Plasma levels of thrombomodulin in pulmonary hypertension

Irregularities of Coagulation in Hypertension

PURPOSE OF REVIEW

This review article summarizes the role of coagulation in the pathogenesis of hypertension. It specifically focuses on significant factors and markers associated with coagulation, including D-dimer, fibrinogen and fibrin, prothrombin, P-selectin, soluble urokinase plasminogen activator receptor, thrombomodulin, tissue factor, tissue plasminogen activator, von Willebrand factor, β-thromboglobulin, and Stuart-Prower factor.

RECENT FINDINGS

D-dimer levels were elevated in hypertensive individuals compared to healthy controls, and the levels increased with the severity of hypertension. These findings indicate that increased coagulation activity of fibrin plays a role in the development of thromboembolic complications in hypertensive patients. Additionally, both fibrinogen levels and D-dimer levels displayed a positive correlation with the duration of hypertension, suggesting that these biomarkers were positively associated with the length of time an individual had been hypertensive. Increased systolic and diastolic blood pressures have been linked to higher levels of prothrombin time and activated partial thromboplastin time in individuals with hypertension as well as those with normal blood pressure. Also, the presence of P-selectin, produced by activated platelets and endothelial cells during angiotensin II stimulation, played a role in the development of cardiac inflammation and fibrosis associated with hypertension. Moreover, the change in systolic blood pressure was associated with baseline soluble urokinase plasminogen activator receptor (suPAR) in hypertensive participants, and the change in suPAR levels was associated with the development of hypertension. Moreover, it was observed a decrease in thrombomodulin expression in the placenta of preeclamptic patients, suggesting its potential involvement in placental dysfunction, possibly driven by an imbalance in angiogenic factors. Tissue factors and autophagy might have significant implications in the pathogenesis of chronic thromboembolic pulmonary hypertension, particularly in the context of vascular remodelling. Likewise, ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) might be a promising biomarker for the early detection of pulmonary arterial hypertension and the von Willebrand factor is a candidate prognostic biomarker. The arterial β-thromboglobulin levels were significantly lower than venous levels. This article concludes that D-dimer, fibrinogen and fibrin, prothrombin, P-selectin, soluble urokinase plasminogen activator receptor, thrombomodulin, tissue factor, tissue plasminogen activator, von Willebrand factor, and β-thromboglobulin are important factors involved in the pathogenesis of hypertension.

Serum Biomarkers in Connective Tissue Disease-Associated Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a life-threatening complication of connective tissue diseases (CTDs) characterised by increased pulmonary arterial pressure and pulmonary vascular resistance. CTD-PAH is the result of a complex interplay among endothelial dysfunction and vascular remodelling, autoimmunity and inflammatory changes, ultimately leading to right heart dysfunction and failure. Due to the non-specific nature of the early symptoms and the lack of consensus on screening strategies-except for systemic sclerosis, with a yearly transthoracic echocardiography as recommended-CTD-PAH is often diagnosed at an advanced stage, when the pulmonary vessels are irreversibly damaged. According to the current guidelines, right heart catheterisation is the gold standard for the diagnosis of PAH; however, this technique is invasive, and may not be available in non-referral centres. Hence, there is a need for non-invasive tools to improve the early diagnosis and disease monitoring of CTD-PAH. Novel serum biomarkers may be an effective solution to this issue, as their detection is non-invasive, has a low cost and is reproducible. Our review aims to describe some of the most promising circulating biomarkers of CTD-PAH, classified according to their role in the pathophysiology of the disease.

Current Trends in Vascular Biomarkers for Systemic Sclerosis: A Narrative Review

Systemic sclerosis (SSc, scleroderma) is a multifaceted rare connective tissue disease whose pathogenesis is dominated by immune dysregulation, small vessel vasculopathy, impaired angiogenesis, and both cutaneous and visceral fibrosis. Microvascular impairment represents the initial event of the disease, preceding fibrosis by months or years and accounting for the main disabling and/or life-threatening clinical manifestations, including telangiectasias, pitting scars, periungual microvascular abnormalities (e.g., giant capillaries, hemorrhages, avascular areas, ramified/bushy capillaries) clinically detectable by nailfold videocapillaroscopy, ischemic digital ulcers, pulmonary arterial hypertension, and scleroderma renal crisis. Despite a variety of available treatment options, treatment of SSc-related vascular disease remains problematic, even considering SSc etherogenity and the quite narrow therapeutic window. In this context, plenty of studies have highlighted the great usefulness in clinical practice of vascular biomarkers allowing clinicians to assess the evolution of the pathological process affecting the vessels, as well as to predict the prognosis and the response to therapy. The current narrative review provides an up-to-date overview of the main candidate vascular biomarkers that have been proposed for SSc, focusing on their main reported associations with characteristic clinical vascular features of the disease.

A wrinkle in time: circadian biology in pulmonary vascular health and disease

An often overlooked element of pulmonary vascular disease is time. Cellular responses to time, which are regulated directly by the core circadian clock, have only recently been elucidated. Despite an extensive collection of data regarding the role of rhythmic contribution to disease pathogenesis (such as systemic hypertension, coronary artery, and renal disease), the roles of key circadian transcription factors in pulmonary hypertension remain understudied. This is despite a large degree of overlap in the pulmonary hypertension and circadian rhythm fields, not only including shared signaling pathways, but also cell-specific effects of the core clock that are known to result in both protective and adverse lung vessel changes. Therefore, the goal of this review is to summarize the current dialogue regarding common pathways in circadian biology, with a specific emphasis on its implications in the progression of pulmonary hypertension. In this work, we emphasize specific proteins involved in the regulation of the core molecular clock while noting the circadian cell-specific changes relevant to vascular remodeling. Finally, we apply this knowledge to the optimization of medical therapy, with a focus on sleep hygiene and the role of chronopharmacology in patients with this disease. In dissecting the unique relationship between time and cellular biology, we aim to provide valuable insight into the practical implications of considering time as a therapeutic variable. Armed with this information, physicians will be positioned to more efficiently use the full four dimensions of patient care, resulting in improved morbidity and mortality of pulmonary hypertension patients.

Circulating Protein Biomarkers in Systemic Sclerosis Related Pulmonary Arterial Hypertension: A Review of Published Data

Pulmonary arterial hypertension (PAH) develops in 7-12% of patients with systemic sclerosis (SSc) and is associated with a 3 year survival of 52%. Early detection by screening is therefore recommended for all patients with SSc. Historically, screening has been performed using echocardiography and measurement of gas transfer. More recently the DETECT protocol, using a combination of biomarkers (including N-terminal pro-brain natriuretic peptide) and clinical parameters, has been developed. The optimal method of screening for PAH with high sensitivity and specificity is, however, not clear. Protein expression differences between different SSc disease phenotypes have been reported, and include alterations in concentration of NT-proBNP, endoglin, soluble vascular endothelial growth factor receptor 1, placenta growth factor, growth differentiation factor-15, vascular endothelial growth factor alpha, resistin-like molecule beta, and soluble thrombomodulin. This review summarizes the current knowledge of these protein changes in patients with SSc and PAH.

Decreased circulating thrombomodulin is improved by tadalafil therapy in hypoxemic patients with advanced pulmonary arterial hypertension

INTRODUCTION

Advanced pulmonary arterial hypertension (PAH) in patients with congenital cardiac communications and right-to-left shunting (Eisenmenger syndrome - PAH-ES) is associated with hypoxemia and decreased circulating levels of thrombomodulin (TM), probably reflecting decreased endothelial TM production. The combination of these two factors has been shown to induce fibrin deposition, with increased risk of thrombosis, a well known complication in this syndrome.

PATIENTS AND METHODS

We tested the hypothesis that vasodilator therapy with the phosphodiesterase-5 inhibitor tadalafil, an approved drug for management of PAH could improve endothelial dysfunction markers, in particular plasma TM, in addition to improving the physical capacity (expected effect of pulmonary vasodilatation) in PAH-ES patients. This was a prospective observational study of treatment-naïve patients subjected to specific PAH therapy. Fifteen patients aged 12 to 51years (median 30years) were treated for 6months with a single daily dose of 40mg oral tadalafil. The physical capacity (distance walked during the 6-min walk test - 6MWD), systemic oxygen saturation and laboratory parameters were measured at baseline, and 90days and 180days of treatment.

RESULTS

Plasma TM, which was decreased at baseline compared to controls (p<0.001) increased at 90 and 180days (p=0.003), and this was directly related (r=0.57, p=0.026) to improvement of oxygen saturation (p=0.008). Heightened baseline tissue-type plasminogen activator decreased during treatment (p=0.010), while heightened von Willebrand factor antigen remained unchanged. The 6MWD improved significantly (p<0.001).

CONCLUSION

Tadalafil therapy improved circulating TM and tissue-type plasminogen activator, in addition to improving the physical capacity and oxygen saturation in PAH-ES patients.

Long-term Behavior of Endothelial and Coagulation Markers in Eisenmenger Syndrome

The long-term behavior of endothelial markers was studied in patients with Eisenmenger syndrome who were subjected to conventional therapy (no vasodilators) and observed for 18 months. Biochemical markers were analyzed comparatively in patients with class II or III symptoms (group 1, n=10) and patients with class IV symptoms (group 2, n=7). Plasma von Willebrand factor antigen (vWF: Ag), thrombomodulin, tissue-type plasminogen activator (t-PA) and its inhibitor (PAI-1), and D-dimer were determined by immunoenzymatic assay at baseline, and at 6, 12, and 18 months. At baseline, the main clinical difference between groups was a decreased peripheral oxygen saturation in group 2 versus group 1 (77±5% and 86±4%, respectively, p=0.001). Basal vWF: Ag and t-PA were increased and thrombomodulin was decreased in both groups in comparison with controls (p<0.0001), while D-dimer was increased in group 2 only (p=0.0003). In response to treatment, there was a decrease in vWF: Ag in both groups (19% and 23%, respectively in groups 1 and 2, at 18 months vs. baseline, p<0.0001) and t-PA in group 1 (38% vs. baseline, p=0.0485). Plasma vWF: Ag tended to be higher in group 2 in comparison with group 1 during the whole follow-up. Levels of PAI-1 greater than 38.4 ng/mL (upper 90% limit for normals) and D-dimer greater than 500 ng/mL were detected in individual patients (both groups) during the follow-up period. Thrombomodulin remained decreased in both groups. Thus, severity of symptoms in the Eisenmenger syndrome appears to correlate with low oxygen saturation and higher vWF: Ag levels. Improvement of endothelial dysfunction may occur in response to treatment, although increased risk for thrombosis persists, in view of residual abnormalities.

Age-Dependent Likelihood of In Situ Thrombosis in Secondary Pulmonary Hypertension

Pulmonary arterial thrombosis (PAT) may complicate the clinical course of pulmonary hypertension associated with congenital heart disease (so-called Eisenmenger syndrome, ES). In this study, variables were sought that could represent risk factors for the occurrence of this complication. Twenty patients aged 11 to 53 (median, 33) years were studied. The presence of PAT (spiral computed tomography angiography) was correlated with age, gender group, PAP, hematocrit, peripheral oxygen saturation (SpO2), and plasma levels of endothelial and coagulation dysfunction markers: von Willebrand factor antigen (vWF: Ag), tissue plasminogen activator (t-PA), and D-dimer (enzyme immunoassay). Patients were classified according to the presence (group 1, N=7), or absence (group 2, N=13) of PAT. Group 1 patients were older (42±8 vs. 27±10 years in group 2, p=0.0051), had lower SpO2 (82±7% vs. 89±6% in group 2, p=0.0462) and increased D-dimer levels (637 vs. 149 ng/mL in group 2, median values, p=0.0235). A trend was observed toward an increase in vWF: Ag (125±29 vs. 103±18 U/dL in group 2, p=0.0789) and t-PA (15.7 vs. 9.4 ng/mL in group 2, median values, p=0.0689). Age was the main variable influencing the occurrence of PAT in multivariate analysis (p=0.0026), with odds ratio of 1.204 per year. The age of 35 years was 86% sensitive and 85% specific for occurrence of PAT. Age correlated positively with t-PA (r=0.57, p=0.0111). Thus, PAT is highly prevalent in ES as an age-dependent event, probably associated with endothelial dysfunction. Prophylactic anticoagulation should be considered before the age of 30 years, in particular in subjects with low SpO2 and increased D-dimer levels.

Standard nonspecific therapies in the management of pulmonary arterial hypertension

Recent advances in pulmonary arterial hypertension (PAH) research have created a new era of PAH-specific therapies. Although these therapeutics have revolutionized PAH therapy, their innovation was predated by supportive but nonspecific medical therapies adapted from their use in more common cardiopulmonary diseases. These therapies include oxygen therapy, diuretics, digoxin, anticoagulation, and high-dose calcium channel blockers. Expert opinion continues to support the use of adjunct therapies based on current pathologic understandings of PAH combined with some evidence extrapolated from small studies. This article discusses why these therapies continue to play an important role in the treatment of patients with PAH.

Effect of thrombomodulin on the development of monocrotaline-induced pulmonary hypertension

PURPOSE

The purpose of the present study was to investigate whether thrombomodulin (TM) prevents the development of pulmonary hypertension (PH) in monocrotaline (MCT)-injected rats.

METHODS

Human recombinant TM (3 mg/kg/2 days) or saline were given to MCT-injected male Sprague-Dawley rats for 19 (n = 14) or 29 (n = 11) days. Control rats (n = 6) were run for 19 days. The mean pulmonary artery pressure (mPAP), right ventricular hypertrophy (RVH), percentages of muscularized peripheral arteries (%muscularization), and medial wall thickness of small muscular arteries (%MWT) were measured. To determine inflammatory and coagulation responses, broncho-alveolar lavage fluid (BALF) was analyzed in another set of rats (n = 29). Western blotting for endothelial nitric oxide synthase (eNOS) and phosphorylated eNOS (peNOS) in the lung tissue was performed in separate rats (n = 13). Survival was determined in 60 rats.

RESULTS

MCT increased mPAP, RVH, %muscularization, and %MWT. TM treatment significantly reduced mPAP, %muscularization, and %MWT in peripheral arteries with an external diameter of 50-100 μm in 19 days after MCT injection, but the effect was lost after 29 days. MCT increased the levels of tumor necrosis factor alpha, monocyte chemoattractant protein-1, and thrombin-antithrombin complex in BALF. Expression of eNOS increased in MCT rats, while peNOS decreased. The relative amount of peNOS to total eNOS increased in MCT/TM rats compared to MCT/Vehicle rats. A Kaplan-Meier survival curve showed no difference with and without TM.

CONCLUSION

Although the administration of TM might slightly delay the progression of MCT-induced PH, the physiological significance for treatment is limited, since the survival rate was not improved.

Calibrated automated thrombography demonstrates hypercoagulability in patients with idiopathic pulmonary arterial hypertension

INTRODUCTION

Pathogenesis of idiopathic pulmonary arterial hypertension (iPAH) includes endothelial dysfunction and in situ thrombosis. A hypercoagulable state has also been postulated but never demonstrated. Our objective was to determine whether patients with iPAH had a hypercoagulable state using calibrated automated thrombography (CAT), a new tool to phenotype coagulation in vitro.

PATIENTS AND METHODS

16 patients with iPAH and 29 controls were studied. In vitro platelet dependent coagulation phenotyping by CAT monitored the activity of thrombin generation over time. Plasma levels of soluble thrombomodulin, tissue factor pathway inhibitor (TFPI) and von Willebrand factor (VWF) were measured as endothelial biomarkers.

RESULTS

Endogenous thrombin potential (ETP) in the absence of activated protein C (APC) tended to be increased in patients compared to controls (1769 versus 1656 nM.min; p=0.053). ETP was higher in the presence of APC 25 nM (ETP-APC) in patients (781 versus 494 nM.min; p=0.005). Five patients had ETP-APC higher than the 95th centile of controls. Other CAT parameters (lag time, peak thrombin and time to peak) were all consistent with some degree of hypercoagulability in patients. Regarding endothelial plasma biomarkers sTM was lower (28.4 versus 40.6 μg/l, p=0.0108) in patients; TFPI antigen and activity (respectively: 14.3 versus 10.5 μg/l, p=0.0167; 1.155 versus 1.070, p=0.0021) and VWF (1300 versus 976%, p=0.0108) were higher in patients.

CONCLUSION

We have demonstrated that at least some patients with iPAH have a hypercoagulable phenotype.

Procoagulant membrane microparticles correlate with the severity of pulmonary arterial hypertension

RATIONALE

Procoagulant microparticles constitute valuable hallmarks of cell damage. Microparticles also behave as cellular effectors.

OBJECTIVES

We hypothesized that the extent of the vascular cell damage measured by circulating microparticles could be related to the severity of pulmonary arterial hypertension (PAH).

METHODS

Circulating biomarkers of vascular damage and cell activation were measured in blood samples from 20 patients with PAH. Samples were withdrawn from occluded pulmonary artery and jugular vein. Peripheral venous blood samples were obtained in 23 control subjects. The microparticle procoagulant abilities were quantified by functional prothrombinase and tissue factor assays and their cellular origin was determined.

MEASUREMENTS AND MAIN RESULTS

Soluble vascular cellular adhesion molecule-1 and proinflammatory markers, such as monocyte chemoattractant protein-1 and highly specific C-reactive protein, were elevated in patients with PAH compared with control subjects. Microparticles bearing active tissue factor and CD105 (endoglin) were also elevated in patients with PAH compared with control subjects (29 +/- 13 vs. 16 +/- 6 fmol/L, P < 0.001, and 1.10 +/- 0.46 vs. 0.49 +/- 0.33 nmol/L phosphatidylserine equivalent, P < 0.001, respectively). A further increase in endothelium-derived CD105 microparticles was observed in pulmonary arterial blood compared with venous blood in patients with PAH (1.73 +/- 0.77, P = 0.038). Microparticles bearing active tissue factor were at a higher level in patients in functional class III and IV and who were walking fewer than 380 m with the six-minute-walk test.

CONCLUSIONS

Circulating markers of endothelium damage, proinflammatory markers, and cell stimulation estimated with circulating microparticles appear to be valuable tools in determining the severity of PAH.

Standard therapies for pulmonary arterial hypertension

After half a century of clinical experience and research, management of pulmonary arterial hypertension remains a challenge. Currently, data to support the use of standard therapies for pulmonary arterial hypertension (oxygen supplementation, diuretics, digoxin, anticoagulation, and calcium channel blockers) are mostly retrospective, uncontrolled prospective, or derived from other diseases with similar but not identical manifestations. In the absence of any further prospective, controlled studies, it is reasonable to use these therapies when they are tolerated. When these therapies are poorly tolerated, however, the threshold for discontinuation should be low.

Increased Thrombogenesity in Patients With Cyanotic Congenital Heart Disease

BACKGROUND

The basic mechanisms of thromboembolism in cyanotic congenital heart disease (CCHD) have not been well clarified. P-selectin on the platelets reflects platelet activation. Thrombomodulin is a critical cofactor for thrombin-mediated activation of protein C and reflects the anticoagulant activity of the endothelium. The present study was performed to evaluate whether platelet activation exists in patients with CCHD.

METHODS AND RESULTS

Platelet P-selectin as a marker of platelet activation, plasma thrombomodulin level and protein C activity as markers of anticoagulant activity of the endothelium and thrombin - antithrombin complex III (TAT) were examined in 35 patients with CCHD. Plasma thrombomodulin level (1.1+/-0.9 vs 2.2+/-0.3 FU/ml) and protein C activity (71.1+/-29.8 vs 117.8+/-24.8%) were significantly lower in patients with CCHD as compared with the control subjects. The levels of plasma TAT (255+/-811 vs 1.9+/-0.9 ng/ml) and P-selectin on platelets (6.3 +/-4.5 vs 3.3+/-0.3 mean fluorescence intensity) were significantly higher in the patients with CCHD than in the controls. Four of the CCHD patients who experienced thromboembolic events had elevated levels of platelet P-selectin (p=0.02) compared with CCHD patients without thromboembolic events.

CONCLUSION

Platelet activation exists in patients with CCHD and it may play an important role in the thromboembolic events in CCHD.

Endothelial cell activity in chronic obstructive pulmonary disease without severe pulmonary hypertension

Pulmonary hypertension is common in patients with chronic obstructive pulmonary disease (COPD), but the precise mechanism of vascular impairment in these patients is unknown. We, therefore, decided to investigate whether endothelial cell dysfunction is present in patients with COPD with a wide range of chronic airflow obstruction before the development of severe pulmonary hypertension. Selected plasma markers of endothelial cell activity were studied: nitrate+nitrite (NO-(2)/NO-(3)), thrombomodulin (TM), tissue factor pathway inhibitor (TFPI), soluble selectins (endothelium sES, leukocyte sLS, platelet sPS), soluble intercellular adhesion molecule-1 (sICAM-1), and soluble platelet endothelial cell adhesion molecule-1 (sPECAM-1). Twenty-five patients with COPD (forced expiratory volume in one second/vital capacity [FEV(1)/VC] < 88% predicted) and 29 healthy control subjects were recruited to the study. Among patients nine had a pulmonary artery systolic pressure (PASP) between 15 and 30 mmHg, 13 between 32 and 38 mmHg, 2 had a PASP of 41 and 42 mmHg, respectively. One patient had severe pulmonary hypertension with a PASP of 70 mmHg. The average FEV(1) of patients with COPD was 46 +/- 4% predicted. As compared to control subjects, patients with COPD showed a significant increase in plasma levels of TM and TFPI, indicating that their endothelial cells are still able to produce potent coagulation inhibitors. Levels of NO-(2)/NO-(3) were similar in the two groups of subjects examined, further suggesting preserved endothelial function in patients with COPD. In regard to adhesion molecules, patients with COPD showed a reduction in sLS, sPS, and sPECAM-1, and an increase in sICAM-1. This study shows that endothelial cell activity is largely preserved in patients with COPD without severe pulmonary hypertension, suggesting that these patients, despite quite severe airway obstruction, retain reasonably normal endothelial function until they develop severe pulmonary hypertension.

Markers of endothelial dysfunction and severity of hypoxaemia in the Eisenmenger syndrome

Endothelial dysfunction has been reported in hypoxaemic patients with the Eisenmenger syndrome, but a direct correlation between levels of endothelial markers and the severity of hypoxaemia has not been explored. With this in mind, we compared the levels in the plasma of tissue-type plasminogen activator, thrombomodulin, and von Willebrand factor in 25 patients with the Eisenmenger syndrome. They had a median age of 31 years, and were divided into 2 groups according to their recent clinical history. Thus, 18 patients were stable, being in functional class II or III, seen as outpatients, and having peripheral saturations of oxygen of 89 plus or minus 5 percent. In contrast, 7 patients were unstable, showing episodes of symptoms placing them in functional class IV, requiring care in hospital, and manifesting saturations of oxygen of 77 plus or minus 5 percent. We were able to follow 12 patients, 8 who were stable and 4 unstable, for 24 months. At baseline, levels of von Willebrand factor were higher in the unstable patients when compared to those who were stable, at 142 plus or minus 29 and 110 plus or minus 25 units per decilitre, respectively (p equal to 0.013). This correlated positively with oxygen desaturation (p less than 0.020). The structural abnormalities also correlated positively with the magnitude of hypoxaemia (p less than 0.020). Levels remained higher in the unstable patients throughout the period of follow-up (p equal to 0.006). Tissue-type plasminogen activator was also increased, at 14.3 plus or minus 8.4 versus 6.5 plus or minus 2.7 nanograms per millilitre in controls (p less than 0.001), whereas thrombomodulin was decreased, with values of 14.4 versus 34.6 nanograms per millilitre in controls (p for median values of less than 0.001). There was no correlation with saturations of oxygen. We conclude that measurement of von Willebrand factor, as compared with tissue-type plasminogen activator and thrombomodulin, will prove a better marker of endothelial response to hypoxaemia in patients with the Eisenmenger syndrome.

Thrombomodulin, von Willebrand factor and E-selectin as plasma markers of endothelial damage/dysfunction and activation in pregnancy induced hypertension

OBJECTIVE

Endothelial disturbance (whether activation, dysfunction or damage) is a likely pathogenic mechanism in pre-eclampsia and pregnancy-induced hypertension (PIH). We set out to determine which of three plasma markers of endothelial disturbance, indicating endothelial activation (E-selectin) or damage/dysfunction (von Willebrand factor (vWf), soluble thrombomodulin), would provide the best discriminator of PIH compared to normotensive pregnancy.

STUDY DESIGN

Cross-sectional study of 36 consecutive women with PIH (age 31+/-6 years) and 36 consecutive women with normotensive pregnancies (age 29+/-5 years) of similar parity. Plasma levels of vWf, E-selectin and thrombomodulin were measured using ELISA.

RESULTS

As expected, women with PIH had significantly higher levels of plasma vWf (by 19%, p=0.003), E-selectin (by 40%, p<0.001) and thrombomodulin (by 61%, p=0.01) than normotensive women. However, on stepwise multiple regression analysis, only thrombomodulin was an independent significant predictor of the presence of PIH (p=0.023).

CONCLUSIONS

We conclude that although vWf, E-selectin and thrombomodulin are all raised in PIH, only thrombomodulin was independently associated with PIH. This molecule could potentially be useful in monitoring and in providing clues in aetiology and pathophysiology, and may have implications for the clinical complications associated with PIH.

Pulmonary thrombosis in adults with Eisenmenger syndrome

OBJECTIVES

We sought to determine the prevalence of pulmonary artery thrombosis in patients with Eisenmenger syndrome and to identify individuals at highest risk.

BACKGROUND

Eisenmenger syndrome is associated with pulmonary arterial thrombus formation. Both the prevalence and the determinants of pulmonary arterial thrombosis are unknown.

METHODS

This is a review of patients with Eisenmenger syndrome seen at the Toronto Congenital Cardiac Centre for Adults, Canada. Patients underwent a contrast-enhanced computed tomographic (CT) scan of the thorax.

RESULTS

Forty-nine consecutive patients with Eisenmenger syndrome were seen in our hospital. Fifteen patients did not undergo CT angiograms; therefore, 34 patients (mean age 42 +/- 10 years) were included in the study. Responsible shunts included ventricular septal defect (65%), atrial septal defect (15%), patent ductus arteriosus (9%), and other (11%). The prevalence of proximal pulmonary artery thrombus was 21% (7/34) of patients. Evidence of more distal vessel thrombosis was observed in 43% (3/7) of the patients who had visible thrombus in the proximal pulmonary arteries. Patients with thrombus were more likely to be female (86% vs. 37%, p = 0.04) and to have lower oxygen saturations (72% +/- 9% vs. 85% +/- 6%, p = 0.01). Differences in functional status did not identify patients at highest risk for thrombosis.

CONCLUSIONS

Patients with Eisenmenger syndrome have a substantial risk of pulmonary artery thrombus formation. Women and patients with lower oxygen saturations are at the highest risk of developing thrombosis. In the context of an increased bleeding tendency in these patients, the role of anticoagulation treatment needs to be determined.

Increase in Thrombomodulin Concentrations After Pulmonary Thromboendarterectomy in Chronic Thromboembolic Pulmonary Hypertension

STUDY OBJECTIVES

The objectives of the study were as follows: (1) to identify differences in endothelial dysfunction and altered hemostasis in patients with chronic thromboembolic pulmonary hypertension (CTEPH) compared with patients with acute pulmonary thromboembolism (APTE) uncomplicated by pulmonary arterial hypertension, by measuring the concentrations of thrombomodulin (TM), a receptor for thrombin and a major anticoagulant proteoglycan on the endothelial membrane, and other plasma factors of coagulation and fibrinolysis; and (2) to examine the effects of thromboendarterectomy on TM levels as a parameter of endothelial cell injury leading to abnormal hemostasis as well as to examine the clinical significance of TM as a marker of endothelial injury.

DESIGN

Prospective comparison of concentrations of TM and other plasma parameters among patients with CTEPH or APTE and control subjects.

PARTICIPANTS

We studied 22 healthy subjects (ie, control subjects), 22 patients who had been clinically stabilized after APTE, and 44 patients with CTEPH. In 21 of the patients with CTEPH, measurements were repeated after they had undergone pulmonary thromboendarterectomy.

MEASUREMENTS AND RESULTS

Plasma concentrations of soluble TM in patients with CTEPH were measured and compared with those in patients with APTE. The mean (+/- SD) TM concentration in the CTEPH group (2.5 +/- 0.7 ng/mL) was significantly lower than that in the control group (4.0 +/- 0.6 ng/mL; p < 0.05). In contrast, the mean plasma TM concentration in the APTE group (4.6 +/- 1.9 ng/mL) was similar to that in the control group. After patients underwent pulmonary thromboendarterectomy, the mean TM concentration increased from 2.0 +/- 0.4 to 2.9 +/- 0.7 ng/mL (p < 0.05). In the CTEPH group, the plasma TM concentration was negatively correlated with mean pulmonary arterial pressure and total pulmonary resistance (p < 0.05).

CONCLUSIONS

A decreased plasma TM concentration may reflect pulmonary vascular endothelial dysfunction leading to altered anticoagulant and fibrinolytic function in CTEPH, which rarely develops after APTE. Plasma TM measurements may be useful in distinguishing CTEPH with severe pulmonary hypertension from recurrent APTE.

Hypertension associated with reduced plasma thrombomodulin levels and a hypercoagulable state in rats

The plasma thrombomodulin (TM) level, an indicator of systemic endothelial cell damage, was measured in spontaneously hypertensive rats (SHR), deoxycorticosteron acetate (DOCA)-induced hypertensive rats and normotensive Wistar-Kyoto (WKY) rats to clarify its changes in hypertension. Plasma TM levels, measured by enzyme-linked immuno-sorbent assay, decreased with aging (5-20-weeks-old) in both SHR and WKY, and they were lower in SHR than age-matched WKY in all ages examined. Deoxycorticosteron acetate-induced hypertensive WKY also showed decreased TM levels compared with normotensive WKY. Accelerated coagulation and fibrinolysis shown by the increases in thrombin-antithrombin complex (TAT) and D-dimer levels were observed in both groups of hypertensive rats. These results suggest that hypertension may decrease plasma TM levels and induce a hypercoagulable state in rats.

Wall tension is a potent negative regulator of in vivo thrombomodulin expression

Thrombomodulin (TM), a key component of the anticoagulant protein C pathway, is a major contributor to vascular thromboresistance. We previously found that TM protein expression is dramatically reduced in autologous vein grafts during the first two weeks after implantation, coincident to a local inflammatory response, and remains suppressed for at least 6 weeks. To determine the proximate cause of TM loss, in vivo gene expression was quantified by real-time PCR. TM gene expression in vein grafts declined >85% during the first postoperative week and remained suppressed >55% at 6 weeks, accounting for the observed changes in protein expression. The effects of vein graft inflammation were evaluated in animals rendered leukopenic with vinblastine before graft implantation. Abrogating the local inflammatory response affected neither TM protein nor gene expression. To determine how hemodynamic forces might modulate TM expression, the surgical protocol was modified to alter blood flow and pressure-induced vessel distension. TM protein and gene expression did not correlate to changes in shear stress but highly correlated to changes in wall tension, both acutely and over time. We conclude that the primary stimulus for altered TM expression in vein grafts is the exposure to arterial pressure. Furthermore, these data identify strain as a novel and important pathway for in vivo TM gene regulation.

Endothelial dysfunction associated with chronic intravascular coagulation in secondary pulmonary hypertension

Altered endothelial anti-thrombotic properties have been observed in primary and secondary pulmonary hypertension. In the Eisenmenger syndrome, correlations of these abnormalities with the clinical status and occurrence of chronic intravascular coagulation (CIC) have not been confirmed. The purpose of this study was to investigate whether the occurrence of CIC, as determined by circulating levels of D-dimer is associated with changes in endothelial markers in Eisenmenger patients; and to identify variables that correlate with the severity of clinical presentation. Twenty-one patients were enrolled (ages, 4-52 years). Plasma levels of D-dimer, tissue plasminogen activator (t-PA), thrombomodulin, and von Willebrand factor antigen (vWF:Ag) were measured with enzyme-linked immunosorbent assay. Univariate and multivariate analyses were used to differentiate patients with stable (group 1, N=12) from those with unstable disease (group 2, N=9). Increased t-PA (p<0.0001) and vWF:Ag (p=0.001) and decreased thrombomodulin (p<0.0001) were associated with increased D-dimer levels (p=0.0201) in patients. Group 2 had a higher prevalence of affected women (p=0.0242), lower arterial oxygen saturation, and higher t-PA levels compared with group 1 (p<0.0001, discriminant analysis). t-PA and vWF:Ag correlated positively in group 2 (r=0.71, p=0.0309), but not in group 1 (r=0.25, p=NS). Two patients in group 2 but none in group 1 had episodes of pulmonary arterial thrombosis. Endothelial dysfunction is associated with evidence of CIC and correlates to some extent with the severity of symptoms in these patients.

Relationship between plasma markers of endothelial cell integrity and the Framingham cardiovascular disease risk-factor scores in apparently healthy individuals

Separate reports have identified differences in plasma levels of the endothelial markers soluble E-selectin, von Willebrand factor (vWf) and soluble thrombomodulin in each of the major modifiable risk factors for atherosclerosis (smoking, hypertension and hypercholesterolaemia), and abnormal levels of some plasma markers predict various adverse cardiovascular events. However, it is unclear whether there is an increasing effect on the endothelium with a worsening risk-factor profile. We measured the three endothelial cell markers by enzyme-linked immunosorbent assay in the plasma of 200 subjects (mean age, 54 years; 58% men) free of the symptoms and clinical signs of atherosclerosis. Levels of the markers were then correlated with the Framingham coronary heart disease (CHD) and cerebrovascular disease (CVD) scores to help determine which (if any) may be useful as good laboratory predictors of future cardiovascular events in prospective epidemiological studies. vWf correlated with CHD (r(s) = 0.269, < 0.001) and CVD risk (r(s) = 0.331, P < 0.001), but soluble E-selectin correlated only with CHD risk (r(s) = 0.163, P = 0.021). We conclude that, of the three specific endothelial markers, vWf correlates most closely with the Framingham risk-factor prediction scores and therefore may be the better plasma endothelial marker of the future development of an atherothrombotic event.

Effect of the new centrally acting antihypertensive agent rilmenidine on endothelial and platelet function in essential hypertension

The aim of the study was to investigate the effect of therapy by rilmenidine on endothelial and platelet function in 23 patients with the early stages of untreated essential hypertension. The measurements were carried out before therapy, after 1 week of placebo administration, after 1 week, after 1 month and after 3 months of therapy. After 1 week of therapy both systolic (SBP) and diastolic blood pressure (DBP) were reduced (P < 0.001) all over the study period. Plasma thrombomodulin (TM) and von Willebrand factor (vWF) as indicators of endothelial dysfunction, and plasma beta-thromboglobulin (betaTG) as an indicator of in vivo platelet activation, were investigated. Fibrinogen as a risk factor for vascular changes was also assayed. Platelet aggregation without stimulation (spontaneous, SPA) and induced by adrenaline (APA) was measured. A decrease of plasma vWF level after 1 month (P < 0.05) and after 3 months (P < 0.05) of therapy was observed. We failed to find any changes of plasma TM and fibrinogen level. A reduction of platelet aggregation was evident after 1 week (SPA and APA, P < 0.05, respectively) but mainly after 1 month (SPA P < 0.01, APA P < 0.05) and after 3 months of therapy (SPA and APA, P < 0.01, respectively). It was accompanied by a decrease of plasma betaTG level after 3 months of therapy (P < 0.05). The vasculoprotective and antiplatelet effect of rilmenidine may be important in terms of the favourable role of antihypertensive drugs in cardiovascular morbidity.

Plasma markers of endothelial dysfunction in pulmonary hypertension

STUDY OBJECTIVES

To evaluate and to correlate endothelial cell dysfunction, using recently available plasma markers, with the magnitude of pulmonary artery pressure in patients with severe pulmonary hypertension (PH).

DESIGN

Selected plasma markers of endothelial cell dysfunction were studied: nitric oxide (NO), thrombomodulin, tissue factor pathway inhibitor, and soluble endothelium, leukocyte, and platelet selectins (sE-, sL-, sP-selectins, respectively).

SETTING

Padova University Hospital and Department of Pathology and Pharmacology, Loyola University of Chicago, Chicago, IL.

PATIENTS

Fifteen patients had severe PH (four men and 11 women; mean age, 49.7 +/- 2.9 years: seven patients had primary pulmonary hypertension [PPH] and eight patients had secondary pulmonary hypertension [SPH]), and 20 patients were healthy control subjects.

MEASUREMENT AND RESULTS

In patients with PH, sP- and sE-selectins were elevated, whereas sL-selectin was lower in comparison with the selectin levels in control subjects. However, the differences between patients with PH and control subjects were significant only for sL-selectin (p < 0.0001) and sE-selectin (p < 0.03). The NO level was significantly lower in patients with PH compared with the NO level in control subjects (p < 0.01). No difference in tissue factor pathway inhibitor level was noted between control subjects and patients with PH. Only a weak correlation was found between thrombomodulin plasma levels and magnitude of systolic pulmonary artery pressure (r = -0.528, p < 0.05).

CONCLUSIONS

Our data are in keeping with the evidence for significant endothelial cell dysfunction in patients with PH and the need for chronic anticoagulation believed to increase survival in these patients. In addition, these data seem to suggest a need for newer agents that are able to increase the antithrombotic endothelial function.

Pathobiology of pulmonary hypertension. The role of platelets and thrombosis

With the rare exceptions of PAH associated with antiphospholipid antibodies, genetic platelet dysfunction, or inherited deficiencies of antithrombotic pathways, the thrombotic lesions are secondary, but frequently occurring, in most cases of primary or secondary PAH. Pulmonary arterial hypertension is associated with thrombotic lesions and persistent vasoconstriction and structural remodeling of PA. Activated platelets interact with the PA wall and may contribute to the functional and structural alterations of pulmonary vessels by releasing vasoactive factors and mitogenic mediators.

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.

High plasma serotonin levels in primary pulmonary hypertension. Effect of long-term epoprostenol (prostacyclin) therapy

Elevated plasma serotonin is associated with primary pulmonary hypertension (PPH). To test whether this elevation could be related to platelet activation, the 2 pools of blood serotonin (platelets and plasma) and plasma 5-hydroxyindoleacetic acid (5-HIAA) as well as markers of platelet activation (alpha(IIb)beta(3), CD36, P-selectin, and CD63 membrane epitopes) were measured in 16 patients with severe PPH (group 1) before and at days 10 and 40 of treatment with a continuous infusion of epoprostenol (prostacyclin). The same biological parameters were also measured in 19 healthy subjects (group 2) and in 10 patients after cardiovascular surgery with extracorporeal circulation (group 3), a condition known to profoundly activate the platelets. Twelve PPH patients showed hemodynamic and clinical improvement, 3 remained stable, and 1 had the treatment stopped because of clinical aggravation. At day 0, mean plasma serotonin (5-hydroxytryptamine [5-HT]) concentration was much higher in PPH patients than in normal subjects (34.4+/-21.2 versus 9.1+/-6.0 nmol/L, respectively; P:<0.001) and positively correlated with total pulmonary resistance. The mean platelet 5-HT content was not significantly different in PPH compared with normal individuals. Mean plasma 5-HIAA concentrations were much higher in PPH than in normal patients (162+/-57 versus 61+/-7 nmol/L, respectively; P<0.001). These parameters did not significantly change during epoprostenol treatment. There was no correlation between the changes in plasma 5-HT during treatment and clinical or hemodynamic improvement. In PPH patients, the mean platelet volume significantly decreased (ANOVA, P<0.01) during treatment. Positive correlations were evidenced between the size of platelets and the number of alpha(IIb)beta(3) and CD36 epitopes. When compared with control platelets, the number of alpha(IIb)beta(3) epitopes detected on PPH platelets at day 0 tended to be higher, but this difference did not reach a statistical significance (41 300+/-7140 for PPH patients versus 36 010+/-3930 for control subjects, P=0.069). The number of CD36 epitopes, in the range of controls at day 0 (11 590+/-5080 for PPH patients versus 11 900+/-1790 for control subjects), decreased during treatment (ANOVA, P=0.038) and became significantly low at day 40 (8660+/-3520, P<0.001). The number of CD63 epitopes was not elevated, and P-selectin was never detected at any time point on PPH platelets. This glycoprotein profile indicates that the platelets of PPH patients were not highly activated but had an accelerated turnover and returned to normal under epoprostenol treatment without change of the elevated plasma serotonin, characteristic of PPH. In conclusion, neither platelet activation nor a significant alteration of the 5-HT endothelial metabolism explains the high level of plasma 5-HT in PPH patients. The 5-HT plasma concentration is not a predictive marker of the severity of PPH, and its evolution is independent of the clinical and hemodynamic status. Treatment by a potent antiaggregating agent, epoprostenol, does not affect the increase of plasma 5-HT, despite a therapeutic benefit.

A cross-sectional and diurnal study of thrombogenesis among patients with chronic atrial fibrillation

OBJECTIVES

First, we sought to determine whether there is diurnal variation in hemostatic factors related to thrombogenesis and hypercoagulability among patients with chronic atrial fibrillation (AF). Second, we sought to determine whether levels of soluble thrombomodulin (sTM), a marker of endothelial function, or soluble P-selectin (sP-sel), an index of platelet activation, are altered in patients with AF as compared with subjects in sinus rhythm.

BACKGROUND

Atrial fibrillation is associated with an increased risk of stroke and thromboembolism and is known to confer a hypercoagulable state, with abnormalities of thrombosis, platelet activation and endothelial cell function. Many cardiovascular events, such as acute myocardial infarction, have thrombosis as an underlying process, and they undergo diurnal variation.

METHODS

Fifty-two patients (45 men, mean [+/- SD] age 66 +/- 6 years) with chronic AF, none of whom received antithrombotic therapy, were studied. Baseline levels of fibrinogen, sP-sel, sTM and von Willebrand factor (vWF) were compared to those levels in matched healthy control subjects in sinus rhythm. In a subgroup of 20 patients, five venous blood samples were collected through an indwelling cannula at 6-h intervals from 12 PM to 12 PM the following day and were analyzed for the same markers.

RESULTS

Patients with chronic AF had higher plasma sP-sel, sTM, vWF and fibrinogen levels as compared with control subjects in sinus rhythm. Significant correlations were found between fibrinogen and sP-sel in patients with AF (r = 0.567 [Spearman], p < 0.001) and in control subjects (r = 0.334, p = 0.016). There was no significant diurnal variation in plasma levels of sP-sel, sTM, vWF or fibrinogen over the 24-h study period (repeated measures analysis of variance, p = NS).

CONCLUSIONS

There is no circadian or diurnal variation in the hypercoagulable state seen in AF, as assessed by plasma fibrinogen and markers of platelet (sP-sel) and endothelial function (vWF and sTM). The persistent hypercoagulable state, together with the loss of diurnal variation in various hemostatic markers, in chronic AF may contribute to the high risk of stroke and thromboembolic complications in these patients.

Soluble thrombomodulin concentration is raised in scleroderma associated pulmonary hypertension

OBJECTIVE

To investigate the expression of thrombomodulin in scleroderma associated pulmonary hypertension.

METHODS

Soluble thrombomodulin (sTM), was measured in plasma samples from 34 scleroderma patients shown to have pulmonary hypertension at echocardiogram, and comparison drawn against samples from 38 scleroderma control patients, and 20 healthy controls. Serial measurements of sTM were performed in the 34 patients with scleroderma associated pulmonary hypertension to investigate possible changes in sTM concentration with progression of the condition.

RESULTS

Mean sTM was raised in scleroderma associated pulmonary hypertension when compared with scleroderma controls (mean sTM 65.4 ng/ml v 43.3 ng/ml, p<0.05), and when compared with healthy controls (mean sTM 38.1 ng/ml, p<0.05). There was no significant difference between mean sTM in scleroderma controls and healthy controls. Mean sTM concentration did not change with progression of pulmonary hypertension.

CONCLUSION

Plasma sTM is raised in scleroderma associated pulmonary hypertension. The pathogenesis of scleroderma associated pulmonary hypertension may be distinct from the pathogenesis of other forms of pulmonary vascular disease.

G-33A mutation in the promoter region of thrombomodulin gene and its association with coronary artery disease and plasma soluble thrombomodulin levels

Thrombomodulin is an endothelial glycoprotein that decreases thrombin activity and activates protein C. A recent study has shown that G-33A promoter mutation of the thrombomodulin gene occurs particularly in Asians. In this study, we analyzed the distribution of G-33A mutation in the promoter region of the thrombomodulin gene in the Chinese population and determined whether the mutation might be a risk for coronary artery disease (CAD). In addition, the influence of this mutation on plasma soluble thrombomodulin levels in patients with CAD was also examined. We studied 320 consecutive patients (mean age 63 years; 73% men) with CAD and 200 age- and sex-matched control subjects. Screening for thrombomodulin G-33A promoter mutation was conducted using polymerase chain reaction, single-strand conformation polymorphism, and direct deoxyribonucleic acid sequencing. The frequency of the G-33A mutation (GA+AA genotypes) was significantly higher in the CAD group (23.8% vs 15.5%, odds ratio [OR] 1.70, p = 0.031). Multiple logistic regression analysis showed that the mutation was an independent risk factor (OR 1.81, p = 0.016) for CAD, as was hypertension (OR 1.44, p = 0.040), diabetes mellitus (OR 2.50, p <0.001), and smoking (OR 2.15, p <0.001). In CAD patients with GG genotype, the soluble thrombomodulin level increased with the extent of CAD (36 +/- 15 vs 47 +/- 18 vs 55 +/- 36 ng/ml in 1-, 2-, or 3-vessel CAD, p <0.001). However, in CAD patients with G-33A mutation, there was no difference between the levels of soluble thrombomodulin (39 +/- 17 vs 37 +/- 15 vs 42 +/- 18 ng/ml, p = NS) in 1-, 2-, or 3-vessel CAD. Our observations suggest that there is a significant association of the G-33A mutation in thrombomodulin gene with CAD, and this mutation may influence the soluble thrombomodulin levels in patients with CAD.

Thrombomodulin: an overview and potential implications in vascular disorders

Thrombomodulin (TM), a high affinity thrombin receptor present on endothelial cell membrane, plays an important role as a natural anticoagulant. It acts as a cofactor of thrombin-catalyzed activation of protein C, and inhibits the procoagulant functions of thrombin. TM is also located in other cells (keratinocytes, osteoblasts, macrophages,...) where it might be involved in cell differentiation or in inflammation. In the presence of cytokines, activated neutrophils and macrophages, endothelial TM is cleaved enzymatically, releasing soluble fragments which circulate in the blood and are eliminated in urine. Plasma TM level (pTM) can be measured using a two-site enzyme-linked immunosorbent assay (ELISA). pTM level is regarded as a molecular marker reflecting injury of endothelial cells. It is often increased in case of diffuse endothelial damage as in disseminated intravascular coagulation, diabetic microangiopathy, Plasmodium falciparum and rickettsial infections. pTM is also a predictive marker of hypertensive complications in pregnancy. In several systemic inflammatory diseases, pTM levels are correlated to the activity of the disease.

Circulating von Willebrand factor antigen as a predictor of short-term prognosis in pulmonary hypertension

STUDY OBJECTIVE

To determine the potential value of plasma von Willebrand factor antigenic activity (vWF:Ag) and other commonly measured clinical variables for predicting which patients with precapillary pulmonary hypertension would be unlikely to survive 1 year.

DESIGN

Prospective clinical study. The data obtained at the beginning of the study were analyzed at the end of the first year of follow-up.

PATIENTS AND METHODS

Forty patients aged 1.2 to 45 years (median, 24 years) entered the study. Eleven patients had primary pulmonary hypertension, and in the remaining ones, pulmonary vascular disease was associated with antiphospholipid syndrome (n = 1), collagen vascular disease (n = 1), schistosomiasis (n = 3), or congenital heart defects (Eisenmenger's syndrome) (n = 24). Plasma vWF:Ag was determined by electroimmunodiffusion, and the results were expressed as the percentage of activity.

RESULTS

Seven of 11 patients with primary pulmonary hypertension but only 4 of 29 patients with secondary pulmonary hypertension died during the follow-up period (p < 0.005). Initial vWF:Ag values were significantly higher in the nonsurvivor group in comparison with the survivors (256.6+/-85.3% and 132.0+/-59.3% activity, respectively; p < 0.0001). The likelihood of fatal outcome as a function of plasma vWF:Ag levels was estimated for primary and secondary pulmonary hypertensive patients using logistic regression analysis. Decreased life expectancy was significantly related to high vWF:Ag levels and an established diagnosis of primary pulmonary hypertension. A plasma vWF:Ag of >240% (p = 0.003) was 54% sensitive and 93% specific for identifying patients who were unlikely to survive 1 year, with an overall predictive value of 75%. No other variables correlated significantly with survival.

CONCLUSION

Plasma vWF:Ag seems to be a useful biochemical index for predicting short-term prognosis in patients with pulmonary hypertension. In contrast to hemodynamic and histopathological predictors of survival, vWF:Ag does not require invasive techniques to be determined. In light of the possibility of false-negative results, serial measurements should be performed over time in patients with vWF:Ag of <240%. This observation proved helpful in two patients in this study.

High expression of endothelial nitric oxide synthase in plexiform lesions of pulmonary hypertension

The pathogenesis of pulmonary hypertension (PH) remains poorly understood. Vasoconstriction, although likely to be a major factor in the disease, varies between patients and studies of a variety of vasoactive substances have sometimes yielded conflicting results. Amongst these substances, alteration of the nitric oxide (NO) system has been cited as a possible pathogenic factor but both reduction and elevation of the expression of endothelial NO-synthase (eNOS) have been reported in pulmonary vessels. The present study has used immunocytochemistry with well-characterized antibodies to eNOS to investigate its expression in lung tissue taken at transplantation from 44 patients with PH (22 primary, 22 secondary) and 12 non-hypertensive controls. Semi-quantitative assessment showed that although the levels of eNOS expression in pulmonary vessels were variable within both hypertensives and controls, a statistically significant (P < 0.01) reduction of immunoreactivity was found in small arterioles from hypertensives compared with controls. In contrast, consistently strong expression of eNOS was seen in the endothelium of plexiform lesions in both the primary and the secondary PH patients. Although a decrease in the NO system of patients with PH has been reported, these findings show a distinct regional distribution of the enzyme with particularly high levels in plexiform lesions, a previously unreported observation, and offer a new perspective on the disease and on the evaluation of possible novel therapeutic approaches.

Pulmonary hypertension in POEMS syndrome: a new feature mediated by cytokines

POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes) syndrome is a rare variant of plasma cell dyscrasia with multiple systemic manifestations. We followed the progress of 20 patients with POEMS syndrome in our institution over a 10-yr period. Pulmonary hypertension (PH) was observed in five patients. All patients suffered dyspnea on exertion, which always appeared during an exacerbation of POEMS syndrome. The typical echocardiographic signs of PH were observed in all of these patients, and the median pulmonary-artery systolic pressure was 57 mm Hg (range, 50 to 65 mm Hg). Mean pulmonary-artery pressure during right side heart catheterization in two patients was 32 mm Hg. No other explanation for the PH could be found. Overproduction of cytokines was found in all cases, with high serum concentrations of interleukin-1beta, interleukin-6, tumor necrosis factor-alpha, and vascular endothelial growth factor. We suggest that PH should be added to the list of symptoms of POEMS syndrome. Cytokines may mediate POEMS syndrome-associated PH, as proposed for the other systemic manifestations of this disorder.

Prognostic value of increased soluble thrombomodulin and increased soluble E-selectin in ischaemic heart disease

Endothelial cell dysfunction is likely to be important in the pathophysiology of ischaemic heart disease and increased levels of endothelial cell markers soluble E-selectin and soluble thrombomodulin may reflect this damage. To determine whether increased levels of these markers were predictive of disease progression, we obtained plasma from 54 patients who had survived a myocardial infarction. Soluble E-selectin and soluble thrombomodulin were measured by ELISA. After 49 months, 24 patients had suffered an additional cardiovascular event such as a second myocardial infarction or requirement for arterial surgery. Soluble E-selectin was 60+/-30 ng/mL in patients who suffered an end-point and was 54+/-23 ng/mL in those without an end-point (p=0.43). Soluble thrombomodulin was 65+/-24 ng/mL in patients who suffered an end-point and was 49+/-19 ng/mL in patients who were free of an end-point (p=0.009). The major risk factors for atherosclerosis (hypercholesterolaemia, hypertension, smoking) or peak creatinine kinase levels were unable to predict the development of an end-point. Using life tables, soluble thrombomodulin had a significant effect on survival free of an end-point (p=0.011). We conclude that the measurement of soluble E-selectin is of limited value in epidemiological studies, and that raised soluble thrombomodulin is a new marker for the progression of atherosclerosis in patients with ischaemic heart disease.

[Thrombomodulin: physiology and clinical applications (excluding systemic diseases)]

Thrombomodulin (TM) is a proteoglycan present on the surface of endothelial and mesothelial cells where it acts as a strong anticoagulant. TM is also located in other cells (keratinocytes, osteoblasts, mononuclear phagocytes...) where it might be involved in cell differentiation or inflammatory processes. The damage of endothelial cells releases cleavage fragments. Plasma TM appears to be a marker of endothelium damage. Plasma TM has been investigated in several disorders: it is usually increased in the case of diffuse endothelial damage.

[Primary pulmonary hypertension: a rare but often fatal complication of Crest syndrome]

In a retrospective study of 194 systemic sclerosis, we selected 37 Crest syndrome patients. Among these 37 patients, five presented a primary pulmonary hypertension. For three of these patients, the evolution of this primary pulmonary hypertension was rapidly fatal, one died of another cause. One died without certitude that death is imputable to HTAP. Diagnosis and management of the evolution of primary pulmonary hypertension may be easily assessed by doppler-echocardiography.