thromboplastin and Aortic-Diseases

Circulating microparticles (cMPs) play important roles in cellular crosstalk and are messengers of cell activation. We have previously reported that platelet-released microparticles (pMPs) stimulate thrombosis and that lipid-lowering treatment as per guidelines in patients with familial hypercholesterolaemia (FH) is not sufficiently effective in reducing pro-inflammatory cell activation and, consequently, CD45+/CD3+-lymphocyte-derived cMP shedding. FH patients, due to life-long vascular exposure to high LDL-cholesterol levels, are at high cardiovascular risk (HCVR) and develop premature coronary artery disease. Our objectives were to investigate a) whether patients with HCVR have cMPs with a prothrombotic phenotype, and b) whether patients with magnetic resonance imaging (MRI) evidence of lipid-rich atherosclerotic lesions have a specific cMP profile regarding prothrombotic protein cargos. cMPs were isolated from HCVR-patients and from age/gender/treatment-matched control patients. cMP phenotype was characterised by triple-labelling flow cytometry. HCVR--patients have higher numbers of pMPs derived from activated platelets as well as of tissue factor-rich microparticles (TF+-cMPs) than controls (P< 0.0001). TF+-cMPs showed procoagulant activity, which associate with atherosclerotic plaque burden, indicating that TF in the cMPs is functional. In HCVR-patients, overall TF+-cMPs (monocyte-derived [CD142+/CD14+] and platelet-derived [CD142+/TSP1+]) and activated pMPs directly correlate with MRI-detected lipid-rich atherosclerotic plaques while inversely correlate with MRI-detected calcified plaques. C-statistics analysis showed that prothrombotic cMPs add significant prognostic value to a risk factor model for the prediction of lipid-rich plaques. In conclusion, the activation status of blood cells in HCVR-patients differed markedly from controls as shown by higher circulating levels of prothrombotic and TF+-cMPs. Prothrombotic cMP numbers identify subclinical atherosclerotic plaque burden.

Topics: Age Factors; Aorta, Thoracic; Aortic Diseases; Asymptomatic Diseases; Biomarkers; Blood Platelets; Calcinosis; Cardiovascular Diseases; Case-Control Studies; Cell-Derived Microparticles; Cohort Studies; Female; Heterozygote; Humans; Hypercholesterolemia; Hyperlipoproteinemia Type II; Lipids; Magnetic Resonance Imaging; Male; Middle Aged; Phenotype; Plaque, Atherosclerotic; Platelet Activation; Risk Factors; Thromboplastin; Thrombospondin 1

Atherothrombosis is the main cause of myocardial infarction and ischemic stroke. Although the extrinsic (tissue factor-factor VIIa [FVIIa]) pathway is considered as a major trigger of coagulation in atherothrombosis, the role of the intrinsic coagulation pathway via coagulation FXII herein is unknown. Here, we studied the roles of the extrinsic and intrinsic coagulation pathways in thrombus formation on atherosclerotic plaques both in vivo and ex vivo.. Plaque rupture after ultrasound treatment evoked immediate formation of subocclusive thrombi in the carotid arteries of Apoe(-/-) mice, which became unstable in the presence of structurally different FXIIa inhibitors. In contrast, inhibition of FVIIa reduced thrombus size at a more initial stage without affecting embolization. Genetic deficiency in FXII (human and mouse) or FXI (mouse) reduced ex vivo whole-blood thrombus and fibrin formation on immobilized plaque homogenates. Localization studies by confocal microscopy indicated that FXIIa bound to thrombi and fibrin particularly in luminal-exposed thrombus areas.. The FVIIa- and FXIIa-triggered coagulation pathways have distinct but complementary roles in atherothrombus formation. The tissue factor-FVIIa pathway contributes to initial thrombus buildup, whereas FXIIa bound to thrombi ensures thrombus stability.

Topics: Animals; Aorta, Thoracic; Aortic Diseases; Apolipoproteins E; Atherosclerosis; Blood Coagulation; Blood Platelets; Carotid Arteries; Carotid Artery Diseases; Cholesterol, Dietary; Disease Models, Animal; Factor VIIa; Factor XI; Factor XII; Factor XII Deficiency; Factor XIIa; Humans; Mice; Mice, Inbred C57BL; Mice, Knockout; Plaque, Atherosclerotic; Rupture, Spontaneous; Thromboplastin; Thrombosis; Time Factors

Acyl-CoA:cholesterol acyltransferase (ACAT) converts cholesterol to cholesteryl esters in plaque foam cells. Complete deficiency of macrophage ACAT has been shown to increase atherosclerosis in hypercholesterolemic mice because of cytotoxicity from free cholesterol accumulation, whereas we previously showed that partial ACAT inhibition by Fujirebio compound F1394 decreased early atherosclerosis development. In this report, we tested F1394 effects on preestablished, advanced lesions of apolipoprotein-E-deficient mice.. Apolipoprotein-E-deficient mice on Western diet for 14 weeks developed advanced plaques, and were either euthanized (Baseline), or continued on Western diet with or without F1394 and euthanized after 14 more weeks. F1394 was not associated with systemic toxicity. Compared with the baseline group, lesion size progressed in both groups; however, F1394 significantly retarded plaque progression and reduced plaque macrophage, free and esterified cholesterol, and tissue factor contents compared with the untreated group. Apoptosis of plaque cells was not increased, consistent with the decrease in lesional free cholesterol. There was no increase in plaque necrosis and unimpaired efferocytosis (phagocytic clearance of apoptotic cells). The effects of F1394 were independent of changes in plasma cholesterol levels.. Partial ACAT inhibition by F1394 lowered plaque cholesterol content and had other antiatherogenic effects in advanced lesions in apolipoprotein-E-deficient mice without overt systemic or plaque toxicity, suggesting the continued potential of ACAT inhibition for the clinical treatment of atherosclerosis, in spite of recent trial data.

Topics: Acetyl-CoA C-Acyltransferase; Animals; Aorta; Aortic Diseases; Apolipoproteins E; Apoptosis; Atherosclerosis; Cholesterol; Cyclohexanes; Diet, Atherogenic; Dioxanes; Disease Models, Animal; Disease Progression; Enzyme Inhibitors; Foam Cells; Male; Mice; Mice, Knockout; Necrosis; Plaque, Atherosclerotic; Thromboplastin

The aim of this study was to investigate the effects of liver X receptors (LXRs)-β preferential activation by LXR-623 (WAY-252623), a novel LXRs agonist, on plaque progression/regression in a rabbit model of advanced atherosclerosis.. Advanced atherosclerosis was induced in New Zealand White Rabbits (n= 41). At the end of atherosclerosis induction, animals underwent a baseline magnetic resonance imaging (MRI) and were randomized to receive LXR-623 (1.5, 5, or 15 mg/kg/day), simvastatin (5 mg/kg/day), or placebo. The combination of LXR-1.5/simvastatin was also tested. After a final MRI, animals were euthanized and their aortas processed for further analysis. Simvastatin significantly reduced lesion progression (-25%; P< 0.01) in comparison with the placebo group. A similar effect was observed in the LXR-1.5 and -5 groups. A significant regression (16.5%; P< 0.01) of existing atherosclerosis was observed in the LXR-1.5/simvastatin group. Histological and molecular analysis showed plaque stabilization in the animals treated with the LXR-1.5 and -5, and LXR-1.5/simvastatin. The effects of LXR-623 were observed in the presence of a non-significant effect on total-cholesterol, low-density lipoproteins-cholesterol, and triglyceride levels.. The results of the present study show that LXR-623 significantly reduces the progression of atherosclerosis and induces plaque regression in combination with simvastatin. These observations could drive future development of novel anti-atherosclerotic therapeutic approaches.

Topics: Animals; Anticholesteremic Agents; Aorta, Abdominal; Aortic Diseases; Atherosclerosis; Chemokine CCL2; Cyclooxygenase 2; Disease Progression; Drug Combinations; Drug Synergism; Indazoles; Liver X Receptors; Magnetic Resonance Angiography; Orphan Nuclear Receptors; Plaque, Atherosclerotic; Rabbits; Random Allocation; Simvastatin; Thromboplastin; Up-Regulation

To assess the effects of aging on arterial thrombus formation by comparing 2-year-old with 11-week-old C57Bl6 mice.. Aging is a major risk factor for cardiovascular disease. In humans, assessing the direct effects of aging on vascular homeostasis is difficult because it occurs in the presence of other risk factors. Arterial thrombosis is the critical event in cardiovascular diseases; however, it is not known whether aging per se promotes its occurrence. Mice represent an interesting system to address this issue because they age without spontaneously developing other risk factors. Organ chamber experiments confirmed the advanced level of aging of old mice. As previously shown, old mice exhibited endothelial dysfunction; however, arterial thrombosis induced by photochemical injury was unchanged. Arterial tissue factor expression and activity; expressions of tissue factor pathway inhibitor, thrombomodulin, and plasminogen activator inhibitor 1; prothrombin time; partial thromboplastin time; thrombin-antithrombin complex; and platelet activation were comparable in both groups.. Although these results cannot be directly extrapolated to humans, this study contributes novel important information on the direct effect of aging on arterial thrombosis and underscores the importance of controlling modifiable risk factors in aged individuals.

Topics: Aging; Animals; Aorta, Thoracic; Aortic Diseases; Base Sequence; Blood Coagulation; Blood Platelets; Carotid Artery Thrombosis; Disease Models, Animal; DNA Primers; Endothelium, Vascular; Humans; Inflammation Mediators; Male; Matrix Metalloproteinase 9; Mice; Mice, Inbred C57BL; Risk Factors; RNA, Messenger; Thromboplastin; Vasodilation

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

Hemorrhage and thrombosis are associated with major vascular and trauma surgery. Release of heparinoids and thrombotic mediators may contribute to these complications and have been described in rabbits after aortic occlusion-reperfusion. We hypothesized that the resuscitative fluid used could reduce heparinoid and thrombotic mediator release after aortic occlusion-reperfusion in rabbits as assessed by thromboelastographic variables (R, reaction time; alpha, angle; and G, a measure of clot strength). Anesthetized rabbits were administered lactated Ringer's solution (n = 8) or PentaLyte (n = 8) at reperfusion after 30 min of ischemia. Blood was obtained before ischemia and after 30 min of reperfusion for thromboelastography under four conditions: 1) unmodified sample, 2) platelet inhibition, 3) heparinase, and 4) platelet inhibition and heparinase. During reperfusion, unmodified samples demonstrated a significant increase in R and decrease in alpha and G that was not affected by PentaLyte. In the presence of heparinase, no significant fluid-specific thromboelastographic differences were noted. However, thrombotic mediator release (discerned by a decrease in R and an increase in alpha) during reperfusion in samples with platelet inhibition and heparinase was significantly attenuated by PentaLyte. PentaLyte administration does not decrease heparinoid release but does decrease thrombotic mediator release after aortic occlusion-reperfusion.

Topics: Animals; Aorta, Thoracic; Aortic Diseases; Arterial Occlusive Diseases; Electrolytes; Glucose; Hematocrit; Hemodynamics; Heparinoids; Hydroxyethyl Starch Derivatives; Rabbits; Reperfusion; Resuscitation; Thromboplastin; Thrombosis

Lumen of aortic aneurysm is usually filled with parietal thrombus. Behaviour of the parietal thrombus is determined by the ratio of coagulation factors to factors of fibrinolytic system. Activity of some factors of coagulation and fibrinolysis in the parietal thrombus of aortic aneurysm was determined using coagulative, fibrinolytic and caseinolytic tests. Retracted, blood clot was a comparative material. Tissue factor activity in the parietal thrombus of the aneurysm was above threefold higher and antiheparin activity was nearly twice higher in comparison to the blood clot. Activity of plasminogen activators in the parietal thrombus was higher than in the blood clot. The parietal thrombus contained fourfold more of the plasminogen. Antiplasmin activity in the thrombus was above twofold lower than in the blood clot. High activity of the tissue factor and substances neutralizing heparin may intensify the thrombus growth. Yet the thrombotic tendency may be balanced by a high activity of plasminogen activators and plasminogen.

Topics: Aortic Aneurysm; Aortic Diseases; Blood Coagulation; Humans; Plasminogen Activators; Thromboplastin; Thrombosis

The distribution and variation of thromboplastic and fibrinolytic activity were studied in various layers of polyester grafts in the dog aorta. One, four and 36 months after implantation, these grafts were removed together with segments of normal arteries and veins and dissected into three layers. The thromboplastic and plasminogen activator activities in these layers were then determined. It was found that in the early post-operative period, the thromboplastic activity in the Dacron graft neointima is very high, whereas that of the plasminogen activator is relatively low. With the passage of time the thromboplastic activity decreases and plasminogen activator activity increases. Similarly the thromboplastic activity in the neomedial and neoadventitial layers of the graft falls as time elapses after the implantation and the fibrinolytic activity gradually increases. These changes in thromboplastic and fibrinolytic activity increase the danger of graft thrombosis in the early post-operative period whereas in the later period they are favourable to maintenance of graft patency.

Topics: Animals; Aorta, Abdominal; Aortic Diseases; Blood Vessel Prosthesis; Dogs; Fibrinolysis; Male; Plasminogen Activators; Polyethylene Terephthalates; Postoperative Complications; Thromboplastin; Thrombosis; Time Factors

A prospective study was performed on 32 consecutive patients undergoing elective operations on the abdominal aorta. Dacron prosthetic grafts were used to replace resected abdominal aortic aneurysms or to bypass aorta-iliac occlusive disease. Complete coagulation studies were performed preoperatively, immediately postoperatively and 24 hours postoperatively. Twenty to 30 per cent of the patients had significant postoperative alterations in prothrombin time, partial thromboplastin time and platelet count. Fibrin monomer, fibrin split products and plasminogen were abnormal in 40 to 80 per cent of the patients postoperatively. Results of preoperative studies showed no significant abnormalities. One of the 32 patients had mild clinical evidence of disseminated intravascular coagulation postoperatively, which was treated with 5 units of heparin per kilogram per hour. Results of the study indicate that aortic grafting procedures frequently produce intravascular coagulation, either local or disseminated. In most patients, this is offset by activation of the fibrinolytic system. However, clinically significant sequelae may result, requiring prompt recognition and treatment.

Topics: Aged; Aorta, Abdominal; Aortic Aneurysm; Aortic Diseases; Arterial Occlusive Diseases; Blood Cell Count; Blood Coagulation Tests; Blood Platelets; Blood Vessel Prosthesis; Disseminated Intravascular Coagulation; Female; Fibrin; Fibrin Fibrinogen Degradation Products; Fibrinogen; Humans; Male; Middle Aged; Postoperative Complications; Prospective Studies; Prothrombin Time; Thromboplastin