The inflammatory receptor CD40 is expressed on human adipocytes: contribution to crosstalk between lymphocytes and adipocytes.

AIMS/HYPOTHESIS: Obesity is associated with adipose tissue inflammation. The CD40 molecule, TNF receptor superfamily member 5 (CD40)/CD40 ligand (CD40L) pathway plays a role in the onset and maintenance of the inflammatory reaction, but has not been studied in human adipose tissue. Our aim was to examine CD40 expression by human adipocytes and its participation in adipose tissue inflammation. METHODS: CD40 expression was investigated in human whole adipose tissue and during adipocyte differentiation by real-time PCR, Western blot and immunohistochemistry. The CD40/CD40L pathway was studied using recombinant CD40L (rCD40L) in adipocyte culture and neutralising antibodies in lymphocyte/adipocyte co-culture. RESULTS: CD40 mRNA levels in subcutaneous adipose tissue were higher in the adipocyte than in the stromal-vascular fraction. CD40 expression was upregulated during adipocyte differentiation. Addition of rCD40L to adipocytes induced mitogen activated protein kinase (MAPK) activation, stimulated inflammatory adipocytokine production, and decreased insulin-induced glucose transport in parallel with a downregulation of IRS1 and GLUT4 (also known as SCL2A4). rCD40L decreased the expression of lipogenic genes and increased lipolysis. CD40 mRNA levels were significantly higher in subcutaneous adipose tissue than in visceral adipose tissue of obese patients and were positively correlated with BMI, and with IL6 and leptin mRNA levels. Lymphocyte/adipocyte co-culture led to an upregulation of proinflammatory adipocytokines and a downregulation of leptin and adiponectin. Physical separation of the two cell types attenuated these effects, suggesting the involvement of a cell-cell contact. Blocking the CD40/CD40L interaction with neutralising antibodies reduced IL-6 secretion from adipocytes. CONCLUSIONS/INTERPRETATION: Adipocyte CD40 may contribute to obesity-related inflammation and insulin resistance. T lymphocytes regulate adipocytokine production through both the release of soluble factor(s) and heterotypic contact with adipocytes involving CD40.

The decrease of fibrinogen is an early predictor of the severity of postpartum hemorrhage.

BACKGROUND: Postpartum hemorrhage (PPH) is a major source of maternal morbidity. OBJECTIVES: This study's objective was to determine whether changes in hemostasis markers during the course of PPH are predictive of its severity. PATIENTS AND METHODS: We enrolled 128 women with PPH requiring uterotonic prostaglandin E2 (sulprostone) infusion. Two groups were defined (severe and non-severe PPH) according to the outcome during the first 24 hours. According to our criteria, 50 of the 128 women had severe PPH. Serial coagulation tests were performed at enrollment (H0), and 1, 2, 4 and 24 hours thereafter. RESULTS: At H0, and through H4, women with severe PPH had significantly lower fibrinogen, factor V, antithrombin activity, protein C antigen, prolonged prothrombin time, and higher D-dimer and TAT complexes than women with non-severe PPH. In multivariate analysis, from H0 to H4, fibrinogen was the only marker associated with the occurrence of severe PPH. At H0, the risk for severe PPH was 2.63-fold higher for each 1 gL(-1) decrease of fibrinogen. The negative predictive value of a fibrinogen concentration >4 gL(-1) was 79% and the positive predictive value of a concentration

Inflammatory, hemostatic, and clinical changes in a baboon experimental model for heatstroke.

The mortality and neurological morbidity in heatstroke have been attributed to the host's inflammatory and hemostatic responses to heat stress, suggesting that immunomodulation may improve outcome. We postulated that an experimental baboon model of heatstroke will reproduce human responses and clinical outcome to allow testing of new therapeutic strategies. Eight anesthetized juvenile baboons (Papio hamadryas) were subjected to heat stress in an incubator maintained at 44-47 degrees C until rectal temperature attained 42.5 degrees C (moderate heatstroke; n = 4) or systolic arterial pressure fell to <90 mmHg (severe heatstroke; n = 4) and were allowed to recover at room temperature. Four sham-heated animals served as a control group. Rectal temperature at the end of heat stress was 42.5 +/- 0.0 and 43.3 +/- 0.1 degrees C, respectively. All heat-stressed animals had systemic inflammation and activated coagulation, indicated by increased plasma IL-6, prothrombin time, activated partial thromboplastin time, and D-dimer levels, and decreased platelet count. Biochemical markers and/or histology evidenced cellular injury/dysfunction: plasma levels of thrombomodulin, creatinine, creatine kinase, lactic dehydrogenase, and alanine aminotransferase were increased, and varying degrees of tissue damage were present in liver, brain, and gut. No baboon with severe heatstroke survived. Neurological morbidity but no mortality was observed in baboons with moderate heatstroke. Nonsurvivors displayed significantly greater coagulopathy, inflammatory activity, and tissue injury than survivors. Sham-heated animals had an uneventful course. Heat stress elicited distinct patterns of inflammatory and hemostatic responses associated with outcome. The baboon model of heatstroke appears suitable for testing whether immunomodulation of the host's responses can improve outcome.

Pentosane polysulfate: the effect on hemostasis of a continuous 3-day infusion.

Pentosane polysulfate (PP) is a sulfated polysaccharide known to exhibit anticoagulant properties that are in part independent of antithrombin III activity. These effects have only been studied in vitro or after single injections in healthy subjects. Our objective was to evaluate the modification of hemostasis induced by a 3-day continuous infusion of PP (4 mg/kg body weight/24 hr) in 10 subjects. No hemorrhagic complication was observed in any patient. Bleeding time was not modified by the infusion, despite a slight decrease in the platelet number. Among the other parameters measured, the automated partial thromboplastin time, prothrombin time, and anti-Xa activity were the most affected by PP. The kinetics of their modifications were quite uniform: clotting times and the anti-Xa effect increased gradually until reaching steady state 24 hours after the start of the infusion. A progressive return to the pretreatment level was then observed during the 6 hours after the end of the infusion. A significant decrease in the factor V concentration was found at day 4. Finally, in contrast with other reported results, no activation of fibrinolysis was induced by PP under the conditions we used, which suggests that discontinuous administration or the route of administration of the drug influences the fibrinolytic effect. In conclusion, we show the excellent tolerance of continuous infusion of PP, detail the modifications in biologic parameters of hemostasis during and after PP infusion, and demonstrate that PP decreases factor V activity.

Pentoxifylline inhibits the expression of tissue factor mRNA in endotoxin-activated human monocytes.

Tissue factor (TF) is a transmembrane glycoprotein which, in association with factor VII(a), is the main activator of coagulation. In illnesses such as Gram-negative endotoxemia, circulating monocytes synthesize and express substantial TF activity, resulting in extensive disseminated intravascular coagulation. We investigated the way in which TF is suppressed by pentoxifylline (PTX), and found that PTX down-regulates immunologic TF expression and specific mRNA production in response to LPS. Since TF mRNA stability is not altered, this effect appears to take place at the transcriptional level.

Interleukin-10 and pentoxifylline inhibit C-reactive protein-induced tissue factor gene expression in peripheral human blood monocytes.

Fibrin deposition is an integral feature of the inflammatory response. In response to C-reactive protein (CRP), an acute-phase reactant, blood monocytes synthesize and express tissue factor (TF), the main initiator of blood coagulation. We report the inhibitory effect of interleukin 10 (IL-10) and that of pentoxifylline, a methyl xanthine derivative, on monocyte expression of TF activity, TF protein and TF mRNA in response to CRP. These agents may be of use in diseases where a TF-induced prothrombotic state is detrimental.

Interleukin-10 inhibits endotoxin-induced tissue factor mRNA production by human monocytes.

In Gram-negative septic shock, human monocytes synthesize and express on their cytoplasmic membrane tissue factor (TF), a potent activator of the coagulation cascades. The role of TF in triggering disseminated intravascular coagulation (DIC) in these patients appears to be clear. We report the suppressive effect of interleukin-10 (IL-10) on endotoxin-induced TF activity and antigen levels, and on the expression of TF mRNA levels in human monocytes. These results emphasize the potential therapeutic value of this cytokine in septic shock, a condition still associated with a high mortality rate.

n-3 polyunsaturated fatty acids raise low-density lipoproteins, high-density lipoprotein 2, and plasminogen-activator inhibitor in healthy young men.

The effects of a moderate supplementation in n-3 polyunsaturated fatty acids (PUFAs) were investigated in 36 young healthy adult males. Factors investigated were lipoprotein (including HDL subfractions and apolipoproteins) and hemostasis indexes, assessed by platelet aggregation and plasminogen-activator-inhibitor (PAI) activity. Fat-controlled diets were prescribed, one with and one without a fish-oil supplement (control diet), successively during 3 wk in random order. Total calorie, fat, and cholesterol intakes were similar in the two diets. Triglycerides in serum and very-low-density lipoproteins were lower and high-density-lipoprotein 2 cholesterol was higher with the n-3 PUFA-supplemented diet. These effects as well as a significant decrease in platelet aggregation can be considered beneficial in terms of cardiovascular risk. However, significant increases in low-density-lipoprotein cholesterol and PAI activity occurred and were correlated. This latter effect could be detrimental.

Increased monocyte procoagulant activity independent of the lupus anticoagulant in patients with systemic lupus erythematosus.

Monocytes can play a role in the activation of coagulation via increased procoagulant activity (PCA). We investigated the level of monocyte PCA in 19 patients with systemic lupus erythematosus (SLE), given the high rate of thrombotic events in this condition. Nine of these subjects also presented the lupus anticoagulant (LA). The PCA generated by patient monocytes was significantly higher than control values and was identified as tissue factor-like. Moreover, the number of monocytes with membrane-associated D dimer, a parameter which we have shown to be correlated with the PCA expressed in vitro by endotoxin-activated monocytes, was also significantly increased. Serum from both groups of patients (i.e. SLE and SLE + LA) stimulated the generation of PCA by control monocytes. By contrast, purified IgG from both patient groups had the same effect as control IgG on PCA generation by control monocytes. The nature of the stimulating agent in the serum was not identified. In conclusion, increased monocyte PCA may account for the increased incidence of thrombosis in SLE patients, although other, superimposed, factors would appear to exist in SLE + LA patients, given the higher incidence of thrombosis in this subgroup.

Intra-coronary thrombolysis with streptokinase or lys-plasminogen/urokinase in acute myocardial infarction: effects on recanalization and blood fibrinolysis.

Forty-two patients with total occlusion of a coronary vessel were treated with intracoronary fibrinolytic agents. Four therapeutic protocols were compared: group I received streptokinase (SK) as a continuous infusion; group II and III received SK as a bolus at different doses and group IV received lysplasminogen (Pg) plus urokinase (UK); maximal doses were 350,000 IU of SK and 250,000 IU of UK plus 75 microK of Pg. Thrombolysis was assessed by coronary angiography. Coagulation studies were performed prior to, 15 min and 6 hr after the end of the thrombolytic treatment. Recanalization was achieved in 27 of the 31 SK-treated patients (87%) and in 7 of the 11 Pg-UK-treated patients (63.6%). The recanalization frequency was the same in the three SK-treated groups, even though when SK was administered as a bolus, the dose was significantly less than when administered on a continuous infusion. Although systemic fibrinolysis occurred in all 4 groups of patients, this effect was less pronounced in the UK-treated patients than in the three SK-treated groups. This study also shows that recanalization can be achieved with a dose of SK lower than the anti-SK antibody level. Haemorrhagic side effects were minimal in all patients studied. Severe defibrination is usually considered a risk of haemorrhage. These preliminary results suggest that bolus injection of SK or the use of UK plus lys-Pg can reduce the level of defibrination and thus the haemorrhagic risk.

Protein tyrosine kinase activation is required for LPS and PMA induction of tissue factor mRNA in human blood monocytes.

Tissue factor (TF) is a transmembrane glycoprotein which assembles with factor VIIa on cell surfaces to form a proteolytically active cofactor-enzyme complex; the TF/VIIa complex initiates the coagulation protease cascade. In response to bacterial lipopolysaccharide (LPS) and phorbol-12 myristate 13-acetate (PMA), monocytes synthesize and express TF on their surface. However, the mechanisms by which LPS and PMA activate TF synthesis by human blood monocytes are not fully understood. As it has been established that LPS and PMA activate protein tyrosine kinase (PTK) in monocytes, we studied the role of PTK in LPS and PMA induction of TF by human blood monocytes. Both LPS- and PMA-induced TF activity was inhibited in a concentration-dependent manner by the protein tyrosine kinase-specific inhibitors herbimycin A and genistein. TF antigen determination confirmed that LPS- and PMA-induced cell surface TF protein levels decreased in parallel to TF functional activity under herbimycin A and genistein treatment. Northern blot analysis of total RNA from LPS- and PMA-stimulated monocytes showed a concentration-dependent decrease in TF mRNA levels in response to herbimycin A and genistein. The rate of decay of LPS-induced TF mRNA, evaluated after the arrest of transcription by actinomycin D was not affected by genistein and herbimycin A, suggesting that the inhibitory effects occur at least partly at the transcriptional level. We conclude that LPS- and PMA-induced TF production by human monocytes is dependent on tyrosine kinase activation.

Evaluation of sensitivity and specificity of a standardized procedure using different reagents for the detection of lupus anticoagulants. The Working Group on Hemostasis of the Société Française de Biologie Clinique and for the Groupe d'Etudes sur I'Hémostase et la Thrombose.

This study was designed to test the sensitivity and specificity of a combination of 3 phospholipid-dependent assays performed with various reagents, for the detection of lupus anticoagulant (LA). Plasmas containing an LA (n = 56) or displaying various confounding pathologies [58 intrinsic pathway factor deficiencies, 9 factor VIII inhibitors, 28 plasmas from patients treated with an oral anticoagulant (OAC)] were selected. In a first step, the efficiency of each assay and reagent was assessed using the Receiving Operating Characteristic (ROC) method. Optimal cut-offs providing both sensitivity and specificity > or = 80% were determined. The APTT assay and most of the phospholipid neutralization assays failed to discriminate factor VIII inhibitors from LA. In a second step, using the optimal cut-offs determined above, the results of all the possible combinations of the 3 assays performed with 4 different reagents were analyzed. Thirteen combinations of reagents allowed > or = 80% of plasmas of each category (LA, factor deficiency or OAC) to be correctly classified (3/3 positive test results in LA-containing plasmas and 0/3 positive results in LA-negative samples).

Endotoxin-induced tissue factor in human monocytes is dependent upon protein kinase C activation.

Tissue factor (TF) is a transmembrane receptor which, in association with factors VII and VIIa, activates factor IX and X, thereby activating the coagulation protease cascades. In response to bacterial lipopolysaccharide (LPS) monocytes transcribe, synthesize and express TF on their surface. We investigated whether LPS-induced TF in human monocytes is mediated by protein kinase C (PKC) activation. The PKC agonists phorbol 12-myristate 13-acetate (PMA) and phorbol 12, 13 dibutyrate (PdBu) were both potent inducers of TF in human monocytes, whereas 4 alpha-12, 13 didecanoate (4 alpha-Pdd) had no such effect. Both LPS- and PMA-induced TF activity were inhibited, in a concentration dependent manner, by three different PKC inhibitors: H7, staurosporine and calphostin C. TF antigen determination confirmed that LPS-induced cell-surface TF protein levels decreased in parallel to TF functional activity under staurosporine treatment. Moreover, Northern blot analysis of total RNA from LPS- or PMA-stimulated monocytes showed a concentration-dependent decrease in TF mRNA levels in response to H7 and staurosporine. The decay rate of LPS-induced TF mRNA evaluated after the arrest of transcription by actinomycin D was not affected by the addition of staurosporine, suggesting that its inhibitory effect occurred at a transcriptional level. We conclude that LPS-induced production of TF and its mRNA by human monocytes are dependent on PKC activation.

Desmopressin has no beneficial effect on excessive postoperative bleeding or blood product requirements associated with cardiopulmonary bypass.

Cardiopulmonary bypass during open-heart surgery is sometimes associated with excessive perioperative bleeding. Following a non-randomized study suggesting that desmopressin acetate (desmopressin) reduced blood product requirements in these patients, we conducted a double-blind, placebo-controlled randomized trial of desmopressin (0.3 micrograms/kg, i. v.) in 92 patients with overt bleeding and a prolonged bleeding time. Mean blood loss during the first 24 h post-treatment was similar in the desmopressin and placebo groups (582 vs 465 ml, respectively; p = 0.15). Red-cell (p = 0.76), fresh frozen plasma (r = 0.66) and platelet unit (p = 0.74) requirements were also similar. The haemostatic effect of desmopressin has been attributed to the release of von Willebrand factor (vWF) and a reduced bleeding time. In our study, vWF and factor VIII:C levels increased while the bleeding time decreased significantly at 90 min and 24 h in both groups and, although vWF and factor VIII:C levels were slightly higher in desmopressin-treated patients at 90 min, the difference was not significant. Thrombin-antithrombin III complex, fibrinogen degradation product and tissue plasminogen activator levels, reflecting activation of the coagulation and fibrinolytic systems, respectively, decreased uniformly in both groups. We conclude that desmopressin is not useful in reducing blood loss or blood product requirements in patients with excessive immediate postoperative bleeding.

Activation of coagulation and fibrinolysis in heatstroke.

Hemorrhagic diathesis and widespread microthrombosis are common in heatstroke. To assess the early stages of coagulopathy in heatstroke, thrombin-antithrombin III (TAT), fibrin monomers, plasmin-alpha 2-antiplasmin (PAP), plasminogen and D-Dimer were measured in 16 heatstroke patients (means +/- SE rectal temperature 42.3 +/- 0.2 degrees C) pre- and postcooling and compared with 8 heatstressed and 23 normal controls. Comparing heatstroke patients with normal controls, TAT, fibrin monomers, PAP and D-Dimer were elevated to (median (range)) 16.5 (4-1000) versus 3.5 (2-7.2) micrograms/l p < 0.001, 16 (4-113) versus 2 (2-9) nM p < 0.001; 3300 (1000-36500) versus 255 (136-462) micrograms/l p < 0.001 and 0.72 (0.22-64.8) versus 0.15 (0.05-0.25) microgram/ml p < 0.01 respectively. Plasminogen decreased to 81% (34-106); PAP, TAT and D-Dimer correlated significantly with hyperthermia (r = 0.577, p = 0.02; r = 0.635, p = 0.01; r = 0.76, p = 0.003). Postcooling PAP decreased to 545 (260-850) micrograms/l p < 0.005, TAT 10 (6-70) micrograms/l, and fibrin monomers 22 (18-86) nM remained unchanged. Heatstressed controls showed mild but significant increase in all markers. Activation of coagulation and fibrinolysis occurs early and is profound and sustained in heatstroke. Cooling seems to attenuate the activation of fibrinolysis only, however, this requires confirmation in a larger study population.

A new T-287C polymorphism in the 5' regulatory region of the tissue factor pathway inhibitor gene. Association study of the T-287C and C-399T polymorphisms with coronary artery disease and plasma TFPI levels.

Tissue factor pathway inhibitor (TFPI) is an important regulator of the extrinsic blood coagulation pathway. We screened the untranslated 5' region of the TFPI gene for polymorphisms and investigated their possible involvement in arterial thrombosis. The allele frequencies of a new polymorphism, located 287 base pairs upstream of the transcription start site (T-287C), and that of the previously described C-399T polymorphism, were similar in cases and controls. In controls, the -287C allele was associated with significantly higher levels of total TFPI antigen, arguing for an effect of this polymorphism on TFPI gene expression. In controls, the C-399T polymorphism did not alter TFPI levels. In the cases, however, decreased total and post-heparin free TFPI levels and increased F1+2 levels were significantly associated with the -399T allele. These findings suggest that the T-287C and C-399T polymorphisms are not associated with an increased risk of coronary heart disease, a result which should be confirmed by a larger study. However, their influence on outcome, or a link with subtypes of acute coronary syndromes, cannot be excluded.

Measurement of low molecular weight heparin ex vivo activities in clinical laboratories using various anti-Xa assays: interlaboratory variability and requirement for an agreed low molecular weight heparin standard.

The only sensitive and convenient assay to assess the biological activity of low molecular weight heparins (LMWHs) is based on the potentiation of activated factor Xa inhibition. Several procedures for measuring the socalled anti Xa activity have been proposed. In this collaborative study including eight laboratories, we have used four different assays (three amidolytic and one clotting based methods) for measuring the anti Xa activity of ex vivo samples obtained after injecting three different LMWHs. The dispersion of the results obtained by calibration against standard heparin could be reduced by using any of the three LMWHs for calibration. A coefficient of variation less than 0.20 between values obtained in different laboratories using a variety of methods seems acceptable. However it is necessary to refer to a common international standard for expressing the results in units and to define, for each of the three products, the therapeutic range.

Binding of an anti D dimer monoclonal antibody to endotoxin-activated monocytes. Demonstration by immunogold-silver staining.

Blood monocytes exposed to a variety of stimuli, of which endotoxin is a potent one, produce and express on their membrane a procoagulant activity (PCA) which can trigger the formation of pericellular fibrin. We have developed an immunogold silver method using a monoclonal anti-D dimer antibody to detect the presence of crosslinked fibrin in derivatives on the monocyte membrane. The in vitro PCA of endotoxin-stimulated monocyte was shown to correlate significantly with the number of D dimer-positive monocytes. We suggest that this method could be used to identify activated monocytes expressing increased PCA.

Monocyte procoagulant activity and membrane-associated D dimer after knee replacement surgery.

We have recently shown that monocyte membrane-associated cross-linked fibrin derivatives (D dimer) can be evidenced by immunogold staining. Using this method, the procoagulant activity (PCA) expressed in vitro by endotoxin-stimulated monocytes has been found to correlate significantly with the number of D dimer-positive monocytes. The incidence of postoperative thrombosis in patients undergoing total knee replacement has been reported by Stulberg et al to be 57%. Since monocytes can play a role, via increased PCA, in the activation of intravascular coagulation, we sought to determine the level of monocyte PCA ex vivo after knee replacement surgery and its possible correlation with the number of D dimer-positive monocytes. Finally, we examined the possible link between these modifications and the occurrence of postoperative deep vein thrombosis (DVT). The PCA expressed by monocytes with or without suboptimal stimulation, the number of D dimer-positive monocytes and the plasma level of D dimer were measured pre- and post-operatively in 11 patients undergoing total knee replacement. Phlebography was performed on day 10 after surgery. A significant increase in the PCA of stimulated monocytes was observed on day 10 after surgery. Moreover, both the number of D dimer-positive monocytes and the plasma level of D dimer increased significantly post-operatively. The number of D dimer-positive monocytes correlated with both monocyte PCA and the plasma D dimer level. The relation between these parameters is discussed. However, neither monocyte PCA nor the number of D dimer-positive monocytes was found to correlate with the occurrence of deep vein thrombosis.

Development of a method to separate lipoprotein-bound and lipoprotein-depleted tissue factor pathway inhibitor. Measurement of free tissue factor pathway inhibitor activity.

The aim of this study was to develop a method to separate lipoprotein-bound from lipoprotein-free tissue factor pathway inhibitor (TFPI) and to measure the TFPI chromogenic activity and antigen in both fractions. This was performed by ultracentrifugation of plasma, after increasing its density to 1.21 g/ml with potassium bromide. Blood was taken from nine volunteers before and after an injection of low-molecular-weight heparin. The ultracentrifugation procedure was adequate, since the mean cholesterol recovery was 91% and only 2% of the cholesterol remained in the lipoprotein-depleted fraction. No free TFPI protein was found in the lipoprotein-rich fraction. Moreover, the amount of free TFPI in the lipoprotein-depleted fraction was close to that found in plasma. Using this method, we confirmed that heparin does not induce an increase in bound TFPI and that the moderate increase in total TFPI antigen in plasma is entirely caused by the enhancement of free TFPI. We then applied the TFPI chromogenic assay to the lipoprotein-depleted fraction to assess the activity of free TFPI. The activity was 0.11+/-0.03 and 0.36+/-0.08 U/ml before and after heparin, respectively (a 3.6-fold increase) while the activity of bound TFPI did not increase at all. We suggest that this method may be an alternative to gel filtration for measuring free TFPI activity, and might be of value in the search for TFPI abnormalities in patients with thrombosis.