Reduced Glomerular Endothelial Thrombomodulin Is Associated with Glomerular Macrophage Infiltration in Diabetic Nephropathy

The endothelial glycoprotein thrombomodulin regulates coagulation, inflammation, and apoptosis. In diabetic mice, reduced thrombomodulin function results in diabetic nephropathy (DN). Furthermore, thrombomodulin treatment reduces renal inflammation and fibrosis. Herein, thrombomodulin expression was examined in human kidney samples to investigate the possibility of targeting thrombomodulin in patients with DN. Glomerular thrombomodulin was analyzed together with the number of glomerular macrophages in 90 autopsied diabetic cases with DN, 55 autopsied diabetic cases without DN, and 37 autopsied cases without diabetes or kidney disease. Thrombomodulin mRNA was measured in glomeruli microdissected from renal biopsies from patients with DN and nondiabetic controls. Finally, glomerular thrombomodulin was measured in diabetic mice following treatment with the selective endothelin A receptor (ET_AR) blocker, atrasentan. In diabetic patients, glomerular thrombomodulin expression was increased at the mRNA level, but decreased at the protein level, compared with nondiabetic controls. Reduced glomerular thrombomodulin was associated with an increased glomerular influx of macrophages. Blocking the ET_AR with atrasentan restored glomerular thrombomodulin protein levels in diabetic mice to normal levels. The reduction in glomerular thrombomodulin in diabetes likely serves as an early proinflammatory step in the pathogenesis of DN. Thrombomodulin protein may be cleaved under diabetic conditions, leading to a compensatory increase in transcription. The nephroprotective effects of ET_AR antagonists in diabetic patients may be attributed to the restoration of glomerular thrombomodulin.

[The influence of simvastatin on hsCRP and some paramneters of hemostasis in patients with ischemic heart disease]

Inflammation and disturbances of the hemostatic system may play a role in pathogenesis and complications of ischemic heart disease. More and more reports indicate that apart from their cholesterol-lowering effect statins also exert other beneficial effects in cardiovascular diseases. Taking this into consideration, the aim of the study was to assess the influence of simvastatin (20 mg per day) on a marker of inflammation - CRP and some parameters of coagulation and fibrinolysis in 22 patients with ischaemic heart disease. Serum lipids, levels of hsCRP, thrombomodulin (TM), vWF, prothrombin fragment 1+2 (F1+2), thrombin-antithrombin complex (TAT), thrombin activatable fibrinolysis inhibitor (TAFI), t-PA, plasmin-antiplasmin complex (PAP) and TAFI activity were assessed before and after one, three and six months simvastatin treatment. After one month therapy of simvastatin, there have been significant reduction of levels of total cholesterol, LDL-cholesterol and triglycerides and these values have remained until the end of the study. No influence on the level of HDL-cholesterol has been observed. After 6 months of treatment significant decrease in the level of hsCRP and increase of the levels TM and vWF with reference to baselines results have been observed. After a 1-and 6-month therapy, the level of TAFI have been significantly increased. Other hemostatic parameters, i.e. levels of F1+2, TAT, t-PA, PAP and TAFI activity have not changed significantly. This prospective study has confirmed high efficacy of lipid-lowering effect and anti-inflammatory properties of simvastatin. Simvastatin influenced some hemo-static parameters, however, these effects were not, in majority, significant.

Effect of the anti-oxidant probucol on soluble thrombomodulin (sTM) in hypercholesterolemic rabbits

INTRODUCTION

Thrombomodulin is an integral endothelial cell membrane protein, exists not only on the surface of endothelial cells but also as soluble fragments circulating in plasma. Probucol has anti-oxidant properties as well as cholesterol-lowering effects and may affect soluble thrombomodulin (sTM).

METHODS

Sixteen rabbits fed with high-cholesterol diet for 8 weeks were randomly divided into two groups: (1) high-cholesterol group (n=8): maintained high-cholesterol diet; (2) probucol group (n=8): the same diet plus probucol for 6 weeks. Control group (n=8) was fed with normal diet for 14 weeks. The levels of sTM and oxidized low-density lipoprotein (OX-LDL) were measured using ELISA.

RESULTS

There were atherosclerotic lesions in aortas and intimal thickness significantly increased in high-cholesterol group. Probucol significantly reduced the lesion area (56.4%+/-9.8% vs 82.5%+/-10.5%) and decreased the intimal thickness (44.65+/-7.25 mum vs 72.21+/-8.32) as compared with high-cholesterol group, all P<0.01. Probucol decreased the level of OX-LDL and sTM as compared with high-cholesterol group, all P<0.05.

CONCLUSIONS

Probucol retarded the plaques formation may relate to decrease plasma OX-LDL and sTM concentration, which may improve endothelial function in hypercholesterolemic rabbit.

Salmeterol enhances pulmonary fibrinolysis in healthy volunteers

OBJECTIVE

Various lung diseases are associated with local activation of coagulation and concurrent inhibition of fibrinolysis. Although salmeterol, a beta2-adrenoceptor agonist with profound bronchodilatory properties, has been studied extensively, the effects of this compound on the pulmonary hemostatic balance are not elucidated.

DESIGN

A single-blinded, placebo-controlled study.

SETTING

University hospital and laboratory.

SUBJECTS

A total of 32 human volunteers.

INTERVENTIONS

Subjects inhaled 100 microg of salmeterol or placebo (t = -30 mins) followed by 100 microg of lipopolysaccharide (LPS) or normal saline (t = 0 mins; n = 8 per group).

MEASUREMENTS AND MAIN RESULTS

Measurements were performed in bronchoalveolar lavage fluid obtained 6 hrs postchallenge. Inhalation of LPS enhanced pulmonary coagulation as determined by an increase in the concentrations of thrombin-antithrombin complexes, factor VIIa, and soluble tissue factor in bronchoalveolar lavage fluid (all p < .05 vs. saline). LPS concurrently inhibited pulmonary fibrinolysis, as reflected by a decrease in bronchoalveolar lavage fluid plasminogen activator activity together with an increase in plasminogen activator inhibitor type 1 (both p < .05 vs. saline). Moreover, LPS inhalation was associated with a suppression of the anticoagulant protein C pathway, as indicated by an increase in soluble thrombomodulin and decreases in protein C and activated protein C levels in bronchoalveolar lavage fluid (all p < .05 vs. saline). Salmeterol, either with or without LPS inhalation, enhanced fibrinolysis (plasminogen activator activity and tissue-type and urokinase-type plasminogen activator levels) but did not influence LPS-induced changes in coagulation or the protein C pathway.

CONCLUSIONS

Salmeterol has profibrinolytic properties in the normal lung and when applied in a model of sterile pulmonary inflammation.

Plasma level of stromal derived factor-1 (SDF-1) is increased in disseminated intravascular coagulation patients who have poor outcomes: In vitro effect of SDF-1 on coagulopathy

Stromal cell-derived factor-1 (SDF-1) is a CXC chemokine that activates and directs the migration of leukocytes that have CXCR4, which is the unique receptor for SDF-1. Although SDF-1/CXCR4 interaction has been implicated in various inflammatory conditions, its role in modulating coagulation has not been determined. We studied the plasma SDF-1 levels in 90 patients with suspected disseminated intravascular coagulation (DIC) and we found that circulating SDF-1 was significantly increased in the overt DIC patients and was also increased in overt DIC patients who have a poor outcome. We then tested in vitro whether SDF-1 can affect the expression of monocyte tissue factor (TF) and endothelial thrombomodulin (TM), and both of these play important roles in coagulopathy. SDF-1 did not affect the expression of surface TF protein and its function and the TF mRNA level in both monocytes and the monocytic leukemia cell line THP-1. SDF-1 also did not change the surface TM expression of endothelial cells. SDF-1 could enhance low-dose ADP induced platelet aggregation, although it failed by itself to induce aggregation. These findings suggest that plasma SDF-1 might be closely associated with hypercoagulability though its action as a platelet activator.

Salvianolic acid B modulates hemostasis properties of human umbilical vein endothelial cells

Salviae miltiorrhizae (SM), a clinical, commonly used herb, can activate blood circulation and resolve stasis. We have investigated the effects of salvianolic acid B (Sal B), a pure compound extracted from the dried SM roots, on fibrinolytic (tissue-type plasminogen activator and plasminogen activator inhibitor, t-PA and PAI) and anticoagulant (thrombomodulin,TM) properties of cultured human umbilical vein endothelial cells (HUVECs). When HUVECs were treated with Sal B, a dose- (0.0125-0.5 mg/ml) and a time-dependent decrease in PAI activity were observed. PAI type 1 (PAI-1) antigen and PAI-1 mRNA expression significantly decreased compared to control values in the conditioned media of HUVECs pretreated with Sal B for 12 h. Moreover, TM activity reached a maximum stimulation of 1.25-fold over control levels in the pretreatment of Sal B for 12 h and t-PA and TM specific mRNA expression also increased (1.7- and 1.8-fold, respectively). In conclusion, Sal B increased the fibrinolytic and anticoagulant potential of cultured HUVECs by up-regulating the expression of t-PA and TM and by down-regulating the expression of PAI-1. These data suggest that Sal B is clinically effective because of its ability to change the gene expression profile of endothelial cells thereby preventing vascular events.

Recombinant human factor VIIa-induced alterations in tissue factor and thrombomodulin in patients with advanced liver cirrhosis

BACKGROUND

Recombinant human factor VIIa (rhFVIIa) is used to treat hemophilia and occasionally individuals with liver disease. The aim of the present study was to investigate the consequences of rhFVIIa in individuals with advanced liver disease in an attempt to understand the mechanism of action of rhFVIIa in this unique population.

METHODS

Levels of plasma tissue factor, plasminogen activator inhibitor-1, tissue factor pathway inhibitor, fibrin split products, D-dimers and free thrombomodulin were measured following the administration of rhFVIIa in 17 subjects. The results were compared to normal controls.

RESULTS

The prothrombin time declined from 20.2 +/- 2.8 s to 14.3 +/- 3.9 s (P < 0.01). No change in the activated partial thromboplastin time occurred. A 15.6% reduction in thrombomodulin was observed (P < 0.05). A mean 75.2% reduction in plasma tissue factor occurred (P < 0.01). Tissue factor pathway inhibitor levels declined to less than the control value (P < 0.05). No changes in plasminogen activator inhibitor-1, fibrin split products or D-dimer levels occurred.

CONCLUSIONS

These data demonstrate that rhFVIIa administration to individuals with liver disease results in (i) a transient improvement in the prothrombin time; (ii) no change in the activated partial thromboplastin time; and (iii) a marked reduction in the levels of thrombomodulin and tissue factor. These data suggest that rhFVIIa binds tissue factor and enhances tissue factor and thrombomodulin clearance from the circulation.

Thrombomodulin: tumour biology and prognostic implications

BACKGROUND

Thrombomodulin (TM) is an endothelial receptor that exerts anti-coagulant, anti-fibrinolytic, and anti-inflammatory activity by inhibiting thrombin and cellular adhesion. There is growing evidence that TM plays a role in tumour behaviour.

METHODS

The electronic literature (1966-2004) was reviewed with a specific focus on tumour biology.

RESULTS

TM is expressed on both the endothelium and tumour cells in several cancers. Loss of expression denotes a more malignant profile with poorer prognosis. Loss of TM is mediated by hypoxia, endotoxin, and various cytokines, while up-regulation can be achieved by pharmacological manipulation (e.g. pentoxyfylline and statins).

CONCLUSION

Originally described as an endothelial anticoagulant, TM plays a key role in tumour biology and prognostics, and provides a potential therapeutic target in impeding cancer spread.

Influence of long-term intervention with dietary counseling, long-chain n-3 fatty acid supplements, or both on circulating markers of endothelial activation in men with long-standing hyperlipidemia

BACKGROUND

Dietary factors and very-long-chain n-3 polyunsaturated fatty acids (n-3 PUFAs) may influence the atherothrombotic process. Elevated concentrations of circulating cell adhesion molecules, thrombomodulin (TM), von Willebrand factor (vWF), and tissue-type plasminogen activator antigen (tPAag) are related to atherothrombotic cardiovascular disease.

OBJECTIVE

The randomized Diet and Omega-3 Intervention Trial (DOIT) targeted a comparison of the effect of 3-y dietary counseling, n-3 PUFA supplementation (2.4 g/d), or both on circulating markers of endothelial activation.

DESIGN

The study included 563 elderly men with long-standing hyperlipidemia. The men were randomly assigned by factorial design into 4 groups: control (no dietary counseling and placebo capsules), dietary counseling (and placebo capsules), n-3 PUFA supplementation (no dietary counseling), and dietary counseling and n-3 PUFA supplementation.

RESULTS

Serum concentrations of fatty acids reflected good compliance. Dietary counseling was followed by significantly reduced concentrations of soluble intercellular adhesion molecule 1 (sICAM-1; P < 0.001), sTM (P = 0.004), and tPAag (P < 0.001) than in subjects without dietary counseling. After n-3 PUFA supplementation, significantly reduced concentrations of sICAM-1 (P < 0.001) and sTM (P = 0.006) were observed when compared with subjects receiving placebo capsules. An increase in tPAag was not significantly different from that observed in subjects receiving placebo capsules. For sICAM-1, a significant effect was observed for both interventions combined.

CONCLUSIONS

Each intervention (dietary counseling or n-3 PUFA supplements) reduced sTM and sICAM-1 concentrations, indicating decreased endothelial activation. The tPAag increase in the groups not receiving dietary counseling (pooled), which indicates progression of atherosclerosis, was significantly counteracted by dietary counseling.

Effects of TNF-α and curcumin on the expression of thrombomodulin and endothelial protein C receptor in human endothelial cells

The objective of this study was to elucidate the effects of tumor necrosis factor-alpha (TNF-alpha) on the expression of thrombomodulin (TM) and endothelial protein C receptor (EPCR) in human endothelial cells as well as the effect of curcumin, a spice and coloring food compound, as a potential therapeutic agent. Human umbilical vein endothelial cells (HUVECs) treated with TNF-alpha (2.0 ng/ml) showed reduced TM mRNA levels by 80%, 97%, 94%, and 97% at 3, 6, 12, and 24 h, respectively (P<0.05), by real-time PCR analysis. Dose-dependent study showed that TM mRNA levels of HUVECs were decreased by 86%, 89%, 91%, and 94% after treatment of TNF-alpha (0, 0.25, 0.5, 1, and 2 ng/ml) for 6 h, respectively (P<0.05). TM protein levels in HUVECs were significantly reduced by 69% in TNF-alpha-treated cells as compared to controls (P<0.05) by Western blot analysis. Secreted protein and activity of TM of HUVEC cultures were also significantly reduced in TNF-alpha-treated cells. In addition, EPCR mRNA levels of HUVECs were significantly reduced in TNF-alpha-treated group as compared to controls (P<0.05). Furthermore, these effects were observed in other types of endothelial cells from human coronary arteries, lung, and skin. Curcumin effectively blocked these effects of TNF-alpha on downregulation of TM and EPCR. These data demonstrate that TNF-alpha significantly decreases expression of TM and EPCR at both mRNA and protein levels in several human endothelial cells. Curcumin can effectively block TNF-alpha-induced endothelial dysfunction. This study suggests a new molecular mechanism of inflammation-induced thrombosis and a new therapeutic strategy to prevent this clinical problem.

Eprosartan effect on fibrinolytic/hemostatic variables in arterial hypertension: a comparative study to losartan

Essential hypertension is often accompanied by abnormalities of the coagulation/fibrinolytic system predisposing to a procoagulant state. The aim of the present study was to examine the comparative efficacy of the angiotensin II type 1 receptor antagonists eprosartan and losartan on plasma levels of hemostatic/fibrinolytic and endothelial function markers in a cohort of previously untreated hypertensive patients. A total of 86 patients whose hypertension was controlled by monotherapy with eprosartan 600 mg (45 patients) or losartan 100 mg (41 patients) were studied. The plasma levels of plasminogen activator inhibitor-1 (PAI-1) antigen, tissue plasminogen activator inhibitor (tPA) antigen, thrombomodulin (TM), tissue factor pathway inhibitor (TFPI) antigen, and fibrinogen were determined before and after 6 months of therapy. Age, sex distribution, body mass index, lipid profile, systolic and diastolic blood pressure levels, and baseline values of the measured markers were similar in both groups. After 6 months of therapy, systolic blood pressure was significantly lower in patients treated with eprosartan, while no differences were observed with respect to diastolic blood pressure. Treatment with both drugs was associated with a significant decrease in PAI-1 antigen, TM, fibrinogen plasma levels and an increase in tPA antigen. The favorable modification of all the above parameters was significantly greater in the eprosartan than in the losartan group, while TFPI plasma levels were decreased to a similar extent with both drugs. In conclusion, the results of our study indicate that 6-month monotherapy with a new angiotensin II type 1 receptor blocker, eprosartan, is associated with a more favorable modification of hemostatic/fibrinolytic status than with losartan.

Statins increase thrombomodulin expression and function in human endothelial cells by a nitric oxide-dependent mechanism and counteract tumor necrosis factor alpha-induced thrombomodulin downregulation

Expression of functionally active thrombomodulin (TM) on the luminal surface of endothelial cells is critical for vascular thromboresistance. TM maintains thrombohemorrhagic homeostasis by forming a complex with thrombin, which subsequently loses its procoagulant properties and instead activates protein C. Acquired deficiency of endothelial TM is of particular pathophysiological significance in sepsis and related disorders. We show here that two different 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins), atorvastatin and simvastatin, strongly increase the expression and functional activity of TM in human umbilical vein endothelial cells, human coronary artery endothelial cells, and EA.hy926 endothelial cells. The increase in endothelial TM conferred by statin was prevented by the addition of mevalonic acid, geranylgeranyl-pyrophosphate, and nitric oxide scavenger, and was mimicked by the addition of a specific inhibitor of geranylgeranyl transferase, as well as by nitric oxide donors. Moreover, statin counteracted tumor necrosis factor alpha-induced downregulation of endothelial cell TM. The increase in endothelial cell TM activity in response to statin constitutes a novel pleiotropic (non-lipid-related) effect of these commonly used compounds, and may be of clinical significance in disorders where deficient endothelial TM and protein C activation play a pathophysiological role.

Hyaluronic acid and endothelial damage due to paracetamol-induced hepatotoxicity

BACKGROUND

Damage to endothelial cells may be an important factor in the complications of acute liver failure, resulting in multi-organ failure. The aim of this study was to assess endothelial cell function in patients with severe hepatotoxicity due to paracetamol ingestion.

PATIENTS AND METHODS

Fifty-eight patients with paracetamol-induced hepatotoxicity were studied for up to 7 days. Serum hyaluronic acid (HA), as a marker of hepatic sinusoidal endothelial cell function, was determined using an enzyme-linked binding assay. Plasma von Willebrand Factor, thrombomodulin and interleukin-8 were also determined using ELISA.

RESULTS

Serum HA on admission was significantly increased (median 6777 ng/ml, range 24-50 967 ng/ml) as compared to normal controls (n = 10, median 21 ng/ml, range 0-50 ng/ml; P < 0.001). In non-survivors (n = 21) HA levels peaked on day 2 after admission (P = 0.044), and then decreased. In the survivors (n = 37) the levels of HA did not increase further. Plasma von Willebrand Factor, plasma thrombomodulin and serum interleukin-8 were significantly increased in the patients as compared to the normal controls (P < 0.001). Serum interleukin-8 was significantly higher in non-survivors in the first 2 days.

CONCLUSIONS

Endothelial function is abnormal in paracetamol-induced hepatotoxicity. Damage to hepatic sinusoidal endothelial cells assessed by serum HA was greater in non-survivors than survivors.

Reduced expression of endothelial cell markers after 1 year treatment with simvastatin and atorvastatin in patients with coronary heart disease

The study was aimed at investigating the effects, after treatment for 1 year, of two different statins on the levels of circulating biochemical markers of endothelial function in patients with established coronary heart disease, with the hypothesis that statins might reduce these levels. Twenty-eight patients were randomized to treatment with atorvastatin and 30 to simvastatin for 1 year. The starting dose in both groups was 20 mg/day. Soluble forms of P-selectin, E-selectin, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) were determined to assess inflammatory activity of the endothelium, and tissue plasminogen activator antigen (tPAag), von Willebrand factor and thrombomodulin for evaluation of the haemostatic function. In the total study population there were significantly reduced levels after 1 year treatment in ICAM-1 (P<0.001), E-selectin (P=0.022) and P-selectin (P<0.001), whereas a significant increase was observed in VCAM-1 (P=0.003). Almost the same pattern was seen within both groups although the increase in VCAM-1 was only seen in the simvastatin group (P=0.017). An overall reduction in tPAag was further observed (P=0.048). The reduction in proinflammatory and to some extent haemostatic markers of endothelial function after 1 year treatment with either simvastatin or atorvastatin may be indicative of a less activated state of the endothelium which possibly may contribute to modulation of the progression of atherosclerosis.

15 deoxy delta12,14 PGJ2 induces procoagulant activity in cultured human endothelial cells

15 deoxy delta12,14 PGJ2 (15d-PGJ2), a high affinity ligand of peroxisome proliferator-activated receptor gamma (PPARgamma) has been proposed to act as a negative feedback regulator of the inflammatory response. We investigated the effect of 15d-PGJ2 on the anticoagulant property of endothelial cells. 15d-PGJ2 stimulated a moderate but sustained increase in tissue factor (TF) activity in HUVECs and EA.hy926 cells while causing a partial loss of thrombomodulin (TM) activity. When cells were co-treated with 15d-PGJ2 and TNF-alpha, the subsequent elevation of TF activity was synergistically increased over that of cells treated with TNF-alpha alone and the decline of TF activity after 24 h was less marked than TNF-alpha alone. The induction of TF by 15d-PGJ2 alone and in combination with TNF-alpha was reduced in the presence of PD 98059, suggesting the participation of the MEK/ERK pathway. The thiazolidinedione PPARgamma agonist ciglitazone had no effect on TF levels but reduced the expression of endothelial protein C receptor. The ability of 15d-PGJ2 to enhance a procoagulant phenotype arising from TNF-alpha suggests a pro-inflammatory role for the prostaglandin.

Decrease of fibrinolytic activity in human endothelial cells by arsenite

Blackfoot disease (BFD) is an endemic peripheral vascular occlusive disease that occurred in the southwest coast of Taiwan. It is believed that arsenic in the drinking water from artesian wells plays an important role in the development of the disease. We have previously shown that BFD patients had significant lower tissue-type plasminogen activator (t-PA) antigen level and higher plasminogen activator inhibitor, Type 1 (PAI-1) antigen level than normal controls. The purpose of this study was to investigate the effects of arsenite on the fibrinolytic and anticoagulant activities of cultured macrovascular and microvascular endothelial cells. Incubation of human microvascular endothelial cells (HMEC-1), but not human umbilical vein endothelial cells (HUVECs), with arsenite caused a decrease of t-PA mRNA level, a rise of both PAI-1 mRNA level and PAI activity. Arsenite could also inhibit the thrombomodulin (TM) mRNA expression and reduce the TM antigen level in HMEC-1. In conclusion, arsenite had a greater effect on HMEC-1 as compared to HUVECs in lowering the fibrinolytic activity and may be responsible for the reduced capacity of fibrinolysis associated with BFD.

Identification of the epidermal growth factor-like domains of thrombomodulin essential for the acceleration of thrombin-mediated inactivation of single-chain urokinase-type plasminogen activator

Single-chain urokinase-type plasminogen activator (scu-PA) can be cleaved by thrombin into a virtually inactive form called thrombin-cleaved two-chain urokinase-type plasminogen activator (tcu-PA/T), a process accelerated by thrombomodulin, which contains six epidermal growth factor (EGF)-like domains. In this study, we identified the EGF-like domains of thrombomodulin required for the acceleration of the inactivation of scu-PA by thrombin using various forms of thrombomodulin (TM). scu-PA was treated with thrombin in the absence and presence of full-length rabbit TM (containing EGF1-6), recombinant TM comprising all of the extracellular domains including EGF1-6 (TMLEO) and recombinant TM comprising EGF4-6 plus the interconnecting region between EGF3 and EGF4 (TMEi4-6), and the tcu-PA/T generated was quantitated in each case. Rabbit TM accelerated the inactivation of scu-PA approximately 35-fold, while both recombinant forms accelerated it only threefold due to the absence of a critical chondroitin sulfate moiety. Subsequently, TME5-6 was prepared by cyanogen bromide digestion of TMEi4-6. TME5-6 bound to thrombin but did not accelerate the activation of protein C. In contrast, the inactivation of scu-PA by thrombin was accelerated to the same extent as that induced by TMLEO and TMEi4-6. This study demonstrates that, in addition to the chondroitin sulfate moiety, only EGF-like domains 5 and 6 are essential for the acceleration of the inactivation of scu-PA by thrombin. This differs from the domains that are critical for activation of protein C (EGF-like domains i4-6) and thrombin activatable fibrinolysis inhibitor (EGF-like domains 3-6).

Signal transduction pathways underlying the expression of tissue factor and thrombomodulin in promyelocytic cells induced to differentiate by retinoid acid and dibutyryl cAMP

Acute promyelocytic leukaemia (APL) may be associated with disseminated intravascular coagulation, as a result of increased tissue factor (TF) expression and reduced thrombomodulin (TM) expression by APL blast cells. During retinoid acid (RA)- and dibutyryl cAMP (dbcAMP)-induced differentiation of the APL cells, there is a marked up-modulation of both the protein kinase A (PKA) and C (PKC) activities. In order to further assess whether these kinases are intimately associated with both the differentiation process and the regulation of TF and TM expression, we have correlated the modulation of their respective pathways with the extent of differentiation and modulation of these cellular receptors. NB4 cells were incubated with all-trans-RA (ATRA) or dbcAMP for up to 48 h. The contribution of phospholipase C (PLC), inositol phosphate (IP), PKC and PKA in the expression of CD11b, TF and TM was studied by the use of specific inhibitors. Myo-inositol uptake and PKC activity increased in cells induced to differentiate by ATRA but the retinoid did not affect cAMP levels or PKA activity. Under treatment with dbcAMP, PKA activity was increased while inositol uptake and PKC activity remained unchanged. Our results show that the effects of ATRA and dbcAMP on promyelocytic cells are closely related, respectively, to the PLC/IP/PKC and the cAMP/PKA pathways. In cells induced to differentiate by ATRA, CD11b expression seems more closely related to inositol uptake than to PKC activity while the expression of TF and TM show the opposite pattern, which suggests cellular events regulated at a different level within a common signal transduction pathway.

Effect of intradermal tumor necrosis factor-alpha-induced inflammation on coagulation factors in dermal vessel endothelium. An in vivo study of human skin biopsies

Inflammatory mediators were shown to exert procoagulant effects on cultured human endothelial cells (EC). In the present study the effect of intradermal application of tumor necrosis factor-alpha (TNF-alpha) on the expression of factors involved in regulation of coagulation at the EC surface, i.e. tissue factor (TF), thrombomodulin (TM) and tissue factor pathway inhibitor (TFPI) was studied in humans in vivo. The endothelial expression of these factors was evaluated immunohistochemically in biopsies taken after intradermal application of 5000 U TNF-alpha in 8 healthy volunteers. After 6 and 22 h biopsies were taken from the injection sites. At TNF-alpha injected sites typical inflammatory changes. e.g. EC upregulation of adhesion molecules and accumulation of leukocytes were detected. In parallel we could document EC expression of TF, downregulation of TM and depletion of tissue factor pathway inhibitor (TFPI) in inflamed areas. Early depletion of endothelial IkappaB alpha at the site of inflammation after application of TNF-alpha points to an activation of the NF-kappaB pathway. Our data suggest that, as shown in in vitro experiments, TNF-alpha activates the NF-kappaB pathway and induces specific procoagulant changes of EC due to expression of TF, down-regulation of TM and depletion of TFPI in vivo in humans. This procoagulant shift in the haemostatic balance on the cell surface, caused by TNF-alpha-induced inflammation, is likely to contribute to thrombosis associated with tissue inflammation in humans.

No effect of methacrylate-based bone cement CMW 1 on the plasmatic phase of coagulation, red blood cells and endothelial cells in vitro

The compatibility of a methacrylate-based bone cement (CMW 1, DePuy International Ltd, England) used for the fixation of joint prostheses was evaluated on plasma, an erythrocyte suspension and cultured human endothelial cells. The extract of the cement was tested, following 1 hour and 7 days of curing. After the contact in vitro of the extract with plasma, activated partial thromboplastin time, antithrombin III, thrombin-antithrombin complexes and fibrin degradation products were assayed. Hemolytic activity was tested by adding the cement extracts to a suspension of erythrocytes. After 4 hours of incubation at 37 degrees C, the hemoglobin concentration was determined on the supernatants by the colorimetric method. The effect of the cement on tissue factor and thrombomodulin production was evaluated on human umbilical vein endothelial cell cultures. Tissue factor was determined in cell lysates by enzyme immunoassay, following 4 hours' incubation of cultures with the cement extract. Thrombomodulin was assayed in cell lysates by enzyme immuno assay, after 24 hours' incubation with the cement extract. The response to all trans-retinoic acid (ATRA) was tested. The cement caused no significant modifications of the coagulation tests, had no hemolytic activity, did not determine tissue factor production and did not modify thrombomodulin, compared to the negative control. The response to stimulation with ATRA was similar to that of the negative control. We conclude that the cement extract does not affect the plasmatic phase of coagulation, has no effect on erythrocytes, does not induce the expression of procoagulant activity by endothelial cells and does not impair their antithrombotic property, within the limits of the tests performed.

1alpha,25-dihydroxyvitamin D(3) and its potent synthetic analogs downregulate tissue factor and upregulate thrombomodulin expression in monocytic cells, counteracting the effects of tumor necrosis factor and oxidized LDL

BACKGROUND

We have recently found that a hormonally active form of vitamin D, 1alpha,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)], exerts anticoagulant effects by upregulating the expression of an anticoagulant glycoprotein, thrombomodulin (TM), and downregulating the expression of a critical coagulation factor, tissue factor (TF), in monocytic cells including human peripheral monocytes. In this study, we investigated the counteracting effects of 1,25(OH)(2)D(3) and its potent analogs on TF induction and TM downregulation by tumor necrosis factor and oxidized LDL in monocytic cells and the modulatory effects of potent analogs on TF and TM expression.

METHODS AND RESULTS

Effects of 1,25(OH)(2)D(3) and its potent synthetic analogs (22R)-22-methyl-20-epi-1,25(OH)(2)D(3) (KY3) and 22-oxacalcitriol on TF and TM antigen levels, cell surface activities, and mRNA levels in monocytic cells were examined. 1, 25(OH)(2)D(3) and its potent analogs showed anticoagulant effects in monocytic cells by downregulating TF and upregulating TM expression, counteracting the effects of tumor necrosis factor and oxidized LDL. KY3 was most potent in its regulatory effect on TF and TM expression.

CONCLUSIONS

Because KY3 has the highest affinity for vitamin D receptor, our findings suggest that TF and TM regulation by 1, 25(OH)(2)D(3) analogs is also mediated by vitamin D receptor. The 1, 25(OH)(2)D(3) analogs KY3 and 22-oxacalcitriol may have the potential to serve as an agent for preventing and treating atherosclerotic and other cytokine-mediated thrombotic diseases and as a tool for studying the molecular mechanisms of TF and TM regulation.

Increased plasma P-selectin and decreased thrombomodulin in pulmonary arterial hypertension were improved by continuous prostacyclin therapy

BACKGROUND

Thrombosis in situ related to endothelial cell injury may contribute to the development of pulmonary hypertension (PH). P-selectin, a leukocyte adhesion receptor present in endothelial cells and platelets, reflects endothelial injury and platelet activation, and thrombomodulin (TM), a receptor for thrombin and a major anticoagulant proteoglycan on the endothelial membrane, reflects the anticoagulant activity of the endothelium.

METHODS AND RESULTS

To assess abnormal coagulation due to endothelial injury in patients with PH, plasma levels of soluble P-selectin and TM were measured in 32 patients with primary PH (PPH), 25 with secondary pulmonary arterial hypertension (sPAH), 31 with pulmonary venous hypertension (PVH), and 17 healthy subjects (Control). These measurements were repeated after continuous infusion of prostacyclin in 15 patients with PPH and 3 with sPAH. P-selectin levels in both the sPAH and PPH groups were significantly higher than those in the Control and PVH groups (P<0.05). Plasma TM level in the PPH group was significantly lower than those in the other groups (P<0.01). After prostacyclin therapy, the lower TM level was increased and the higher P-selectin level was decreased (P<0.05).

CONCLUSIONS

Decreased TM and increased P-selectin in PPH and sPAH may reflect in situ thrombosis due to endothelial injury. Prostacyclin may act not only as a vasodilator but also as an agent that improves endothelial injury and altered hemostasis in pulmonary arterial injury.

A pilot study of streptokinase-induced endothelial injury and platelet activation following acute myocardial infarction

OBJECTIVE

To relate the changes in serum vitamin E, an essential antioxidant, to changes in fibrinogen, as well as indices of endothelial damage [as indicated by plasma markers, soluble thrombomodulin (sTM) and von Willebrand factor (vWf), and an index of platelet activation (soluble P selectin (sPsel)], in myocardial infarction treated with thrombolytic therapy.

DESIGN AND SETTING

Prospective longitudinal pilot study in a teaching hospital Coronary Care Unit.

SUBJECTS AND INTERVENTION

Seventeen patients (12 men: mean age (62 years +/- SD 11 years) admitted with acute myocardial infarction (AMI), who were given thrombolytic therapy, and 59 healthy controls.

RESULTS

Baseline levels of fibrinogen (Mann-Whitney test, P = 0.0055) and vWf (P < 0.001) were significantly higher than controls, but sPsel, sTM or vitamin E levels were not significantly different. Following thrombolysis, as expected, median concentrations of plasma fibrinogen fell profoundly (Friedman ANOVA P < 0.001) so that after 45 min, levels were undetectable in 13 patients. At 24-h median fibrinogen concentration had recovered to approximately 30% of baseline (P < 0.01) and was still undetectable in three patients. Levels of vWf and sPsel increased steadily, reaching significance after three hours (both P < 0.05). However, levels of sTM rose immediately after thrombolysis, peaking between 1 and 3 h, and remained elevated at 24 h. These increases corresponded to a simultaneous early fall in serum vitamin E concentrations.

CONCLUSION

The present pilot study demonstrates significant endothelial damage and platelet activation in association with increased oxidative stress following streptokinase therapy for AMI.

Third-generation thrombolytic drugs

Several third-generation thrombolytic agents have been developed. They are either conjugates of plasminogen activators with monoclonal antibodies against fibrin, platelets, or thrombomodulin; mutants, variants, and hybrids of alteplase and prourokinase (amediplase); or new molecules of animal (vampire bat) or bacterial (Staphylococcus aureus) origin. These variations may lengthen the drug's half-life, increase resistance to plasma protease inhibitors, or cause more selective binding to fibrin. Compared with the second-generation agent (alteplase), third-generation thrombolytic agents such as monteplase, tenecteplase, reteplase, lanoteplase, pamiteplase, and staphylokinase result in a greater angiographic patency rate in patients with acute myocardial infarction, although, thus far, mortality rates have been similar for those few drugs that have been studied in large-scale trials. Bleeding risk, however, may be greater.

Upregulation of thrombomodulin antigen levels in U937 cells by combined stimulation with estradiol-17beta and vitamin K2 (menaquinone 4)

The expression of thrombomodulin (TM) and tissue factor (TF) antigens by estradiol and vitamin K2 were studied in human leukemic cell lines including U937 (monoblastic leukemia), NB4 (acute promyelocytic leukemia), and HL60 (acute myeloblastic leukemia). Combined stimulation with estradiol-17beta and menaquinone 4 (MK4), homologue of vitamin K2, showed a remarkable increase of total TM antigen level only in U937 cells among these leukemic cell lines, whereas a single treatment of each agent showed a modest or a moderate increase. A synergistic effect of cotreatment with estradiol-17beta and MK4 was observed in an optimum concentration of 1.0 micromol of estradiol-17beta and 1.0 micromol of MK4. Estrogen receptors were detected only in U937 cells among these cell lines, and the competitive assay with an antiestrogenic agent showed a suppression on TM expression in a dose-dependent manner. In the mean time, concerning expression of TF antigens, if at all, only a very slight decrease was observed by costimulation with estradiol-17beta and MK4 in U937 and NB4 cells, whereas all-trans-retinoic acid (ATRA) showed a remarkable decrease in surface TF antigen levels in NB4 cells and also a modest decrease in U937 cells. These findings suggest that estradiol-17beta would up-regulate TM antigen expression via estrogen receptors and in cooperation with MK4, showing a different mechanism from ATRA.

Treatment of nonproliferative diabetic retinopathy with Defibrotide in noninsulin-dependent diabetes mellitus: a pilot study

PURPOSE

Microvascular alterations, impairment of coagulation, ischemia and diffuse endothelial damage are related to the progression of diabetic retinopathy. Defibrotide has been demonstrated to produce profibrinolytic, cytoprotective and vasofacilatory activities. The aim of the present study was to evaluate the therapeutic effect of Defibrotide in the treatment of nonproliferative diabetic retinopathy.

METHODS

Two randomized age- and sex-matched groups (cases and controls) of 35 NIDDM patients presenting non-proliferative diabetic retinopathy were included in this study: cases were treated with Defibrotide (800-1600 mg daily) for two years.

RESULTS

All tested parameters (ETDRS visual acuity; computerized perimetry; retinography; fluorescein angiography), improved significantly (p<0.001) in Defibrotide-treated patients compared to controls. In our opinion, Defibrotide's manifold effects on vascular endothelia may account for this improvement by stimulation of tPA, PGI2, PGE2, thrombomodulin and modulation of endothelin-1 release.

CONCLUSIONS

Our preliminary data seem to suggest that Defibrotide could be proposed for medical treatment of nonproliferative diabetic retinopathy.

Hyperhomocyst(e)inemia and endothelial dysfunction in IDDM

OBJECTIVE

Considering that elevated blood levels of homocyst(e)ine represent a known independent risk factor for macrovascular disease, we assessed the link between hyperhomocyst(e)inemia and diabetic microvascular complications.

RESEARCH DESIGN AND METHODS

Homocyst(e)ine and thrombomodulin plasma levels, a marker of endothelial cell damage, were measured before and 3 h after oral methionine loading in 75 patients with stable, well-controlled IDDM and 40 healthy control subjects matched for sex and age. Exclusion criteria were hyperlipidemia, hypertension, smoking, or positive family history for cardiovascular disease.

RESULTS

IDDM patients had higher pre- and postload homocyst(e)ine plasma levels than did healthy control subjects (12.0 vs. 7.7 mumol/l and 27.6 vs. 16.0 mumol/l; P < 0.001). Of 75 IDDM patients, 26 had homocyst(e)ine plasma levels above the normal range (defined as mean +2 SD of values obtained in the control group). The IDDM patients with hyperhomocyst(e)inemia had higher thrombomodulin plasma levels (62.2 vs. 38.2 ng/ml; P < 0.001), higher albumin excretion rates (485 vs. 115 mg/l; P < 0.005), and a higher prevalence of late diabetic complications (nephropathy, 76 vs. 33%; retinopathy, 69 vs. 51%; neuropathy, 57 vs. 41%; macroangiopathy, 57 vs. 33%) compared with IDDM patients with normal plasma homocyst(e)ine. In vitro experiments with human umbilical vein cells show an increased release of thrombomodulin into the culture supernatant only when endothelial cells were pretreated with advanced glycation end product (AGE)-albumin before L-homocystine was added. A synergistic action of homocyst(e)ine and AGEs might contribute to vascular complications of patients with diabetes.

CONCLUSIONS

Hyperhomocyst(e)inemia is common in nephropathic diabetic patients and may contribute to the enhanced morbidity and mortality from cardiovascular diseases characteristically observed in IDDM patients with diabetic nephropathy.

Hyperhomocyst(e)inemia and endothelial dysfunction in IDDM

OBJECTIVE

While elevated blood levels of homocyst(e)ine represent an independent risk factor for macrovascular disease, we assessed the link between hyperhomocyst(e)inemia and diabetic microvascular diseases.

RESEARCH DESIGN AND METHODS

Plasma levels of homocyst(e)ine and thrombomodulin (TM), markers of endothelial cell damage, were measured before and 3 h after oral methionine loading in 75 patients with IDDM and 40 healthy control subjects matched for sex and age. Exclusion criteria were hyperlipidemia, hypertension, smoking, or positive family history for cardiovascular disease.

RESULTS

IDDM patients had higher pre- and postload plasma levels of homocyst(e)ine than did healthy control subjects (12.0 vs. 7.7 mumol/l and 27.6 vs. 16.0 mumol/l; P < 0.001). Of 75 IDDM patients, 26 had plasma homocyst(e)ine levels above the normal range (means +/- 2 SD of values obtained in the control group). These IDDM patients with hyperhomocyst(e)inemia had higher plasma TM levels (62.2 vs. 38.2 ng/ml, P < 0.001), higher albumin excretion rates (485 vs. 115 mg/l, P < 0.005), and a higher prevalence of late diabetic complications (nephropathy, 76 vs. 33%; retinopathy, 69 vs. 51%; neuropathy, 57 vs. 41%; and macroangiopathy, 57 vs. 33%) compared with IDDM patients with normal plasma homocyst(e)ine. In vitro experiments with human umbilical vein cells showed an increased release of TM into the culture supernatant only when endothelial cells were pretreated with advanced glycation end product (AGE)-albumin before L-homocystine was added. A synergistic action of homocyst(e)ine and AGEs might contribute to vascular complications in patients with diabetes.

CONCLUSIONS

Hyperhomocyst(e)inemia is common in nephropathic diabetic patients and may contribute to the enhanced morbidity and mortality from cardiovascular diseases characteristically observed in IDDM patients with diabetic nephropathy.

Expression of von Willebrand factor, P-selectin (CD62P) and thrombomodulin in human endothelial cells in culture modulated by cyclosporin A

Endothelial cells were isolated from human umbilical veins and from saphenous veins and were cultured in the presence and absence of cyclosporin A (CSA). Cell morphology and growth characteristics were monitored continuously by video recording microscopy. The cells and culture supernatants were analysed for von Willebrand Factor (VWF), P-Selectin (CD62P) and thrombomodulin (TM) by immunocytochemistry and immunoassay. CSA had little effect on confluent cells in culture. In contrast, the characteristics of both umbilical vein and saphenous vein cells were markedly altered when CSA was added to subconfluent cultures. Under these conditions, CSA did not appear to be directly cytotoxic at the concentrations used but marked changes in cell morphology including the appearance of large multinucleate forms were recorded. Increased amounts of VWF and TM were detected in the culture supernatants of cells grown continuously in the presence of CSA and correspondingly depressed expression of cell associated antigens was observed. Heterogeneous and depressed distribution of CD62P was seen after 5-6 days culture but cellular expression of this ligand did not appear to be affected specifically by the presence of CSA. In addition, mechanically disrupted confluent endothelial cells failed to recover in the presence of CSA as effectively as similar cells grown in the absence of CSA. The results showed that CSA disturbed actively growing cells more severely than quiescent cells and might help to clarify the role of CSA in vascular disturbances in vivo.

Plasmodium falciparum-infected erythrocytes adhere to the proteoglycan thrombomodulin in static and flow-based systems

Plasmodium falciparum-infected erythrocytes can bind to the glycosaminoglycan chondroitin sulfate A. In this paper, we demonstrate that thrombomodulin, a proteoglycan present on endothelial cells and placental syncytiotrophoblasts, supports binding of selected lines of P. falciparum-infected erythrocytes in both static and flow-based assays, and that adhesion is dependent on the presence of the chondroitin sulfate A chain of thrombomodulin. Chondroitinase treatment of thrombomodulin abolished binding, and free chondroitin sulfate A prevented it, whereas other soluble glycosaminoglycans had little or no effect. Soluble thrombomodulin (with, but not without, its chondroitin sulfate chain) inhibited binding at 40 micrograms/ml, but not at physiological concentrations. Parasitized erythrocytes bound to cells expressing thrombomodulin, including human umbilical vein endothelial cells and A549 cells, and binding was inhibited by free chondroitin sulfate A. Established binding to A549 cells or to immobilized thrombomodulin was substantially reversed by chondroitin sulfate A at 10 micrograms/ml. The chondroitin sulfate chain of thrombomodulin is a receptor for malaria-infected erythrocytes in static assays and under physiological flow.

Influence of long-term continuous intravenous administration of pentoxifylline on endothelial-related coagulation in critically ill patients

OBJECTIVE

To determine the influence of pentoxifylline on endothelial-associated coagulation.

DESIGN

Prospective, randomized, placebo-controlled study.

SETTING

A surgical intensive care unit of a university hospital.

PATIENTS

Consecutive patients (n = 60) with trauma or sepsis secondary to major (nontrauma) surgery. All patients received controlled mechanical ventilation.

INTERVENTIONS

According to a randomized sequence, the patients either received pentoxifylline continuously over 5 days (1.5 mg/kg/hr iv) (trauma-pentoxifylline group [n = 15], sepsis-pentoxifylline group [n=15] or saline solution as placebo (trauma-control group [n = 15], sepsis-control group [n = 15].

MEASUREMENTS AND MAIN RESULTS

In addition to the standard coagulation screen, thrombomodulin, protein C, (free) protein S, and thrombin-antithrombin plasma concentrations were measured by enzyme-linked immunosorbent assays. Intensive care therapy, hemodynamics, and changes of Acute Physiology and Chronic Health Evaluation II score were comparable for pentoxifylline-treated and nontreated patients. An average dose of 2.5 g/day of pentoxifylline (range 2.2 to 2.9) was infused into the pentoxifylline-treated patients. At baseline, plasma thrombomodulin concentrations were higher in the septic patients than in the trauma patients. Thrombomodulin plasma concentrations increased significantly more in the control patients (trauma: from 38.9 +/- 10.5 to 59.9 +/- 10.1 ng/mL; sepsis: from 49.7 +/- 12.1 to 72.3 +/- 11.2 ng/mL) than in the pentoxifylline-treated patients (trauma: from 37.9 +/- 11.9 to 50.2 +/- 9.2 ng/mL; sepsis from 51.9 +/- 10.1 to 63.3 +/- 10.2). Starting from similar baseline values, protein C concentration increased significantly more in the sepsis-pentoxifylline patients (from 52.0 +/- 11.1% to 69.1 +/- 11.1%) than in the untreated septic patients (from 50.1 +/- 10.0% to 52.5 +/- 9.5%). There were no significant differences between the pentoxifylline-treated and nontreated groups for protein S and thrombin-antithrombin concentrations. Standard coagulation parameters (fibrinogen, activated partial thromboplastin time, antithrombin III) did not differ between these groups either.

CONCLUSIONS

Continuous intravenous administration of pentoxifylline for 5 days beneficially influenced the thrombomodulin/protein C/protein S system in both the trauma and septic patients.

Successful treatment of livedo vasculitis with beraprost sodium: a possible mechanism of thrombomodulin upregulation

BACKGROUND

Livedo vasculitis is thought to be a thrombogenic disorder. We demonstrated that thrombomodulin (TM) expression on the endothelial cells in livedo vasculitis was markedly reduced, while blood tests of coagulation and fibrinolytic activities were within the normal range.

OBJECTIVE

Since prostacyclin (PGI2) upregulates the TM expression of endothelial cells, we tried a PGI2 analogue for the treatment of livedo vasculitis.

METHOD

Four patients with livedo vasculitis were started on a regimen of beraprost sodium (120 micrograms daily). Additional intake of low-dose aspirin was combinated with a maintenance dose of beraprost sodium (60 micrograms daily).

RESULT

All 4 patients experienced a clinical improvement with a combination therapy with beraprost sodium and low-dose aspirin.

CONCLUSION

We propose that PGI2 analogue therapy is useful for the treatment of livedo vasculitis, since the drug upregulates TM expression in this disorder.

Diabetic muscle infarction: a new perspective on pathogenesis and management

Two patients with insulin dependent diabetes mellitus developed recurrent episodes of focal muscle pain and swelling. Clinical evaluation, magnetic resonance imaging (MRI) and muscle biopsy confirmed the diagnosis of recurrent hemorrhagic muscle infarctions. Our studies suggest that muscle infarction occurred because of hypercoagulability and associated vascular endothelial damage. Based on these findings we recommend long-term anticoagulation to prevent recurrent infarction.