thromboplastin and Carotid-Stenosis

Arterioarterial thromboembolism from extracranial internal carotid artery (ICA) stenosis is an important pathogenic mechanism of ischemic stroke. However, even a high-grade ICA stenosis carries a greatly variable annual risk of stroke, as high as 13% following a recent occurrence of transient or minor cerebral ischemia or as low as 1-2% in clinically asymptomatic patients. There is increasing evidence that inflammatory processes play a central role in atherosclerosis and particularly in plaque destabilization converting chronic atherosclerosis into an acute neurological disorder. In thromboendarterectomy specimens from patients with high-grade ICA stenoses, the extent of inflammatory infiltration and the expression of matrixmetalloproteinase-9 correlated to clinical and ultrasonic features of plaque destabilization such as cerebral microembolism. Inflammation might become a new therapeutic target in symptomatic carotid artery disease.

Topics: Carotid Artery, Internal; Carotid Stenosis; Humans; Intracranial Embolism; Macrophages; Metalloendopeptidases; T-Lymphocytes; Thromboplastin

It has been established positive correlation of the degree of stenosis and intima-media thickness of carotid arteries with the following biochemical parameters: total cholesterol, LDL cholesterol, Apo-B, Lp(a), triglycerides, hs-C-reactive protein(CRP), interleukines (IL-1beta and IL-6), fibrinogen, D-dimers. Negative correlation was stated with respect to HDL cholesterol, Apo-A-1, protein C. Relation between the parameters of the blood lipid spectre, proteins and mediators of inflammation as well as those of hemostasis enables us to approach pathophysiological mechanisms of carotid atherosclerosis, define the processes of inflammation and atherosclerosis.

Topics: Carotid Artery Diseases; Carotid Stenosis; Cholesterol, HDL; Cholesterol, LDL; Female; Humans; Interleukin-1beta; Interleukin-6; Male; Middle Aged; Prothrombin; Thromboplastin

Abciximab, a nonselective glycoprotein IIb/IIIa inhibitor, was shown to reduce peri-interventional stroke rate in carotid stenting. We evaluated the effect of adjunct abciximab therapy on monocyte-platelet cross talk and neurological deficit in unprotected carotid stenting and compared its efficacy with distal filter protection.. Fifty patients were randomized to either standard antithrombotic therapy (n=30) consisting of aspirin, clopidogrel, and heparin or adjunct bolus (0.25 mg/kg) and 12-hour infusion (0.125 microg x kg(-1) x min(-1)) of abciximab (n=20). A third cohort of patients was stented with filter protection (n=30). Monocyte-platelet aggregate formation and monocyte tissue factor expression were determined by whole blood flow cytometry, and F1.2 generation and soluble CD40 ligand (sCD40L) were determined by immunoassay.. The incidence of peri-interventional ischemic episodes (23% versus 10%; P=0.2) and the number of de novo ischemic lesions detected by diffusion-weighted MRI (47% versus 30%; P=0.17) were not significantly different between standard antithrombotic therapy and adjunct abciximab but were reduced with filter protection (P=0.023). However, the number of transient ischemic attacks was lower (P=0.05) and the National Institutes of Health Stroke Score rapidly decreased in patients with adjunct abciximab. This clinical improvement was paralleled by a reduction in the postinterventional percentage of activated monocyte-platelet aggregates (CD62P+/CD14+; P=0.018) and the number of tissue factor-positive monocytes (TF+/CD14+; P=0.005). Both abciximab and filter protection suppressed F1.2 generation and significantly reduced sCD40L.. Abciximab limits thrombus propagation and thrombus stabilization after carotid stenting by reducing monocyte-platelet cross talk and sCD40L. Although abciximab seems inferior to filter devices in peri-interventional cerebral protection, it may be considered in patients who do not allow placement of protection devices.

Topics: Abciximab; Aged; Angioplasty; Antibodies, Monoclonal; Anticoagulants; Blood Vessel Prosthesis Implantation; Brain Ischemia; Carotid Stenosis; Cell Aggregation; Chemotherapy, Adjuvant; Cohort Studies; Female; Fibrinolytic Agents; Filtration; Hemorrhage; Humans; Immunoglobulin Fab Fragments; Ischemic Attack, Transient; Male; Monocytes; Platelet Aggregation Inhibitors; Platelet Glycoprotein GPIIb-IIIa Complex; Stents; Thromboplastin; Treatment Outcome

The procoagulant protein tissue factor (TF) has been implicated in thromboembolic complications associated with advanced atherosclerosis. In this study, we investigated whether TF expression in high-grade stenoses of the internal carotid artery (ICA) is associated with clinical features of plaque destabilization and addressed the relationship between TF expression and plaque inflammation.. In 36 consecutive patients undergoing surgery for high-grade ICA stenosis, clinical evidence of plaque instability was provided by the recent occurrence of ischemic symptoms attributable to the stenosis and the detection of cerebral microembolism by means of transcranial Doppler ultrasound monitoring of the ipsilateral middle cerebral artery. Endarterectomy specimens were stained immunocytochemically for TF expression as well as macrophage (CD68) and T cell (CD3) infiltration.. Morphologically, TF immunoreactivity was codistributed with plaque inflammation and predominantly localized to CD68+ macrophages. Accordingly, statistical analysis revealed a significant association of TF expression with plaque infiltration by macrophages (P<0.0001) and T cells (P=0.013). Plaques extensively stained for TF (median of TF+ total section area >40% in semiquantitative assessment) were more frequent in symptomatic (12/27) than in asymptomatic patients (1/9). Conversely, plaques exhibiting little TF expression (median of TF+ section area <20%) were more frequent in asymptomatic (3/9) than in symptomatic (1/27) patients (P=0.016). Likewise, we found a highly significant association of TF expression with the occurrence of cerebral microembolism (P=0.008).. Induction of TF at sites of plaque inflammation may play an important role in the destabilization of high-grade ICA stenosis.

Topics: Carotid Artery, Internal; Carotid Stenosis; Disease Progression; Endarterectomy, Carotid; Humans; Immunohistochemistry; Inflammation; Intracranial Embolism; Ischemic Attack, Transient; Macrophages; Prospective Studies; Severity of Illness Index; T-Lymphocytes; Thromboplastin; Ultrasonography, Doppler, Transcranial

Expression of tissue factor (TF) on the surface of activated monocytes may trigger thrombosis, leading to clotting risk, inflammation, and atherosclerosis. TF-positive microparticles (MP-TF) represent a functionally active form of TF that may be promulgated by long-term HIV infection. We hypothesized that greater MP-TF activity is associated with carotid artery plaque in HIV+ women.. In a case-control study nested within the Women's Interagency HIV Study (WIHS), eligible HIV+ participants underwent B-mode carotid artery ultrasound at 2 study visits occurring 7 years apart. Cases were defined by the presence of at least 1 carotid artery plaque assessed at either visit. Cases were matched 1:2 to controls who were found not to have carotid artery plaques.. Conditional logistic regression estimated the association of MP-TF activity with the presence of carotid artery plaque, adjusting for demographic and behavioral characteristics, HIV-related factors, cardiometabolic risk factors, and serum inflammation biomarkers (high-sensitivity C-reactive protein, IL-6, sCD14, sCD163, Gal-3, and Gal-3BP).. Elevated MP-TF activity (>0.537 pg/mL) was found to be significantly associated with greater odds of plaque (adjusted odds ratio 3.86, 95% confidence interval: 1.06 to 14.07, P = 0.04). The association was attenuated after further adjustment for IL-6 but was unaffected by adjustment for other biomarkers including those denoting monocyte activation.. Our findings suggest a link among HIV infection, innate immune system perturbation, coagulation, and atherosclerosis.

Topics: Adult; Carotid Stenosis; Case-Control Studies; Female; HIV Infections; Humans; Middle Aged; Thromboplastin; Ultrasonography

Monocytes and monocyte-derived microvesicles (MVs) are the main source of circulating tissue factor (TF). Increased monocyte TF expression and increased circulating levels of procoagulant MVs contribute to the formation of a prothrombotic state in patients with cardiovascular disease. Interleukin (IL)-33 is a pro-inflammatory cytokine involved in atherosclerosis and other inflammatory diseases, but its role in regulating thrombosis is still unclear. The aim of the present study was to investigate the effects of IL-33 on the procoagulant properties of human monocytes and monocyte-derived MVs. IL-33 induced a time- and concentration-dependent increase of monocyte TF mRNA and protein levels via binding to the ST2-receptor and activation of the NF-κB-pathway. The IL-33 treated monocytes also released CD14+TF+ MVs and IL-33 was found to increase the TF activity of both the isolated monocytes and monocyte-derived MVs. The monocytes were classified into subsets according to their CD14 and CD16 expression. Intermediate monocytes (IM) showed the highest ST2 receptor expression, followed by non-classical monocytes (NCM), and classical monocytes (CM). IL-33 induced a significant increase of TF only in the IM (p<0.01), with a tendency in NCM (p=0.06), but no increase was observed in CM. Finally, plasma levels of IL-33 were positively correlated with CD14+TF+ MVs in patients undergoing carotid endarterectomy (r=0.480; p=0.032; n=20). We hereby provide novel evidence that the proinflammatory cytokine IL-33 induces differential TF expression and activity in monocyte subsets, as well as the release of procoagulant MVs. In this manner, IL-33 may contribute to the formation of a prothrombotic state characteristic for cardiovascular disease.

Topics: Aged; Carotid Stenosis; Cell-Derived Microparticles; Cells, Cultured; Female; Humans; Interleukin-1 Receptor-Like 1 Protein; Interleukin-33; Lipopolysaccharide Receptors; Male; Middle Aged; Monocytes; NF-kappa B; Recombinant Proteins; RNA, Messenger; Thromboplastin; Thrombosis

Humoral autoimmune-mediated inflammation plays a role in atherogenesis, and potentially in arterial thrombosis. Anti-apolipoprotein A-1 (apoA-1) IgG have been reported to represent emergent mediators of atherogenesis through Toll-like receptors (TLR) 2, 4 and CD14 signalling. We investigated the role of anti-apoA-1 IgG on tissue factor (TF) expression and activation, a key coagulation regulator underlying atherothrombosis. Atherothrombosis features were determined by immunohistochemical TF staining of human carotid biopsies derived from patients with severe carotid stenosis undergoing elective surgery (n=176), and on aortic roots of different genetic backgrounds mice (ApoE-/-; TLR2-/-ApoE-/- and TLR4-/-ApoE-/-) exposed to passive immunisation with anti-apoA-1 IgG. Human serum levels of anti-apoA-1 IgG were measured by ELISA. In vitro, on human-monocyte-derived-macrophages (HMDM) the anti-apoA-1 IgG increased TF expression and activity were analysed by FACS and chromogenic assays in presence of different pharmacological inhibitors. Human serum anti-apoA-1 IgG levels significantly correlated to intraplaque TF expression in carotid biopsies (r=0.31, p<0.001), which was predictive of clinically symptomatic lesions. On HMDM, anti-apoA-1 IgG induced a TLR2, 4 and CD14-dependent increase in TF expression and activity, involving NF-kappaB and a c-Jun N-terminal kinase-dependent AP-1 transcription factors. In ApoE-/- mice, anti-apoA-1 IgG passive immunisation significantly enhanced intraplaque TF expression when compared to control IgG. This effect was lost in both TLR2-/-ApoE-/- and TLR4-/-ApoE-/- mice. These results demonstrate that anti-apoA-1 IgG are associated with TF expression in human atherosclerotic plaques, induce TF expression in vitro and in vivo through TLR2 and 4 signalling, supporting a possible causal relationship between anti-apoA-1 IgG and atherothrombosis.

Topics: Aged; Aged, 80 and over; Animals; Apolipoprotein A-I; Autoantibodies; Carotid Stenosis; Cohort Studies; Female; Humans; Immunoglobulin G; Male; MAP Kinase Signaling System; Mice; Mice, Knockout; Mice, Knockout, ApoE; Plaque, Atherosclerotic; Prospective Studies; Thromboplastin; Thrombosis; Toll-Like Receptor 2; Toll-Like Receptor 4

The efficiency of cellular uptake of triplex‑forming oligodexinucleotides (TFO), and the inhibition of tissue factor (TF) is low. The aim of the present study was to improve the absorption of TFO, and increase the inhibition of TF induced by shear stress both in vitro and in vivo, by using an ultrasound‑targeted microbubble destruction (UTMD)‑based delivery system. TFO‑conjugated lipid ultrasonic microbubbles (TFO‑M) were first constructed and characterised. The absorption of TFO was observed by a fluorescence‑based method, and the inhibition of TF by immunofluorescence and quantitative polymerase chain reaction. ECV304 human umbilical vein endothelial cells were subjected to fluid shear stress for 6 h after treatment with TFO conjugated lipid ultrasonic microbubbles without sonication (TFO‑M group); TFO alone; TFO conjugated lipid ultrasonic microbubbles, plus immediate sonication (TFO+U group and TFO‑M+U group); or mock treated with 0.9% NaCl only (SSRE group). The in vivo experiments were established in a similar manner to the in vitro experiments, except that TFO or TFO‑M was injected into rats through the tail vein. Six hours after the preparation of a carotid stenosis model, the rats were humanely sacrificed. The transfection efficiency of TFO in the TFO‑M+U group was higher as compared with the TFO‑M and TFO+U group (P<0.01). The protein and mRNA expression of TF in the TFO‑M+U group was significantly decreased both in vitro and in vivo (P<0.01), as compared with the TFO‑M, TFO+U and SSRE groups. The UTMD‑based TFO delivery system promoted the -absorption of TFO and the inhibition of TF, and was therefore considered to be favorable for preventing thrombosis induced by shear stress.

Topics: Animals; Carotid Arteries; Carotid Stenosis; Cells, Cultured; Disease Models, Animal; Endothelial Cells; Fluorescein-5-isothiocyanate; Gene Expression; Human Umbilical Vein Endothelial Cells; Humans; Lipids; Microbubbles; Oligodeoxyribonucleotides; Rats; Rats, Sprague-Dawley; RNA, Messenger; Shear Strength; Sonication; Thromboplastin; Transfection

Tissue factor (TF) expression is increased in inflammatory atherosclerotic plaques and has been related to plaque thrombogenicity. Blood-borne TF activity seems to contribute to a procoagulant state in patients with vascular risk factors. The aim of this study was to assess whether the expression of TF in carotid plaques from patients undergoing carotid endarterectomy (CEA) or/and blood-borne ('circulating') TF activity could predict future vascular complications.. A total of 105 consecutive patients (85 male and 20 female aged 61-77 years)undergoing CEA for high-grade internal carotid artery were included in the study. Carotid artery specimens were classified into active (n = 52; rich in inflammatory cells) and nonactive plaques (n = 53; poor in inflammatory cells or fibrous). TF mRNA levels in carotid plaques were assessed by real-time PCR (TaqMan Low-Density Arrays) and TF protein levels by Western blot. Blood-borne TF activity and other biochemical parameters, including low-density lipoprotein cholesterol (LDLc) levels and high-sensitivity C-reactive protein, were measured prior to surgery. Patients were followed up for 1 year and vascular and nonvascular complications were scored.. TF expression was higher in active CEA plaques. Patients with active CEA plaques exhibited higher plasma LDLc levels (3.6 +/- 0.7 vs. 2.1 +/- 1 mM, p < 0.05) that positively correlated with plaque TF mRNA levels (p = 0.0125; r = 0.9). Blood-borne TF activity did not correlate with plasma LDLc levels and was unrelated to the anatomo-pathological characteristic of the CEA plaques (thrombosis, rupture, inflammation, lipid core, necrosis or calcification). Circulating TF activity predicted vascular complications at 1 year, including fatal (OR, 1.18; 95% CI, 0.6-2.2, p < 0.01) and nonfatal ischemic stroke (OR, 1.22; 95% CI, 0.5-2.0, p < 0.05) and symptomatic peripheral vascular disease (OR, 1.48; 95% CI, 0.4-2.6, p < 0.005).. Blood-borne TF activity prior to CEA but not local TF expression or plasma LDLc levels predict cerebrovascular and peripheral vascular disease events at 1 year in elderly patients subjected to CEA for high-grade carotid stenosis.

Topics: Aged; Carotid Artery, Internal; Carotid Stenosis; Cerebrovascular Disorders; Cholesterol, LDL; Endarterectomy, Carotid; Female; Follow-Up Studies; Humans; Male; Middle Aged; Predictive Value of Tests; RNA, Messenger; Thromboplastin; Time Factors; Treatment Outcome

People with hypertension display an inflammatory pattern that includes increased plasma concentrations of monocyte chemoattractant protein 1 (MCP-1) and C-reactive protein (CRP) and enhanced expression of tissue factor (TF) mRNA in blood monocytes.. In this study, we investigated the relationship between CRP concentrations and TF and MCP-1 mRNA expression in unstimulated and lipopolysaccharide (LPS)-stimulated monocytes isolated from hypertensives with or without an increase in carotid intima-media thickness (IMT). We also investigated the expression of TF and MCP-1 mRNA and MCP-1 protein after in vitro addition of CRP to monocytes. We measured CRP (by immunonephelometry) and monocyte expression of TF and MCP-1 (by real-time PCR) in 80 untreated hypertensive patients without clinical cardiovascular disease (CVD) or additional risk factors for CVD compared with 41 controls. Based on IMT measured by carotid Doppler ultrasonography, patients were classified into the categories of normal (< or =1 mm) or abnormal (>1 mm). TF and MCP-1 mRNA and MCP-1 protein (by Western blotting) were measured after in vitro addition of CRP to monocytes from 10 randomized controls as well as 10 hypertensives with IMT < or =1 mm and 10 with IMT >1 mm.. CRP and TF and MCP-1 mRNA concentrations were significantly higher in IMT >1 mm hypertensives vs those with IMT < or =1 mm and controls. CRP had no effect on monocyte TF mRNA from either hypertensives or controls. CRP-stimulated monocytes from hypertensives, however, showed increased MCP-1 mRNA and protein expression compared with controls and LPS-stimulated cells.. Our findings suggest that the inflammatory response of blood monocytes plays an important role in the development of atherosclerosis and hypertension.

Topics: Adult; C-Reactive Protein; Carotid Arteries; Carotid Artery, Common; Carotid Artery, Internal; Carotid Stenosis; Cells, Cultured; Chemokine CCL2; Female; Humans; Hypertension; Lipopolysaccharides; Male; Monocytes; Thromboplastin; Tunica Intima; Tunica Media; Ultrasonography

Severely stenotic, symptomatic carotid atheromas are associated with a high risk of stroke in the short term. Although carotid endarterectomy is effective in reducing this stroke risk, it is frequently not applied within the time window for significant benefit. We investigated the effect of peroxisome proliferator-activated receptor (PPAR) -alpha and -gamma ligands in acutely modifying tissue factor (TF) and tissue factor pathway inhibitor (TFPI) in unstable carotid atheromas.. During a 3-year period, 64 patients who had experienced a transient ischemic attack or stroke with good recovery within 6 weeks before surgery and 12 asymptomatic patients with a >70% carotid stenosis were recruited. The expression of PPAR-alpha and -gamma was investigated in endarterectomy samples. The effects of the PPAR-alpha and -gamma ligands fenofibrate and rosiglitazone were investigated in cell culture experiments. Targeted biopsy specimens from endarterectomy samples (n=48) were incubated with medication for 4 days. TF and TFPI were assessed by immunohistochemistry, Western blot analysis, flow cytometry, and activity assays.. PPAR-gamma1 but not -alpha was downregulated in atheromas removed from patients with recent symptoms and no evidence of diabetes. Fenofibrate but not rosiglitazone impaired the induction of TF in human endothelial cells and reduced resting levels of TF activity in vascular smooth muscle cells. Rosiglitazone but not fenofibrate increased TFPI secretion from human endothelial cells. Both fenofibrate (100+/-18.7% to 56.6+/-8.8%, P=0.005; 0.2664+/-0.0696 to 0.1771+/-0.0310, P=0.02) and rosiglitazone (100+/-22% to 88.3+/-20%, P=0.02; 0.3113+/-0.0729 to 0.2287+/-0.0415, P=0.04) reduced TF expression and activity, respectively, in atheroma biopsy specimens. A low expression of TFPI was found in atheroma biopsy specimens with little evidence of TFPI activity.. This study suggests that both PPAR-alpha and -gamma ligands have beneficial effects in acutely reducing TF in unstable carotid atheromas.

Topics: Aged; Aged, 80 and over; Carotid Stenosis; Female; Fenofibrate; Humans; Ischemic Attack, Transient; Ligands; Lipoproteins; Male; Middle Aged; Peroxisome Proliferator-Activated Receptors; PPAR alpha; PPAR gamma; Rosiglitazone; Signal Transduction; Stroke; Thiazolidinediones; Thromboplastin

To study the effect of antiparallel phosphorothioate triplex-forming oligonucleotide (apsTFO) matching with the shear stress response element (SSRE) of tissue factor (TF) gene promoter region on the expression of TF in endothelial cells (ECs) of rat common carotid artery stenosis.. The model of common carotid artery middle segment stenosis was established by silica gel pipe loop ligation in SD rats. The mRNA expression and protein synthesis of TF, early growth response-1 (Egr-1) and specificity protein 1 (Sp1) were measured by in situ hybridization (ISH) and immunohistochemistry (IHC) technique. GT21-apsTFO, GT20-apsTFO, GT20-psTFO and FITC-labeled apsTFO, matching with the SSRE of TF gene promoter region, were designed, and intravenously injected into rats at 0.5 h before operation. TFO was detected 4 h after the operation, and the mRNA expression and protein synthesis of TF, Egr-1 and Sp1 were detected 6 h after the operation.. There were much fluorescence in vascular tissue, especially in the nuclear of ECs 4.5 h after the injection of apsTFO. The mRNA expression and protein synthesis of TF reduced by 22% - 23% with injection of GT20-apsTFO 6.5 h after stenosis (P < 0.01) and by 10% - 11% with GT21-apsTFO at the same time (P < 0.05). The inhibition by GT20-apsTFO was stronger than that of the GT21-apsTFO (P < 0.05). The expression of TF was not inhibited by the GT20-psTFO (P > 0.05). The mRNA expression and protein synthesis of Egr-1 and Sp1 did not change in the rat treated with GT20-apsTFO, GT20-psTFO and GT21-apsTFO (P > 0.05).. apsTFO could mero-inhibit the expression of TF gene but could not change the expression of Egr-1 and Sp1 protein.

Topics: Animals; Carotid Stenosis; Early Growth Response Protein 1; Endothelial Cells; Gene Expression; Immunohistochemistry; In Situ Hybridization; Male; Oligonucleotides; Rats; Rats, Sprague-Dawley; RNA, Messenger; Shear Strength; Sp1 Transcription Factor; Stress, Mechanical; 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

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

Tissue factor (TF) is normally expressed at low levels in the media of blood vessels, but it is readily induced after vessel injury. It is not known whether vascular damage per se or thrombus formation is responsible for this phenomenon.. Cyclic flow variations (CFVs), attributable to recurrent thrombus formation, were induced in stenotic rabbit carotid arteries with endothelial injury. CFVs were observed for 30 minutes and 2, 4, and 8 hours in different groups of animals. Another group of rabbits pretreated with hirudin before inducing arterial damage to inhibit thrombus formation was observed for 8 hours. Arterial sections were immunostained for TF. Undamaged arteries served as controls. In additional rabbits, in situ hybridization experiments were performed. No TF expression was observed in the media of control vessels, whereas a progressive increase in TF mRNA and protein expression was observed in carotid arteries as CFVs progressed. No increase in TF expression was observed in animals pretreated with hirudin. In vitro experiments demonstrated that TF mRNA is induced in smooth muscle cells stimulated with activated platelets as well as with some platelet-derived mediators.. This phenomenon may contribute to sustain intravascular thrombus formation after the initial thrombogenic stimulus.

Topics: Animals; Blood Platelets; Carotid Arteries; Carotid Artery Thrombosis; Carotid Stenosis; Disease Models, Animal; In Situ Hybridization; Monocytes; Muscle, Smooth, Vascular; Neutrophils; Platelet Activating Factor; Platelet-Derived Growth Factor; Rabbits; Recurrence; Regional Blood Flow; RNA, Messenger; Thromboplastin; Tunica Intima; Tunica Media

Defined angiographically, no-reflow (NR) manifests as an acute reduction in coronary flow in the absence of epicardial vessel obstruction. One candidate protein to cause coronary NR is tissue factor (TF), which is abundant in atherosclerotic plaque and a cofactor for activated plasma coagulation factor VII. Scrapings from atherosclerotic carotid arteries contained TF activity (corresponding to 33.03 +/- 13.00 pg/cm(2) luminal plaque surface). Active TF was sedimented, indicating that TF was associated with membranes. Coronary blood was drawn from 6 patients undergoing coronary interventions with the distal protection device PercuSurge GuardWire (Traatek, Miami, FL). Fine particulate material that was recovered from coronary blood showed TF activity (corresponding to 91.1 +/- 62.16 pg/mL authentic TF). To examine the role of TF in acute coronary NR, blood was drawn via a catheter from coronary vessels in 13 patients during NR and after restoration of flow. Mean TF antigen levels were elevated during NR (194.3 +/- 142.8 pg/mL) as compared with levels after flow restoration (73.27 +/- 31.90 pg/mL; P =.02). To dissect the effects of particulate material and purified TF on flow, selective intracoronary injection of atherosclerotic material or purified relipidated TF was performed in a porcine model. TF induced NR in the model, thus strengthening the concept that TF is causal, not just a bystander to atherosclerotic plaque material. The data suggest that active TF is released from dissected coronary atherosclerotic plaque and is one of the factors causing the NR phenomenon. Thus, blood-borne TF in the coronary circulation is a major determinant of flow.

Topics: Angioplasty; Animals; Blood Flow Velocity; Carotid Stenosis; Coronary Artery Disease; Coronary Circulation; Hemostasis; Humans; Immunohistochemistry; Injections, Intra-Arterial; Models, Animal; Stents; Swine; Thromboplastin

Tissue factor pathway inhibitor (TFPI) is the sole known inhibitor of the extrinsic coagulation pathway of physiological importance; however, its role in modulating thrombosis in vivo is still unclear.. Intravascular thrombosis was initiated by placing an external constrictor around endothelially injured rabbit carotid arteries (n=10). Carotid blood flow velocity was measured by a Doppler flow probe. After placement of the constrictor, cyclic flow reductions (CFRs), due to recurrent thrombosis, developed at the site of stenosis. Transstenotic TFPI plasma activity was measured in blood samples before induction of CFRs and after 30, 60, and 180 minutes of CFRs. TFPI plasma activity distal to the site of thrombosis was significantly lower than the corresponding proximal values at 30, 60, and 180 minutes of CFRs. In addition, a progressive decrease in TFPI plasma activity was observed in both the proximal and the distal samples, indicating consumption of TFPI during thrombus formation. In 10 additional rabbits, CFRs were abolished by administration of aspirin (10 mg/kg). In the animals in which aspirin abolished CFRs, endogenous TFPI was depleted by a bolus of a polyclonal antibody against rabbit TFPI, and the effects on restoration of CFRs were monitored. In 5 of 6 animals in which aspirin abolished CFRs, depletion of endogenous TFPI activity caused full restoration of CFRs.. The data of the present study support the involvement of endogenous TFPI in the process of thrombus formation in vivo and its active role in modulating arterial thrombosis.

Topics: Animals; Antibodies; Aspirin; Blood Coagulation; Blood Flow Velocity; Carotid Artery Injuries; Carotid Stenosis; Disease Models, Animal; Endothelium, Vascular; Female; Male; Platelet Aggregation Inhibitors; Rabbits; Thromboplastin; Thrombosis

Fibrin(ogen) is the major matrix ligand for beta3 integrins. If alpha(v)beta3 is the major receptor for fibrin(ogen) on intimal smooth muscle cells, we might expect to see this integrin associated with fibrin(ogen). Eighty-four specimens obtained from endarterectomies of 14 patients were studied. Fibrin was frequently observed in carotid intima even at the non-atherosclerotic areas. As for beta1 and beta3 integrins, beta1 was predominant in intima. The alpha(v)beta3 integrin expression was less frequent than alpha5beta1, another receptor for fibrin(ogen), in diffuse intimal thickening, fibrous cap and advanced plaques. Furthermore, alpha(v)beta3 was generally negative on smooth muscle cells in recent plaque ruptures. In conclusion, we suggest more attention should be paid on abundant fibrin matrix in intima. Histologically, the alpha5beta1 integrin rather than the alpha(v)beta3 is the major receptor for fibrin in intimal smooth muscle cells.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Antibodies, Monoclonal; Antibody Specificity; Blotting, Western; Carotid Arteries; Carotid Artery Injuries; Carotid Stenosis; Endarterectomy, Carotid; Fibrin; Fibrinogen; Hemorrhage; Humans; Immunohistochemistry; Integrins; Ligands; Male; Middle Aged; Muscle, Smooth, Vascular; Receptors, Fibronectin; Receptors, Vitronectin; Thromboplastin; Tunica Intima

Tissue factor (TF) is a transmembrane protein that binds factor VII/VIIa, thus activating the extrinsic blood coagulation pathway. Since this pathway appears to be involved in the formation of intravascular thrombi, the anti-rabbit TF monoclonal antibody, AP-1, was produced and tested as an antithrombotic agent in a rabbit model of recurrent intravascular thrombosis. In this model, a plastic constrictor is positioned around the injured rabbit carotid arteries, and flow is monitored with a Doppler flow probe. This produces cyclic flow variation (CFV) in the carotid artery, which is caused by recurrent formation and dislodgment of thrombi at the site of the stenosis. After monitoring CFV pattern for 30 minutes, AP-1 was infused intravenously into nine rabbits at doses of 0.05 to 1.5 mg/kg body weight, and a control monoclonal antibody that does not react with rabbit TF was infused into four additional rabbits. In all rabbits receiving AP-1, CFV was abolished, and a steady normal blood flow was restored, indicating that thrombus formation had been blocked by AP-1. By contrast, in all rabbits that received the control monoclonal antibody, CFV continued unaltered. There was no change in the partial thromboplastin time and ex vivo platelet aggregation to several different agonists after infusion of AP-1, indicating an absence of systemic effects on the coagulation process. We conclude that activation of the extrinsic coagulation pathway has a key role in triggering intravascular thrombosis and that an anti-TF monoclonal antibody is an effective antithrombotic agent that could have therapeutic potential for humans.

Topics: Animals; Antibodies, Monoclonal; Carotid Arteries; Carotid Stenosis; Female; Immunohistochemistry; Male; Rabbits; Thromboplastin; Thrombosis; Tissue Distribution