The increased thrombin generation in acute patients was determined by higher FII and lower antithrombin, while increased free TFPI mediated this effect. When the groups are classified by etiology, all stroke sub-types except cardioembolic have increased TFPI and decreased AT and total thrombin produced.

Conclusion

Augmented thrombin generation in acute stroke/TIA is to some extent determined by altered plasma levels of coagulation factors.     

Circulating monocytes mirror the imbalance in TF and TFPI expression in carotid atherosclerotic plaques with lipid-rich and calcified morphology

Background

Thrombogenicity of atherosclerotic plaque largely depends on plaque morphology and their content of tissue factor (TF) and tissue factor pathway inhibitor (TFPI). The relationship between morphological composition of plaque (lipid-rich or calcified) and expression of TF and TFPI in circulating blood monocytes and within the plaques is not characterized.

Objective

To investigate whether lipid-rich (echolucent) or calcified (echogenic) morphology of carotid atherosclerotic plaques is associated with differences in TF and TFPI expression in circulating blood monocytes and within carotid atherosclerotic plaques.

Methods

We studied levels of monocyte TF and TFPI mRNA and protein expression and association with traditional risk factors for atherosclerosis in asymptomatic subjects with echolucent (n = 20) or echogenic (n = 20) carotid plaques, or controls without carotid atherosclerosis (n = 20) determined by ultrasonography. Sections of calcified or lipid-rich carotid plaques obtained from symptomatic patients were assessed for TF and TFPI antigen expression.

Results

TF and TFPI surface presentation, surface TF/TFPI ratio, and TF activity were higher in monocytes obtained from subjects with echolucent than with echogenic plaques or controls without carotid atherosclerosis. Multiple regression analyses revealed inverse association between serum apoA1 and monocyte surface TF antigen expression (p = 0.007), and positive association between serum apoB and monocyte surface TFPI expression (p = 0.028). Sections from lipid-rich carotid plaques contained 2.5-fold more TF and 1.5-fold more TFPI antigens relative to calcified lesions, also yielding a higher TF/TFPI ratio.

Conclusions

Our findings indicate that circulating monocytes of asymptomatic individuals with echolucent lipid-rich carotid atherosclerosis express an imbalance between TF and TFPI expression cohering with changes found within advanced carotid atherosclerotic plaques obtained from symptomatic patients.     

Factor Seven Activating Protease (FSAP) levels during normal pregnancy and in women using oral contraceptives

Introduction

Factor seven activating protease (FSAP) is a plasma serine protease involved in haemostasis and remodeling processes. We have investigated whether pregnancy or the use of oral contraceptives (OCs) influences circulating FSAP levels. The effect of female sex hormones on FSAP expression in cultured cells was also determined.

Materials and Methods

FSAP levels and activity was measured in plasma samples obtained at different gestation stages from healthy pregnant women (n = 101), from non-pregnant women, pre-menopausal women who currently use OCs (n = 48), and non-pregnant women who did not use OCs (n = 69).

Results

In late pregnancy the plasma FSAP antigen (median 2.28 PEU/ml [range 1.11 to 2.62 PEU/ml]; p < 0.001 vs control group) and activity (median 2.98 PEU/ml [range 1.05 to 4.24 PEU/ml]; p < 0.001 vs control group) was significantly higher compared with levels in non-pregnant women and remained elevated after delivery. Plasma FSAP levels in women using OCs was also significantly elevated compared to the control group. Ex vivo experiments demonstrated enhanced FSAP expression in monocytes isolated from women using OCs. In vitro experiments showed that FSAP mRNA levels were strongly induced by estradiol in monocytes but not in hepatocytes.

Conclusions

Increased levels of circulating FSAP in pregnancy and in women using OCs indicate that hormonal status critically influences FSAP expression. Hormonal influences could be observed in monocytes in vivo and ex-vivo but not in hepatocytes indicating cell-specific regulation. Future studies designed to investigate the role of FSAP in haemostasis and remodeling processes should consider the role of female sex hormones on FSAP expression.     

Gene expression analysis of HUVEC in response to TF-binding

Introduction

Tissue factor (TF), the cofactor for factor VII/VIIa (FVII/FVIIa) and initiator of the extrinsic pathway, is transiently expressed on intravascular cells under control of cytokines and growth factors. In addition, endothelial cells express a binding site for external TF. In the present study, we investigated gene expression of endothelial cells derived from human umbilical veins (HUVEC) in response to TF-binding to identify differentially expressed genes.

Materials and methods

HUVEC were treated with recombinant relipidated TF (Innovin) versus nontreated cells, as well as TF/FVIIa versus FVIIa alone. TF binding was measured by ELISA. Gene expression profiles were examined using HG-U133 plus 2.0 arrays (Affymetrix).

Results

Gene expression analysis of HUVEC showed 148 up-regulated and 29 down-regulated genes 4 h after TF binding. Notably, the genes, which were significantly up- and down-regulated, either by TF alone or by the complex of TF/FVIIa, exhibited a complete overlap, indicating that activation of endothelial cells after binding of external added TF does not depend on FVIIa as has been demonstrated for TF-expressing cells. TF-mediated regulation of gene expression of several genes, involved in regulation of apoptosis, cell adhesion, cell motility, and angiogenesis, was confirmed by qPCR. Furthermore, in case of SELE, TGFB2, TNFAIP3, TNFSF4, TNFSF18, TAGLN, CXCL1, PCF11 antibodies directed to TF clearly inhibited TF-mediated regulation of gene expression.

Conclusions

The results demonstrate that interaction of TF with HUVEC via a binding site, independent from FVIIa, may result in regulation of a variety of genes involved in arteriosclerosis, cancer, and cardiovascular diseases.     

Murine strain differences in hemostasis and thrombosis and tissue factor pathway inhibitor

Introduction

Differences among murine strains often lead to differential responses in models of human disease. The aim of the current study was to investigate whether differences exist among strains in models of hemostasis and thrombosis and whether these differences are reflected in differences in the tissue factor (TF) pathway.

Methods

We examined baseline hemostatic parameters and the response to FeCl3-induced arterial thrombosis and a tail vein bleeding model in C57BL/6J (C57), 129S1/SvImJ (129S), and Balb/cJ (BalbC) mice. Finally, we examined TF and tissue factor pathway inhibitor (TFPI) activities in blood and expression in vascular tissue to determine whether these factors covary with a thrombotic phenotype.

Results

No differences were observed in PT or aPTT among strains. 129S mice had lower platelet counts (p < 0.001). BalbC had an increased rate of occlusion (mean occlusion time of 330 ± 45 sec) in a FeCl₃-induced model of thrombosis when compared to C57 (1182 ± 349 sec) or 129 S (1442 ± 281 sec) (p < 0.05). Similarly, BalbC demonstrated reduced blood loss in tail bleeding experiments when compared to C57 and 129S. Vascular expression of TF and TFPI content did not correlate with the thrombotic phenotype of BalbC. However, circulating TFPI activities were lower in BalbC compared to both C57 and 129S mice. When normalized to circulating TF activities, BalbC had lower circulating TFPI activity than C57 and 129S, and there was a significant correlation between tail bleeding and normalized TFPI activity (r = 0.67).

Conclusions

These data suggest that there are significant differences among strains in thrombosis and hemostasis and that circulating TFPI activity correlates with these differences.     

Activation of coagulation in amniotic fluid during normal human pregnancy

Introduction

Amniotic fluid (AF) is an important medium for fetal development which exhibits high procoagulant activities; however, the role of these procoagulants during pregnancy has not been elucidated and might be associated with pregnancy complications. The current study aimed to evaluate factor X (FX) activation and its association with tissue factor (TF), tissue factor pathway inhibitor (TFPI) and coagulation activation markers in AF during normal human pregnancy.

Methods

Activation of FX and concentration of TF, free TFPI, D-dimer and prothrombin fragments (F1 + 2) were evaluated in AF samples obtained for chromosome analysis from 91 women with normal pregnancy: 65 samples were taken from patients at 16-20 weeks of gestation, 9 samples were drawn at 21-30 weeks and 17 samples−after 30 weeks of gestation.

Results

Activation of FX in AF significantly increased during normal pregnancy (from 65 ± 41 to 205 ± 80 equivalent RVV ng/mg total protein, P < 0.0001). TF and TFPI levels in AF also rose with gestational age. In contrast, the AF concentration of D-dimer and F1 + 2, markers of coagulation activation significantly decreased when expressed per mg total protein. Levels of free TFPI correlated with TF (r = 0.5, P < 0.001), and were 8-fold higher than those of TF during pregnancy.

Conclusion

High levels of TFPI might be associated with the inhibition of procoagulant activity in amniotic fluid during normal pregnancy, which may account for the rarity of clinical amniotic fluid embolism.     

New observations on procoagulant properties of amniotic fluid: Microparticles (MPs) and tissue factor-bearing MPs (MPs-TF), comparison with maternal blood plasma

Introduction

Microparticles (MPs) are submicron fragments of the cell membrane affecting many biological processes, e.g. coagulation. The aim of the study was to determine (i) MPs and (ii) tissue factor bearing MPs (MPs-TF) in the amniotic fluid and in blood plasma of parturient women, as well as to assess (iii) TF and TFPI.

Material and methods

The study group consisted of 38 women laboring at term, whereas the control group included 20 non-pregnant women. ELISA method was used to evaluate MPs, MPs-TF, TF and TFPI.

Results

The levels of MPs and MPs-TF were significantly higher in the amniotic fluid than in blood plasma of parturient women: the level of MPs was 41.08 times higher (medians: 246.48 nM PS vs. 6.00 nM PS, respectively, p < 0.001), and the level of MPs-TF was 18.59 times higher (medians: 90.16 pg/ml vs. 4.85 pg/ml, respectively) (p < 0.001).

Conclusions

1. Microparticles (MPs) and tissue factor-bearing MPs (MPs-TF) are constituent components of amniotic fluid. 2. It is reasonable to assume that these components together with tissue factor (TF) and its inhibitor (TFPI) can participate in life-threatening coagulation disturbances in amniotic fluid embolism, and to take into consideration their impact on fetal development.     

Tumour expresion of tissue factor and tissue factor pathway inhibitor in ovarian cancer- relationship with venous thrombosis risk

Introduction

Ovarian cancer is known to display a particular association with venous thromboembolism (VTE) with reports up to 42% of patients developing thromboembolic complications. Tissue Factor (TF) and its inhibitor Tissue Factor Pathway Inhibitor (TFPI) have been implicated in VTE risk in cancer. The aim of this study was to measure tumour derived TF and TFPI and to investigate their potential role in VTE in ovarian cancer patients.

Methods

TF and TFPI mRNA expression was measured using TaqMan real time PCR in 99 ovarian tumour samples. Nineteen cases complicated by VTE were matched to 19 cases without VTE. TF and TFPI protein levels were measured using ELISA and immunohistochemistry was used to localize TF expression. The role of TF expression on overall survival was also determined.

Results

TF mRNA and protein expression was increased in tumours from patients with clear cell carcinoma (p < 0.001). TF protein expression was also increased in endometroid carcinoma (P < 0.01) compared with benign tumours. TFPI mRNA expression was increased in clear cell carcinoma (P < 0.01). TF mRNA and antigen level was increased in malignant tumours of patients who developed VTE compared with matched malignant õtumours of patients who remained thrombosis free (P < 0.01). There was no difference in TFPI expression between the two groups.

Conclusion

TF expression in ovarian cancer is significantly higher in patients who develop VTE. TF expression was increased in clear cell ovarian cancer and endometroid cancer and this may explain the higher risk of VTE in these subgroups. TF derived from these tumours may be the trigger for VTE in ovarian cancer.     

Platelet activation and endogenous thrombin potential in pre-eclampsia

Introduction

Platelets and the coagulation system may be involved in the pathogenesis of pre-eclampsia. We investigated whether platelet and coagulation activation markers, are elevated in pre-eclampsia.

Materials/methods

Case-control study in which activated platelets, platelet-monocyte/ neutrophil aggregates, platelet microparticles (measured by flow cytometry) and four markers of thrombin generation capacity (endogenous thrombin potential (ETP), peak height, lag time and time to peak) using the Calibrated Automated Thrombogram system were assessed in pregnant women of similar gestational age with (n = 46) and without (n = 46) pre-eclampsia, and in healthy non-pregnant women (n = 42).

Results

The percentage of, CD62P+ platelets (p = 0.013), CD62P+ platelet microparticles (p = 0.029) and platelet-monocyte aggregates (p = 0.019) were significantly higher in women with pre-eclampsia than the pregnant controls. Both groups of pregnant women had significantly higher ETP and peak height (p  < 0.001) than the healthy non pregnant group and the women with pre-eclampsia had significantly higher ETP and peak height (p < 0.001) than the normotensive pregnant controls.

Conclusion

In the most comprehensive laboratory analysis to date, we found evidence of both platelet and coagulation activation in women with pre-eclampsia.     

Activated factor XI and tissue factor in chronic obstructive pulmonary disease: links with inflammation and thrombin generation

Introduction

Increased cardiovascular mortality and risk of venous thromboembolism are serious extra-pulmonary complications of chronic obstructive pulmonary disease (COPD). Previously, circulating active tissue factor (TF) and factor XIa (FXIa) have been reported to be associated with acute coronary syndromes.

Objective

To measure plasma FXIa and active TF, prothrombin fragment 1.2 (F1.2), and markers of systemic inflammation (C-reactive protein [CRP], interleukin-6 [IL-6], tumor necrosis factor α [TNFα] and matrix metalloproteinase 9 [MMP-9]) in 60 patients with documented stable COPD free of previous thromboembolic events.

Methods

In-house clotting assays using inhibitory monoclonal antibodies against FXIa and TF.

Results

FXIa was detected in 9 (15%) and TF activity in 7 (11.7%) COPD patients. Subjects positive for FXIa and/or TF (n = 10; 16.7%) had higher F1.2 (median [interquartile range], 398 [216] vs 192 [42] pM, p < 0.000001), fibrinogen (5.58 [2.01] vs 3.97 [2.47] g/L, p = 0.0007), CRP (14.75 [1.20] vs 1.88 [2.95] mg/L, p < 0.000001), IL-6 (8.14 [4.74] vs 2.45 [2.24] pg/mL, p = 0.00002), and right ventricular systolic pressure (47 [15] vs 38 [12] mmHg, p = 0.023), and lower vital capacity (66 [15] vs 80 [17] % predicted, p = 0.04) than COPD patients without detectable FXIa and TF. COPD severity was not associated with the presence of circulating FXIa and active TF.

Conclusions

This is the first study to show that active FXIa and TF are present in stable COPD patients, who exhibit enhanced systemic inflammation and thrombin generation. Our findings suggest a new prothrombotic mechanism which might contribute to elevated risk of thromboembolic complications in COPD.     

Increased heparanase level and procoagulant activity in orthopedic surgery patients receiving prophylactic dose of enoxaparin

Background

Orthopedic hip and knee surgeries are followed by a hypercoagulable state. Heparanase is implicated in inflammation, coagulation activation and angiogenesis. Recently, heparanase was shown to directly interact with tissue factor (TF) and to enhance the generation of factor Xa (Nadir et al., Haematologica, 2010). In addition, an assay assessing heparanase procoagulant activity has been lately developed (Nadir et al., Thromb Res, 2011). In the present study heparanase level and procoagulant activity in patients undergoing orthopedic surgery were assessed.

Methods

The study group included 50 orthopedic patients. 31 patients underwent hip surgery and 19 had knee operation. 15 individuals suffered from traumatic hip fractures and 35 had osteoarthrosis of hip or knee joints. All patients received prophylactic dose of enoxaparin starting 6-8 hours post operation and lasting for 5 weeks. Plasma samples were drawn preoperatively and at 1 hour, 1 week and 1 month post operation. Samples were tested for heparanase levels by ELISA and TF/heparanase complex activity, TF activity, heparanase procoagulant activity, factor Xa and thrombin levels using chromogenic substrates.

Results

Heparanase levels were significantly higher 1 hour and 1 week post operatively compared to preoperative levels (p < 0.05, p < 0.005, respectively). The most dramatic changes were observed in heparanase procoagulant activity reaching a 2 fold increase 1 week postoperatively and 1.7 fold increase 1 month after surgery (p < 0.0001, p < 0.0001, respectively). Levels of factor Xa and thrombin did not significantly change.

Conclusions

Heparanase is involved in coagulation activation of orthopedic surgery patients. Heparanase procoagulant activity is highest 1 week postoperatively and remains high 1 month after operation. Considering extending prophylactic anticoagulant therapy or evaluating heparanase procoagulant activity may potentially prevent late thrombotic events.     

Chronic viral hepatitis C, oxidative stress and the coagulation/fibrinolysis system in haemodialysis patients

Introduction

The aim of the present study was to establish whether the presence of chronic viral hepatitis (PVH) could be implicated in the elevation of oxidative stress (SOX) and haemostasis system in haemodialysis (HD) patients.

Matherials and methods

In HD patients with and without PVH and in controls we compared the markers of: coagulation pathway- tissue factor (TF) and its inhibitor (TFPI), prothrombin fragment F _1 + 2 (F _1 + 2); fibrinolysis: tissue-type plasminogen activator (tPA), urokinase-type plasminogen activator (uPA) and its soluble receptor (suPAR), plasminogen activator inhibitor 1 (PAI-1), plasmin/antiplasmin complexes (PAP); and a marker of SOX - Cu/Zn superoxide dismutase (Cu/Zn SOD) levels.

Results

Patients, particularly those with PVH, showed a significant increase in the markers of the coagulation, fibrinolysis and oxidative status as compared to controls. All parameters of coagulation/fibrinolysis system were directly associated with the PVH and Cu/Zn SOD levels, and there was a relationship between the PVH and Cu/Zn SOD levels. Multivariable analysis showed that PVH and increased SOX were identified as independent variables significantly associated with the disturbances of coagulation/fibrinolysis system in these patients.

Conclusions

We concluded that PVH is a novel determinant of the increased oxidative stress as well as the disturbances of coagulation/fibrinolysis system in haemodialysis patients.     

Detection of endogenous tissue factor levels in plasma using the calibrated automated thrombogram assay

Background

The calibrated automated thrombogram (CAT) assay measures thrombin generation in plasma.

Objective

Use the CAT assay to detect endogenous tissue factor (TF) in recalcified platelet-rich plasma (PRP) and platelet-free plasma (PFP).

Methods

Blood from healthy volunteers was collected into citrate and incubated at 37 °C with or without lipopolysaccharide (LPS) for 5 hours. PRP and PFP were prepared and clotting was initiated by recalcification. Thrombin generation was measured using the CAT assay.

Results

The lag time (LT) was significantly shortened in PRP prepared from LPS-treated blood compared with untreated blood (10 ± 3 min versus 20 ± 6 min), and this change was reversed by the addition of inactivated human factor VIIa. LPS stimulation did not change the peak thrombin. Similar results were observed in PFP (21 ± 4 min versus 35 ± 5 min). LPS stimulation also significantly reduced the LT of PRP and PFP derived from blood containing citrate and a factor XIIa inhibitor. Finally, a low concentration of exogenous TF shortened the LT of PFP prepared from unstimulated, citrated blood without affecting the peak thrombin.

Conclusion

Changes in LT in the CAT assay can be used to monitor levels of endogenous TF in citrated plasma.     

Characterization of negatively charged phospholipids and cell origin of microparticles in women with gestational vascular complications

Introduction

Gestational vascular complications (GVC) are a major cause of maternal and fetal morbidity which can be potentially reduced by LMWH. Microparticles (MPs) are involved in thrombosis and inflammation. However, characterization and role of MPs in GVC have not been elucidated.

Materials and Methods

MPs were isolated from non-pregnant women, healthy pregnant women, women with GVC (hypertension or preeclamptic toxemia (PET)) and women with a history of pregnancy complications who were treated with LMWH. MP count, cell origin and expression of negatively charged phospholipids were evaluated.

Results

Total numbers of MPs were similar in the study cohorts, with a non-significant trend toward an increase in the pregnant groups, while percentage of MPs bearing negatively charged phospholipids was significantly reduced in all the pregnancy groups. Endothelial CD144-MPs were elevated in the GVC groups compared to the healthy pregnant cohort. Endothelial CD31 +/CD41-MPs were decreased in the LMWH group compared to women with PET. Percentage of placental trophoblast MPs was similar in all pregnancy groups and platelet MPs were reduced in healthy pregnant compared to non-pregnant women. Notably, percent of MPs bearing negatively charged phospholipids correlated only with platelet MPs, but not with endothelial, trophoblast or leukocyte MPs.

Conclusion(s)

Presence of negatively charged phospholipids cannot be considered universal characteristics of MPs in pregnancy. MPs may reflect the vascular injury characterizing GVC pathology.     

Anti-phospholipid antibodies contribute to arteriosclerosis in patients with systemic lupus erythematosus through induction of tissue factor expression and cytokine production from peripheral blood mononuclear cells

Introduction

In systemic lupus erythematosus (SLE) patients, the prevalence of arteriosclerosis obliterans (ASO) is high despite a lack of common risk factors for ASO. The main objective of this study was to investigate a possible direct role of anti-phospholipid antibodies (aPLs), which are frequently detected in SLE patients, in the pathogenesis of ASO.

Materials and Methods

We examined tissue factor (TF) expression on the monocyte surface by flow cytometric analysis in 89 SLE patients with or without ASO and/or aPLs and studied the in vitro effect of purified IgG fractions from plasma of SLE patients or normal healthy volunteers (aPLs(+) IgG, n = 8; aPLs(−) IgG, n = 6; Normal IgG, n = 6) on the expression of TF and production of TNF-α and IL-1β in healthy peripheral blood mononuclear cells (PBMCs) or isolated monocytes.

Results

We confirmed that high expression of monocyte TF was strongly associated with the prevalence of ASO and the presence of aPLs. Treatments of PBMCs with aPLs(−) IgG or normal IgG did not significantly increase expression of TF, TNF-α, and IL-1β messenger RNA (mRNA) and the production of TNF-α and IL-1β. However, stimulation of PBMCs with aPLs(+) IgG caused significant increase in expression of TF, TNF-α, and IL-1β mRNA. Moreover, aPLs(+) IgG stimulated PBMCs and significantly enhanced the production of TNF-α and IL-1β.

Conclusion

These results suggest that IgG-aPLs cause persistently high TF expression and inflammatory cytokine production by interacting with peripheral blood monocytes and lymphocytes, which may be an important mechanism in the pathogenesis of ASO peculiar to SLE patients.