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PubMed1991

Cerebral infarction in patients with nephrotic syndrome.

We describe two adult patients who presented with acute cerebral infarction and were found to have a hypercoagulable state due to nephrotic syndrome. One patient had a deficiency of free protein-S. The other patient had a pulmonary embolus 4 months after the stroke. Our cases demonstrate that the hypercoagulable state associated with nephrotic syndrome can be associated with cerebral arterial thrombosis and infarction in adults. Examination of the urine remains an important part of the evaluation of patients with recent stroke. The presence of severe proteinuria and a low serum albumin content should prompt consideration of a hypercoagulable state. Our experience suggests that anticoagulant drugs may be required to reduce the risk of new thrombotic events.

Adult↗
PubMed2000

Trousseau's syndrome and acute arterial thrombosis.

This report describes three patients treated for acute arterial thrombosis due to malignancy-related hypercoagulability (Trousseau's syndrome). The average age was 59yr. There were two women and one man. The cancers were breast, lung, and pancreas. Atherosclerosis or nonneoplastic hypercoagulable states did not appear to be a factor in any patient. One patient who presented with irreversible arm ischemia and Stage IV breast cancer underwent primary amputation. The other two patients underwent immediate surgical thrombectomy and thrombolytic therapy, and malignancy was discovered during postoperative workup for hypercoagulable states. Both ultimately required amputation. All three patients died due to cancer less than one year after presentation. When a hypercoagulable state is suspected as the cause of acute arterial thrombosis, an evaluation for occult malignancy is indicated. Although aggressive revascularization attempts may be appropriate, the prognosis for limb salvage and long-term survival is poor.

Adenocarcinoma↗
PubMed1997

Atrial fibrillation activates platelets and coagulation in a time-dependent manner: a study in patients with paroxysmal atrial fibrillation.

OBJECTIVES: To determine whether atrial fibrillation (AF) alone affects the fibrinocoagulation system, we examined the relation between fibrinocoagulation activity and duration of AF in patients with paroxysmal AF (PAF). BACKGROUND: Patients with chronic AF are at higher risk for stroke and a hypercoagulative state. It is not clear whether this hypercoagulative state is attributable to AF alone or to the underlying disease. There are no reports on the fibrinocoagulation properties in PAF. METHODS: Fibrinocoagulation variables in 21 patients with PAF were measured during AF and 7 days after recovery of sinus rhythm. There were positive correlations between the duration of AF and beta-thromboglobulin, platelet factor 4, thrombin-antithrombin III complex and fibrinogen. These variables increased significantly 12 h after the occurrence of PAF; thus, patients were classified into two groups according to the duration of PAF: PAF-I group (< 12 h, n = 10), PAF-II group (> or = 12 h, n = 11). Nine age-matched, healthy subjects formed the control group. RESULTS: Levels of beta-thromboglobulin and platelet factor 4 were significantly higher (p < 0.001) by two-way repeated measures analysis of variance (ANOVA), and thrombin-antithrombin III complex and fibrinogen levels tended to be but were not significantly higher (p = 0.06, ANOVA), in the PAF-II group than in the PAF-I group. There were no significant differences between groups in activated partial thromboplastin time, D-dimer or plasmin inhibitor complex. CONCLUSIONS: These results indicate that AF itself enhances platelet aggregation and coagulation, which are influenced by the duration of AF. The acceleration of platelet activity and coagulability occurred 12 h after the occurrence of AF.

Analysis of Variance↗
PubMed2001

Laboratory markers of hypercoagulability.

Investigations carried out over the last 40 years have demonstrated that coronary artery thrombosis is the critical event underlying myocardial infarction and unstable angina. The existence of a prolonged hypercoagulable state preceding the thrombotic event has been postulated for some time and significant associations have been established between the plasma concentrations of a number of hemostatic variables and the frequency of myocardial infarction. High plasma fibrinogen, factor VII/VIIa, tissue-type plasminogen activator and plasminogen activator inhibitor levels have been associated with at least as great a risk of developing myocardial (re)infarction or sudden death as high cholesterol levels, especially in the young. In the last year more sensitive assays have been developed, and they should allow a precise biochemical definition of hypercoagulable states. The significance of these new assays and their role in defining a hypercoagulable state in different conditions are analyzed.

Angina, Unstable↗
PubMed1996

Antiphospholipid syndrome manifested by ischemic stroke in a patient with Crohn's disease.

Cerebrovascular accidents are rare but well documented in patients with Crohn's disease. Up to 10% of hypercoagulable state manifestations reported in association with inflammatory bowel disease are ischemic strokes. However, no clear mediating factor has thus far been suggested. A 44-year-old woman with Crohn's disease for 25 years developed a left temporal stroke associated with anticardiolipin antibody and lupus anticoagulant suggesting antiphospholipid syndrome. A thorough evaluation did not reveal any other risk factor for ischemic stroke. No possible sources of emboli were found in the carotids and heart, and no deficiencies of protein C and activated protein C, protein S, and anti-thrombin III leading to hypercoagulable state were present. There may be a possible association between antiphospholipid syndrome and hypercoagulable state in Crohn's disease.

Adult↗
PubMedDate not supplied

Effects of psychological stress and psychiatric disorders on blood coagulation and fibrinolysis: a biobehavioral pathway to coronary artery disease?

OBJECTIVE: A hypercoagulable state before overt thrombosis resulting from an imbalance between the coagulation and fibrinolysis systems is related to cardiovascular disease progression and acute coronary syndromes. Psychological stressors and depressive and anxiety disorders also are associated with coronary artery disease. This review explores whether changes in blood coagulation, anticoagulant, and fibrinolytic activity may constitute psychobiological pathways that link psychological factors with coronary syndromes. METHODS: Literature on coagulation, anticoagulation, and fibrinolysis measures in conjunction with psychological factors (mental stress, psychosocial strain, and psychiatric disorders) was identified by MEDLINE search back to 1966 and through checking the bibliographies of these sources. Sixty-eight articles were critically reviewed. RESULTS: In healthy subjects, acute mental stress simultaneously activates coagulation (ie, fibrinogen or von Willebrand factor) and fibrinolysis (ie, tissue-type plasminogen activator) within a physiological range. In patients with atherosclerosis and impaired endothelial anticoagulant function, however, procoagulant responses to acute stressors may outweigh anticoagulant mechanisms and thereby promote a hypercoagulable state. Chronic psychosocial stressors (job strain or low socioeconomic status) are related to a hypercoagulable state reflected by increased procoagulant molecules (ie, fibrinogen or coagulation factor VII) and by reduced fibrinolytic capacity. There is also some evidence that points to hypercoagulability in depression. CONCLUSIONS: Different categories of psychological measures to varying extent are associated with characteristic patterns of coagulation and fibrinolysis activity. Associations between psychological factors and several coagulation and fibrinolysis variables related to atherosclerosis provide a plausible biobehavioral link to coronary artery disease.

Anxiety Disorders↗
PubMedDate not supplied

Adenosine diphosphate-induced platelet aggregation in the states of hypercoagulability.

One hundred and seven patients with congestive heart failure, myocardial infarction and arteriosclerotic heart disease were studied by adenosine diphosphate-induced platelet aggregation, fibrinogen levels and ethanol gelation test. Both increases and decreases in platelet aggregation were observed. A significantly high percentage of patients showed a decreased platelet aggregation which was especially marked in the more acute as opposed to the less acute phase. In addition, most patients exhibited a marked shift from abnormal to normal platelet aggregation or vise-versa within a short time period. This pattern of platelet aggregation suggests an active role of platelets in the states of hypercoagulability. The hypercoagulability of these patients was further substantiated by a high percentage of positive ethanol gelation tests and high fibrinogen levels.

Adenosine Diphosphate↗
PubMed2002

Low molecular weight heparin (bemiparin sodium) and the coagulation profile of patients with heart failure.

BACKGROUND: Congestive heart failure (CHF) is associated with a hypercoagulable state. PATIENTS AND METHODS: A single-center, randomized, double-blind, placebo-controlled trial was performed to test the hypothesis that a prophylactic dose of low molecular weight heparin (bemiparin sodium 3500 IU/daily subcutaneously) will modify a hypercoagulable state in CHF. This study included 100 patients with CHF (New York Heart Association classification II to IV). All patients underwent 3 blood tests, at baseline (before randomization), 24 hours after randomization, and before hospital discharge or within 10 days from randomization. RESULTS: In comparison of baseline bemiparin sodium 3500 IU/daily subcutaneously with after 24 hours, there was a significant decrease in plasma levels of D-dimer (-13.8 ng/mL; P =.01) and prothrombin fragments 1 and 2 (-0.11 nmol/L; P =.01), whereas protein C was significantly increased (+3.5%; P =.03). In comparison of baseline bemiparin sodium 3500 IU/daily subcutaneously with after 4 to 10 days of therapy, there were significantly decreased plasma levels for factor VII:c (-3.0%; P =.01), D-dimer (-44.0 ng/mL; P =.002), and thrombin-antithrombin complex (-0.7 microg/L; P =.0001), whereas protein C was significantly increased (+16.0%; P =.03). On the other hand, in the group of patients treated with placebo after 24 hours, a significant decrease was observed of protein C (-4.0%; P =.04). After 24 hours, the changes from baseline were significantly different for some of the hemostatic factors in comparison of bemiparin sodium 3500 IU/daily and placebo (factor VII:c: -1.7 versus 0.0%; P =.04; D-dimer: -14 versus +24.3 ng/mL; P =.009; prothrombin fragments 1 and 2: -0.11 versus +0.11 nmol/L; P =.01; protein C: +3.5 versus -4.0%; P =.01). Also at discharge, the changes from baseline were different for some of the markers in comparison of bemiparin sodium with placebo (D-dimer: -44 versus 3.8 ng/mL; P =.002; thrombin-antithrombin complex: -0.70 versus +0.14 microg/L; P =.002; protein C: +16.0 versus +0.5%; P =.02). CONCLUSION: Our findings suggest that a hypercoagulable state in heart failure can be modified with bemiparin sodium therapy.

Aged↗
PubMed1995

Alterations of coagulation and fibrinolytic and kallikrein-kinin systems in the acute and postacute phases in patients with unstable angina pectoris.

BACKGROUND: Unstable angina pectoris is frequently associated with intracoronary thrombus formation. In a prospective study, we investigated in 35 patients with unstable angina pectoris markers of coagulation and the kallikrein-kinin and fibrinolytic systems in the acute and postacute phases. METHODS AND RESULTS: We determined serially in the patients up to 10 days after admission factor XII and the beta-factor XIIa inhibition, kallikrein-like activity, prekallikrein, C1-esterase inhibitor, kallikrein inhibition, high molecular weight kininogen as indicators of the contact phase and bradykinin generation, thrombin-antithrombin III (TAT) complex as marker of the activated coagulation cascade, fibrinogen, plasminogen, plasminogen activator inhibitor-1 (PAI-1), tissue-type plasminogen activator (TPA), and D-dimers as indicators of the fibrinolytic system. Data were compared with those from control subjects (n = 25) and from patients with stable angina pectoris (n = 25). In patients with unstable angina pectoris, initially the contact phase and the kallikrein-kinin system were markedly elevated (factor XII, 96 +/- 5% versus 117 +/- 5%; kallikrein-like activity, 35.7 +/- 2.9 versus 27.4 +/- 1.3 U/L; high molecular weight kininogen, 52.7 +/- 5.2% versus 87.7 +/- 3.9%; P < .01 versus control subjects). Contact-phase activation persisted for the following 10 days, whereas the initially enhanced bradykinin generation normalized after 2 days. Furthermore, we had evidence of a hypercoagulative state (TAT, 10.9 +/- 3.1 versus 4.5 +/- 0.7 micrograms/L, P < .05; D-dimer, 474 +/- 81 versus 272 +/- 71 ng/mL) persisting longer than the clinically symptomatic period in association with disturbed fibrinolysis (TPA, 15.9 +/- 1.9 versus 5.1 +/- 0.4 ng/mL; P < .01; PAI-1, 9.9 +/- 2.6 versus 4.6 +/- 1.6 AU/mL; P = NS) in the presence of elevated fibrinogen levels. CONCLUSIONS: Our data indicate that in patients with unstable angina pectoris, intracoronary thrombus formation is associated with a hypercoagulative state, including activation of the contact phase and of the kallikrein system and increased bradykinin generation. The persistence of this hypercoagulative state, together with a disturbed fibrinolysis, might indicate an increased risk for further coronary events.

Acute Disease↗
PubMed2006

Prevention and repair of circulatory shock and cerebral ischemia/injury by various agents in experimental heatstroke.

The current report summarized animal models of heatstroke experimentation that advance our current knowledge of therapeutic effects on cerebrovascular dysfunction, hypercoagulable state and/or systemic inflammation with various agents in the setting of heatstroke. This was a narrative review of selected published primary basic literature from MEDLINE for 1973-2006. It was found that rodents shared with humans almost the same heatstroke reactions such as hyperpyrexia, hypotension, hyperventilation, pulmonary edema, hepatic and renal failure, hypercoagulable state, metabolic acidosis, systemic inflammation, and cerebral ischemia, injury and dysfunction. Therefore, the rodent model would allow testing of new therapeutic strategies for heatstroke. It was found that brain cooling produced by infusion of cold (4 degrees C) normal saline via the jugular vein or whole body cooling improved survival during heatstroke by reducing cerebrovascular dysfunction, multiple organ failure, systemic inflammation and hypercoagulable state. However, even under the absence of brain or whole body cooling, these heatstroke reactions still could be reversed by treating with the following agents: (1) free radical scavengers; (2) human recombinant protein C: (3) platonin; (4) hyperbaric oxygen; (5) hydroxyethyl starch, hypertonic solution, or human albumin; (6) glucocorticoids; (7) interleukin-1 receptor antagonists; (8) L-arginine; (9) estrogen; and (10) human umbilical cord blood cells or CD +34 cells. Before initiation of heat stress, prior manipulations with one of the following measures were found to be able to protect against heatstroke syndromes: (1) systemic delivery of inducible nitric oxide synthase inhibitors, mu-opioid receptor antagonists, endothelin-1A receptor antagonists, dopaminergic or serotoninergic nerve depletor or receptor antagonists, or glutamate receptor antagonists; or (2) heat shock protein 72 preconditioning.

Animals↗
PubMedDate not supplied

Hypercoagulability in otologic patients.

INTRODUCTION: Three patients with otologic disorders developed complications related to hypercoagulability. This report was prepared to increase the awareness among otolaryngologists of the diagnosis and management of hypercoagulable states, and to encourage expert consultation when indicated. MATERIALS AND METHODS: One patient with dural venous sinus thrombosis complicating an otitis media, one patient with a large glomus jugulare tumor, and one patient with a sudden sensorineural hearing loss were treated by the otolaryngology service. Suspicious thromboembolic events were evaluated by the hematology service, and appropriate anticoagulative therapy was recommended. RESULTS: One patient with an inherited hypercoagulopathy and two patients with acquired hypercoagulopathies were treated for otologic problems. Two of the patients were stabilized and discharged on life-long anticoagulation therapy. The third patient, in spite of intensive medical and surgical support, eventually succumbed to complications to which an acquired hypercoagulable state made a significant contribution. Expert consultants made the hematologic diagnoses and treatment recommendations. CONCLUSION: Otolaryngologists should be aware that hypercoagulable states may now be more accurately diagnosed and characterized, and that thorough investigation of thromboembolic events may affect treatment decisions.

Adult↗
PubMed1998

[Cerebral infarction associated with nephrotic syndrome in a young adult: a case report].

We report a 19-year-old man who developed a cerebral infarction in the territory of the anterior choroidal artery and showed a hypercoagulable state and nephrotic syndrome after diarrhea and appetite loss. He had suffered from nephrotic syndrome from the age of three and had been treated for five years. MR-angiography showed an occlusion originating in the right internal carotid artery. The right anterior and middle cerebral arteries were imaged from the left internal carotid artery via the anterior communication artery. He showed symptoms of left hemiparesis, agnosia, loss of activity, anasarca and left hypacusis following his clinical course, but had recovered from all but left hemiparesis following medical treatments including steroid therapy. The histologic finding by a renal biopsy revealed focal glomerulosclerosis. In this case, we considered that when he was in a hypercoagulable state and had a second attack of nephrotic syndrome because of inflammation and dehydration due to diarrhea and appetite loss, his hypercoagulable state grew worse, and he then developed a cerebral infarction. When one see a patient with nephrotic syndrome, one should be attentive to the possibility of a complication of cerebral infarction.

Adult↗
PubMed2002

Coagulation changes in individuals with sickle cell trait.

Sickle cell disorders, such as Hb SS and Hb SC, are associated with a hypercoagulable state that may contribute to the vaso-occlusive episodes observed in the disorders. To what extent increased coagulation activity occurs in individuals with sickle cell trait has had limited study. Because such information may help clarify clinical and pathologic findings that may occur in these individuals and may be useful in clarifying the hypercoagulable state in sickle cell disease, we have examined individuals with Hb AS to determine the extent that increased coagulation activity does occur. We measured d-dimers, thrombin-antithrombin (TAT) complexes, prothrombin fragment 1.2 (F1.2), absolute blood monocyte levels, proteins C and S, and isotypes of antiphospholipid antibodies in individuals with Hb AS and in matched controls (Hb AA). Results showed that d-dimers, TAT, and F1.2 were increased significantly above normal levels. Absolute blood monocyte levels were increased. The d-dimers, TAT, F1.2, and monocyte counts showed significant increasing trends through groups of increasing severity (Hb AA, Hb AS, Hb SC, and Hb SS). Our study shows that individuals with Hb AS have increased coagulation activity, with d-dimers, TAT, and F1.2 being consistent indicators. The measures of coagulation activity in Hb AS are lower than in patients with Hb SC and Hb SS disease. These results extend our previous observation that the degree of coagulation activation parallels the degree of disease severity among sickle cell genotypes. The findings suggest that monocytosis, with the possible expression of monocyte-derived tissue factor, and the associated hypercoagulable state are driven by disease severity.

Adult↗
PubMed2000

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.

Aged↗
PubMed1994

Markers of thrombin and plasmin generation in patients with inherited thrombophilia.

AIM: To determine the prevalence of a biochemically detectable hypercoagulable state, defined in terms of increased thrombin or plasmin generation, in patients with phenotypically characterised thrombophilia. METHODS: Plasma concentrations of the prothrombin activation peptide F1.2 and fibrin degradation (FbDP) and fibrinogen degradation products (FgDP) were measured by enzyme immunoassay in 104 patients deficient in natural anticoagulants, and 35 unaffected relatives. RESULTS: Increased concentrations of F1.2, FbDP, and FgDP were present in 18, 25, and 19 of 104 patients, respectively. There were no correlations between F1.2, FbDP, and FgDP concentrations, or between these parameters and concentrations of natural anticoagulants except for a negative correlation between protein C concentrations and FgDP (rho = -0.46, p = 0.009). CONCLUSION: A biochemically detectable hypercoagulable state is present in some patients with asymptomatic thrombophilia. Markers of plasmin generation may be increased more frequently in thrombophilia than markers of thrombin generation. This finding should prompt the inclusion of markers of plasmin generation in prospective longitudinal cohort studies to determine the predictive value of a hypercoagulable state, defined by either excessive thrombin or plasmin generation, for the development of venous thromboembolism.

Adult↗
PubMed1995

Takayasu's arteritis in Kuwait.

The present study describes the epidemiological profile and clinical features of Takayasu's arteritis (TA) in Kuwait, as well as its association with other autoimmune diseases and primary hypercoagulable states. Thirteen patients were included from its start on 1 January 1989 till 30 June 1994. Diagnosis of TA was established by angiographic studies. Twelve patients were Arabs and 7 were Kuwaiti nationals. Five patients were males and renal disease secondary to isolated involvement of the abdominal aorta (TA, type II) was the main presentation in 4 patients. Coagulation tests were performed in 7 patients and included antiphospholipid antibody (aPL) assay as well as protein S, protein C and antithrombin III activity. Only one manifested recurrent thrombosis and laboratory tests confirmed the presence of a hypercoagulable state secondary to aPL and protein S deficiency. Serological tests of systemic lupus erythematosis (SLE) were positive in this patient. These data indicate that TA is not a rare disease in the Arabic population. In our study, female predominance was not a common feature of TA and renal disease secondary to TA type II disease was commonly encountered. The association of TA with SLE and primary hypercoagulable states was not a consistent finding in our patients with TA, and hence, the proposed role for thrombotic vasculopathy in the pathogenesis and progression of this disease was unfounded.

Adolescent↗
PubMed1980

An evaluation of antithrombin III laboratory tests.

Three laboratory tests for the measurement of antithrombin III (AT III) were evaluated. The tests measured functional AT III in serum and plasma, and the third measured AT III antigen in plasma. Normal values for each method were obtained by testing samples from 20 normal subjects. Each test was then performed on specimens from 15 patients clinically suspected of having hypercoagulable states. Each determination was run in duplicate. The hypercoagulable states included disseminated intravascular coagulation, pulmonary embolism, and pregnancy. Two-thirds of these patients were found to have antithrombin III levels below the normal range by all three of the methods studied. Patients who had decreased AT III activity in the functional assays also had decreased AT III antigen.

Adult↗
PubMed2003

Probing antiphospholipid-mediated thrombosis: the interplay between anticardiolipin antibodies and endothelial cells.

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

Animals↗