thromboplastin and Arteriosclerosis

Rupture of an atherosclerotic plaque with subsequent thrombosis and myocardial ischemia is the patho-physiological mechanism in acute coronary syndromes. Tissue factor (TF) as the main initiator of the extrinsic coagulation cascade plays a central role in the pathogenesis of acute coronary syndromes. The extent of the thrombotic process is modulated by local vascular TF of the ruptured plaque as well as by circulating TF. In addition, TF alters signaling pathways and, thereby, contributes to inflammatory reactions and vascular remodeling. This review addresses current concepts of the role of TF in acute coronary syndromes and discusses potential consequences and therapeutic approaches.

Topics: Acute Disease; Arteriosclerosis; Coronary Disease; Humans; Myocardial Ischemia; Syndrome; Thromboplastin

The 3-hydroxy-3-methylglutaryl (HMG)-coenzyme A (CoA) reductase inhibitors (statins) have been shown to exhibit several vascular protective effects, including antithrombotic properties, that are not related to changes in lipid profile. There is growing evidence that treatment with statins can lead to a significant downregulation of the blood coagulation cascade, most probably as a result of decreased tissue factor expression, which leads to reduced thrombin generation. Accordingly, statin use has been associated with impairment of several coagulant reactions catalyzed by this enzyme. Moreover, evidence indicates that statins, via increased thrombomodulin expression on endothelial cells, may enhance the activity of the protein C anticoagulant pathway. Most of the antithrombotic effects of statins are attributed to the inhibition of isoprenylation of signaling proteins. These novel properties of statins, suggesting that these drugs might act as mild anticoagulants, may explain, at least in part, the therapeutic benefits observed in a wide spectrum of patients with varying cholesterol levels, including subjects with acute coronary events. The HMG-CoA reductase inhibitors (statins) have been shown to exhibit several vascular protective effects, including antithrombotic properties, that are not related to changes in lipid profile. Treatment with statins can lead to a significant downregulation of the blood coagulation cascade, most probably as a result of decreased tissue factor expression, which leads to reduced thrombin generation.

Topics: Animals; Anticholesteremic Agents; Anticoagulants; Arteriosclerosis; Blood Coagulation; Blood Coagulation Factors; Blood Proteins; Factor VII; Fibrinogen; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Models, Biological; Protein Prenylation; Protein Processing, Post-Translational; Staphylococcal Protein A; Thrombin; Thrombomodulin; Thrombophilia; Thromboplastin; Venous Thrombosis

Topics: Apoptosis; Arteries; Arteriosclerosis; Blood Coagulation; Blood Platelets; Humans; Inflammation; Thrombin; Thromboplastin; Thrombosis; Venous Thrombosis

Hemostatic factors play a crucial role in generating thrombotic plugs at sites of vascular damage (atherothrombosis). However, whether hemostatic factors contribute directly or indirectly to the pathogenesis of atherosclerosis remains uncertain. Autopsy studies have revealed that intimal thickening represents the first stage of atherosclerosis and that lipid-rich plaque arises from such lesions. Several factors contribute to the start of intimal thickening. Platelets release several growth factors and bioactive agents that play a central role in development of not only thrombus but also of intimal thickening. We have been investigating which coagulation factors simultaneously, or subsequently with platelet aggregation, participate in thrombus formation. Tissue factor (TF) is an essential initiator of blood coagulation that is expressed in various stages of atherosclerotic lesions in humans and other animals. Factors including thrombin and fibrin, which are downstream of the coagulation cascade activated by TF, also contribute to atherosclerosis. TF is involved in cell migration, embryogenesis and angiogenesis. Thus TF, in addition to factors downstream of the coagulation cascade and the protease-activated receptor 2 activation system, would be a multifactorial regulator of atherogenesis.

Topics: Arteriosclerosis; Blood Coagulation; Fibrin; Humans; Receptor, PAR-2; Thrombin; Thromboplastin

Overexpression and exposition of tissue factor (TF) in atherosclerotic plaques and/or arterial thrombi are critical events in atherothrombosis. TF, the receptor for factor VII (FVII) and activated factor VII (FVIIa), is the principal initiator of blood coagulation and induces thrombin generation leading to fibrin formation and platelet activation. TF also plays a major role in cell migration and angiogenesis. TF activity is downregulated by Tissue Factor Pathway Inhibitor (TFPI), a Kunitz-type inhibitor, which forms a neutralizing complex with TF, FVIIa and activated factor X. In physiological conditions, TF is absent from vascular cells which come into contact with flowing blood and is present as an inactive pool in fibroblasts and smooth muscle cells (SMC). In contrast, TF is widely expressed in atherosclerotic plaques and is found in macrophages, SMCs, and foam-cells and also in extracellular matrix and acellular lipid-rich core. TF expression is up-regulated by inflammatory cytokines and oxidized lipids. Plaque thrombogenicity is directly correlated to their TF content. After fibrous cap disruption, TF is exposed on plaque surface and triggers thrombus formation leading to arterial lumen occlusion and/or downstream embolization. In coronary and carotid plaques, TF content was found to be higher in plaques from symptomatic than asymptomatic patients. Soluble forms of TF and microparticles of monocyte and platelet origin, and bearing TF, constitute "blood-born TF". The contribution of this TF pool to arterial thrombosis is still under discussion. TF pathway is a target for new therapeutic agents that can decrease TF activity, such as active site-inactivated factor VIIa, recombinant TFPI and antibodies against TF or peptides interfering with TF-FVIIa complex activity.

Topics: Arteriosclerosis; Cardiovascular Diseases; Cell Movement; Fibroblasts; Hemostatics; Humans; Inflammation; Muscle, Smooth; Neovascularization, Pathologic; Thromboplastin

Atherothrombosis, defined as atherosclerotic lesion disruption with superimposed thrombus formation, is the major cause of acute coronary syndromes and cardiovascular deaths. It is the leading cause of morbidity and mortality in the industrialized world. Plaque composition, rather than luminal stenosis, is recognized as the major determinant of this disease. Since tissue factor is found within atheroma and also in the bloodstream of atherosclerotic patients, it likely plays a key role in determining both plaque and blood thrombogenicity. Ongoing clinical and preclinical studies are evaluating the therapeutic possibilities of specific inhibition of the tissue factor pathway. Here, we will review the role of tissue factor in atherothrombosis.

Topics: Arteriosclerosis; Heart Diseases; Humans; Thromboplastin; Thrombosis

Atherothrombosis, defined as atherosclerotic lesion disruption with superimposed thrombus formation, is the major cause of acute coronary syndromes and cardiovascular deaths. It is the leading cause of morbidity and mortality in the industrialized world. Plaque composition, rather than luminal stenosis, is recognized as the major determinant of this disease. Since tissue factor is found within atheroma and also in the bloodstream of atherosclerotic patients, it likely plays a key role in determining both plaque and blood thrombogenicity. Ongoing clinical and preclinical studies are evaluating the therapeutic possibilities of specific inhibition of the tissue factor pathway. Here, we will review the role of tissue factor in atherothrombosis and therapeutic applications.

Topics: Arteriosclerosis; Factor VII; Factor X; Humans; Thrombin; Thromboplastin

Crucial advances in our understanding of the pathogenesis of atherothrombosis, defined as atherosclerosis and its thrombotic complications, have been achieved during the past two decades. The historical hypothesis of pathogenesis ("lipid accumulation") has evolved to integrate several factors contributing to the initiation and evolution of this complex disease. Endothelial dysfunction is considered to be the earliest event in atherogenesis. Inflammation and apoptosis play critical roles in its progression and onset. Tissue factor is postulated to be a central actor in determining plaque thrombogenicity. A hyperreactive state of the blood ("vulnerable blood") may be responsible for one-third of all the acute coronary syndromes. This review will discuss emerging concepts in the pathogenesis of and therapeutic approaches to atherothrombotic disease.

Topics: Acute Disease; Apoptosis; Arteriosclerosis; Endothelium; Humans; Inflammation; Risk Factors; Thromboplastin; Thrombosis

Lipoprotein(a) (Lp[a]) continues to be a controversial molecule regarding its role in human vascular disease. Although the physiologic role of this molecule is still unclear, novel discoveries within the last few years have suggested numerous mechanisms whereby Lp(a) may contribute to atherosclerosis and its complications in human subjects. These effects may differentially occur in vascular tissue and circulating blood compartments. A complex interplay between tissue-specific effects is probably more relevant to the pathogenicity of this molecule than one single effect alone. This review briefly describes the structure of Lp(a) in relation to its biochemical function, summarizing the current literature on various pathophysiologic mechanisms of Lp(a)-induced vascular disease and the role of cell and tissue-specific effects in promoting atherogenesis and thrombosis.

Topics: Arteriosclerosis; Blood Coagulation; Endothelium, Vascular; Humans; Lipoprotein(a); Thromboplastin; Thrombosis

The transmembrane glycoprotein tissue factor (TF) is the initiator of the coagulation cascade in vivo. When TF is exposed to blood, it forms a high-affinity complex with the coagulation factors factor VII/activated factor VIIa (FVII/VIIa), activating factor IX and factor X, and ultimately leading to the formation of an insoluble fibrin clot. TF plays an essential role in hemostasis by restraining hemorrhage after vessel wall injury. An overview of biological and physiological aspects of TF, covering aspects consequential for thrombosis and hemostasis such as TF cell biology and biochemistry, blood-borne (circulating) TF, TF associated with microparticles, TF encryption-decryption, and regulation of TF activity and expression is presented. However, the emerging role of TF in the pathogenesis of diseases such as sepsis, atherosclerosis, certain cancers and diseases characterized by pathological fibrin deposition such as disseminated intravascular coagulation and thrombosis, has directed attention to the development of novel inhibitors of tissue factor for use as antithrombotic drugs. The main advantage of inhibitors of the TF*FVIIa pathway is that such inhibitors have the potential of inhibiting the coagulation cascade at its earliest stage. Thus, such therapeutics exert minimal disturbance of systemic hemostasis since they act locally at the site of vascular injury.

Topics: Animals; Arteriosclerosis; Blood Coagulation; Blood Coagulation Disorders; Blood Coagulation Factors; Blood Vessels; Disseminated Intravascular Coagulation; Fibrin; Gene Expression Regulation; Humans; Neoplasms; Sepsis; Thromboplastin; Thrombosis

Our increasing appreciation of the importance of inflammation in vascular disease has focused attention on the molecules that direct the migration of leukocytes from the blood stream to the vessel wall. In this review, we summarize roles of the chemokines, a family of small secreted proteins that selectively recruit monocytes, neutrophils, and lymphocytes to sites of vascular injury, inflammation, and developing atherosclerosis. Chemokines induce chemotaxis through the activation of G-protein-coupled receptors, and the receptors that a given leukocyte expresses determines the chemokines to which it will respond. Monocyte chemoattractant protein 1 (MCP-1), acting through its receptor CCR2, appears to play an early and important role in the recruitment of monocytes to atherosclerotic lesions and in the formation of intimal hyperplasia after arterial injury. Acute thrombosis is an often fatal complication of atherosclerotic plaque rupture, and recent evidence suggests that MCP-1 contributes to thrombin generation and thrombus formation by generating tissue factor. Because of their critical roles in monocyte recruitment in vascular and nonvascular diseases, MCP-1 and CCR2 have become important therapeutic targets, and efforts are underway to develop potent and specific antagonists of these and related chemokines.

Topics: Animals; Apolipoproteins E; Arteriosclerosis; Chemokine CCL2; Chemokines; Chemotaxis, Leukocyte; Endothelium, Vascular; Foam Cells; Humans; Hyperplasia; Mice; Mice, Knockout; Neovascularization, Physiologic; Rabbits; Rats; Receptors, CCR2; Receptors, Chemokine; Sus scrofa; Thrombin; Thromboplastin; Tunica Intima; Vascular Diseases; Vasculitis

Tissue factor (TF) is a transmembrane glycoprotein, currently considered as being the major regulator of the coagulation cascade and the initiator of thrombogenesis in vivo. When TF comes in contact with blood, it forms a high-affinity complex with factors VII/VIIa, activating factors IX and X and thus leading to the formation of an insoluble fibrin clot. The regulation of TF-VIIa activity plays a key role in blood-vessel wall interactions. Selective patterns of cellular expression of TF are observed in tissues. TF is constitutively localized only on the surface of cells anatomically separated from the blood, where it plays an essential role in hemostasis by limiting hemorrhage after vessel wall injury. A number of pathophysiologic stimuli are capable of inducing TF transcription and activity in endothelial cells and monocytes. An aberrant TF expression in contact with blood is implicated in thrombotic complications of atherosclerosis, including acute myocardial infarction. Recent findings have demonstrated cell-derived microparticles containing TF in the circulating blood of patients with acute coronary syndromes, capable of triggering and propagating thrombus growth. This observation suggests a new view of thrombosis that does not necessarily require the exposure of vessel wall-derived TF at the site of vascular injury to initiate and propagate thrombosis.

Topics: Angina, Unstable; Animals; Arteriosclerosis; Blood Coagulation; Cardiovascular Diseases; Disease Models, Animal; Factor IX; Factor VII; Factor VIIa; Factor X; Fibrinolytic Agents; Helminth Proteins; Hemostasis; Humans; Myocardial Infarction; Syndrome; Thromboplastin; Thrombosis

Tissue factor is a key enzyme in coagulation process. It is primary known as a cofactor for factor VIIa-mediated triggering of blood coagulation, which proceeds in a cascade of extracellular reactions. Tissue factor forms a catalytic complex with VIIa and intitiates coagulation by activating factor IX and X, ultimately resulting in thrombin formation. Being a transmembranic glycoprotein it takes a signalling information to another cell activity after endothelium or other tissue damage. Tissue factor plays a pivotal role in blood clotting physiology and pathology especialy in atherothrombosis. Thrombogenic tissue factor on cell-derived microparticles is present in the circulating blood of patients with acute coronary syndromes. Tissue factor is found in adventitia of blood vessels and the lipid core of atherosclerotic plaques (but not in vascular cells contacting directly with blood). Although the molecular mechanisms responsible for these phenomena remain unclear, it is thought that they are brought about by the action of intracellular signaling, resulting in gene transcription and subsequent protein synthesis. By expressing on monocyte or macrofage cell membrane surface it is involved in proinflammatory action and plaque destabilisation. This shifted the emphasis to investigations of what happened on the cell surface, and later to the cell biology of tissue factor and its inducibility in monocytes/macrophages and endothelial cells. Recent studies have suggested that tissue factor also plays non-hemostatic roles in blood vessel development, tumor angiogenesis and metastasis, inflamation. Tissue factor upregulates a number of genes involved in regulation of growth, transcription, and cellular motility, as well as cytokines, makes it possible to suggest a link between the formation of the tissue factor / VIIa complex and the cellular processes. Regulation of tissue factor activity by natural tissue factor pathway inhibitor (synthesized by vascular endothelial cells) or by special drugs is a new insight in thrombosis and vessel reocclusion preventive therapy. Tissue factor concentration in circulating blood has a higher informativity comparing to troponine and CRB values.

Topics: Age Factors; Aged; Arteriosclerosis; Blood Coagulation; C-Reactive Protein; Diabetes Complications; Female; Humans; Hypercholesterolemia; Hypertension; Male; Myocardial Infarction; Risk Factors; Sex Factors; Syndrome; Thromboplastin; Thrombosis; Troponin T

It is generally accepted that the initial event in coagulation and intravascular thrombus formation is the exposure of cell-surface protein, such as tissue factor (TF). TF is exposed to the flowing blood as a consequence of vascular injury induced, for instance, by PTCA, or by spontaneous rupture of an atherosclerotic plaque. Expression of TF may also be induced in monocytes and endothelial cells in several conditions such as sepsis and cancer, causing a more generalized activation of clotting. In addition to its essential role in hemostasis, TF may be also implicated in several pathophysiological processes, such as intracellular signaling, cell proliferation, and inflammation. For all these reasons, TF has been the subject of intense research focus. Many experimental studies have demonstrated that inhibition of TF:factor VIIa procoagulant activity is a powerful inhibitor of in vivo thrombosis and that this approach usually results in a less-pronounced bleeding tendency compared with other "more classical" antithrombotic interventions. Alternative approaches may be represented by antibodies directed against TF, by transfection of the arterial wall with natural inhibitors of the TF:factor VIIa complex, such as the TF pathway inhibitor, or with catalytic RNA (ribozyme), which could inhibit the expression of the TF protein by the disruption of cellular TF mRNA. All these approaches seem particularly attractive because they may result in complete inhibition of local thrombosis without incurring potentially harmful systemic effects. Further studies are warranted to determine the efficacy and safety of such approaches in patients.

Topics: Animals; Arteriosclerosis; Blood Coagulation; Factor VIIIa; Fibrinolytic Agents; Humans; Lipoproteins; Signal Transduction; Thromboplastin; Thrombosis

Exposure of blood to tissue factor (TF) sets off the coagulation cascade. TF is a transmembrane protein that serves as an essential cofactor for activated coagulation factor VII (FVIIa). TF may be exposed locally by vascular injury (such as balloon angioplasty) or by spontaneous rupture of an atherosclerotic plaque. Expression of TF may also be induced on monocytes and endothelial cells in conditions like sepsis and cancer, causing a more generalised activation of clotting. TF may thus play a central role in thrombosis in a number of settings, and attention has turned to blocking TF as a means to prevent thrombosis. Inhibiting the inducible expression of TF by monocytes can be achieved by 'deactivating' cytokines, such as interleukin (IL)-4, -10 and -13, or by certain prostanoids; by drugs that modify signal transduction, such as pentoxifylline, retinoic acid or vitamin D(3), or by antisense oligonucleotides. Such approaches are for the most part at a preclinical stage. The function of TF can be blocked by antibodies that prevent the binding of FVIIa to TF; by active site-inhibited FVIIa, which competes with native FVIIa for binding; by antibodies or small molecules that block the function of the TF/FVIIa complex; and by molecules, such as TF pathway inhibitor or nematode anticoagulant peptide C2, which inhibit the active site of FVIIa in the TF/FVIIa complex after first binding to activated factor X. The latter two agents have entered Phase II clinical trials. Perhaps most intriguing is the use of anti-TF agents locally, which holds the promise of stopping thrombosis at a specific site of injury without the bleeding risk associated with systemic anticoagulation.

Topics: Angiotensin-Converting Enzyme Inhibitors; Animals; Antibodies, Monoclonal; Arteriosclerosis; Blood Coagulation; Clinical Trials as Topic; Cytokines; Drug Design; Endothelium, Vascular; Enzyme Activation; Factor VIIa; Fibrinolytic Agents; Glycoproteins; Helminth Proteins; Hemorrhage; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Lipoproteins; Mice; Monocytes; Multiprotein Complexes; Neoplasms; Oligonucleotides, Antisense; Prostaglandins; Signal Transduction; Swine; Swine, Miniature; Thrombophilia; Thromboplastin; Thrombosis

To review the experimental and clinical evidence of the emerging role of tissue factor in intravascular thrombosis and to examine evidence supporting the potential use of tissue factor pathway inhibitor as an antithrombotic therapeutic agent.. A PubMed search was conducted encompassing articles in the English language relating to tissue factor and tissue factor pathway inhibitor in intravascular coagulation.. Tissue factor, a membrane-bound procoagulant glycoprotein, is the initiator of the extrinsic clotting cascade, which is the predominant coagulation pathway in vivo. The traditional view localizes tissue factor to extravascular sites, where it remains sequestered from circulating factor VII until vascular integrity is disrupted or until tissue factor expression is induced in endothelial cells or monocytes. This perspective has been challenged since the discovery of tissue factor antigen in plasma, on circulating microparticles, and on leukocytes in whole blood. Recently, the apparent role of tissue factor has expanded with the demonstration that this molecule also functions as a signaling receptor. Recombinant tissue factor pathway inhibitor, an analogue of the physiologic inhibitor of tissue factor, is a potent inhibitor of thrombus formation in experimental models. In summary, the tissue factor pathway initiates thrombosis in vivo. In addition to its classic tissue-bound distribution, recently discovered blood-borne tissue factor may have an important procoagulant function. Despite showing promise in early human studies, a recently completed phase 3 trial of recombinant tissue factor pathway inhibitor in severe sepsis failed to show a reduction in the primary end point of 28-day all-cause mortality. Tissue factor pathway inhibitor, however, remains a plausible therapeutic agent in other conditions of increased thrombogenicity, such as acute coronary syndromes, and further studies to examine this potential are warranted.

Topics: Animals; Anticoagulants; Arteriosclerosis; Hemostatics; Humans; Lipoproteins; Sepsis; Thromboplastin; Thrombosis

Protease-activated receptors (PARs) are vascular sensors for signaling of the trypsinlike coagulation serine proteases that play key roles in cardiovascular medicine. In the initiation phase of coagulation, tissue factor (TF) orchestrates the assembly of VIIa with substrate X, forming a ternary complex in which product Xa is generated. The resulting TF-VIIa-Xa complex is an efficient activator of PAR1 and PAR2. TF initiation of the coagulation cascade is thus intimately linked to inflammatory cell signaling. Inflammation is an increasingly appreciated component of the vulnerable atherosclerotic plaque. Targeting inflammatory cell signaling events of the coagulation system may become an important aspect of efforts to improve antithrombotic therapy.

Topics: Animals; Arteriosclerosis; Binding Sites; Blood Coagulation Factors; CHO Cells; Cricetinae; Cysteine Endopeptidases; Factor Xa; Humans; Models, Molecular; Neoplasm Proteins; Protein Binding; Protein Conformation; Receptor, PAR-1; Receptor, PAR-2; Receptors, Thrombin; Signal Transduction; Thrombin; Thromboplastin; Transfection

Tissue factor pathway inhibitor (TFPI) is a multivalent, Kunitz-type plasma proteinase inhibitor that modulates tissue factor-dependent coagulation in vivo. TFPI possesses a peculiar two-step mechanism of action; it directly inhibits activated factor X and subsequently produces feedback inhibition of the factor VIIa/tissue factor catalytic complex in a factor Xa-dependent fashion. TFPI biochemistry and physiology have been extensively studied during the last decade. Its pathophysiologic role in thrombotic disorders has, however, only recently started to be unraveled. In particular, circulating plasma TFPI levels have been found to modulate the activity of the tissue factor-dependent coagulation cascade. In animal models, neutralization of circulating TFPI activity results in restoration of intravascular thrombus formation previously abolished by aspirin. In patients with acute myocardial infarction, TFPI plasma levels measured in blood samples obtained from the coronary sinus were significantly lower than those measured in blood obtained from the ascending aorta, indicating acute consumption of TFPI within the coronary circulation of patients with intracoronary thrombosis. Finally, recent data indicate that transfection of the arterial wall with the gene coding for TFPI is an effective therapeutic intervention to prevent intravascular thrombus formation. Taken together, these observations underline the pathophysiologic importance of TFPI in regulating the procoagulant activity of tissue factor and open new potential therapeutic approaches for the treatment of thrombotic disorders.

Topics: Amino Acid Sequence; Animals; Anticoagulants; Arteriosclerosis; Blood Coagulation; Humans; Lipoproteins; Molecular Sequence Data; Thromboplastin; Thrombosis

To describe the characteristics of thrombus formation on atherosclerotic plaques, the clinical expression of atherothrombosis in vascular disease, and some of the most recent therapeutic approaches in cardiovascular disease.. MEDLINE search for English-language articles on thrombosis and atherosclerosis published up to January 2000. Abstracts of recent international meetings on new aspects of thrombus formation and new therapeutic options were reviewed, and references from identified articles were selected and reviewed.. Experimental, basic, clinical, and epidemiologic studies related to the pathophysiology of thrombosis on atherosclerotic lesions. Therapeutic approaches were obtained from experimental studies and large clinical investigations.. Arterial vessel wall substrate, rheologic conditions, and blood thrombogenicity influence the process of thrombus formation in arteries. Thrombus formation on disrupted atherosclerotic plaques or arterial erosions frequently causes acute coronary syndromes. Severe atherosclerosis of the aorta has been identified as an important morphologic indicator of an increased risk for thromboembolism. Current antithrombotic therapies available as long-term treatment for patients with cardiovascular disease are often not effective enough to prevent acute thrombotic events and deterioration of atherosclerosis.. Improved understanding of the pathophysiology of thrombus formation on atherosclerotic plaques has led to the development of new therapeutic approaches. Glycoprotein IIb/IIIa, tissue factor, factor Xa, and thrombin inhibitors as well as combined antithrombotic therapy, such as aspirin plus a thienopyridine plus warfarin, are being evaluated as new possible options for the treatment of arterial thrombosis.. Long-term treatment with potent antithrombotic drugs, such as tissue factor or factor Xa inhibitors, that effectively block thrombosis without causing bleeding complications could help reduce death from cardiovascular disease.

Topics: Arteriosclerosis; Clinical Trials as Topic; Disease Progression; Drug Therapy, Combination; Factor Xa Inhibitors; Hemorheology; Humans; Platelet Aggregation Inhibitors; Platelet Glycoprotein GPIIb-IIIa Complex; Risk Factors; Thromboembolism; Thromboplastin

Thrombus formation on a disrupted atherosclerotic plaque is a threatening event that leads to vessel occlusion and acute ischemia. In this current perspective, we present evidence for apoptosis as a major determinant of the thrombogenicity of the plaque lipid core and a potential contributor to plaque erosion and associated thrombosis. Moreover, apoptosis may directly affect blood thrombogenicity through the release of apoptotic cells and microparticles into the bloodstream.

Topics: Angina, Unstable; Animals; Apoptosis; Arteriosclerosis; Blood Coagulation; Embolism; Humans; Inflammation; Myocardial Infarction; Phosphatidylserines; Stroke; Thromboplastin; Thrombosis

Clinical manifestations of atherosclerosis are the consequences of atherosclerotic plaque rupture that triggers thrombus formation. Tissue factor (TF) is a key element in the initiation of the coagulation cascade and is crucial in thrombus formation following plaque disruption. TF activity is highly dependent on the presence of phosphatidylserine (PS), an anionic phospholipid that is redistributed on the cell surface during apoptotic death conferring a potent procoagulant activity to the apoptotic cell. Apoptosis occurs in the human atherosclerotic plaque and shed membrane apoptotic microparticles rich in PS are produced in considerable amounts within the lipid core. These microparticles carry almost all TF activity and are responsible for the procoagulant activity of the plaque. Moreover, luminal endothelial cell apoptosis might be responsible for thrombus formation on eroded plaques without rupture. Apoptosis might also play a major role in blood thrombogenicity via circulating procoagulant microparticles that are found at high levels in patients with acute coronary syndromes.

Topics: Animals; Apoptosis; Arteriosclerosis; Humans; Phosphatidylserines; Thromboplastin; Thrombosis

Topics: Arteriosclerosis; Blood Coagulation Factors; Blood Platelets; Endothelium, Vascular; Factor VIII; Fibrinogen; Hemostasis; Hepatocytes; Humans; Interleukin-6; Leukocytes; Models, Biological; Receptors, Interleukin-6; Thromboplastin; Thrombosis; Venous Thrombosis; von Willebrand Factor

Tissue factor, a 47 kDa membrane glycoprotein, lies at the basis of the extrinsic pathway of the coagulation cascade. Interaction of TF with factor VIIa results in the formation of fibrin from fibrinogen, thereby inducing the formation of a blood clot. In addition to this well-established role in blood coagulation, TF is associated with various other physiological processes such as sepsis, inflammation, angiogenesis, metastasis and atherosclerosis. The molecular basis of the latter events is slowly emerging. It has become clear that TF-FVIIa interaction elicits a variety of intracellular signalling events that may be implicated in these actions. These events include the sequential activation of Src-like kinases, MAP kinases, small GTPases and calcium signalling. How this progress in the understanding of TF associated signal transduction may generate answers as to the mechanism through which TF exerts it pleiotropic effects will be focus of this review.

Topics: Animals; Arteriosclerosis; Blood Coagulation; Calcium Signaling; Cytokines; Disseminated Intravascular Coagulation; Factor VIIa; Fibroblasts; Gene Expression Regulation; GTP Phosphohydrolases; Humans; Inflammation; Lipoproteins; Lipoproteins, LDL; MAP Kinase Signaling System; Mice; Mice, Knockout; Muscle, Smooth, Vascular; Neoplasm Metastasis; Neoplasms; Neovascularization, Physiologic; Papio; Phagocytes; Sepsis; Signal Transduction; src-Family Kinases; Thromboplastin

Topics: Animals; Arachidonic Acids; Arteriosclerosis; Aspirin; Cyclooxygenase Inhibitors; Humans; Thromboplastin; Thrombosis

Topics: Arteriosclerosis; Coronary Artery Disease; Coronary Vessels; Humans; Muscle, Smooth, Vascular; Thromboplastin; Thrombosis

Thrombosis is a key feature of the initiation and progression of atherosclerosis and its clinical sequelae. Acute thrombosis can lead to arterial occlusion and consequently provoke myocardial infarction, unstable angina, stroke and sudden death. Acute thrombosis can also be a complication of arterial bypass surgery, balloon angioplasty, atherectomy, or coronary artery stenting. The thrombotic response is influenced by several factors, among them the thrombogenicity of the vessel wall and of certain blood components as well as their interaction with the lipid pool. Tissue factor (TF) is considered to be the primary cofactor of cellular origin that is involved in activation of the coagulation pathway. The active form of TF has been shown to be present in specimens of human coronary artery in association both with acellular lipid areas and with macrophages and smooth muscle cells, which suggests that TF plays a major role in determining plaque thrombogenicity. We discuss here what is currently known about the role of tissue factor in atherogenesis, and focus attention on pharmacological approaches in this area.

Topics: Arteriosclerosis; Coronary Artery Disease; Coronary Thrombosis; Coronary Vessels; Humans; Thromboplastin; Thrombosis

Atherosclerosis is vascular disease characterized by thickening, hardening, and remodelling of the arterial wall. Occlusive vascular disease most often results from thrombosis superimposed on atherosclerotic plaque. Lipoproteins enter the vessel wall, promoting the recruitment of monocytes, which imbibe lipids and become foam cells. Smooth muscle cells invade these early plaques, producing connective tissue fibrils that form a fibrous cap over the lipid center; rupture of this cap is an important cause of thrombosis. The specific topography of early atherosclerotic lesions is primarily attributed to wall shear stress, one of hemodynamic forces. Inflammatory mediators regulate processes that determine the composition of the plaque's fibrous cap, a structure that separates blood from the thrombogenic lipid core. Factors involved in coagulation, such as thrombin, can regulate non-thrombotic functions of vascular wall cells such as smooth muscle proliferation or cytokine release. Tissue factor is a major regulator of coagulation and hemostasis. When the plaques are ruptured or eroded, exposure of cellular and extracellular tissue factor to circulating blood play a pivotal role in mediating fibrin-rich thrombus formation leading to acute coronary syndromes. Several serial angiographic studies have demonstrated that over 70% of acute coronary syndromes evolve from mildly to moderately obstructive atherosclerotic plaques.

Topics: Arteriosclerosis; Coronary Artery Disease; Humans; Thromboplastin; Thrombosis

The last few years have provided increasing evidence to support a major role for TF in the initiation and propagation of thrombosis after acute arterial injury. Although thrombotic occlusion occurs in a small minority of patients undergoing acute coronary interventions or bypass surgery, mural thrombi are likely to be present in almost all cases. These thrombi may stimulate SMC and promote the development of intimal hyperplasia and luminal narrowing. The use of inhibitors of TF and factor VIIa, therefore, may not only be valuable for inhibiting thrombus formation associated with acute arterial interventions, but may also have benefit in attenuating intimal hyperplasia. Although this paper focuses on the role of TF in establishing a procoagulant state after arterial injury, the fibrinolytic system undoubtedly plays a role in balancing the effects of increased TF production in the arterial wall. This is underscored by the success of activators of fibrinolysis (tissue plasminogen activator, streptokinase, urokinase) in revascularization in the setting of acute myocardial infarction and is reviewed elsewhere. Likewise, local regulation of TFPI in the atherosclerotic plaque and injured vessel wall may be important in attenuating the effects of increased TF synthesis and accumulation. It has been assumed that the primary source of active TF after arterial injury is either SMC or invading macrophages and that active TF is anchored to the surface of these cells. Recent data have suggested that the majority of cell-associated TF is either encrypted on the cell surface or present in an intracellular pool. Arterial injury may, therefore, involve the de-encryption of surface TF or the release of intracellular TF. In addition, active vascular TF may be present in microparticles that are not anchored to the arterial wall and may be washed into the circulation. The procoagulant state may be further accentuated by the accumulation of bloodborne TF at sites of arterial injury and in developing thrombi. This TF is likely to arise from circulating leukocytes, including neutrophils and monocytes. These studies suggest that the cellular processing of TF may be an important target for inhibiting thrombotic complications associated with arterial injury and acute coronary events.

Topics: Animals; Arteries; Arteriosclerosis; Endothelium, Vascular; Fibrinolysis; Humans; Hyperplasia; Muscle, Smooth, Vascular; RNA, Messenger; Thromboplastin; Thrombosis

Intravascular thrombus often occurs when the rupture or fissure of an atherosclerotic plaque exposes procoagulant elements lying below the plaque surface. This process of plaque rupture is the result both of passive mechanical forces and an active cell-mediated mechanism. Recently a number of investigators have developed imaging technologies based on magnetic resonance to characterize atherosclerotic lesions or the use of radioactively labeled platelets to dynamically visualize clot formation and lysis in vivo. These methods may permit early detection of developing thrombus, improve selection of treatment, and allow direct monitoring of the progression of antithrombotic therapy.

Topics: Anticoagulants; Arteriosclerosis; Humans; Hypolipidemic Agents; Macrophages; Magnetic Resonance Imaging; Thromboplastin

Tissue factor (TF) protein was overexpressed by macrophages and smooth muscle cells (SMCs) and deposited in the extracellular matrix of atherosclerotic intimas, probably resulting in enhanced procoagulant activity and the intimate participation in either thrombus formation or intimal fibrin deposition after the exposure of flowing blood and permeated fibrinogen to TF in atherosclerotic lesions. On the other hand, APO(a) was localized both in the stroma and within some macrophages. Fibrin deposition, which was more frequently detected in the matrix of advanced lesions than in that of early lesions, occasionally colocated with cell- and matrix-associated TF and APO(a) deposited in the matrix. These findings further support the hypothesis that the coagulation and fibrinolysis systems can play an essential role in the initiation and progression of atherosclerosis through fibrin deposition both in atherosclerotic plaques and on the arterial surface by neointimal hypercoagulability and a hypofibrinolytic state, which can also participate in SMC proliferation due to the decreased activation of TGF-beta by embedded and deposited APO(a). The clinical implications of these phenomena may thus contribute to future investigations in the prevention and treatment of atherosclerotic diseases.

Topics: Animals; Arteriosclerosis; Fibrin; Fibrinolysis; Humans; Lipoprotein(a); Thromboplastin

TF is a major regulator of coagulation and hemostasis. High levels of TF antigen and activity are detected in atherosclerotic lesions, particularly in the advanced lesions. When the plaques are ruptured or eroded, exposure of cellular and extracellular TF to circulating blood play a pivotal role in mediating fibrin-rich thrombus formation leading to acute coronary syndromes. On the other hand, activation of blood coagulation and deficiency of coagulation inhibitors, without endothelial cell denudation, are considered to be an important factor of thrombogenesis in the microcirculation. The imbalance between TF and TFPI seems to be important in promoting fibrin thrombus formation in the lung of endotoxin induced DIC condition.

Topics: Animals; Arteriosclerosis; Hemostatics; Humans; Rabbits; Rats; Thromboplastin; Thrombosis

TF antigen and activity are found in abundance in human atherosclerotic plaques, particularly in the lipid-rich core. TF is also readily induced in the arterial wall by balloon injury and accumulates in the resulting neointima. In chronic atherosclerosis, the macrophage is likely to be the major source of TF within the plaque. TF accumulates as an early event associated with the migration of monocytes to the vessel wall in response to chemoattractants, such as MCP-1, and their differentiation into macrophages. As SMC become activated in the developing plaque, they provide a second source of TF. Macrophages and SMC accumulate lipid and become foam cells, ultimately degenerating into a necrotic core rich in TF. Spontaneous plaque rupture or acute interventions expose active TF in the core to circulating blood, triggering thrombosis. In acute arterial injury, SMC appear to be the chief source of TF. In normal vessels, the induction of TF in the medial SMC is not sufficient to generate fibrin, presumably because the TF is not readily accessible on the luminal surface. In contrast, endothelial denudation of previously injured arteries may expose intimal TF to circulating blood, resulting in rapid fibrin deposition. In advanced human atherosclerosis, it is likely that even in areas that do not contain "unstable" or "stable" plaques, the vessel wall is not normal and more closely resembles that of a previously injured artery possessing an active intima. Interventions, such as balloon angioplasty, coronary atherectomy, or stent placement may expose intimal TF, leading to fibrin deposition. As the initiator of coagulation, TF is a potential target for inhibiting the thrombotic complications of atherosclerosis. TFPI (reviewed in 52) is currently under clinical investigation as an anticoagulant and its effects on intimal hyperplasia in animal models are being studied. Direct factor Xa inhibitors, such as tick anticoagulant peptide (TAP) and leech anticoagulant peptide (ATS), are also under investigation (53-54). Finally, the recent crystallization of TF (55) and the TF:VIIa (56) should provide important new insights into the design of molecules for directly inhibiting TF.

Topics: Animals; Arteries; Arteriosclerosis; Endothelium, Vascular; Humans; Macrophages; Muscle, Smooth, Vascular; Thromboplastin

Topics: Arteriosclerosis; Hemostasis; Humans; Immunohistochemistry; Monocytes; Neovascularization, Pathologic; Signal Transduction; Thromboplastin; Thrombosis

Over the last years numerous studies have focussed on the in vivo expression of tissue factor (TF) in health and disease. The selective perivascular distribution of TF and the lethal effects of TF knockouts have added strong support to the widely accepted view that TF plays a pivotal role in the initiation of blood coagulation during physiological hemostasis. Inappropriate in vivo expression of TF, particularly by cells that do not express this protein under normal conditions (mainly monocyte-macrophages and endothelial cells), has been documented and is likely responsible for fibrin deposition in a variety of pathological conditions, among which sepsis-associated disseminated intravascular coagulation (DIC) and thromboembolic disease. In malignancy, in vivo expression of TF by tumor cells and/or by host cells has been implicated not only in intratumoral and systemic activation of blood coagulation but also in tumor growth and dissemination.

Topics: Arteriosclerosis; Disseminated Intravascular Coagulation; Humans; Neoplasms; Reference Values; Thrombophlebitis; Thromboplastin; Thrombosis

Topics: Arteriosclerosis; Humans; Phagocytes; Thromboplastin; Thrombosis

The basic mechanisms of atherosclerotic progression leading to the acute coronary syndromes (ACS) have been elucidated during the last few years. In this brief presentation, we outline 1) Definition of Atherosclerotic Lesions: eight morphologically different lesions are defined (Type I to VI) in various phases of disease. 2) Vulnerable Lipid-Rich Plaques and the ACS: The type IV and Va lesions tend to be relatively small in size, but soft or vulnerable to a "passive" phenomenon of plaque disruption; in addition, an "active" macrophage-dependent enzymatic (genesis of metalloproteinase) phenomenon of plaque disruption is evolving. 3) Thrombosis: we have shown that monocytes/macrophages in lipid-rich plaques may play a detrimental role after plaque disruption, promoting thrombin generation and thrombosis through the tissue factor pathway that can be prevented by tissue factor pathway inhibition; such pathway of thrombosis appears to be critical in the development of the ACS. 4) Effect of Lipid-Modifying Strategies and other Risk Factors on the Vulnerable Lipid-Rich Plaques: when high LDL-cholesterol is reduced therapeutically, efflux from the plaques of the liquid or sterified cholesterol, and also its hydrolysis into cholesterol crystals depositing in the vessel wall, predominate over the influx of LDL-cholesterol; consequently, there is a decrease in the softness of the plaque and so, presumably in the "passive" phenomenon of plaque disruption; modification of other risk factors presumably also favorably affect LDL-cholesterol influx and efflux. 5) Antithrombotic Strategies: the evolving antithrombotic approaches under investigation are briefly outlined.

Topics: Anticoagulants; Arteriosclerosis; Aspirin; Clinical Trials as Topic; Coronary Thrombosis; Disease Progression; Drug Therapy, Combination; Endothelium, Vascular; Fibrinolytic Agents; Humans; Lipids; Models, Biological; Platelet Aggregation Inhibitors; Rupture, Spontaneous; Thromboembolism; Thromboplastin; Warfarin

Much has been learned about tissue factor during the past 25 years and much is yet to be learned. On the biochemical level, the association of TF:VIIa with factor X is yet to be resolved. The mechanism by which TF is transported from the nucleus to the plasma membrane has yet to even be approached. Thus, those of us studying this interesting and fundamentally important molecule have much work in the future.

Topics: Arteriosclerosis; Cells, Cultured; Factor VIIa; Factor X; Humans; Kinetics; Macromolecular Substances; Membrane Lipids; Phospholipids; Protein Binding; Thromboplastin

Recent evidence suggests that long-chain saturated fatty acids (i.e. stearic acid), produced on lipolysis of triglyceride-rich lipoproteins in the interface of circulating remnant particles provide a contact surface that activates the contact system of coagulation and subsequently activates factor VII. Increased level of circulating activated factor VII is probably of little consequence to a healthy individual with minimal expression of tissue factor in the vasculature. However, at a site of an atheromatous plaque or at a vascular injury site where there is tissue factor activity, increased circulating activated factor VII is expected to generate thrombin at a higher rate. Propagation of the prothrombotic environment will be facilitated on expression of additional tissue factor that is induced by the local increased concentration of thrombin. Thrombin with its receptor-mediated interactions with blood and vessel wall cells can signal inflammatory and proliferative responses such as those that occur in atheroma.

Topics: Animals; Arteriosclerosis; Blood Coagulation; Blood Proteins; Factor VII; Humans; Lipoproteins; Thrombin; Thromboplastin; Thrombosis

Topics: Animals; Arteriosclerosis; Humans; Platelet-Derived Growth Factor; Thrombin; Thromboplastin; Thrombosis

The coagulation enzyme thrombin, a serine protease like all other coagulation factors, plays a central role in the hemostatic processes engaged after injurious events. It induces, with particular efficacy, the aggregation of blood platelets (primary hemostasis) and accounts, via splitting of fibrinogen to fibrin, for the event actually responsible for the coagulation of blood (secondary hemostasis). As is well-known, thrombin itself is generated by a cascade of activation events involving various coagulation factors (F). In this respect the "tissue factor" (TF, formerly known as thromboplastin), in combination with F VIIa, attains decisive significance, not only in the extrinsic pathway of coagulation (activation of F X-->Xa), but also in the intrinsic pathway (activation of F IX-->IXa). Under physiological circumstances, platelet aggregation and coagulation are restricted to the area of the vascular lesion, since the surrounding intact endothelium inhibits an intraluminal spreading of both processes. These "antithrombotic" features of the endothelium encompass antiaggregatory mechanisms (formation and release of prostacyclin [PGI2], adenosine, EDRF [NO], degradation of ADP and other nucleotides mediated by ecto-nucleotidases) as well as anti-coagulatory properties (formation and release of "tissue factor pathway inhibitor" [TFPI], which blocks the coagulation cascade by joining F Xa, TF and F VIIa into an inactive complex, thrombomodulin--thrombin induced activation of protein C, which, together with protein S, inactivates F Va and F VIIIa, thereby attenuating further generation of thrombin, and the heparan sulfate-enhanced activation of antithrombin III and heparin-cofactor II).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Arteriosclerosis; Blood Coagulation Factors; Blood Platelets; Endothelium, Vascular; Fibrinolysis; Hemostasis; Humans; Platelet Aggregation; Thrombin; Thromboplastin

In response to vascular injury, such as occurs in acute or chronic atherosclerosis, vascular smooth muscle cells (VSMCs) proliferate and migrate, ultimately contributing to vessel narrowing. Several growth agonists, including platelet-derived growth factor and fibroblast growth factor, are known to cause VSMCs to proliferate and are believed to be present at sites of vessel injury. Targets for inhibiting VSMC growth or migration in the presence of multiple growth agonists include genes that are induced in common by VSMC growth factors. This article summarizes the in vivo and in vitro findings of experiments designed to investigate the regulation of tissue factor in VSMCs in 2 animal models. The findings demonstrate that tissue factor is rapidly induced by growth factors in VSMC culture and by balloon injury in aortic media, and they suggest that VSMCs may play a major role in mediating the early thrombotic response. Strategies designed to inhibit the response of VSMCs to growth agonists may therefore have important implications for the treatment of intravascular thrombosis.

Topics: Animals; Arteriosclerosis; Gene Expression Regulation; In Vitro Techniques; Muscle, Smooth, Vascular; Thromboplastin

The localization of tissue factor (TF) in atherosclerotic plaques of human aortas was immunohistochemically examined using rabbit anti-IgG against recombinant TF, which was expressed in E. coli. TF, the initiator of the extrinsic coagulation pathway, was ubiquitously present in atherosclerotic intima, and was expressed mainly by macrophages, but not by endothelial cells. It has been suggested that some macrophages in atherosclerotic intima co-express both molecules of TF and platelet-derived growth factor-B chain. We have developed a morphometrically quantitative in vitro assay for angiogenesis, using endothelial cultures on collagen gel incorporating plasminogen. With this method, we have obtained findings suggesting that plasminogen and plasminogen activators (PAs), especially urokinase-type PA (uPA) derived from endothelial cells, enhance angiogenic activity, probably by increasing endothelial migration. uPA was immunohistochemically observed to be primarily cell-associated on the focal contract areas, probably via its receptors on endothelial cells. These findings may support the hypothesis that the activation and regulation of the pericellular fibrinolysis system is closely related to angiogenesis.

Topics: Animals; Arteriosclerosis; Cattle; Coronary Thrombosis; Endothelium, Vascular; Fibrinolysis; Humans; Immunohistochemistry; Macrophages; Models, Cardiovascular; Neovascularization, Pathologic; Plasminogen Inactivators; Thromboplastin; Thrombosis; Urokinase-Type Plasminogen Activator

Topics: Animals; Arteries; Arteriosclerosis; Blood Coagulation; Catheterization; Cell Adhesion; Cell Movement; Cholesterol, Dietary; Endothelium; Endotoxins; Epoprostenol; Growth Substances; Interleukin-1; Models, Biological; Monocytes; Muscle, Smooth, Vascular; Platelet-Derived Growth Factor; Rabbits; Rats; Thromboplastin; Wound Healing

The importance of the blood coagulation sequence as an integral part in the pathogenesis of diseases inside as well as outside the blood vessels is becoming increasingly apparent. Mononuclear phagocytes have important functions in initiation of coagulation by producing several procoagulant substances, including thromboplastin, the potent trigger of the extrinsic pathway. Increasing evidence demonstrates the clinical importance of monocyte and macrophage thromboplastin synthesis in the pathogenesis of a variety of diseases. This review surveys the role of monocyte/macrophage thromboplastin in relation to inflammatory diseases, cancer, disseminated intravascular coagulation and diseases of the blood vessels, thrombosis and atherosclerosis.

Topics: Arteriosclerosis; Arthritis, Rheumatoid; Cysteine Endopeptidases; Disseminated Intravascular Coagulation; Endopeptidases; Glomerulonephritis; Graft Rejection; Humans; Hypersensitivity, Delayed; Kidney Transplantation; Membrane Proteins; Monocytes; Neoplasm Proteins; Pulmonary Embolism; Thromboplastin

As knowledge of blood coagulation has advanced we have begun to examine not only the clinical entities associated with hemorrhage but also a group in which thrombosis represents the major problem. Thrombotic disorders believed to be associated with coagulation are recognized clinically but seldom investigated in the laboratory. The present approach to the problem is based on theoretical and experimental knowledge and a rapidly developing body of clinical information related to the role of platelets and antithrombin III in the initiation and control of thrombosis.

Topics: Arteries; Arteriosclerosis; Blood Coagulation; Blood Coagulation Factors; Blood Platelets; Blood Vessels; Cell Survival; Endotoxins; Factor V; Factor VIII; Fibrin Fibrinogen Degradation Products; Fibrinogen; Fibrinopeptide A; Humans; Thromboplastin; Thrombosis; Veins

Topics: Animals; Arteries; Arteriosclerosis; Blood Coagulation; Blood Coagulation Factors; Blood Platelets; Endothelium; Fatty Acids; Fatty Acids, Nonesterified; Humans; Hyperlipidemias; Lipids; Phospholipids; Platelet Adhesiveness; Platelet Aggregation; Prostaglandins; Thromboplastin; Thrombosis

Increased numbers of CD146-defined circulating endothelial cells (CECs), as are present in the peripheral blood of patients suffering acute coronary syndromes, imply injury to the endothelium. Endothelial damage can also be assessed by the measurement of plasma levels of von Willebrand factor (vWf). Increased levels of procoagulant plasma tissue factor (TF), arising from monocytes/macrophages and endothelial cells, is present in atherosclerosis. We hypothesised increased CECs in patients with ischaemic rest pain (IRP) of the lower limb due to peripheral atherosclerosis and comparable to that seen in patients with acute myocardial infarction (AMI), when compared to patients with intermittent claudication (IC) or healthy controls that would correlate with vWf and TF.. We recruited 20 patients in each of four groups: (i) IRP of the lower limb; (ii) AMI; (iii) 'stable' IC; and (iv) healthy controls. CD146-expressing CECs were measured by immumomagnetic separation and counting under a fluorescence microscope; plasma vWf and TF by ELISA.. In IRP, median (IQR) CEC levels were 3.5 (2.0-5.8) cells/ml, in IC were 1.1 (0.6-2.9) cells/ml, and in healthy controls were 1.0 (0.5-1.7) cells/ml (p<0.001). The levels of vWf (p=0.034) and TF (p=0.007) were also significantly different between the groups, with the highest levels in patients with IRP. Levels of CECs correlated with vWf (rs=0.4, p=0.002) and TF ( rs=0.296, p=0.021 ). In AMI, CEC levels were higher than those in IRP at 4.9 (3.6-8.4) cells/ml (p=0.0385).. This study demonstrates evidence of direct endothelial cell injury (i.e. raised CECs) in patients with IRP that correlated with vWf and TF, but that this is less severe than in AMI.

Topics: Aged; Analysis of Variance; Antigens, CD; Arteriosclerosis; CD146 Antigen; Endothelial Cells; Endothelium, Vascular; Enzyme-Linked Immunosorbent Assay; Female; Humans; Intermittent Claudication; Ischemia; Leg; Male; Membrane Glycoproteins; Middle Aged; Myocardial Infarction; Neural Cell Adhesion Molecules; Pain; Thromboplastin; von Willebrand Factor

Mediterranean and high carbohydrate diets play a dominant role in the prevention of atherosclerosis as a result of their lipid lowering effect. However, diets can also have a protective effect in other ways, such as modulating tissue factor expression in circulating monocytes.. Forty-one subjects participated in this randomised crossover study consisting of three dietary periods: a saturated fat enriched diet (SFA), a low fat and high carbohydrate diet (CHO), and a Mediterranean diet. Plasma levels of total cholesterol, triglycerides, low density lipoprotein (LDL-C) and high density lipoprotein (HDL-C) were determined at the end of each dietary period, as was the expression of tissue factor (TF) in circulating monocytes isolated from blood samples. Total cholesterol, LDL-C, HDL-C and TF expression were lower after the Mediterranean and high carbohydrate diets than after the SFA diet, and there was a positive correlation between LDL-C levels and monocyte TF expression.. High carbohydrate and Mediterranean diets reduce the expression of TF in circulating monocytes.

Topics: Adult; Analysis of Variance; Arteriosclerosis; Blood Chemical Analysis; Cholesterol, HDL; Cholesterol, LDL; Cross-Over Studies; Diet, Fat-Restricted; Diet, Mediterranean; Dietary Carbohydrates; Female; Humans; Male; Monocytes; Probability; Reference Values; Thromboplastin

Peripheral artery disease (PAD) and intermittent claudication are common in men aged over 55 years. Once the diagnosis has been made, very few patients suffer from a deterioration of the disease. Those that do deteriorate tend to do so due to thrombosis of an affected artery. It is apparent that the disruption in the vessel wall accounts for some of the cause of the thrombosis but blood constituents also play a role. We hypothesized that levels of soluble P-selectin (sP-sel, a marker of platelet activation), von Willebrand factor (vWf, an index of endothelial damage/dysfunction), tissue factor (TF, a coagulation protein involved in the 'extrinsic' coagulation pathway) and fibrinogen would be abnormally elevated in relation to disease severity and correlated with each other, and related to ethnicity, in a multiethnic population of patients with PAD. To test this hypothesis, we studied 234 patients (80% white, 7% Indo-Asian, 13% Afro-Caribbean) with confirmed PAD [ankle brachial pressure index (ABPI)< or =0.8] and 50 healthy controls. All of the indices studied were increased in patients over controls (p<0.05). None of the indices of the hypercoagulable state were significantly different between the three ethnic groups studied. Patients with ischaemic rest pain were shown to have higher levels of plasma fibrinogen (p<0.001) although none of the other prothrombotic markers were increased in this group. Furthermore, fibrinogen was higher in cases whose ABPI was below the median (<0.52) when compared to those less severely affected, with an inverse correlation between fibrinogen and ABPI (Spearman, r=-0.178, p=0.009). In conclusion, we found a prothrombotic state in patients with PAD with increased levels of markers of endothelial damage/dysfunction, platelet activation and thrombosis, which may contribute to the pathogenesis of this condition. However, disease severity was only related to plasma fibrinogen levels.

Topics: Aged; Arteries; Arteriosclerosis; Asian People; Biomarkers; Black People; Causality; Comorbidity; Endothelium, Vascular; Female; Fibrinogen; Humans; Intermittent Claudication; Male; P-Selectin; Peripheral Vascular Diseases; Risk Assessment; Risk Factors; Severity of Illness Index; Statistics as Topic; Thromboplastin; Thrombosis; United Kingdom; von Willebrand Factor; White People

Triglyceride-rich lipoproteins (TGLs) are atherogenic. However, their cellular mechanisms remain largely unexplained. This study examined the effects of isolated remnant-like lipoprotein particles (RLPs) on the expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and tissue factor (TF), proatherothrombogenic molecules, in cultured human endothelial cells.. RLPs were isolated from plasma of hypertriglyceridemic patients by use of the immunoaffinity gel mixture of anti-apoA-1 and anti-apoB-100 monoclonal antibodies. The incubation of cells with RLPs significantly upregulated mRNA and protein expression of these molecules. Total TGLs (d<1.006) and LDL had fewer or minimal effects on expression of these molecules compared with RLPs. RLPs increased intracellular oxidant levels, as assessed with an oxidant-sensitive probe. Combined incubation with alpha-tocopherol or N-acetylcysteine, both antioxidants, suppressed RLP-induced increase in expression of these molecules. In patients with higher plasma levels of RLPs, plasma levels of soluble forms of ICAM-1 and VCAM-1 were significantly higher than in patients with lower RLP levels. Treatment with alpha-tocopherol for 1 month decreased levels of the soluble adhesion molecules concomitantly with an increase in resistance of RLPs to oxidative modification in patients with high RLP levels.. RLPs upregulated endothelial expression of ICAM-1, VCAM-1, and TF, proatherothrombogenic molecules, partly through a redox-sensitive mechanism. RLPs may have an important role in atherothrombotic complications in hypertriglyceridemic patients.

Topics: Arteriosclerosis; Cells, Cultured; Culture Media; DNA; Endothelium, Vascular; Humans; Hypertriglyceridemia; Intercellular Adhesion Molecule-1; Lipid Peroxides; Lipoproteins; NF-kappa B; Oxidation-Reduction; Peptide Fragments; RNA, Messenger; Solubility; Thromboplastin; Vascular Cell Adhesion Molecule-1; Vitamin E

Our purpose was to investigate the effects of hormone replacement therapy on the reactivity of monocytes and platelets in whole blood, measured by tissue factor activity, tumor necrosis factor-alpha, and thromboxane B2.. Thirty-two women were randomized into either transdermal or oral combined hormone replacement therapy and underwent blood sampling before and after 3 and 12 months of treatment. The tissue factor activity in monocytes was measured both in unstimulated whole blood and after a weak lipopolysaccharide stimulation. Tumor necrosis factor-alpha and thromboxane B2 formation in plasma were measured after a weak lipopolysaccharide stimulation of whole blood.. After 12 months of hormone replacement therapy there were significant reductions of tissue factor activity in both unstimulated and lipopolysaccharide-stimulated monocytes (p < 0.001) and significant reductions in the formation of tumor necrosis factor-alpha (p < 0.03) and thromboxane B2 (p < 0.02). There were no differences in these parameters between the transdermal and the oral groups. No changes were observed after 3 months of therapy.. Twelve months of hormone replacement therapy reduces cellular activation of blood monocytes and platelets; these changes may account for some of the beneficial effects in reducing the risk of cardiovascular disease.

Topics: Administration, Cutaneous; Administration, Oral; Adult; Arteriosclerosis; Blood Platelets; Estradiol; Estrogen Replacement Therapy; Female; Humans; Medroxyprogesterone; Middle Aged; Monocytes; Norethindrone; Thromboplastin; Thrombosis; Thromboxane B2; Tumor Necrosis Factor-alpha

Morphology of atherosclerotic plaque is a major determinant of plaque thrombogenicity. Calcified atherosclerotic lesions are less prone to thrombosis and contain less tissue factor (TF) than lipid-rich plaques. Although bone morphogenetic protein (BMP)-2 is a known mediator of vascular calcification, the role of BMP-2 in the regulation of plaque thrombogenicity has not been established. We hypothesized that the expression of BMP-2 within highly calcified atherosclerotic plaques inhibits TF expression and reduces thrombogenicity of calcified lesions. In the present study, we measured levels of TF and BMP-2 in human calcified and lipid-rich carotid plaques and studied the effects of BMP-2 on TF expression in human monocytes in vitro. Quantitative immunohistochemical analysis of endarterectomy specimens for TF and BMP-2 revealed that calcified plaques contained nearly three-times less TF antigen than lipid-rich ones. In contrast, calcified plaques expressed two-times more BMP-2 antigen than lipid-rich lesions. BMP-2 markedly decreased protein expression and surface redistribution of TF in activated human monocytes in vitro. BMP-2-mediated inhibition of TF expression in monocytes/macrophages could contribute to reduced thrombogenicity of calcified atherosclerotic plaques.

Topics: Arteriosclerosis; Blotting, Western; Bone Morphogenetic Protein 2; Carotid Arteries; Cells, Cultured; Endarterectomy; Flow Cytometry; Gene Expression; Histocytochemistry; Humans; Lipids; Lipopolysaccharides; Macrophage Activation; Macrophages; Microscopy, Confocal; Monocytes; Plaque, Atherosclerotic; Thromboplastin; Thrombosis; Vascular Calcification

Procoagulant microparticles (MP) constitute valuable hallmarks of vascular cell damage at the crossroad of atherothrombosis processes. Detectable at low concentrations in the blood flow of healthy individuals, elevated levels of procoagulant microparticles are characteristic features of most cardiovascular risk factors. Circulating MP support cellular cross-talk leading to vascular inflammation, endothelial dysfunction, leukocyte adhesion and recruitment possibly contributing to plaque growth with consecutive development of local thrombosis and altered vasomotion. Within the plaque, MP shed by apoptotic monocytes and smooth muscle cells are major determinant of plaque thrombogenicity mainly through the presence of tissue factor (TF) activity. Besides this procoagulant potential, trapped MP could contribute to plaque vulnerability through multiple pathways including angiogenesis, extracellular matrix proteolysis, recruitment of inflammatory cells, smooth muscle cell and endothelial apoptosis. Having long been considered sufficient to initiate coagulation following plaque disruption, the role assigned to plaque-bound TF does not appear physically realistic at a macroscopic scale, the swift growth of the thrombus probably involving blood-borne TF conveyed by circulating MP. As participants in crucial steps of atherosclerotic disease, MP can now be viewed as "partners in crime" in acute ischemic syndromes.

Topics: Arteriosclerosis; Cell Communication; Cell Membrane; Humans; Particle Size; Thrombophilia; Thromboplastin; Thrombosis

Endothelial abnormalities and a hypercoagulable state may contribute to increased cardiovascular risk in diabetes mellitus, particularly in patients with overt cardiovascular disease (CVD). We sought to determine the effect of intensified multi-factorial cardiovascular risk intervention on indices of endothelial abnormality and hypercoagulability in diabetes, and if patients with overt CVD would derive similar benefit as those without.. We measured plasma von Willebrand factor (vWf, an index of endothelial damage/dysfunction), soluble E-selectin (sE-sel, marking endothelial activation) and tissue factor (TF, an initiator of coagulation) by ELISA in 94 patients with diabetes mellitus (38 with CVD and 56 without overt CVD) and 34 comparable controls. Thirty-three patients with CVD and 31 without overt CVD then participated in multi-factorial cardiovascular risk intervention over 1 year.. Plasma levels of vWf (P = 0.009), sE-sel (P < 0.001) and TF (P < 0.001) were significantly higher in diabetic patients compared with controls, with TF highest in patients with overt CVD. Intensive multi-factorial intervention resulted in reductions in glycated haemoglobin (HbA(1c)), total and LDL-cholesterol (all P < 0.05), but no significant weight change. This was associated with reductions in vWf in patients with (by 26%P = 0.003), and without (by 47%, P < 0.001), overt CVD. TF was reduced only in patients without overt CVD (by 45%, P < 0.001). There were no significant changes in sE-sel levels in either group.. Endothelial abnormalities in diabetes are only partially influenced by contemporary intensified multi-factorial cardiovascular risk intervention. These data suggest the need for earlier and more aggressive risk factor intervention.

Topics: Aged; Angiotensin-Converting Enzyme Inhibitors; Arteriosclerosis; Case-Control Studies; Cholesterol; Cholesterol, LDL; Diabetes Mellitus, Type 2; Drug Therapy, Combination; E-Selectin; Female; Follow-Up Studies; Glycated Hemoglobin; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Male; Middle Aged; Platelet Aggregation Inhibitors; Statistics, Nonparametric; Sulfonylurea Compounds; Thromboplastin; Treatment Outcome; von Willebrand Factor

Epidemiological studies suggest the potential importance of an inflammatory component in atherosclerosis and support the hypothesis that immune responses to Ags of pathogens cross-react with homologous host proteins due to molecular mimicry. Protein candidates involved may be the stress-induced proteins known as heat shock proteins (HSP). In this study, we report that atherosclerotic plaques harbor in vivo-activated CD4(+) T cells that recognize the human 60-kDa HSP. Such in vivo-activated 60-kDa HSP-specific T cells are not detectable in the peripheral blood. In patients with positive serology and PCR for Chlamydia pneumoniae DNA, but not in patients negative for both, most of plaque-derived T cells specific for human 60-kDa HSP also recognized the C. pneumoniae 60-kDa HSP. We characterized the submolecular specificity of such 60-kDa HSP-specific plaque-derived T cells and identified both the self- and cross-reactive epitopes of that autoantigen. On challenge with human 60-kDa HSP, most of the plaque-derived T cells expressed Th type 1 functions, including cytotoxicity and help for monocyte tissue factor production. We suggest that arterial endothelial cells, undergoing classical atherosclerosis risk factors and conditioned by Th type 1 cytokines, express self 60-kDa HSP, which becomes target for both autoreactive T cells and cross-reactive T cells to microbial 60-kDa HSP via a mechanism of molecular mimicry. This hypothesis is in agreement with the notion that immunization with HSP exacerbates atherosclerosis, whereas immunosuppression and T cell depletion prevent the formation of arteriosclerotic lesions in experimental animals.

Topics: Aged; Amino Acid Sequence; Antigen Presentation; Arteriosclerosis; Autoantigens; CD4-Positive T-Lymphocytes; Cell Movement; Chaperonin 60; Chlamydophila pneumoniae; Clone Cells; Cytokines; Epitopes, T-Lymphocyte; Female; Humans; Jurkat Cells; Lymphocyte Activation; Male; Middle Aged; Molecular Mimicry; Molecular Sequence Data; Monocytes; Thromboplastin

To determine the concentration of tissue factor (TF), tissue factor pathway inhibitor (TFPI) and vascular endothelial growth factor A (VEGF-A) in carotid plaques.. Thirty-eight consecutive patients (20 symptomatic, 18 asymptomatic) undergoing carotid endarterectomy were enrolled into the current study. The concentration of TF, TFPI and VEGF-A in carotid plaque homogenates and blood plasma was measured using enzyme immunoassay.. The concentration of TF in carotid plaque homogenates was 60 fold higher than in blood plasma. There were no statistically significant differences between the concentration of TF, TFPI and VEGF-A in symptomatic and asymptomatic plaques. Carotid plaques of diabetic patients contained an increased level of TF and VEGF-A ( p = 0.002, p = 0.005). The plaque concentration of VEGF-A was elevated among older patients ( p = 0.02). Carotid plaques of non-smokers contained an increased level of TFPI ( p = 0.03). The concentration of TF, TFPI and VEGF-A in carotid plaques correlated positively with plasma level of these factors ( R = 0.86; p < 0.0001; R = 0.91; p < 0.0001; R = 0.80; p = 0.001, respectively). A highly positive correlation between concentration of VEGF-A and TF, TFPI in carotid plaques was also observed ( R = 0.75; p < 0.001; R = 0.62; p < 0.001, respectively).. TF, TFPI and VEGF-A concentrations do not differ in atheroma removed from symptomatic and asymptomatic patients but are higher in diabetic patients. There is a highly positive correlation between the level of VEGF-A and TF, TFPI in carotid plaques.

Topics: Aged; Arteriosclerosis; Biomarkers; Carotid Stenosis; Endarterectomy, Carotid; Female; Follow-Up Studies; Humans; Immunoenzyme Techniques; Lipoproteins; Male; Risk Factors; Sensitivity and Specificity; Thromboplastin; Vascular Endothelial Growth Factor A

To determine the relationship between plasma C-reactive protein (CRP) concentrations and monocyte tissue factor (TF) expression induced in vitro by combinations of CRP, ss2-glycoprotein I (ss2-GPI), and lipopolysaccharide (LPS).. Peripheral blood mononuclear cells (PBMC) from 26 healthy individuals and 31 patients with inflammatory rheumatic diseases (IRD) were cultured with combinations of CRP, purified or recombinant ss2-GPI, and LPS and monocyte TF procoagulant activity, TF antigen, and TF mRNA were measured. Results were examined against plasma CRP levels.. Monocytes from patients with IRD expressed significantly more TF when stimulated with CRP compared to normal monocytes (p = 0.002). An incremental positive correlation was observed between plasma CRP levels and TF induced by CRP or ss2-GPI. Significantly more TF was induced with CRP combined with ss2-GPI, compared to ss2-GPI alone, either with costimulation or CRP priming. Conversely, when combined with LPS, ss2-GPI suppressed TF induction in a dose-dependent manner on normal PBMC but not on PBMC from patients with IRD. The loss of suppression correlated strongly with plasma CRP levels.. This study shows a remarkably consistent effect of CRP on monocyte TF expression. Systemic inflammation associated with elevated plasma CRP conferred a phenotype on PBMC, whereby incremental priming with respect to TF expression (induced by CRP itself or ss2-GPI) was apparent, and ss2-GPI-mediated inhibition of TF expression induced by LPS was incrementally lost. CRP regulation of monocyte TF could contribute to the higher than expected atherosclerotic vascular disease seen in patients with IRD.

Topics: Adult; Arteriosclerosis; Arthritis, Rheumatoid; beta 2-Glycoprotein I; C-Reactive Protein; Cells, Cultured; Female; Glycoproteins; Humans; Lipopolysaccharides; Male; Middle Aged; Monocytes; Thromboplastin; Up-Regulation

Tissue factor (TF), which is expressed in atherosclerotic plaques and colocalizes with oxidized lipids, initiates the thrombogenic process. We have analyzed the effect of aldehydes derived from peroxidation of polyunsaturated fatty acids on TF expression in human vascular smooth muscle cells (HVSMC). Our results demonstrate that hexanal and 2,4-decadienal (2,4-DDE), two apolar aldehydes, increase TF expression. Exposure of HVSMC to hexanal for 2 h led to TF protein levels up to seven times higher than untreated cells whereas 2,4-DDE for 30 min led to them being up to 2.2 times higher. This induction of TF antigen by aldehydes correlates with an increase in TF mRNA levels. Electrophoretic mobility shift assays (EMSAs) showed that the binding activity of the transcription factor AP-1 (c-Fos/c-Jun) to TF promoter was elevated in response to these oxidation products. This enhancement was associated to an increase of c-fos transcriptional activity, which was reversible by pretreatment with simvastatin. We conclude that the induction of TF by aldehydes might contribute to the severity of atherogenesis.

Topics: Aldehydes; Arteriosclerosis; Blotting, Western; Cells, Cultured; Electrophoretic Mobility Shift Assay; Gene Expression Regulation; Genes, fos; Humans; Lipid Peroxidation; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Promoter Regions, Genetic; Reverse Transcriptase Polymerase Chain Reaction; Thromboplastin; Thrombosis; Transcription Factor AP-1

Early growth response-1 (Egr-1) regulates expression of proinflammatory and procoagulant genes in acute cell stress. Experimental evidence suggested that Egr-1 transcripts were upregulated in human atherosclerotic plaques versus adjacent unaffected tissue. To test the impact of Egr-1 in chronic vascular stress, we examined its role in a murine model of atherosclerosis. Real-time PCR analysis of aortae retrieved from apoE-/- mice demonstrated increased Egr-1 transcripts in an age-dependent manner, compared with aortae retrieved from C57BL/6 control animals. Therefore, homozygous Egr-1-/- mice were bred into the apoE-/- background. Homozygous double-knockout mice (Egr-1-/-/apoE-/-) in the C57BL/6 background were maintained on normal chow diet. At age 14 and 24 weeks, atherosclerotic lesion area and complexity at the aortic root were strikingly decreased in mice deficient in both Egr-1 and apoE compared with mice deficient in apoE alone. In parallel, transcripts for genes regulating the inflammatory/prothrombotic response were diminished in Egr-1-/-/apoE-/- aortae versus apoE-/-. In vitro, oxidized low-density lipoprotein (OxLDL), a key factor inciting atherogenic mechanisms in the vasculature, upregulated Egr-1 expression in monocytes via the MEK-ERK1/2 pathway. We conclude that Egr-1 broadly regulates expression of molecules critically linked to atherogenesis and lesion progression.

Topics: Animals; Aorta; Apolipoproteins E; Arteriosclerosis; Blood Glucose; Calcium-Calmodulin-Dependent Protein Kinases; Cell Line; Chemokine CCL2; Cholesterol; Disease Progression; DNA-Binding Proteins; Early Growth Response Protein 1; Enzyme Inhibitors; Female; Flavonoids; Gene Expression; Immediate-Early Proteins; Intercellular Adhesion Molecule-1; Interleukin-1; Lipoproteins, LDL; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Phosphorylation; Plasminogen Activator Inhibitor 1; RNA, Messenger; Thromboplastin; Time Factors; Transcription Factors; Triglycerides; Vascular Cell Adhesion Molecule-1

Tissue factor (TF) expressed in arterial atherosclerotic plaque plays a key role in activating the extrinsic coagulation pathway and triggering acute coronary syndromes. In this study, we developed and characterized a TF-factor (F)VIIa-mediated thrombosis model in rabbits. Balloon catheter-induced endothelial denudation in the femoral artery and a 4-week high cholesterol diet produced a localized atherosclerotic plaque at the injured site. High levels of TF mRNA and TF protein antigen (152 +/- 25 vs. 49 +/- 12 pg mg-1 protein in normal vessels) were detected in these atherosclerotic plaques. Plasma FVII coagulant activity (FVII:C) was significantly increased in the hypercholesterolemic rabbits (36 +/- 1 s) compared with the normal rabbits (44 +/- 1 s, P < 0.0001). Plaque rupture was induced by balloon angioplasty, which resulted in thrombus formation in the injured vessel segment after a brief period of stasis. FVIIai, a specific TF-FVIIa inhibitor, was administered intravenously to rabbits before plaque rupture at 0.3 and 1.0 mg kg-1. FVIIai dose-dependently reduced thrombus mass (14.7 +/- 2.5 and 5.9 +/- 2.2 mg, respectively, vs. 21.6 +/- 1.9 mg in the control group). PD198961, a novel factor Xa inhibitor, and argatroban, a thrombin inhibitor, also dose-dependently inhibited thrombosis. These results indicate that thrombus formation in this model is initiated by the activation of TF-FVIIa pathway, which is attributed to TF expression in the atherosclerotic plaque and enhanced plasma FVII coagulant activity. This model may be useful for evaluating in vivo efficacy of new antithrombotic drugs, particularly TF-FVIIa inhibitors.

Topics: Animals; Arteriosclerosis; Disease Models, Animal; Factor VIIa; Fibrinolytic Agents; Gene Expression; Hypercholesterolemia; Lipids; Rabbits; RNA, Messenger; Thromboplastin; Thrombosis

Rapid re-occlusion of an atheromatous vessel after angioplasty may occur through yet incompletely known mechanisms. Atheromatous plaque has been shown to contain tissue factor (TF) activity. When atheroma extracts (atheroma) and platelets are incubated together a powerful prothrombinase is rapidly generated, which neither platelets nor atheroma alone can generate. Large amounts of thrombin were generated in minutes by many atheroma-platelet mixtures. However in these mixtures, generation of factor (F)Xa activity was not enhanced, but was in fact decreased by platelet tissue factor pathway inhibitor (TFPI) activity. Leukocytes had no appreciable effect in these short-term experiments. Although levels of factor VII and FX in atheroma were extremely low, antibodies to each of these factors inhibited prothrombinase formation. So did an antibody to factor V. A FXa inhibitor, DX 9065a, was very effective in preventing prothrombinase generation. These findings may explain the rapid occlusion that has been observed after angioplasty and point to avenues of prevention.

Topics: Arteriosclerosis; Blood Platelets; Carotid Arteries; Cells, Cultured; Factor V; Factor VII; Factor Xa; Humans; In Vitro Techniques; Lipoproteins; Thrombin; Thromboplastin; Thrombosis

Nuclear factor kappa B (NF-kappa B) activation has been observed in human atherosclerotic plaques and is enhanced in unstable coronary plaques, but whether such activation has a protective or pathophysiological role remains to be determined. We addressed this question by developing a short-term culture system of cells isolated from human atherosclerotic tissue, allowing efficient gene transfer to directly investigate signaling pathways in human atherosclerosis. We found that NF-kappa B is activated in these cells and that this activity involves p65, p50, and c-Rel but not p52 or RelB. This NF-kappa B activation can be blocked by overexpression of I kappa B alpha or dominant-negative I kappa B kinase (IKK)-2 but not dominant-negative IKK-1 or NF-kappa B-inducing kinase, resulting in selective inhibition of inflammatory cytokines (tumor necrosis factor alpha, IL-6, and IL-8), tissue factor, and matrix metalloproteinases without affecting the antiinflammatory cytokine IL-10 or tissue inhibitor of matrix metalloproteinases. Our results demonstrate that the canonical pathway of NF-kappa B activation that involves p65, p50, c-Rel, and IKK-2 is activated in human atherosclerosis and results in selective up-regulation of major proinflammatory and prothrombotic mediators of the disease.

Topics: Actins; Adenoviridae; Arteriosclerosis; CD3 Complex; CD40 Ligand; Cells, Cultured; Gene Transfer, Horizontal; Humans; I-kappa B Kinase; Inflammation; Interleukin-6; Interleukin-8; Matrix Metalloproteinase Inhibitors; Matrix Metalloproteinases; Myocytes, Smooth Muscle; NF-kappa B; NF-kappa B p50 Subunit; NF-kappaB-Inducing Kinase; Protein Serine-Threonine Kinases; Thromboplastin; Thrombosis; Tissue Inhibitor of Metalloproteinase-1; Transcription Factor RelA

Macrophages associated with arterial wall lipid deposition contribute to inflammatory processes. Tissue factor (TF) has been implicated in the thrombogenicity of atherosclerotic plaques. Intimal cells undergoing apoptosis have been postulated as a source for TF. However, there is only limited knowledge of cell type, plaque component, and conditions associated with TF expression and apoptosis. We examined the hypothesis that macrophages exposed to conditions of lipid-rich plaque undergo apoptosis and express TF.. In human carotid (n=15) and coronary (n=6) atherosclerotic plaques, TF and caspase-3 mRNA and protein expression (evaluated by in situ hybridization and immunohistochemistry) were increased significantly in lipid-rich compared with fibrous plaque components (P<0.01) and correlated with high macrophage content (P<0.05). Double-labeling studies demonstrated colocalization of TF and active caspase-3. In hyperlipidemic mice, expression of TF and active caspase-3 was observed simultaneously and colocalized in neointimal macrophages after arterial injury. In neointima of normolipidemic animals, TF and active caspase-3 were absent after arterial injury. In monocytes cultured in the presence of oxidized LDL, strong induction and colocalization of TF and active caspase-3 were found compared with baseline (P<0.05). Both antigens were significantly decreased after cotreatment with a caspase inhibitor (P<0.05) and were absent in untreated control cells.. The expression of TF as the primary cell-associated activator of the coagulation pathway proves to be closely related to macrophages undergoing apoptosis in conditions of lipid-rich plaque, pointing to a key role of lipid content and inflammatory cell viability in determining plaque thrombogenicity.

Topics: Animals; Apoptosis; Arteriosclerosis; Caspase 3; Caspases; Foam Cells; Gene Expression; Humans; Inflammation; Male; Mice; Mice, Inbred C57BL; Monocytes; Thromboplastin; Thrombosis

The mechanisms of thrombosis on plaque erosion are poorly understood. We examined the potential role of endothelial apoptosis in endothelial erosion and vessel thrombosis.. Segments of New Zealand White rabbit femoral arteries were temporarily isolated in vivo. One artery was incubated with staurosporin for 30 minutes, whereas the contralateral artery was incubated with saline and served as control. Three days later, thrombosis was evaluated angiographically and histologically. TUNEL score in the endothelial layer was significantly increased in staurosporin-treated arteries compared with controls (2.43+/-0.30 versus 0.93+/-0.44, respectively; P=0.001). Large areas of endothelial denudation were detectable in staurosporin-treated vessels, whereas endothelium integrity was almost preserved in the saline group. Vessel thrombosis occurred in 58% of staurosporin-treated arteries (7 of 12) but in only 8% of saline-treated segments (P<0.01). Immunoreactivities for tissue factor, platelets, and fibrin were detectable within the thrombus. Addition of ZVAD-fmk (0.1 mmol/L) significantly reduced the occurrence of thrombosis (1 of 7 arteries or 14%, P=0.04). These results were confirmed in balloon-injured atheromatous arteries.. In vivo induction of endothelial apoptosis leads to both vessel thrombosis and endothelial denudation. Endothelial apoptosis may be a critical step in the transition from a stable endothelialized plaque to plaque erosion and thrombosis.

Topics: Amino Acid Chloromethyl Ketones; Animals; Apoptosis; Arteriosclerosis; Catheterization; Cysteine Proteinase Inhibitors; Endothelial Cells; Endothelium, Vascular; Femoral Artery; Fibrin; In Situ Nick-End Labeling; Platelet Count; Rabbits; Staurosporine; Thromboplastin; Thrombosis; Tunica Intima

Tissue factor (TF) is the main initiator of coagulation in vivo. Recently, however, a role for TF as a cell receptor involved in signal transduction has been suggested. The aim of the present study was to assess whether activated factor VII (FVIIa) binding to TF could induce smooth muscle cell (SMC) proliferation and to clarify the possible intracellular mechanism(s) responsible for this proliferation.. Cell proliferation was induced by FVIIa in a dose-dependent manner, as assessed by [3H]thymidine incorporation and direct cell counting, whereas no response was observed with active site-inhibited FVIIa (FVIIai), which is identical to FVIIa but is devoid of enzymatic activity. Similarly, no proliferation was observed when binding of FVIIa to TF was prevented by the monoclonal anti-TF antibody AP-1. Activation of the p44/42 mitogen-activated protein (MAP) kinase (extracellular signal-regulated kinases 1 and 2 [ERK 1/2]) pathway on binding of FVIIa to TF was demonstrated by transient ERK phosphorylation in Western blots and by suppression of proliferation with the specific MEK (MAP kinase/ERK kinase) inhibitor UO126. ERK phosphorylation was not observed with FVIIai or when cells were pretreated with AP-1.. These data indicate a specific effect by which binding of FVIIa to TF on the surface of SMCs induces proliferation via a coagulation-independent mechanism and possibly indicate a new link between coagulation, inflammation, and atherosclerosis.

Topics: Animals; Antibodies, Monoclonal; Aorta, Thoracic; Arteriosclerosis; Binding Sites; Blood Coagulation; Butadienes; Cell Division; Cells, Cultured; Enzyme Activation; Enzyme Inhibitors; Factor VIIa; Humans; Inflammation; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Nitriles; Phosphorylation; Protein Binding; Protein Processing, Post-Translational; Rabbits; Recombinant Fusion Proteins; Signal Transduction; Thromboplastin

Topics: Arteriosclerosis; Coronary Thrombosis; Death, Sudden, Cardiac; Disease Progression; Endothelium, Vascular; Female; Glutathione; Humans; Hypochlorous Acid; Inflammation Mediators; Macrophages; Male; Models, Biological; Peroxidase; Rupture, Spontaneous; Thrombophilia; Thromboplastin

Tissue factor (TF) and plasminogen activator inhibitor-1 (PAI-1) activity and/or expression are upregulated in obesity. We investigated TF and PAI-1 mRNA expression in adipose tissues of cholesterol-fed rabbits, and the effects of fenofibrate.. Male rabbits were fed either a normal or high-cholesterol diet for 8 weeks. After 4 weeks, those fed high-cholesterol diets were randomly assigned to 30 mg/kg/day fenofibrate and starch. At the end of 12 weeks, subcutaneous adipose was collected. The concentration of TF and PAI-1 mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR). The plasma activities of TF and PAI-1 were determined with ELISA and chromogenic substrate method, respectively.. The atherogenic diet caused a consistent increase in serum concentrations of total cholesterol (TC) (p<0.05) and did not significantly affect serum triglyceride (TG) concentrations, and increased TF and PAI-1 mRNA expression in adipose tissues (1.149+/-0.014 and 1.200+/-0.012, respectively) as compared to the normal diet (1.034+/-0.011 and 1.098+/-0.013, respectively) (p<0.01). The plasma activities of TF [(74.4+/-28.8) ng/l] and PAI-1 [(15.6+/-1.9) x 10(3) AU/l] in high-cholesterol diet group were higher than those of normal diet group [(33.1+/-10.7) ng/l and (6.9+/-0.9) x 10(3) AU/l, respectively, p<0.05]. Four-week fenofibrate treatment resulted in significant decrease of TF (1.017+/-0.010) and PAI-1 mRNA (1.061+/-0.011, p<0.01), the plasma activity of TF [(40.3+/-12.2) ng/l, p<0.05] and PAI-1 [(7.5+/-1.5) x 10(3) AU/l, p<0.01] also decreased significantly, and the concentrations of lipids were not changed.. TF and PAI-1 mRNA expression and plasma activities increased in adipose tissue of cholesterol-fed rabbits. Fenofibrate reduced TF and PAI-1 expression and plasma activity in adipose, suggesting that fenofibrate treatment reduces thrombosis risk, and may have an antithrombotic effect independent of its lipid-lowering.

Topics: Adipose Tissue; Animals; Arteriosclerosis; Cholesterol; Cholesterol, Dietary; Diet; Enzyme-Linked Immunosorbent Assay; Fenofibrate; Fibrinolysis; Hypolipidemic Agents; Male; Plasminogen Activator Inhibitor 1; Rabbits; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Thromboplastin

Activation of vascular smooth muscle cells (SMCs) by platelet-derived growth factor (PDGF) is a seminal event in the initiation and progression of the atherosclerotic lesion and may contribute to atherosclerotic plaque instability with plaque rupture and thrombus formation. Tissue factor (TF), a prothrombotic molecule expressed by various cell types within atherosclerotic plaques, is thought to play a major role in thrombus formation after plaque rupture. This study examined intracellular signaling pathways leading to TF expression and Egr-1 activation, a key element in tissue factor transcription, by PDGF-BB in rat SMCs. PDGF-BB induced TF mRNA and protein expression in a time-dependent manner. Early growth response factor-1 (Egr-1) binding activity was also induced by PDGF-BB, as well as phosphorylation of extracellular signal-regulated kinase. PDGF-BB-induced Egr-1 activation was suppressed by inhibitors of 2 upstream activators of Egr-1, extracellular signal-regulated kinase (ERK) and Src family kinases, whereas antioxidants, phosphatidylinositol 3-phosphate kinase, and p38 MAPK inhibitors had no effect. PDGF-BB-stimulated expression of the transcriptional co-repressor NAB2 was time-dependent. Furthermore, transient transfections of SMCs with wild-type and mutated TF promoter constructs showed that the Egr-1 binding region is an important transcriptional regulator of PDGF-BB-induced TF expression. Taken together, the results suggest that PDGF-BB induces TF expression and activity in SMC by a Src family kinases/ERK/Egr-1 signaling pathway and may therefore contribute to thrombus formation in advanced atherosclerosis and restenosis.

Topics: Animals; Arteriosclerosis; Becaplermin; Cells, Cultured; DNA-Binding Proteins; Early Growth Response Protein 1; Extracellular Signal-Regulated MAP Kinases; Gene Expression Regulation; Humans; Immediate-Early Proteins; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; p38 Mitogen-Activated Protein Kinases; Phosphatidylinositol 3-Kinases; Platelet-Derived Growth Factor; Proto-Oncogene Proteins c-sis; Rats; Rats, Sprague-Dawley; Signal Transduction; src-Family Kinases; Thromboplastin; Thrombosis; Transcription Factors

Topics: Adult; Aged; Arteriosclerosis; Factor VIIa; Female; Humans; Hypertension; Lipoproteins; Male; Middle Aged; Thromboplastin

Coagulation is initiated by the interaction of tissue factor (TF) with plasma coagulation factors VII (FVII) and X (FX). TF is highly expressed in atherosclerotic lesions, but little is known about the synthesis of FX or FVII outside of the liver. Previous studies suggested that macrophages synthesize FVII. We therefore hypothesized that macrophages within atherosclerotic lesions may produce FVII, leading to partial activation of the coagulation cascade.. Immunohistochemistry was performed using antibodies against FVII, FX, and TF on normal and atherosclerotic vessels. In atherosclerotic lesions, FVII immunostaining was colocalized with TF in macrophages and spindle-shaped smooth muscle cells. FVII mRNA was also detected in these cells using in situ hybridization, suggesting the local synthesis of FVII in atherosclerosis. Reverse transcriptase-polymerase chain reaction confirmed the presence of FVII mRNA in normal and atherosclerotic vessels as well as smooth muscle cells, fibroblasts, and keratinocytes in vitro.. The localization of FVII synthesis outside the liver may be indicative of other cellular functions for this coagulation protein. The observed coexpression of TF and FVII may contribute to autocrine signaling via thrombin-independent mechanisms and may represent a novel mechanism contributing to growth in the setting of vascular disease.

Topics: Animals; Aorta; Aortic Diseases; Arteriosclerosis; Brachial Artery; Carotid Arteries; Carotid Artery Diseases; Factor VII; Factor X; Fibroblasts; Humans; Immunohistochemistry; In Situ Hybridization; Keratinocytes; Liver; Macrophages; Muscle, Smooth, Vascular; Papio; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Thromboplastin

Oxidative modification of LDL, which dysregulates the homeostasis between blood and vascular cells, and alterations of endothelial function are considered among the early events in the pathogenesis of atherosclerosis. This study was designed to evaluate the impact of progressive LDL oxidation on the thrombotic response both in vitro and in vivo, and to address the potential effect of antioxidants. Tissue factor was induced by progressive LDL oxidation in HUVEC, and this event was in parallel to the appearance of the apoptotic phenotype. Both these phenomena were mediated by ERK1/2 activation and were prevented by LDL pre-enrichment with antioxidants. In contrast, antioxidants failed to affect tPA and PAI-1 secretion, which was increased by LDL, either native or oxidized. Tissue factor-pathway inhibitor was also increased upon HUVEC exposure to progressively oxidized LDL. LDL, in the presence of an oxidative agent, trigger a thrombogenic response in vivo, mostly TF-dependent, in an in situ model of platelet deposition. This effect was markedly attenuated when LDL were enriched with antioxidants. It can be concluded that vascular thrombogenicity is induced by progressive LDL oxidation and that alterations of the antioxidant/oxidant balance of the LDL particle in favor of the antioxidant tone are protective against the thrombotic response triggered by oxidative stress. The extrapolation of these data in a clinical setting, even if not easy, offers potential insights for the use of antioxidants in the prevention of thrombotic complications associated with atherothrombosis.

Topics: Antioxidants; Apoptosis; Arteriosclerosis; Cells, Cultured; Endothelium, Vascular; Humans; Lipoproteins; Lipoproteins, LDL; MAP Kinase Signaling System; Oxidation-Reduction; Plasminogen Activator Inhibitor 1; Thromboplastin; Thrombosis; Tissue Plasminogen Activator

Recent studies suggest that the beneficial effects of 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors (statins) in reducing cardiovascular events may in part, be independent of their capacity to lower plasma lipids. To test this hypothesis, simvastatin (50 mg/kg/d) was administered to 30-week-old apolipoprotein E deficient mice (apo E-/-) for 12, 18 and 24 weeks. In contrast to other experimental models and humans, simvastatin treatment increases plasma cholesterol levels in apo E-/- mice. Quantitative real-time polymerase chain reaction was used to quantify expression of tissue factor (TF) and monocyte chemoattractant protein-1 (MCP-1) in the aorta of each mouse. Expression of TF was reduced to 34, 24, and 13% of control levels at 12, 18 and 24 weeks, respectively, of simvastatin administration. Advanced lesions in the innominate arteries of the simvastatin treated mice had reduced levels of TF, fewer macrophages and reduced expression of early growth response-1 (Egr-1). In vitro studies in mouse macrophages demonstrated decreased lipopolysaccharide induced binding of nuclear proteins to the Egr-1 consensus DNA sequence following pretreatment with simvastatin. RNA levels for MCP-1 were reduced to 30% of control values following 24 weeks of simvastatin treatment. In conclusion, these data suggest that chronic administration of simvastatin to older apo E-/- mice can inhibit the expression of pro-thrombotic/pro-inflammatory genes within established atherosclerotic lesions via mechanisms that are independent of reductions in plasma lipids.

Topics: Animals; Apolipoproteins E; Arteriosclerosis; Base Sequence; Chemokine CCL2; Cholesterol; Culture Techniques; Disease Models, Animal; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Immunohistochemistry; Male; Mice; Mice, Inbred Strains; Molecular Sequence Data; Probability; Reverse Transcriptase Polymerase Chain Reaction; Sensitivity and Specificity; Severity of Illness Index; Simvastatin; Thromboplastin

Restenosis is responsible to approximately 30% of long-term failure following therapeutic vascular procedures. Thrombosis plays a key role in the development of restenosis. Thrombin-specific inhibitors have been considered as one type of candidates for the prevention of restenosis. Previous studies by our group demonstrated that a novel thrombin-specific inhibitor, hirulog-like peptide (HLP), reduced balloon catheter-induced neointima formation in rat carotid arteries. The present study examined the effect of HLP on angioplasty-induced restenosis in carotid arteries of atherosclerotic rabbits. New Zealand white rabbits were subject to air desiccation of the lumen of the right carotid arteries, then received high cholesterol/fat diet for 3 weeks. The rabbits were intravenously infused with HLP (1.6 mg/(kg/h)) or saline (n=7 per group) for 4 h started before angioplasty which dilated atherosclerotic lesions in right common carotid artery. Four weeks after the angioplasty, neointimal area, stenosis and neointima/media ratio in injured carotid arteries were reduced in atherosclerotic rabbits treated with HLP compared to saline controls by 62, 39 and 59% (P<0.05). The expression of tissue factor (TF) and transforming growth factor (TGF)-beta in the neointima of carotid arteries of rabbits treated with HLP was significantly weaker than saline controls (P<0.05 or <0.01). Activated partial thromboplastin time and bleeding time in HLP-treated rabbits were not significantly prolonged compared to controls. The results of the present study suggest that HLP may substantially reduce angioplasty-induced restenosis in atherosclerotic rabbits without increasing bleeding tendency. The inhibition on the expression of TF and TGF-beta in the neointima of the arterial wall may contribute to the preventive effect of HLP on restenosis in atherosclerotic rabbits.

Topics: Animals; Arteriosclerosis; Bleeding Time; Carotid Artery, Common; Carotid Stenosis; Collagen; Hirudins; Humans; Immunohistochemistry; Male; Partial Thromboplastin Time; Peptide Fragments; Rabbits; Rats; Recombinant Proteins; Recurrence; Thromboplastin; Transforming Growth Factor beta; Tunica Intima

Increasing evidence points toward a prothrombotic state in hypertension and atherosclerosis, conditions associated with thrombosis-related complications, such as myocardial infarction and stroke. We hypothesized that this increased risk of thrombogenesis may be related to endothelial damage/dysfunction and abnormal angiogenesis, and thus, an increased risk of future cardiovascular disease. Thrombogenesis, endothelial damage/dysfunction, and angiogenesis can be assessed by measurement of tissue factor (TF), von Willebrand Factor (vWF), flow-mediated dilatation (FMD), and vascular endothelial growth factor (VEGF), respectively. To test this hypothesis, we measured TF, vWF, FMD, and VEGF in 76 patients with systemic hypertension (71 men; mean age 64; mean blood pressure 167/72 mm Hg), considered additional risk factors such as diabetes, and related them to the patient's 10-year cardiovascular and cerebrovascular risk score using the Framingham equation. Patients were compared with 48 healthy normotensive controls. In these patients, the effects of 6 months of intensified blood pressure and (where appropriate) lipid-lowering treatment were investigated. In our patients, TF, VEGF, and vWF levels were higher, but FMD was lower (all p <0.001) compared with the controls. All markers correlated with each other and with both cardiovascular and cerebrovascular risk scores (all p <0.001). After intensified blood pressure and hypercholesterolemia treatment, total cholesterol, blood pressure, TF, VEGF, and vWF levels all decreased, whereas FMD increased (all p <0.001). Thus, in subjects with hypertension and other risk factors, endothelial damage/dysfunction (and thus, atherogenesis), thrombogenesis, and angiogenesis are abnormal, correlate with overall cardiovascular risk, and importantly, can be related to each other in a "Birmingham Vascular Triangle." Furthermore, these processes are beneficially affected by intensive blood pressure and lipid treatment.

Topics: Arteriosclerosis; Endothelial Growth Factors; Endothelium, Vascular; Female; Humans; Hypercholesterolemia; Hypertension; Intercellular Signaling Peptides and Proteins; Lymphokines; Male; Middle Aged; Neovascularization, Pathologic; Risk Factors; Thrombophilia; Thromboplastin; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors; Vasodilation; von Willebrand Factor

The withdrawal of 3-hydroxy-3-methylglutaryl-coenzyme A-reductase inhibitors (statins) deteriorates endothelial function. We determined in vascular smooth muscle cells whether statin withdrawal leads to the expression of proinflammatory genes involved in the development and progression of arteriosclerosis.. The withdrawal of cerivastatin from pretreated vascular smooth muscle cells induced an increase in monocyte chemoattractant protein 1 (MCP-1) and tissue factor (TF) mRNA expression and enhanced MCP-1 secretion as well as cell surface TF activity. In the presence of cerivastatin, this effect was mimicked by geranylgeranyl pyrophosphate or mevalonate. Withdrawal-induced MCP-1 expression was sensitive to PD98059, SB203580, and diphenylene iodonium, suggesting an involvement of extracellular signal-regulated kinase 1/2, p38 mitogen-activated protein kinase, and the NADPH oxidase. Withdrawal increased the activity of extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinase and enhanced radical generation. Because the latter effect may result from an Rac-mediated activation of the NADPH oxidase, the effect of withdrawal on Rac translocation was studied. Statin treatment induced an increase in Rac-1 content in the cytoplasm. On withdrawal, however, an "overshoot" translocation of Rac to the plasma membrane occurred.. These observations suggest that statin withdrawal results in the activation of Rac and enhanced oxidative stress. The subsequent activation of redox-activated signal-transduction cascades results in the expression of MCP-1 and TF.

Topics: Animals; Aorta; Arteriosclerosis; Cells, Cultured; Chemokine CCL2; Gene Expression Regulation; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Male; Mitogen-Activated Protein Kinases; Muscle, Smooth, Vascular; NADPH Oxidases; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Pyridines; Rats; Rats, Wistar; Reactive Oxygen Species; Thromboplastin

As apoptosis of neo-intimal SMCs is a feature of advanced atherosclerotic plaques, the procoagulant properties of SMCs of synthetic phenotype undergoing apoptosis were investigated. SMCs isolated from rat aorta obtained 10 days after balloon injury, previously found to up-regulate Tissue Factor (TF) and Tissue Factor Inhibitor (TFPI) and to release large amounts of TFPI (Ghrib et al. Thromb Haemost 2002;87:1043-50), were sensitive to the apoptosis induced by Fas-ligand. During this process, surface TF activity rose by a factor 10 over 6 hours, in parallel with a proportional increase in prothrombinase, while TF protein expressed at the membrane significantly decreased. The microparticles (MPs) produced during SMC death bore intact and functional TF, but the release of TFPI did not change, so that the balance shifted to a procoagulant state during apoptosis. Shed MPs enhanced thrombus formation in flowing whole blood over collagen coated-glass slides. Apoptotic SMCs in atherosclerotic plaques represent a reservoir of highly thrombogenic material, released into the blood stream in case of spontaneous or mechanical plaque disruption.

Topics: Animals; Aorta; Apoptosis; Arteriosclerosis; Fas Ligand Protein; Membrane Glycoproteins; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Rats; Rats, Wistar; Thromboplastin; Thrombosis

Tissue factor (TF), the main initiator of blood coagulation, is involved in cellular migration and angiogenesis processes. TF is expressed strongly in lipid-rich plaques and probably plays an important role in the thrombotic complications of plaque rupture. This study analyzes the effect of dietary lipid lowering on TF expression and cellular modifications in angioplasty-induced rabbit plaque rupture.. After experimental plaque rupture by balloon angioplasty in atheromatous rabbits, animals were assigned a 0.2% or a 2% cholesterol diet, and the TF content of arterial wall and the associated histological modifications were analyzed after 4 weeks. Early effects of lipid lowering were observed: The increase of TF expression in the vascular wall was stronger in the 2% than in the 0.2% cholesterol diet group (iliac arteries: 1226+/-308 versus 72+/-29 mU TF/g artery, P<0.005). Immunohistochemistry indicated that TF expression was associated with sprout of neovessels, which was more pronounced in the 2% than in the 0.2% cholesterol group.. This study shows that dietary lipid lowering decreases the thrombotic potential of ruptured atherosclerotic plaques through TF decrease. Moreover, high TF expression is associated with marked angiogenesis in the vascular wall, which is reduced by lipid lowering. These results provide further arguments for strong dietary lipid lowering to reduce plaque instability and thrombogenicity.

Topics: Angioplasty, Balloon; Animals; Arteries; Arteriosclerosis; Cells, Cultured; Cholesterol; Diet, Atherogenic; Immunohistochemistry; Lipids; Male; Monocytes; Phenotype; Rabbits; Thromboplastin

Inflammation contributes to atherosclerotic plaque initiation and progression. Recent studies suggest that anti-inflammatory drugs such as cyclooxygenase-2 (Cox-2) inhibitors have anti-atherogenic effects. The current study was designed to investigate whether administration of a Cox-2 inhibitor to older apolipoprotein E deficient (apo E-/-) mice with established lesions alters the composition and increases the stability of the lesions.. The Cox-2 inhibitor Celecoxib was administered in chow to 26-week-old, male, apo E-/- mice exhibiting advanced, unstable atherosclerotic lesions within the innominate/brachiocephalic artery. Mice administered Celecoxib had no significant changes in serum cholesterol or the average cross sectional area of atherosclerotic lesion in the innominate artery after 15 weeks of treatment in comparison to non-treated control mice. Histological analyses of sections of the innominate artery demonstrated no significant changes in the frequency of markers of advanced and unstable atherosclerotic plaques, including intra-plaque hemorrhage, vascular calcification, thinning of the fibrous cap, size of the necrotic core and macrophage content. There were also no significant differences in the content of Cox-2 within the lesions. Quantitative real time polymerase chain reaction with mRNA isolated from the aorta of each mouse revealed no significant changes in the expression of tissue factor and inducible nitric oxide synthase. However, mRNA levels for MCP-1 were increased fivefold following 15 weeks of treatment with Celecoxib in comparison to non-treated control mice.. These data suggest that Celecoxib has no effect on the composition of advanced atherosclerotic lesions in older apo E-/- mice.

Topics: Actins; Animals; Anti-Inflammatory Agents; Apolipoproteins E; Arteriosclerosis; Brachiocephalic Trunk; Celecoxib; Chemokine CCL2; Cholesterol; Cyclooxygenase 2; Isoenzymes; Male; Mice; Mice, Knockout; Models, Animal; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Prostaglandin-Endoperoxide Synthases; Pyrazoles; Reverse Transcriptase Polymerase Chain Reaction; Sulfonamides; Thromboplastin; Treatment Failure

Oncostatin M (OSM) is a cytokine of the interleukin-6 (IL-6) family secreted by activated monocytes, and is expressed in atherosclerotic plaque. Smooth muscle cells (SMC), by expressing tissue factor (TF) and tissue factor pathway inhibitor (TFPI) can contribute to the thrombogenicity of atherosclerotic plaque. Consequently, the aim of this study was to evaluate the effects of OSM on the procoagulant activity of SMC. We observed that OSM induced in a concentration-dependent manner a potent procoagulant activity (PCA) that was related in part to an increased synthesis of TF, both at the cell membrane and in SMC lysates. The increased expression of TF on SMC membrane induced by OSM was sustained and was still observed 24 h after stimulation by OSM. IL-6 and leukaemia inhibitory factor (LIF), two OSM-related cytokines, did not significantly modify TF expression at the surface of SMC. In addition to its effects on TF, OSM decreased the secretion of TFPI in the supernatants of SMC, as well as in the lysates, but was devoid of effect on TFPI bound at the membrane of SMC. IL-6 and LIF reduced also TFPI secretion, which could explain why the PCA of SMC lysates treated by IL-6 or LIF was increased, despite an absence of effect on TF expression. In conclusion, these data support the hypothesis that by increasing the PCA of SMC, OSM might be involved in the thrombotic complications associated with plaque rupture.

Topics: Aorta; Arteriosclerosis; Cell-Free System; Cells, Cultured; Enzyme-Linked Immunosorbent Assay; Flow Cytometry; Gene Expression Regulation; Growth Inhibitors; Humans; Interleukin-6; Leukemia Inhibitory Factor; Lipoproteins; Lymphokines; Membrane Proteins; Muscle, Smooth, Vascular; Oncostatin M; Peptides; Recombinant Proteins; Reverse Transcriptase Polymerase Chain Reaction; Risk Factors; Rupture, Spontaneous; Thromboplastin

Topics: Arteriosclerosis; Coronary Artery Disease; Coronary Thrombosis; Disease Progression; Endothelium, Vascular; Humans; Magnetic Resonance Imaging; Risk Factors; Thromboplastin; Vasa Vasorum

Some of the statin-induced reduction in cardiac events in patients with atherosclerosis may be derived from mechanisms independent of lipid lowering. This study tested in nonhuman primates whether statins can influence inflammation (indicated by vascular cell adhesion molecule-1, interleukin-1beta, tissue factor, and macrophages) and features of plaque stability (indicated by collagen and smooth muscle cells) independent of their effect on plasma cholesterol level.. Adult male cynomolgus monkeys (n=12 per group) consumed an atherogenic diet for 12 months while receiving (1) no treatment (control), (2) pravastatin (Prava, 40 mg/kg per day), or (3) simvastatin (Simva, 20 mg/kg per day). Dietary cholesterol was adjusted to equalize plasma cholesterol levels among groups. Although the intima/media ratio in the abdominal aorta did not differ among groups, drug treatment reduced inflammation and features of plaque vulnerability. Macrophage content in the lesions of statin-treated animals was lowered (2.4-fold with Prava and 1.3-fold with Simva; both P<0.001 versus control). Furthermore, lesions had approximately 2-fold less vascular cell adhesion molecule-1, interleukin-1beta, and tissue factor expression in statin-treated versus control animals (P<0.005). Lesional smooth muscle cell and collagen content was 2.1-fold greater in the Prava-treated group (P<0.001) and 1.5-fold greater in the Simva-treated group (P<0.005) than in the control group.. In primates, these results provide further support for the beneficial effect of statins on plaque inflammation and stability in addition to cholesterol lowering.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Arteriosclerosis; Cholesterol; Cholesterol, Dietary; Drug Administration Schedule; Endothelium, Vascular; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Lipids; Lipoproteins; Macaca fascicularis; Male; Matrix Metalloproteinases; Pravastatin; Simvastatin; Thromboplastin; Tunica Intima; Tunica Media; Vascular Cell Adhesion Molecule-1; Vasodilation

Topics: Animals; Anticoagulants; Arteriosclerosis; Aspirin; Fibrinolytic Agents; Heparin; Humans; Lipoproteins; Myocardial Infarction; Platelet Aggregation Inhibitors; Thrombolytic Therapy; Thromboplastin; Thrombosis

Tissue factor (TF) plays an important role in the pathogenesis of atherosclerotic, sepsis and disseminated intravascular coagulation (DIC). TF pathway is therefore an attractive therapeutic target in a number of disease states. Here two TF mutants were developed and named MCsTF and MFsTF, in which the amino acids of active sites were mutated. Both of them were expressed in E.coli and used to inhibit TF pathway through competitive FVII/VIIa binding with TF. The results indicated that rMCsTF almost lost all activities of FX activation and procoagulation, and rMFsTF lost 90% activity. The specific catalytic constant ( k ( cat )/ K (m)) of FX activation by the complex formed by FVIIa with rMCsTF or rMFsTF were 2.0% and 3.7%, respectively, compared to that of rsTF. The inhibition effects of the mutants were studied in vitro, and it appeared that the prothrombin time were prolonged in a dose-dependent manner. Therefore, these mutants of TF may become new kind of specific inhibitors of TF pathway, as a promising drug for the treatment of patients with over-expression of TF.

Topics: Arteriosclerosis; Cloning, Molecular; Disseminated Intravascular Coagulation; DNA, Complementary; Escherichia coli; Gene Expression; Humans; Mutation; Thromboplastin

Thrombosis is the major mechanism underlying acute complications of atherosclerosis. Although thrombogenicity of atherosclerotic plaques has been ascribed to activation of the extrinsic pathway of blood coagulation, in the present study we investigated contribution of the intrinsic factor VIII (fVIII)-dependent pathway. We found that in vitro exposure of human macrophages and smooth muscle cells (SMCs) to atherogenic oxidized low-density lipoprotein (oxLDL) enhances their ability to support activity of 2 major complexes of the intrinsic pathway, Xase and prothrombinase, leading to a 20- and 10-fold increase in thrombin formation, respectively. In contrast, human aortic endothelial cells were less responsive to oxLDL. The increase in the intrinsic procoagulant activity was related to formation of additional fVIII binding sites due to enhanced translocation of phosphatidylserine to the outer surface of oxLDL-treated cells and a 5-fold higher affinity of interaction between components of the Xase complex, activated factors VIII and IX. Processes occurring at early apoptotic stages, including changes in the cell membrane induced by free radicals, may be related to activation of the intrinsic pathway as suggested by effects of inhibitors of early apoptosis on thrombin formation. Immunohistochemical studies on human atherectomy specimens revealed the presence of fVIII in the vicinity of macrophages and SMCs in atheromatous regions with massive deposits of oxLDL, supporting the possible involvement of the intrinsic pathway in thrombus formation in vivo. Our data predict that the intrinsic pathway significantly enhances thrombogenicity of atherosclerotic lesions after removal of the endothelial layer and exposure of SMCs and macrophages to blood flow.

Topics: Aorta; Apoptosis; Arteriosclerosis; Blood Coagulation Factors; Cysteine Endopeptidases; Endothelium, Vascular; Factor IXa; Factor VIII; Factor VIIIa; Humans; Kinetics; Lipoproteins, LDL; Macrophages; Muscle, Smooth, Vascular; Neoplasm Proteins; Thrombin; Thromboplastin; Thrombosis

Hemodynamic forces play a critical role in the pathogenesis of atherosclerosis as evidenced by the focal nature of the disease. Oscillatory shear stress characterizes the hemodynamic environment of plaque-prone areas as opposed to unidirectional shear stress typical of plaque-free areas. These particular flow conditions modulate atherosclerosis-related genes. Tissue factor (TF) initiates blood coagulation, contributes to vascular remodeling, and is therefore a potential contributor in the development/progression of atherosclerosis. We investigated the effect of oscillatory and unidirectional flows on TF using an in vitro perfusion system. Human endothelial cells exposed for 24 h to oscillatory shear stress, significantly increased TF mRNA, and TF protein expression (1.5- and 1.75-fold, respectively, p < 0.01), and surface TF activity (twofolds-increase). Expression of TF inhibitor (TFPI), mRNA and protein, remained unchanged as compared to static conditions. Conversely, cells exposed to unidirectional shear, showed a decrease in TF activity with a significant increase in TFPI mRNA and protein expression (1.5- and 1.8-fold, respectively, p < 0.01). These results show for the first time that pulsatile oscillatory shear stress induces a pro-coagulant phenotype of endothelial cells which may favor formation/progression of atherothrombotic lesions.

Topics: Apoptosis; Arteriosclerosis; Cell Line; Endothelium, Vascular; Equipment Design; Hemodynamics; Humans; Models, Cardiovascular; Perfusion; Periodicity; Stress, Mechanical; Thromboplastin; Up-Regulation

Unstable atherosclerotic plaques that cause acute coronary events usually contain abundant macrophages expressing matrix metalloproteinases (MMPs) and tissue factor (TF), molecules that probably contribute to plaque rupture and subsequent thrombus formation. Lipid lowering with HMG-CoA reductase inhibitors reduces acute coronary events.. To test whether lipid lowering with an HMG-CoA reductase inhibitor retards macrophage accumulation in rabbit atheroma, we administered cerivastatin to immature Watanabe heritable hyperlipidemic rabbits (cerivastatin group, n=10, cerivastatin 0.6 mg x kg(-1) x d(-1); control group, n=9, saline 0.6 mL x kg(-1) x d(-1)) for 32 weeks and measured macrophage accumulation and expression of MMPs and TF. Serum cholesterol levels after 32 weeks were 809+/-40 mg/dL (control group) and 481+/-24 mg/dL (treated group). Cerivastatin diminished accumulation of macrophages in aortic atheroma. Macrophage expression of MMP-1, MMP-3, MMP-9, and TF also decreased with cerivastatin treatment. Cerivastatin reduced the number of macrophages expressing histone mRNA (a sensitive marker of cell proliferation) detected by in situ hybridization but did not alter macrophages bearing a marker of death (TUNEL staining). Cerivastatin treatment (>or=0.01 micromol/L) also reduced growth, proteolytic activity due to MMP-9, and TF expression in cultured human monocyte/macrophages.. These results suggest that lipid lowering with HMG-CoA reductase inhibitors alters plaque biology by reducing proliferation and activation of macrophages, prominent sources of molecules responsible for plaque instability and thrombogenicity.

Topics: Animals; Arteriosclerosis; Cell Division; Cell Survival; Cells, Cultured; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Macrophages; Matrix Metalloproteinase 1; Matrix Metalloproteinase 3; Matrix Metalloproteinase 9; Matrix Metalloproteinases; Pyridines; Rabbits; Thromboplastin

Topics: Arteriosclerosis; C-Reactive Protein; Drug Interactions; Hormone Replacement Therapy; Hormones; Humans; Monocytes; Thromboplastin

Topics: Angioplasty, Balloon, Coronary; Animals; Arteriosclerosis; Blood Coagulation; Constriction, Pathologic; Disease Models, Animal; Disease Progression; Humans; Rats; Thromboplastin; Thrombosis; Tunica Intima

Although hyperhomocysteinemia (HHcy) is a well-known risk factor for the development of cardiovascular disease, the underlying molecular mechanisms are not fully elucidated. Here we show that induction of HHcy in apoE-null mice by a diet enriched in methionine but depleted in folate and vitamins B6 and B12 increased atherosclerotic lesion area and complexity, and enhanced expression of receptor for advanced glycation end products (RAGE), VCAM-1, tissue factor, and MMP-9 in the vasculature. These homocysteine-mediated (HC-mediated) effects were significantly suppressed, in parallel with decreased levels of plasma HC, upon dietary supplementation with folate and vitamins B6/B12. These findings implicate HHcy in atherosclerotic plaque progression and stability, and they suggest that dietary enrichment in vitamins essential for the metabolism of HC may impart protective effects in the vasculature.

Topics: Animals; Apolipoproteins E; Arteriosclerosis; Cells, Cultured; Diet; Disease Models, Animal; Folic Acid; Humans; Hyperhomocysteinemia; Immunohistochemistry; Male; Matrix Metalloproteinase 9; Methionine; Mice; Mice, Inbred C57BL; Mice, Knockout; Pyridoxine; Receptor for Advanced Glycation End Products; Receptors, Immunologic; Thromboplastin; Vascular Cell Adhesion Molecule-1; Vasculitis; Vitamin B 12

Tissue factor initiates blood coagulation after atherosclerotic plaque disruption. Tissue factor pathway inhibitor (TFPI) inhibits tissue factor activity and may reduce thrombus formation in this setting. We evaluated the effect of heterozygous TFPI deficiency on the development of atherosclerosis and thrombosis in atherosclerosis-prone mice.. Mice with a combined heterozygous TFPI deficiency and homozygous apolipoprotein E deficiency (TFPI(+/-)/apoE(-/-)) were generated by crossbreeding, and they were analyzed for atherosclerosis throughout the vascular tree. Compared with mice with a normal TFPI genotype (TFPI(+/+)/apoE(-/-)), mice with a TFPI deficiency exhibited a greater atherosclerotic burden involving the carotid and common iliac arteries. Staining for active tissue factor within the plaque revealed more activity in TFPI(+/-)/apoE(-/-) mice compared with TFPI(+/+)/apoE(-/-) mice. Consistent with increased plaque tissue factor activity, the time to occlusive thrombosis after photochemical carotid plaque injury was significantly decreased in TFPI(+/-)/apoE(-/-) mice.. These observations indicate that TFPI protects from atherosclerosis and is an important regulator of the thrombosis that occurs in the setting of atherosclerosis.

Topics: Animals; Apolipoproteins E; Arteriosclerosis; Blood Vessels; Carotid Arteries; Carotid Artery Injuries; Factor VIIa; Female; Genotype; Lipoproteins; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Thromboplastin; Thrombosis

Topics: Animals; Arteriosclerosis; Humans; Inflammation; Mice; Models, Cardiovascular; Thromboplastin; Thrombosis

Tissue factor (TF) is a low-molecular-weight glycoprotein that initiates the extrinsic clotting cascade and is considered a major regulator of arterial thrombogenicity. TF pathway inhibitor (TFPI) is a major physiological inhibitor of TF-initiated coagulation. The aim of this study was to define the complex interplay between TF and TFPI and the regulation of vascular thrombogenicity in a model of vascular remodeling. To determine the levels and pattern of vascular expression of TF and TFPI associated with vascular remodeling, a murine model of flow cessation was studied. TF activity of the arteries increased after ligation (P<0.05). Quantitative analysis of homogenates of remodeled carotid arteries revealed increased TF expression but unchanged TFPI expression compared with normal carotid arteries, resulting in enhanced TF activity. To determine the potential therapeutic role of TFPI in this thrombogenic state, mice were treated with intravascular adenoviral delivery of either murine TFPI (Ad-mTFPImyc) or a control adenovirus (Ad-DeltaE1). Overexpression of TFPI decreased vascular TF activity compared with viral control (P<0.01). Overexpression of TFPI inhibited neointimal formation (P=0.038), resulting in enhanced luminal area (P=0.001) 4 weeks after flow cessation. In this murine model of vascular remodeling, an imbalance between TF and TFPI expression is generated, resulting in increased TF activity. Overexpression of TFPI in this model inhibits vascular TF activity and results in attenuation of vascular remodeling associated with flow interruption.

Topics: Animals; Arteriosclerosis; Carotid Artery Thrombosis; Genetic Therapy; Lipoproteins; Mice; Mice, Inbred C57BL; Thromboplastin

The infiltration and activation of inflammatory cells play an important role in the formation and stability of coronary atherosclerotic plaque in patients with acute coronary syndrome. In this study, we evaluated the effect of trapidil, an anti-platelet agent, on atheroma-related functions of human T cells and monocytes. Trapidil and anti-CD154 (CD40 ligand) antibody inhibited the increase of procoagulant activity in the mixed lymphocyte reaction; trapidil also suppressed the induction of tissue factor, monocyte chemoattractant protein-1 (MCP-1) and matrix metalloproteinase-9 in the mixed lymphocyte reaction. Trapidil did not alter CD154 expression on isolated T cells, but it diminished CD40 expression on isolated monocytes and human monocytic leukemia THP-1 cells stimulated with interferon-gamma. Moreover, trapidil reduced MCP-1 production of isolated monocytes and THP-1 cells stimulated with interferon-gamma plus CD154-transfected cells. This effect was not seen with other tested anti-platelet agents and coronary vasodilators. In conclusion, trapidil directly acts on monocytes/macrophages to lower their susceptibility to CD154 on T cells.

Topics: Animals; Antibodies, Monoclonal; Arteriosclerosis; CD40 Antigens; CD40 Ligand; Cell Line; Chemokine CCL2; Coculture Techniques; Dose-Response Relationship, Drug; Humans; Interferon-gamma; Lymphocyte Culture Test, Mixed; Matrix Metalloproteinase 9; Monocytes; Platelet Aggregation Inhibitors; T-Lymphocytes; Thromboplastin; Trapidil; Tumor Cells, Cultured

The present series of experiments provide evidence that FVII is synthesized outside of the liver and is found in a variety of cells in normal and atherosclerotic vessels. In normal vessels FVII was localized to the endothelial cell layer and in adventitial fibroblasts at sites where tissue factor (TF) is also found. In early and advanced atherosclerotic lesions, FVII was mostly found in macrophage- rich regions colocalized with TF. Foam cells and macrophages in the necrotic core adjacent to the cholesterol clefts and foamy macrophages in early intimal thickenings all showed strong cytoplasmic staining with FVII antibodies. Although it is possible that FVII protein staining found in normal and atherosclerotic vessels originated from the blood, the finding of FVII mRNA by both in situ hybridization and RT-PCR suggests that these tissues are sites of FVII synthesis. Additional work demonstrated synthesis of FVII in a variety of tissues and smooth muscle cells and fibroblasts in vitro. The distribution of FVII synthesis in extrahepatic tissues and more recent data regarding thrombin-independent signaling as a consequence of FVII/TF binding may suggest the possibility of other cellular functions for this coagulation factor.

Topics: Aorta; Arteriosclerosis; Factor VII; Factor X; Humans; Liver; Muscle, Smooth, Vascular; Necrosis; Organ Specificity; Reference Values; Thromboplastin

Tissue factor (TF) instigates the extrinsic pathway of blood coagulation. Plaque disruption and exposure of circulating factor VII/VIIa to subendothelial procoagulants such as TF leads to intravascular thrombosis, a frequent cause of acute atherosclerotic events. Although the expression of TF in the intima of human atherosclerotic lesions is well established, little is known about the mechanisms of TF regulation in vascular smooth muscle cells (SMC). We demonstrate here that TF colocalizes with the receptor CD40 on lesional SMC within atherosclerotic lesions in situ. In cultured vascular SMC, ligation of CD40 with native CD40 ligand (CD40L) derived from activated T lymphocytes or recombinant human CD40L (rCD40L) induced the transient expression of TF on the cell surface (as determined by FACS analysis) in a concentration- and time-dependent manner and enhanced total cell-associated TF (as determined by ELISA). CD40L-induced TF on vascular SMC is functional and activates coagulation. In accordance with the increased TF activity, stimulation of vascular SMC with rCD40L did not affect either protein expression or activity of tissue factor pathway inhibitors. In summary, these findings demonstrate the potential of the CD40/CD40L signaling pathway to augment the procoagulant activity in human vascular SMC. Because TF and CD40 colocalize on lesional SMC in human atheroma, CD40/CD40L signaling may contribute to the TF expression and hence to increased thrombogenicity of plaques during the inflammatory responses of atherogenesis and arterial injury.

Topics: Arteriosclerosis; CD40 Antigens; CD40 Ligand; Cell Membrane; Cells, Cultured; Humans; Lipoproteins; Membrane Glycoproteins; Muscle, Smooth, Vascular; Thromboplastin

CC chemokine receptors are important modulators of inflammation. Although CC chemokine receptors have been found predominantly on leukocytes, recent studies have suggested that vascular smooth muscle cells respond to CC chemokines. We now report that human smooth muscle cells express CCR5, a co-receptor for human immunodeficiency virus. CCR5 mRNA was detectable by RNA blot hybridization in human aortic and coronary artery smooth muscle cells. The cDNA generated by reverse transcription-polymerase chain reaction from aortic smooth muscle cells had 100% identity throughout the entire coding region with the CCR5 cloned from THP-1 cells. By immunohistochemistry, CCR5 and the CCR5 ligand, macrophage inflammatory protein-1beta (MIP-1beta), were detected in smooth muscle cells and macrophages of the atherosclerotic plaque. In smooth muscle cell culture, MIP-1beta induced a significant increase in intracellular calcium concentrations, which was blocked by an antibody to CCR5. In addition, MIP-1beta caused a calcium-dependent increase in tissue factor activity. Tissue factor is the initiator of coagulation and is thought to play a key role in arterial thrombosis. These data suggest that human arterial smooth muscle cells express functional CCR5 receptors and MIP-1beta is an agonist for these cells.

Topics: Aorta; Arteriosclerosis; Calcium; Chelating Agents; Chemokine CCL4; Coronary Vessels; Dose-Response Relationship, Drug; Egtazic Acid; Endothelium, Vascular; Humans; Immunohistochemistry; Inflammation; Macrophage Inflammatory Proteins; Muscle, Smooth, Vascular; Receptors, CCR5; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Thromboplastin; Thrombosis; Time Factors; Umbilical Cord

Topics: Animals; Arteriosclerosis; DNA-Binding Proteins; Early Growth Response Protein 1; Endothelium, Vascular; Humans; Immediate-Early Proteins; Ischemia; Mice; Mice, Knockout; Platelet-Derived Growth Factor; Thromboplastin; Transcription Factors; Zinc Fingers

Oxidation of low density lipoprotein (LDL) by glucose-derived radicals may play a role in the aetiology of atherosclerosis in diabetes. Salicylate was shown to scavenge certain radicals. In the present study, aspirin, salicylate and its metabolites 2,5- and 2, 3-dihydroxybenzoic acid (DHBA) were tested for their ability to impair LDL oxidation by glucose. Only the DHBA derivatives, when present during LDL modification, inhibited LDL oxidation and the increase in endothelial tissue factor synthesis induced by glucose oxidised LDL. The LDL glycation reaction was not affected by DHBA. The antioxidative action of DHBA may be attributed to free radical scavenging and/or chelation of transition metal ions catalysing glucose autoxidation.

Topics: Arteriosclerosis; Aspirin; Cells, Cultured; Diabetic Angiopathies; Endothelium, Vascular; Gentisates; Glucose; Humans; Hydroxybenzoates; Iron Chelating Agents; Lipoproteins, LDL; Male; Oxidation-Reduction; Prodrugs; Reactive Oxygen Species; Salicylic Acid; Thromboplastin

So far it is not clear how erythropoietin affects the anticoagulant properties of vascular endothelium in uremia. Since serotonin is also thought to play a role in the pathogenesis of thrombosis, the aim of the study was to evaluate major components of extrinsic coagulation pathway, markers of endothelial cell injury, lipoprotein (a) and peripheral serotonergic mechanisms during rHuEPO therapy in hemodialyzed patients. The study was performed on chronically hemodialyzed patients divided into two groups: with rHuEPO treatment and without rHuEPO therapy in relation to the control group. In uremic patients, thrombomodulin and von Willebrand factor, activity of factor VII, tissue factor pathway inhibitor (TFPI) activity, TFPI and tissue factor (TF) concentrations, lipoprotein (a) level were significantly higher when compared to healthy volunteers. Treatment with rHuEPO resulted in a further significant rise in markers of endothelial cell injury: thrombomodulin and von Willebrand factor and TFPI concentration. Extrinsic coagulation factors: activities of factor VII and X, TFPI activity and TF activity and concentration, lipoprotein (a) and vitronectin remained unchanged during rHuEPO therapy. Platelet serotonin content and whole blood serotonin were significantly lower in uremic patients relative to healthy volunteers and during rHuEPO treatment they increased significantly. Whole blood serotonin reached normal values. Plasma serotonin, significantly elevated in uremia, did not change during rHuEPO therapy. Serotonin uptake by uremic platelets was significantly impaired and remained unaltered during rHuEPO administration. Serotonin release by uremic platelets was also significantly depressed but a significant improvement was observed in rHuEPO-treated patients. Our data suggest that endothelial injury, TF pathway components and peripheral serotonergic system disturbances may predispose to thromboembolic complications and play a role in the pathogenesis of atherosclerosis in uremic patients, particularly treated with rHuEPO. Increase in TFPI may compensate the increase in TF in these patients.

Topics: Adult; Aged; Arteriosclerosis; Blood Coagulation; Blood Platelets; Case-Control Studies; Endothelium, Vascular; Erythropoietin; Female; Humans; Lipoproteins; Male; Middle Aged; Recombinant Proteins; Renal Dialysis; Serotonin; Thromboplastin; Thrombosis; Uremia

Tissue factor (TF) pathway inhibitor (TFPI) is the major downregulator of the procoagulant activity of the TF-factor VIIa (FVIIa) complex (TF. FVII). The active TF present in the atherosclerotic vessel wall is proposed to be responsible for the major complication of primary atherosclerosis, namely, acute thrombosis after plaque rupture, but our knowledge of the sites of TFPI expression in relation to TF remains fragmentary. The aim of this study was to investigate the expression, localization, and activity of TFPI and its relation to the activity and distribution of TF in the normal and atherosclerotic vessel wall. We applied a novel approach in which serial cross sections of human vascular segments were used to perform a complete set of assays: immunolabeling for TFPI and/or TF, in situ hybridization for the expression of TFPI mRNA, ELISA for the determination of TFPI antigen, and functional assay for the activity of TFPI and TF. In healthy vessels, TFPI protein and mRNA are present in luminal and microvascular endothelial cells (ECs) and in the medial smooth muscle cells (SMCs). In atherosclerotic vessels, TFPI protein and mRNA frequently colocalized with TF in ECs overlying the plaque and in microvessels, as well as in the medial and neointimal SMCs, and in macrophages and T cells in areas surrounding the necrotic core. At the ultrastructural level, immunogold electron microscopy confirmed the localization of TFPI in ECs, macrophages/foam cells, and SMCs. In ECs and SMCs, the gold particles decorated the plasmalemma proper and the caveolae. ELISA on cross sections revealed that atherosclerotic tissues contain more TFPI than do the healthy vessels. TFPI was functionally active against TF. FVIIa-induced coagulation, and its activity was higher in those tissues that display less TF. The largest amount of TFPI and TF were detected in complicated arterial plaques. By immunofluorescence, TFPI colocalized with platelet- and fibrin-rich areas within the organized thrombi. Atherosclerotic vessel sections promote activation of factor X, which is dependent on the presence of TF and enhanced by preincubation of the sections with anti-TFPI IgG. Taken altogether, our results suggest that TFPI is largely expressed in the normal vessel wall and enhanced in the atherosclerotic vessel, in a manner suggesting a significant role of TFPI in the regulation of TF activity.

Topics: Arteriosclerosis; Blood Vessels; Endothelium, Vascular; Factor VII; Factor X; Fluorescent Antibody Technique; Gene Expression; Humans; Immunohistochemistry; In Situ Hybridization; Lipoproteins; Macrophages; Microscopy, Confocal; Microscopy, Immunoelectron; Muscle, Smooth, Vascular; RNA, Messenger; Thromboplastin

Tissue factor located in the atherosclerotic plaque might cause the clinically significant thrombotic events associated with end-stage disease. It might also affect intimal area by increasing matrix accumulation and stimulating smooth muscle cell (SMC) migration and proliferation. To test this hypothesis, we overexpressed tissue factor in a rat model of the human fibrous plaque.. A neointima was generated by seeding tissue factor-overexpressing rat SMCs onto the luminal surface of a balloon-injured syngeneic rat carotid artery. The cells attached and expressed tissue factor over the long term. Mural thrombus accumulation was present at 4 and 7 days and increased neointimal SMC numbers and area by 2-fold at 2 and 4 weeks. Tissue factor overexpression accelerated reendothelialization compared with controls at 2 weeks and 1 month. Tissue factor-overexpressing SMCs exhibited increased migration both in vitro and in vivo. The increased migration by tissue factor-overexpressing SMCs in vitro was not dependent on activation of the coagulation cascade and could be blocked by an inhibitor of tissue factor.. These results suggest that tissue factor plays a direct role in neointimal development by coagulation-dependent and -independent pathways.

Topics: Animals; Arteriosclerosis; Blood Coagulation; Blood Platelets; Blotting, Northern; Carotid Artery Injuries; Catheterization; Cell Movement; Cells, Cultured; Endothelium, Vascular; Factor VIIa; Gene Expression; Male; Microscopy, Electron, Scanning; Muscle, Smooth, Vascular; Rats; Rats, Inbred F344; RNA, Messenger; Thromboplastin; Thrombosis; Tunica Intima

Smoking increases the risk of atherothrombotic events. To determine whether smoking influences plaque thrombogenicity, we examined the effect of cigarette smoking and aspirin use on tissue factor (TF) expression in atherosclerotic plaques.. A total of 23 apoE-/- mice were exposed to cigarette smoke with (n=9) or without (n=14) aspirin treatment. Eleven mice who were exposed to filtered room air served as controls. Aortic root plaques of mice exposed to smoke had higher immunoreactivity for TF (14+/-4% versus 6.4+/-3%; P=0.0005), vascular cell adhesion molecule-1 (15+/-4% versus 5+/-2%; P=0.002), and macrophages (16+/-5% versus 6+/-2%; P=0.002) compared with nonsmoking controls. Aspirin treatment attenuated smoking-induced changes in plaque composition. In human plaques obtained by carotid endarterectomy, TF immunoreactivity (8+/-5% versus 2+/-2%; P=0.0002) and activity (P=0. 03) were higher in the plaques from smokers (n=28) than those from nonsmokers (n=28). Aspirin use was associated with reduced TF expression in smokers (9+/-8% versus 3+/-4%; P=0.0017).. Our results suggest increased plaque TF expression and thrombogenicity as a novel mechanism for the increased risk of atherothrombotic events in smokers. Treatment with aspirin may reduce TF expression.

Topics: Aged; Animals; Aorta; Apolipoproteins E; Arteriosclerosis; Aspirin; Carotid Arteries; Carotid Artery Diseases; Female; Humans; Male; Mice; Mice, Knockout; Middle Aged; Smoking; Thromboplastin; Thrombosis

Topics: Animals; Apoptosis; Arteriosclerosis; Cholesterol, Dietary; Diet, Fat-Restricted; Humans; Thromboplastin

The specific role of apoptosis in human atherosclerosis remains unknown. During apoptotic cell death, phosphatidylserine exposure on the cell surface confers a high tissue-factor (TF)-dependent procoagulant activity.. In this study, we examined the role of apoptotic cell death in the promotion of plaque thrombogenicity. TF expression and its relation to apoptosis was analyzed in 16 human atherosclerotic plaques by the use of immunohistochemical techniques. The presence of shed membrane apoptotic microparticles was analyzed in extracts from 6 human atherosclerotic plaques and 3 underlying arterial walls. The microparticles were captured by annexin V and their amounts estimated with respect to their phospholipid content by use of a prothrombinase assay. The prothrombogenic potential of the microparticles was further assessed by the measurement of total and microparticle-dependent TF activity in the extracts. The cell origin of the microparticles was determined after capture by specific antibodies. We were able to detect marked TF expression in the plaques in close proximity to apoptotic cells and debris, suggesting a potential interaction between TF and the apoptotic cell surfaces. High levels of shed membrane apoptotic microparticles were detected in extracts from atherosclerotic plaques but not in the underlying arterial walls (29.5+/-3.7 nmol/L phosphatidylserine equivalent versus 1.3+/-0.4 nmol/L, respectively, P<0.02). The microparticles were mainly of monocytic and lymphocytic origin and retained 97+/-2% of total TF activity, indicating a direct causal relationship between shed membrane microparticles and procoagulant activity of plaque extracts.. These results indicate that shed membrane microparticles with procoagulant potential are produced in human atherosclerotic plaques. Apoptosis could be a critical determinant of plaque thrombogenicity after plaque rupture.

Topics: Acute Disease; Apoptosis; Arteriosclerosis; Carotid Arteries; Cell Membrane; Endothelium, Vascular; Humans; In Situ Nick-End Labeling; Microspheres; Phosphatidylserines; Thromboplastin; Thrombosis

Plaque disruption and subsequent thrombus formation lead to acute coronary syndromes and progression of atherosclerotic disease. Tissue factor (TF) appears to mediate plaque thrombogenicity. Tissue factor pathway inhibitor (TFPI) is the major physiological inhibitor of TF. This study analyzes the role of TF on thrombogenicity of disrupted human atherosclerotic plaques and the therapeutic possibilities of its specific inhibition.. Human atherosclerotic and normal arterial segments were exposed to heparinized blood at flow conditions modeling medium-grade coronary stenosis in the Badimon perfusion chamber. The antithrombotic effects of the specific inhibition of plaque TF was assessed by reduction in the deposition of radiolabeled platelets and fibrin(ogen) and immunohistochemical analysis of perfused arteries. TF activity was inhibited by both recombinant TFPI and a polyclonal antibody against human TF. Human lipid-rich plaques were more thrombogenic than less advanced atherosclerotic plaques. Specific inhibition of TF activity reduced plaque thrombogenicity, inhibiting both platelet and fibrin(ogen) deposition (580 versus 194 plateletsx10(6)/cm2; P<0.01, and 652 versus 172x10(12) molecules of Fg/cm2; P<0.05, respectively) and thrombosis (immunohistochemistry).. This study documents the key role of TF activity in acute arterial thrombosis after atherosclerotic plaque disruption and provides evidence of the benefit of blocking plaque TF activity. Therefore the inhibition of the TF pathway opens a new therapeutic strategy in the prevention of acute coronary thrombosis after plaque disruption.

Topics: Animals; Arteriosclerosis; Blood Platelets; Cadaver; Humans; Immunohistochemistry; Lipid Metabolism; Lipoproteins; Middle Aged; Perfusion; Recombinant Proteins; Reference Values; Swine; Thromboplastin; Thrombosis

This study investigated whether spontaneous lipid enrichment of human macrophages affects their thrombogenic potential as measured by increased production of tissue factor (TF) and plasminogen activation inhibitor types 1 and 2 (PAI-1 and PAI-2). Macrophages were obtained following a 7-day culture period of monocytes, isolated from the same donor, in autologous serum (HS) or in fetal bovine serum (FBS). Those cultured in HS underwent marked lipid accumulation relative to those cultured in FBS that was accompanied by increased production of TF and PAI-1, but not of PAI-2, and decreased production of interleukin-1beta. They also contained more arachidonic and linoleic acid and lower amounts of n-3 polyunsaturated fatty acids, particularly docosahexaenoic acid (22: 6). These data indicate that the transformation of macrophages into foam cells results in an increase in their thrombogenic and antifibrinolytic potential and provide a possible explanation of the thrombotic sequelae frequently consequent on plaque fissuring and disruption.

Topics: Arteriosclerosis; Cell Adhesion; Cells, Cultured; Fetal Blood; Foam Cells; Humans; Interleukin-1; Lipid Metabolism; Macrophage Activation; Macrophages; Monocytes; Plasminogen Activator Inhibitor 1; Thromboplastin

Tissue factor activity (TFa) is a major activator of the coagulation cascade and may play a role in atheroma-induced thrombosis. Monocyte-macrophages (MO-MF) generate considerable quantities of TFa when stimulated by a variety of inducers. To test the hypothesis that MO could be induced by atheromatous plaque to generate TFa, plaque extracts obtained from patients with obstructive atheromatous disease were used. These extracts were also assayed for constitutive TFa. The constitutive activity was variable from extract to extract but could be very high, up to 250 U TFa. The TFa induced in MO could be also very high, up to 200 U (i.e. 1/5 of the TFa of full strength rabbit brain thromboplastin). These findings point to a major role for MO-MF TFa in the induction or thrombosis by atheromatous plaque.

Topics: Animals; Arteriosclerosis; Humans; Monocytes; Rabbits; Thromboplastin; Thrombosis

The mechanisms by which lipid lowering reduces the incidence of acute thrombotic complications of coronary atheroma in clinical trials remains unknown. Tissue factor (TF) overexpressed in atheroma may accelerate thrombus formation at the sites of plaque disruption. A cell surface cytokine CD40 ligand (CD40L) enhances TF expression in vitro.. To test the hypothesis that lipid lowering reduces TF expression and activity, we produced atheroma in rabbit aortas by balloon injury and cholesterol feeding for 4 months (Baseline group, n=15), followed by either a chow diet (Low group, n=10) or a continued high-cholesterol diet for 16 months (High group, n=5). Immunolocalization of TF, CD40L, and its receptor CD40 was quantified by computer-assisted color image analysis. Macrophages in atheroma of the Baseline and High groups strongly expressed TF. Intimal smooth muscle cells and endothelial cells also contained immunoreactive TF. Regions of expression of CD40L and CD40 colocalized with TF. Protein expression of TF diminished substantially in the Low group in association with reduced expression of CD40L and CD40. In situ binding of TF to factors VIIa and X, detected by digoxigenin-labeled factors VIIa and X, colocalized with TF protein in atheroma and decreased after lipid lowering. We also determined reduced TF biological activity in the Low group by use of a chromogenic assay. The level of TF mRNA detected by reverse transcription-polymerase chain reaction also decreased after lipid lowering.. These results suggest decreased expression and activity of TF as a novel mechanism of reduced incidence of thrombotic complications of atherosclerosis by lipid lowering.

Topics: Animals; Arteriosclerosis; CD40 Antigens; Cholesterol, Dietary; Factor VIIa; Factor X; Lipids; Male; Rabbits; RNA, Messenger; Thromboplastin

Recent reports link C. pneumoniae infection of arteriosclerotic lesions to the precipitation of acute coronary syndromes, which also feature tissue factor and plasminogen activator inhibitor 1 (PAI-1) overexpression. We investigated whether or not C. pneumoniae can induce thrombogenicity by upregulation of procoagulant proteins.. Human vascular endothelial and smooth muscle cells were infected with a strain of C. pneumoniae isolated from an arteriosclerotic coronary artery. Tissue factor, PAI-1, and interleukin-6 expression was increased in infected cells. Concomitantly, NF-kappaB was activated and IkappaBalpha degraded. p50/p65 heterodimers were identified as the components responsible for the NF-kappaB activity.. These data provide evidence that C. pneumoniae infection can induce procoagulant protein and proinflammatory cytokine expression. This cellular response is accompanied by activation of NF-kappaB. Our results demonstrate how C. pneumoniae infection may initiate acute coronary syndromes.

Topics: Arteriosclerosis; Blood Vessels; Chlamydia; Chlamydophila pneumoniae; Endothelium, Vascular; Humans; Muscle, Smooth, Vascular; NF-kappa B; Plasminogen Activator Inhibitor 1; Risk Factors; Thromboplastin; Time Factors

There is evidence that tissue factor (TF) is a major contributor to the thrombogenicity of a ruptured atherosclerotic plaque. Nitric oxide (NO) has antiatherogenic and antithrombotic properties. We investigated whether L-arginine (L-arg), the endogenous precursor of NO, might affect the ability of monocytes to produce TF.. We studied TF expression in 18 rabbits with atherosclerosis induced by bilateral iliac damage and 10 weeks of a 2% cholesterol diet. Six weeks after the initiation of the diet, an angioplasty was performed. After angioplasty, the surviving rabbits (n=15) were randomized to receive L-arg (2.25%) supplementation in drinking water (L-arg group, n=8) or no treatment (untreated group, n=7). TF expression was evaluated in mononuclear cells from arterial blood in the presence and absence of endotoxin stimulation. Monocyte TF expression, as assessed with an amidolytic assay, did not differ significantly before or after the induction of atherosclerotic lesions (87+/-15 versus 70+/-12 mU of TF/1000 monocytes, P=NS). Endotoxin-stimulated TF activity increased significantly 4 weeks after angioplasty (138+/-22 versus 70+/-12 mU of TF/1000 monocytes, P=0.02). This increase was blunted by L-arg (43+/-16 mU of TF/1000 monocytes, P=0.01).. This study demonstrates that angioplasty-induced plaque rupture is associated with a marked increase in monocyte TF response that is blunted by the oral administration of L-arg. This suggests that the documented antithrombotic properties of NO may be related in part to an inhibitory effect on monocyte TF response.

Topics: Angioplasty, Balloon; Animals; Arginine; Arteriosclerosis; Diet; Hypercholesterolemia; Leukocyte Count; Lipids; Male; Monocytes; Platelet Count; Rabbits; Thromboplastin

To assess the representativity of small vascular samples with regard to the expression of six important factors in atherosclerotic vessels.. Circumferential frozen sections of iliac and femoral arteries (n = 9) from patients undergoing reconstructive bypass surgery.. Immunohistochemistry with antibodies against macrophages (CD68), tumour necrosis factor alpha, tissue factor, tissue plasminogen activator, urokinase plasminogen activator and plasminogen activator inhibitor type 1. The distribution of these antigens was characterised by computer assisted image analysis. Antigen positive area in randomly chosen samples of varying size was compared with antigen positive area in the whole vessel transections.. Marked heterogeneity was found with respect to the expression of these factors in atherosclerotic vessels. The representativity of samples was highly dependent on the size of the samples. PAI-1 was more evenly expressed compared to the other antigens.. Estimates of the expression of these factors based on small samples from atherosclerotic arteries are unreliable.

Topics: Antigens, CD; Antigens, Differentiation, Myelomonocytic; Arteriosclerosis; Femoral Artery; Fibrinolytic Agents; Humans; Iliac Artery; Immunohistochemistry; Macrophages; Plasminogen Activator Inhibitor 1; Plasminogen Activators; Thromboplastin; Tumor Necrosis Factor-alpha

The thrombogenicity of a disrupted atherosclerotic lesion is dependent on the nature and extent of the plaque components exposed to flowing blood together with local rheology and a variety of systemic factors. We previously reported on the different thrombogenicity of the various types of human atherosclerotic lesions when exposed to flowing blood in a well-characterized perfusion system. This study examines the role of tissue factor in the thrombogenicity of different types of atherosclerotic plaques and their components.. Fifty human arterial segments (5 foam cell-rich, 9 collagen-rich, and 10 lipid-rich atherosclerotic lesions and 26 normal, nonatherosclerotic segments) were exposed to heparinized blood at high shear rate conditions in the Badimon perfusion chamber. The thrombogenicity of the arterial specimens was assessed by 111In-labeled platelets. After perfusion, specimens were stained for tissue factor by use of an in situ binding assay for factor VIIa. Tissue factor in specimens was semiquantitatively assessed on a scale of 0 to 3. Platelet deposition on the lipid-rich atheromatous core was significantly higher than on all other substrates (P = .0002). The lipid-rich core also exhibited the most intense tissue factor staining (3 +/- 0.1 arbitrary units) compared with other arterial components. Comparison of all specimens showed a positive correlation between quantitative platelet deposition and tissue factor staining score (r = .35, P < .01).. Our results show that tissue factor is present in lipid-rich human atherosclerotic plaques and suggest that it is an important determinant of the thrombogenicity of human atherosclerotic lesions after spontaneous or mechanical plaque disruption.

Topics: Animals; Aorta; Arteriosclerosis; Blood Physiological Phenomena; Blood Platelets; Digoxigenin; Factor VIIa; Humans; Recombinant Proteins; Swine; Thromboplastin; Thrombosis

We examined the effect of fluvastatin, the first entirely synthetic 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor that is structurally different from other vastatins, on tissue factor (TF) expression in human macrophages spontaneously differentiated in culture from blood monocytes. Fluvastatin decreased TF activity in a dose-dependent manner (1 to 5 mumol/L) in both unstimulated and lipopolysaccharide-stimulated macrophages, and this reduction paralleled the decrease in immunologically recognized TF protein. The same results were obtained with another lipophilic vastatin, simvastatin, but not with hydrophilic pravastatin. The reduction in TF expression was also observed in macrophages enriched in cholesterol after exposure to 50 micrograms/mL acetylated low density lipoprotein. The inhibitory effect of fluvastatin on TF activity and antigen was fully reversible by coincubation with 100 mumol/L mevalonate or 10 mumol/L all-trans-geranylgeraniol but not with dolichol, farnesol, or geraniol. Suppression of TF antigen and activity was accompanied by a diminution in TF mRNA levels, which was completely prevented by mevalonate. Furthermore, fluvastatin impaired bacterial lipopolysaccharide-induced binding of c-Rel/p65 heterodimers to a kappa B site in the TF promoter, indicating that this drug influences induction of the TF gene. We conclude that lipophilic vastatins inhibit TF expression in macrophages, and because this effect is prevented by mevalonate and geranylgeraniol, a geranylgeranylated protein plays a crucial role in the regulation of TF biosynthesis. The suppression of TF in macrophages by vastatins indicates a potential mechanism by which these drugs interfere with the formation and progression of atherosclerotic plaque as well as thrombotic events in hyperlipidemic patients.

Topics: Arteriosclerosis; Blood Cells; Cells, Cultured; Cholesterol; Enzyme Inhibitors; Fatty Acids, Monounsaturated; Fluvastatin; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Indoles; Lipopolysaccharides; Macrophages; Mevalonic Acid; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-rel; RNA, Messenger; Thromboplastin; Thrombosis

Plaque disruption with thrombosis commonly causes the acute coronary syndromes. Macrophages, abundant at sites of plaque rupture, release proteinases that weaken plaques and express tissue factor (TF), which initiates thrombosis. The signals that induce expression of these macrophage functions, particularly TF, remain obscure. Recent studies have localized the receptor CD40 and its ligand in human atheroma. This study tested the hypothesis that ligation of CD40 can activate key mononuclear phagocyte functions related to clinical manifestations of atheroma.. Stimulation of human monocytes/macrophages through CD40 by either membranes from activated T cells or recombinant CD40L (rCD40L) induced expression of interstitial collagenase, stromelysin, and TF protein and activity. In contrast, the soluble cytokines interleukin-1 or tumor necrosis factor-alpha did not induce or weakly induced TF expression. Neutralization with anti-CD40L antibody markedly inhibited these actions of both T-cell membranes and rCD40L.. By inducing the expression of matrix-degrading proteinases and of TF procoagulant, CD40 signaling may contribute to the triggering of acute coronary events.

Topics: Arteriosclerosis; Blotting, Western; CD40 Antigens; Collagenases; Flow Cytometry; Humans; Ligands; Macrophage Activation; Macrophages; Matrix Metalloproteinase 3; Monocytes; Signal Transduction; Thromboplastin

Tissue factor (TF) is a transmembrane protein that serves as the major initiator of the blood coagulation cascade. The overexpression of TF antigen and mRNA has previously been reported in advanced atherosclerotic lesions. Recently TF procoagulant activity has also been identified in these lesions. However, localization and activity of TF in various stages of atherosclerosis have not yet been reported. We studied TF localization and its activity in three stages of the human atherosclerotic lesions (diffuse intimal thickening, fatty streak, and atheromatous plaque). The thoracic aortas were obtained from 23 autopsy cases and were examined immunohistochemically using an anti-human TF polyclonal antibody and biotinylated factor VIIa (FVIIa) as a probe to test the FVIIa-binding ability of TF. In addition, the TF-mediated activation of factor X (FX) was quantitatively assessed using a chromogenic assay. In lesions of the diffuse intimal thickening and the fatty streak, almost all of intimal smooth muscle cells (SMCs), macrophages, and endothelial cells were positive for TF. In the atheromatous plaques, TF antigen was detected extensively in the extracellular matrix as well as in the intimal cells. TF in all stages of atherosclerotic lesions had the ability to bind biotinylated FVIIa. TF activity was detected in each lesion and was more prominent in fatty streaks and atheromatous plaques than in the diffuse intimal thickening. These results indicate that active TF is expressed in the early stage of atherosclerotic lesions as well as in the advanced stage, and it contributes to the thrombotic property of human atherosclerotic lesions.

Topics: Adolescent; Adult; Aged; Antigens; Aorta, Thoracic; Arteriosclerosis; Biotin; Chromogenic Compounds; Factor VIIa; Factor X; Female; Humans; Immunohistochemistry; Male; Middle Aged; Protein Binding; Thromboplastin

Monocyte chemoattractant protein-1 (MCP-1) is a C-C chemokine thought to play a major role in recruiting monocytes to the atherosclerotic plaque. Tissue factor (TF), the initiator of coagulation, is found in the atherosclerotic plaque, macrophages, and human aortic smooth muscle cells (SMC). The exposure of TF during plaque rupture likely induces acute thrombosis, leading to myocardial infarction and stroke. This report demonstrates that MCP-1 induces the accumulation of TF mRNA and protein in SMC and in THP-1 myelomonocytic leukemia cells. MCP-1 also induces TF activity on the surface of human SMC. The induction of TF by MCP-1 in SMC is inhibited by pertussis toxin, suggesting that the SMC MCP-1 receptor is coupled to a Gi-protein. Chelation of intracellular calcium and inhibition of protein kinase C block the induction of TF by MCP-1, suggesting that in SMC it is mediated by activation of phospholipase C. SMC bind MCP-1 with a Kd similar to that previously reported for macrophages. However, mRNA encoding the macrophage MCP-1 receptors, CCR2A and B, is not present in SMC, indicating that they possess a distinct MCP-1 receptor. These data suggest that in addition to being a chemoattractant, MCP-1 may have a procoagulant function and raise the possibility of an autocrine pathway in which MCP-1, secreted by SMC and macrophages, induces TF activity in these same cells.

Topics: Animals; Arteriosclerosis; Calcium; Cell Line; Chemokine CCL2; Enzyme Activation; Humans; Monocytes; Muscle, Smooth, Vascular; Protein Kinase C; Rabbits; RNA, Messenger; Signal Transduction; Thromboplastin; Thrombosis

Tissue factor pathway inhibitor (TFPI) is a potent inhibitor of tissue factor (TF) -initiated coagulation and may play a role in regulating coagulation in atherosclerotic plaques. The expression of TFPI protein and mRNA was examined by immunohistology and in situ hybridization in normal human and rabbit arteries, in human carotid arteries with advanced atherosclerosis, and in atherosclerotic aortas from cholesterol-fed rabbits. In normal human and rabbit arteries, TFPI protein and mRNA were detected in the adventitial layer but were undetectable in the luminal endothelium. In the medial smooth muscle layer of rabbits, weak expression of TFPI mRNA, but not protein, was detected; in that of humans, neither TFPI mRNA nor protein was detectable. In atherosclerotic arteries, TFPI protein and mRNA were detected in three of six internal carotid plaques from patients undergoing endarterectomy, and mRNA alone was detected in one further specimen. TFPI protein was found in areas of the plaque where TF was abundant and colocalized with macrophages, suggesting that these cells are responsible for TFPI synthesis. TFPI protein and mRNA were also detected in fatty-streak lesions in 18 of 19 rabbits fed a high-cholesterol diet for periods between 4 and 16 weeks. In these macrophage-rich lesions, expression of TFPI protein and mRNA was most intense at the base of the plaques. These studies suggest that TFPI is expressed in the adventitial layer of large arteries and that in atherosclerotic vessels, TFPI is expressed by macrophages in focal areas throughout the plaque. Local production of TFPI may regulate procoagulant activity and thrombotic events within atherosclerotic plaques.

Topics: Aged; Aged, 80 and over; Animals; Aorta; Arteries; Arteriosclerosis; Endothelium, Vascular; Female; Fibrinolytic Agents; Humans; Immunohistochemistry; In Situ Hybridization; Lipoproteins; Male; Microcirculation; Middle Aged; Rabbits; RNA, Messenger; Thromboplastin

Tissue factor (TF) plays a key role as a primary initiator on the extrinsic coagulation cascade. Recently, upregulation of TF has been reported in human atherosclerotic lesions. We investigated the effects of TF on migration and proliferation of cultured smooth muscle cells (SMCs) from rabbit aortas. We tested three kinds of recombinant human TF (L-TF: the full length of TF with relipidation, NL-TF: the full length of TF without relipidation, and S-TF: a soluble form of TF1-219). Only L-TF had coagulant activity. All kinds of TF showed the chemotactic migration activity for SMCs. The migration ability of TFs was comparable to those of platelet-derived growth factor (PDGF)-BB and basic fibroblast-growth factor (bFGF), and was inhibited by anti-TF polyclonal and monoclonal antibodies. On the other hand, none of the forms of TF induced SMC proliferation. These results indicate that TF is not only a coagulation factor but also a strong chemotactic factor for vascular SMCs, and suggest that TF could play an important role in atherogenesis as well as in hemostasis and thrombosis.

Topics: Animals; Aorta; Arteriosclerosis; Cell Division; Cell Movement; Cells, Cultured; Male; Muscle, Smooth, Vascular; Rabbits; Thromboplastin

We examined the immunohistochemical distribution of tissue factor (TF), apolipoprotein (a) (apo(a)) in atherosclerotic intimas of human thoracic aortas obtained from 51 autopsies in order to analyze the mechanism of fibrinogen-fibrin transition as a part of thrombogenic properties of atherosclerotic intimas. TF was overexpressed mainly by macrophages in both fatty streaks and more advanced lesions, while it was also scatteringly deposited in the matrix of advanced lesions, especially in the atheromatous gruel. TF-positive macrophages were frequently intermingled at the base of fibrin thrombi formed on the eroded intimas. On the other hand, apo(a) was localized in the stroma and within some macrophages, and also in the mural thrombi. Fibrinogen and fibrin were more frequently detected in the matrix of advanced lesions than in that of early lesions. Fibrin was occasionally co-located with cell- and matrix-associated TF and apo(a) deposited in matrix. These findings suggest that the overexpressed TF in the atherosclerotic intima plays a critical role in the initiation of fibrin formation. This could result from either fibrinogen permeating into the intima or from rupture of the fibrous cap overlying atheromas. Apo(a) deposited in the atherosclerotic intima may also participate in the persistent deposition of fibrin.

Topics: Adult; Aged; Aged, 80 and over; Aorta, Thoracic; Apolipoproteins; Apoprotein(a); Arteriosclerosis; Female; Fibrin; Fibrinogen; Humans; Immunohistochemistry; Lipoprotein(a); Male; Middle Aged; Thromboplastin

Tissue factor (TF) is an initiation cofactor of the extrinsic pathway of coagulation. Although the overexpression of TF antigen and mRNA have been previously demonstrated in atherosclerotic lesions using both immunohistochemical and in situ hybridization techniques, it still remains unclear as to whether TF activity is overexpressed in atherosclerotic plaque in vivo. In thoracic aortas obtained from cholesterol-fed rabbits for 10-20 weeks, the TF-mediated activation of factor X was quantitatively assessed on the intimal surface of the aortas ex vivo using a chromogenic substrate S-2222 and the findings were then compared with the immunohistochemical distribution of TF antigen. Non-atherosclerotic intimas showed only a weak amount of TF activity, while the adventitia contained a significantly high amount of activity. In the atherosclerotic intimas where TF antigen was overexpressed by foamy and non-foamy macrophages and smooth muscle cells but not by endothelial cells, TF activity was apparently enhanced to a level similar to that in the adventitia. Scanning electron microscopy revealed a perturbation of the intimal surface of the atherosclerotic aorta. These findings suggest that TF activity is apparently enhanced in subendothelial atherosclerotic lesions and, therefore, endothelial denudation, which results in the exposure of active TF to flowing blood, leads to thrombosis and its sequelae in atherosclerotic lesions.

Topics: Animals; Aorta; Arteriosclerosis; Cholesterol, Dietary; Diet, Atherogenic; Immunohistochemistry; Male; Microscopy, Electron, Scanning; Rabbits; Thromboplastin; Tunica Intima

Recent observations suggest that thrombosis in vivo is initiated via the tissue factor (TF) pathway. The TF activity of human coronary atheroma has not been reported.. Directional coronary atherectomy (DCA) specimens from 63 lesions were analyzed with the use of a quantitative TF-specific activity assay. The median content of TF was 10 ng/g plaque (95% CI, 6 to 13 ng/g; range, 0 to 47 ng/g). After homogenization of the specimens, TF activity was detected in 28 of 31 lesions (90%). With a polyclonal anti-human TF antibody, the use of immunohistochemistry detected TF antigen in 43 of 50 lesions (86%); TF antigen was expressed in cellular and acellular areas of the plaque. Histologically defined thrombus was present in 19 of the 43 lesions with detectable TF antigen and in none of the 7 lesions without detectable TF antigen (19 of 43 versus 0 of 7; P < .02). TF antigen was undetectable with immunohistochemistry in 4 of 13 restenotic lesions (31%) and in 3 of 37 de novo lesions (8%) (P < .05).. TF contributes to the procoagulant activity of most atherosclerotic lesions treated with DCA. The association of immunohistochemically detectable TF with plaque thrombus suggests that TF plays a role in coronary thrombosis. Diminished TF expression in restenotic lesions may in part account for the lower complication rate that has been associated with DCA of restenotic versus de novo lesions. Inhibition of TF may represent a therapeutic goal for the prevention of thrombotic complications associated with percutaneous coronary interventions.

Topics: Antigens; Arteriosclerosis; Biological Availability; Coronary Artery Disease; Factor Xa; Humans; Immunohistochemistry; Staining and Labeling; Thromboplastin; Time Factors

Monocytes induced to express tissue factor (TF), the initiator of the clotting cascade, might play an important role in the pathogenesis of atherosclerosis. We have investigated the TF-inducing capacity of two factors thought to be involved in atherogenesis, i.e. the platelet derived growth factor-BB (PDGF-BB) and monocyte chemotactic protein-1 (MCP-1), a member of the chemokine superfamily. PDGF-BB and MCP-1 are potent chemotactic and activating factors for human blood monocytes. alpha-thrombin which is known to induce TF in endothelial cells and that recently has been shown to induce secretion of MCP-1 from endothelial cells and monocytes was also studied. PDGF-BB induced a dose-dependent expression of TF-antigen in monocytes with maximal response at 20-50 ng/mL. At higher concentrations the expression was reduced. No synergistic effect between PDGF-BB and LPS was seen. MCP-1 also induced a dose-dependent TF-expression with maximal response at 50 ng/mL. In contrast to these results thrombin did not. MCP-1 had a slight, but not significant, priming effect on LPS-induced TF expression. These data show that PDGF-BB and MCP-1 are potent inducers of TF in human peripheral blood monocytes. We suggest that this TF-induction might be an important link between hemostasis and inflammation.

Topics: Arteriosclerosis; Becaplermin; Chemokine CCL2; Gene Expression Regulation; Humans; Lipopolysaccharides; Lymphocyte Activation; Lymphocytes; Monocytes; Platelet-Derived Growth Factor; Proto-Oncogene Proteins c-sis; Stimulation, Chemical; Thrombin; Thromboplastin

The mechanism responsible for the thrombotic complications of atherosclerotic plaques is not well understood. Although a role for tissue factor (TF) has been hypothesized, there are scant data on the presence, location, quantity, and activity of TF in atherosclerotic plaques. The purpose of this study was to show the localization of TF in human atherosclerotic plaques. Digoxigenin-labeled factors VIIa and X were used to demonstrate their specific binding sites in formalin-fixed, paraffin-embedded human arteries by incubation of sections with the labeled factor and localization of TF:factor(s) complexes by immunohistochemical staining for digoxigenin. In sections of atherosclerotic plaques, diffuse staining was most intense in the relatively acellular, lipid-rich core but was also present intracellularly in macrophages and smooth muscle cells and, to a lesser extent, in the relatively acellular fibrous tissue of the plaque. Endothelial cells overlying plaques and occasional medial smooth muscle cells stained positively as well. The adventitia routinely stained for TF in both normal and diseased artery segments. Staining for labeled factor VIIa was blocked when sections were preincubated with a 10-fold excess of unlabeled factor VIIa or with a polyclonal antihuman TF antibody. Binding of labeled factors VIIa and X was Ca(2+)-dependent. In conclusion, binding of digoxigenin-labeled factors VIIa and X shows that the lipid rich core of atherosclerotic plaques contains high levels of extracellular TF. This location may be responsible for the rapid initiation of thrombosis when lipid rich atherosclerotic plaques rupture and the core contents are exposed to flowing blood.

Topics: Animals; Arteries; Arteriosclerosis; Coronary Vessels; Digoxigenin; Factor VIIa; Factor X; Humans; Immunohistochemistry; Protein Binding; Skin; Staining and Labeling; Thromboplastin

TF protein was overexpressed by macrophages and smooth muscle cells and deposited in the extracellular matrix of atheroclerotic intimas. TF activity was also enhanced in the atherosclerotic intima, probably resulting in either thrombus formation or intimal fibrin deposition after the exposure of flowing blood and imbibed fibrinogen to TF in atherosclerotic lesions. These findings further support the hypothesis that the coagulation and fibrinolysis systems can play an essential role in the initiation and progression of atherosclerosis, and the clinical implications of this phenomenon may thus contribute to future investigations in the prevention and treatment of atherosclerotic diseases.

Topics: Adult; Aged; Animals; Aorta; Apolipoproteins A; Arteriosclerosis; Enzyme Activation; Factor X; Fibrin; Fibrinogen; Humans; Immunohistochemistry; Middle Aged; Rabbits; Thromboplastin

The expression of tissue factor (TF) antigen by circulating monocytes, cultured macrophages, and macrophages associated with atherosclerotic lesions was ultrastructurally analysed using immunogold labeling. A subpopulation of macrophages associated with the intimal surface overlying lesions had a significant TF expression. Macrophages and macrophage foam cells that projected from the intima into the arterial lumen also expressed a high level of TF (14-fold increase over control). In contrast, circulating monocytes and macrophages in culture did not express TF above background control levels. This TF expression by macrophages in vivo but not by macrophages cultured from either normal or hypercholesterolemic animals suggests that monocyte activation and macrophage transition, as measured by TF expression, is lesion-dependent and not stimulated solely by intimal attachment, surface migration, or hypercholesterolemia. These results further suggest that macrophages and foam cells associated with early lesions of atherosclerosis can initiate fibrin formation, which could contribute to lesion complications and transition to a fibromuscular stage.

Topics: Animals; Arteriosclerosis; Cell Line; Cholesterol; Columbidae; Foam Cells; Immunohistochemistry; Macrophages; Microscopy, Electron; Microscopy, Electron, Scanning; Monocytes; Thromboplastin

We have previously demonstrated that human aortic endothelium exhibits morphologic heterogeneity in situ, and this heterogeneity can be reproduced in culture. In this study, we have compared prothrombotic properties of cultured endothelial cells (EC) from areas of human aorta at high risk for atherosclerosis (HP-EC) with EC from areas at low risk (LP-EC). Using paired cultures from the same donors, we have found that the expression of cell surface thrombomodulin (TM)--as measured by the ability to generate activated protein C (APC) from protein C in the presence of thrombin--is relatively reduced on HP-EC compared to LP-EC (respectively, 4.98 +/- 4.43 vs. 5.83 +/- 4.37 pM APC/min/cm2; p = .03, n = 12). Furthermore, HP-EC more efficiently assemble the prothrombinase complex on their cellular surface, resulting in an increased rate of thrombin generation from prothrombin (9.81 +/- 3.10 (HP-EC) vs. 7.96 +/- 3.20 nM thrombin/min/cm2 (LP-EC); p less than .03, n = 7). The combination of reduced TM expression and increased prothrombinase complex assembly on HP-EC suggests a prothrombotic phenotype in these cells. These findings may be important in the pathogenesis of thrombosis associated with atherosclerotic plaques.

Topics: Aorta; Arteriosclerosis; Cells, Cultured; Endothelium, Vascular; Humans; Immunohistochemistry; Phenotype; Protein C; Receptors, Cell Surface; Receptors, Thrombin; Silver Staining; Thrombin; Thromboplastin; Thrombosis

Increasing evidence suggests that the formation of oxidized low-density lipoprotein (Ox-LDL) in vivo is associated with the development of atherosclerotic vascular disease. We investigated the effects of Ox-LDL on two vascular endothelial cell coagulant properties, tissue factor expression, and protein C activation. The Ox-LDL increased human arterial and venous endothelial cell tissue factor activity, with 100 micrograms/ml of Ox-LDL increasing factor activity fourfold. Native LDL modified by incubation with cultured human arterial and venous endothelial cells also induced endothelial cell tissue factor activity. This modification was blocked by coincubation with the antioxidants, probucol or ascorbic acid. It was determined, based on inhibition by known scavenger receptor antagonists (fucoidin, dextran sulfate), that binding of Ox-LDL via the acetyl LDL (scavenger) receptor was partially responsible for the increase in tissue factor expression. Whereas endothelial cell tissue factor expression was increased by incubation with Ox-LDL, protein C activation was reduced approximately 80% by incubating cultured endothelial cells with Ox-LDL. The effect of Ox-LDL on protein C activation was not inhibited by antagonists to the scavenger receptor. These data indicating that an atherogenic lipoprotein can regulate key vascular coagulant activities provide an additional link between vascular disease and thrombosis.

Topics: Anticoagulants; Arteriosclerosis; Ascorbic Acid; Cells, Cultured; Dextran Sulfate; Dose-Response Relationship, Drug; Endothelium, Vascular; Factor VII; Factor X; Humans; In Vitro Techniques; Lipoproteins, LDL; Oxidation-Reduction; Polysaccharides; Probucol; Protein C; Thromboplastin

Tissue factor (TF)-producing cells were identified in normal human vessels and atherosclerotic plaques by in situ hybridization and immunohistochemistry using a specific riboprobe for TF mRNA and a polyclonal antibody directed against human TF protein. TF mRNA and protein were absent from endothelial cells lining normal internal mammary artery and saphenous vein samples. In normal vessels TF was found to be synthesized in scattered cells present in the tunica media as well as fibroblast-like adventitial cells surrounding vessels. Atherosclerotic plaques contained many cells synthesizing TF mRNA and protein. Macrophages present as foam cells and monocytes adjacent to the cholesterol clefts contained TF mRNA and protein, as did mesenchymal-appearing intimal cells. Significant TF protein staining was found deposited in the extracellular matrix surrounding mRNA-positive cells adjacent to the cholesterol clefts and within the necrotic cores. These results suggest that deposition of TF protein in the matrix of the necrotic core of the atherosclerotic plaque may contribute to the hyperthrombotic state of human atherosclerotic vessels.

Topics: Arteries; Arteriosclerosis; Endothelium, Vascular; Fibroblasts; Humans; Immunohistochemistry; Nucleic Acid Hybridization; Thromboplastin; Veins

A remarkable variation in monocyte activation among individuals was observed when blood from different people was incubated with lipopolysaccharides. To elucidate this phenomenon, we studied intracellular signals associated with monocyte activation. This was done by measuring induced thromboplastin synthesis. An inhibitor of phospholipase A2 blocked the lipopolysaccharide induced synthesis of thromboplastin. Thus, release of arachidonic acid (20: 4) seemed to be necessary to activate the monocytes. Nordihydroguaiaretic acid, a lipoxygenase inhibitor, had no effect on the monocyte activation in subjects with a low response to lipopolysaccharides (low responders); this contrasted with nearly 80% inhibition in individuals with very sensitive cells (high responders). Taking aspirin raised monocyte activation by an average of 50%, this was caused by the effect of aspirin on the platelets. Platelets enhanced the lipopolysaccharide activation of monocytes 2-3 fold. The high response phenomenon was partially due to platelets. When platelets in the blood of high responders were substituted with platelets from low responders, the monocyte activation fell by up to 70%. Fatty acids seemed to play a central role in the activation of monocytes. Intake of cod liver resulted in significant reduction of induced thromboplastin synthesis. It is suggested that those who are high responders may be more susceptible to developing atherosclerosis.

Topics: Arteriosclerosis; Blood Platelets; Dietary Fats; Fatty Acids; Humans; Monocytes; Thromboplastin; Thromboxane B2

Atherosclerotic lesions have been reported to contain herpes simplex virus 1 (HSV-1) genomic material. This, and other previous evidence, suggests that latent viral infection may be an atherogenic trigger. Moreover, active HSV-1 lesions manifest marked fibrin deposition in microvessels. In this report we show that very early infection of human endothelial cells with HSV-1 appears to alter surface conformation as detected by merocyanine 540 staining. Concomitantly, the efficiency of prothrombinase complex assembly increases, resulting in a 2- to 3-fold accelerated rate of thrombin generation on the cell surface. Increased thrombin generation is probably doubly procoagulant, since we also demonstrate that thrombin-induced platelet accumulation on HSV-infected endothelium (50.7 +/- 9.3%) is increased compared to uninfected endothelium (9.5 +/- 2.1%; P less than 0.002). Associated with HSV infection, prostacyclin secretion in response to thrombin is diminished by a factor of 20, probably explaining the enhanced platelet attachment. We conclude that HSV infection shifts endothelial cell properties from anticoagulant to procoagulant, both by promoting prothrombinase complex formation and function and by increasing platelet binding, well before cell disruption takes place. Virus-induced changes in the endothelial plasma membrane and diminished prostacyclin secretion are suggested as the pathways for this pathophysiologic mechanism, which may be germane to atherosclerotic thrombosis as well as HSV-mediated tissue necrosis.

Topics: Arteriosclerosis; Blood Platelets; Cell Adhesion; Cell Aggregation; Endothelium; Herpes Simplex; Humans; Indomethacin; Pyrimidinones; Simplexvirus; Thrombin; Thromboplastin

Topics: Animals; Apolipoprotein A-I; Apolipoproteins; Arteriosclerosis; Blood Coagulation; Brain; Cattle; Factor VII; Factor VIIa; Factor X; Female; Humans; In Vitro Techniques; Lipoproteins, HDL; Placenta; Pregnancy; Thromboplastin

Topics: Adult; Anticoagulants; Arteriosclerosis; Aspirin; Blood Coagulation; Cells, Cultured; Erythrocytes; Female; Humans; In Vitro Techniques; Male; Middle Aged; Thrombin; Thromboplastin

Intact arterial vessel wall is not thrombogenic. Disorders of the endothelium in connection with pathological coditions such such as atherosclerosis, hyperlipidaemia, hypertension and hyperuricemia induce interaction of surfaces of high thromboplastic activity with the blood stream. In such situations local formation of thrombin will take place immediately. Evidence is presented for the essential and unique activation of the extrinsic pathway of the plasmatic coagulation system. The local formation of thrombin at pathologically altered arterial wall seems to be an important trigger for arterial thrombosis and haemostasis. It could be that in vivo the initial step of thrombogenesis depends upon the formation of the activator complex between tissue-thromboplastin and factor VII.

Topics: Aged; Aorta, Abdominal; Arteries; Arteriosclerosis; Blood Coagulation; Factor VII Deficiency; Humans; Middle Aged; Partial Thromboplastin Time; Prothrombin Time; Reference Values; Thromboplastin

Topics: Animals; Arteriosclerosis; Brain; Chemical Phenomena; Chemistry; Drug Therapy, Combination; Fibrinolysis; Heparin; Rats; Thromboplastin

A study of human erythrocytes in healthy and sick persons showed changes in the erythrocytes procoagulant activity, namely a reduction of the whole cell thromboplastin activity despite a sufficient procoagulant factor content. A term "functional insufficiency of thromboplastin factor of erythrocytes" or briefly "erythrocytic thrombopathy" is suggested for the above-mentioned changes of erythrocytes, similar with the changes of platelet procoagulant properties in one of the thrombopathy forms.

Topics: Adolescent; Adult; Arteriosclerosis; Erythrocytes; Humans; Kidney Diseases; Middle Aged; Thromboplastin

Topics: Adolescent; Adult; Aged; Arteriosclerosis; Blood Coagulation; Erythrocytes; Female; Humans; Kidney Diseases; Male; Middle Aged; Thrombin; Thromboplastin

Topics: Adult; Aged; Aging; Arteriosclerosis; Blood Coagulation; Cells, Cultured; Child; Child, Preschool; Factor VII; Female; Fibroblasts; Humans; Male; Middle Aged; Progeria; Thromboplastin; Werner Syndrome

Topics: Animals; Antithrombins; Arteriosclerosis; Blood Cell Count; Blood Coagulation; Blood Coagulation Factors; Blood Coagulation Tests; Blood Platelets; Carnivora; Cross Reactions; Factor X; Fibrin; Fibrinogen; Haplorhini; Humans; Phosphatidylethanolamines; Prothrombin Time; Species Specificity; Thrombin; Thromboplastin; Thrombosis

Topics: Animals; Arteriosclerosis; Blood Coagulation; Blood Vessels; Epinephrine; Fibrinolysis; Heparin; Rats; Thromboplastin

Topics: Aged; Arteriosclerosis; Blood Cell Count; Blood Coagulation Tests; Blood Platelets; Cholesterol; Densitometry; Female; Fibrinolysis; Heparinoids; Humans; Lipids; Lipoproteins; Male; Middle Aged; Platelet Adhesiveness; Thrombin; Thromboplastin; Time Factors

Topics: Adult; Animals; Arteriosclerosis; Blood Coagulation; Brain Chemistry; Cadaver; Ceramides; Cholesterol; Chromatography, Thin Layer; Coronary Disease; Female; Humans; Male; Marsupialia; Middle Aged; Muscles; Prothrombin Time; Rats; Snakes; Stress, Physiological; Thromboplastin; Venoms

Topics: Animals; Antifibrinolytic Agents; Arteriosclerosis; Blood Coagulation; Cholesterol; Diet, Atherogenic; Fibrinogen; Fibrinolysis; Heparin; Hypercholesterolemia; Kinetics; Male; Plasma; Rats; Thromboplastin; Time Factors; Vitamin B Complex

Topics: Adult; Arteriosclerosis; Cell Aggregation; Dextrans; Erythrocytes; Female; Humans; Male; Middle Aged; Thromboplastin

Peroxidase-conjugated antibodies were used to determine the histologic and cytologic localization of bovine and human tissue factor (thromboplastin). Tissue factor antigen was found in highest concentration in the intima of blood vessels, particularly in the plasma membranes of endothelial cells and in human atheromatous plaques. Tissue factor was also found limited to the plasma membranes of many cell types. The presence of tissue factor in the plasma membranes of endothelial cells and atheromata suggests that it may play a significant role in hemostasis and thrombosis.

Topics: Animals; Antigen-Antibody Reactions; Antigens; Aorta; Arteries; Arteriosclerosis; Blood Vessels; Cattle; Cell Membrane; Epithelial Cells; Epithelium; Histocytochemistry; Humans; Liver; Lung; Myocardium; Peroxidases; Pulmonary Artery; Rabbits; Thromboplastin

Topics: Administration, Oral; Alcohols; Arteriosclerosis; Blood Coagulation; Blood Coagulation Tests; Capillaries; Glycine; Humans; Indicators and Reagents; Thromboplastin; Time Factors; Toxins, Biological

Topics: Adult; Aged; Aorta; Arteriosclerosis; Coronary Disease; Fluorescent Antibody Technique; Humans; Lipoproteins; Middle Aged; Thromboplastin

Topics: Acid Phosphatase; Adenosine Triphosphatases; Adolescent; Adult; Age Factors; Aged; Aorta; Arteriosclerosis; Esterases; Fibroblasts; Histiocytes; Histocytochemistry; Humans; Leucyl Aminopeptidase; Lipid Metabolism; Middle Aged; Nucleotidases; Proteins; Thromboplastin

Topics: Animals; Aorta; Arteriosclerosis; Blood Coagulation; Cholesterol; Diet, Atherogenic; Factor V; Factor VII; Factor X; Heparin; Humans; Rabbits; Thromboplastin

Topics: Adolescent; Adult; Age Factors; Aged; Animals; Aorta; Arteriosclerosis; Blood Coagulation; Blood Platelets; Cattle; Centrifugation; Child; Child, Preschool; Factor V; Factor VII; Female; Fibrin; Fibrinogen; Horses; Humans; Infant; Infant, Newborn; Male; Middle Aged; Prothrombin; Thromboplastin; Time Factors

Topics: Adult; Aged; Arteriosclerosis; Blood Coagulation; Blood Platelets; Coronary Disease; Epinephrine; Erythrocytes; Female; Humans; In Vitro Techniques; Male; Middle Aged; Thromboplastin

Topics: Arteriosclerosis; Blood Coagulation; Blood Coagulation Tests; Blood Platelets; Extracorporeal Circulation; Fibrin; Fibrinolysis; Hemorrhage; Heparin; Heparin Antagonists; Humans; Hyperlipidemias; Hypersensitivity; Natriuresis; Osteoporosis; Protamines; Prothrombin Time; Thromboembolism; Thrombophlebitis; Thromboplastin

Topics: Age Factors; Anticoagulants; Arteries; Arteriosclerosis; Dipyridamole; Humans; Lipid Metabolism; Nucleosides; Papaverine; Plasminogen; Serine; Sulfinpyrazone; Thromboplastin; Thrombosis

Topics: Aged; Arteries; Arteriosclerosis; Blood Coagulation Tests; Blood Platelets; Hemorrhage; Humans; Thrombin; Thromboplastin; Thrombosis

Topics: Adult; Aged; Arteriosclerosis; Blood Coagulation Disorders; Blood Coagulation Tests; Coronary Disease; Female; Humans; Intracranial Arteriosclerosis; Male; Middle Aged; Thromboplastin; Thrombosis

Topics: Arteriosclerosis; Chronic Disease; Erythrocytes; Fibrinogen; Glomerulonephritis; Humans; Kidney Diseases; Lipid Metabolism; Thromboplastin

Topics: Adult; Arteriosclerosis; Blood Coagulation Tests; Cholesterol; Coronary Disease; Female; Fibrinolysin; Heparinoids; Humans; Intracranial Arteriosclerosis; Lipids; Male; Middle Aged; Thromboplastin; Thrombosis

Topics: Arteriosclerosis; Blood Coagulation Disorders; Humans; Thromboplastin

Topics: Arteriosclerosis; Hemorrhagic Disorders; Heparin; Lipoproteins; Myocardial Infarction; Oxalates; Thromboplastin

Topics: Adrenal Cortex Hormones; Anticoagulants; Arteriosclerosis; Blood Platelet Disorders; Coronary Disease; Fats; Female; Humans; Intracranial Embolism; Intracranial Embolism and Thrombosis; Neoplasms; Pharmacology; Postoperative Complications; Pregnancy; Pregnancy Complications; Pregnancy Complications, Hematologic; Thrombophilia; Thromboplastin; Thrombosis

Topics: Aorta; Arteries; Arteriosclerosis; Blood Coagulation; Cerebral Arteries; Coronary Vessels; Fibrin; Fibrinolysis; Glycoproteins; Humans; Metabolism; Plasma; Prothrombin Time; Thrombelastography; Thromboplastin

Topics: Animals; Arteriosclerosis; Blood Coagulation; Factor VII; Hemostasis; Hemostatics; Hypertension; Lipid Metabolism; Physiology; Rabbits; Research; Thromboplastin

Topics: Aorta; Arteriosclerosis; Humans; Thromboplastin

Topics: Arteriosclerosis; Arteritis; Cholesterol; Humans; Hypercholesterolemia; Hypertension; Hypertension, Pulmonary; Lung; Pulmonary Artery; Thromboplastin; Thrombosis

Topics: Animals; Arteries; Arteriosclerosis; Cardiovascular System; Cats; Cattle; Dogs; Fibrin; Fibrinolysis; Guinea Pigs; Haplorhini; Horses; Rabbits; Rats; Research; Swine; Thromboplastin; Veins

Topics: Adenosine Triphosphate; Anticoagulants; Arteriosclerosis; Metabolism; Pharmacology; Thromboplastin

Topics: Adenosine Triphosphate; Aging; Arteriosclerosis; Blood Coagulation; Coagulants; Diphosphates; Fibrinogen; Geriatrics; Humans; Thrombin; Thromboplastin; Thrombosis

Topics: Aorta; Arteries; Arteriosclerosis; Thromboplastin; Veins

Topics: Aorta; Arteriosclerosis; Fibrinolysis; Thrombolytic Therapy; Thromboplastin

Topics: Arteries; Arteriosclerosis; Arteriosclerosis Obliterans; Humans; Thromboplastin

Topics: Animals; Aorta; Arteriosclerosis; Atherosclerosis; Blood Coagulation; Cholesterol; Fibrinolysin; Heparin; Heparinoids; Plasminogen; Rabbits; Thrombolytic Therapy; Thromboplastin

Topics: Anticoagulants; Arteriosclerosis; Atherosclerosis; Blood Platelets; Fibrinolysis; Humans; Thromboplastin

Topics: Arteriosclerosis; Factor Xa; Humans; Thromboplastin

Topics: Arteriosclerosis; Blood Coagulation; Humans; Thromboplastin