Pathogenesis Of Thrombus Formation Research Articles

The Role of Leukocytes in the Formation of Neutrophil Extracellular Traps and Thrombosis in Ph-Negative Myeloproliferative Neoplasms: A Literature Review

Thrombotic complications often cause death in patients with chronic Ph-negative myeloproliferative neoplasms (MPNs). In spite of numerous studies, the pathogenesis of thrombus formation in MPN patients remains unclear. Its mechanism is complex and is determined by many factors. One of the essential phases in thrombogenesis is characterized by the activation of cell mechanisms and formation of neutrophil extracellular traps (NETs). NETs consist of DNA strands, histones, granular proteins and along with pathogen destruction provide an ideal matrix for platelet and clotting mechanism activation.

The Role of Von Willebrand Factor in the Pathogenesis of Pulmonary Vascular Thrombosis in COVID-19.

The increased plasma levels of von Willebrand factor (VWF) in patients with COVID-19 was reported in many studies, and its correlation with disease severity and mortality suggest its important role in the pathogenesis of thrombosis in COVID-19. We performed histological and immunohistochemical studies of the lungs of 29 patients who died from COVID-19. We found a significant increase in the intensity of immunohistochemical reaction for VWF in the pulmonary vascular endothelium when the disease duration was more than 10 days. In the patients who had thrombotic complications, the VWF immunostaining in the pulmonary vascular endothelium was significantly more intense than in nonsurvivors without thrombotic complications. Duration of disease and thrombotic complications were found to be independent predictors of increased VWF immunostaining in the endothelium of pulmonary vessels. We also revealed that bacterial pneumonia was associated with increased VWF staining intensity in pulmonary arterial, arteriolar, and venular endothelium, while lung ventilation was an independent predictor of increased VWF immunostaining in arterial endothelium. The results of the study demonstrated an important role of endothelial VWF in the pathogenesis of thrombus formation in COVID-19.

ТРОМБОЗЫ МАГИСТРАЛЬНЫХ ВЕН В ПРАКТИКЕ ВРАЧА ИНТЕНСИВНОЙ ТЕРАПИИ

Purpose. To draw the attention of specialists to the question of incidence of catheterassociated and catheter-induced thrombosis in patients in intensive care units. To assess methods of visualization and monitoring of the great veins state using ultrasound. To evaluate various links in the pathogenesis of thrombus formation and the possibilities of prevention and treatment. Materials and methods. More than 3500 ultrasound examinations have been performed in over 850 patients, both in the ICU and after the transfer of patients to specialized departments. The study included children aged from 1,5 months to 18 and adults, with one or more central venous catheters (CVCs). In the absence of contraindications, patients received prophylactic anticoagulant therapy (heparin at a dose of 50-100 U/kg/day). Ultrasound was performed with a frequency of 4 to 85 times in one patient, depending on the detection and severity of CAT. The studies were carried out in B-mode using color and/or energy mapping on ultrasound scanners Philips HD 11 (Philips, USA), SonoSite MicroMaxx (USA), Logiq E8 (GE, USA), Mindrey M 7 (Mindrey, China), Samsung HM 70 (Samsung, South Korea) using linear multi-frequency sensors 10-16 MHz. The patients underwent a complex ultrasound examination of the superior or inferior vena cava (depending on the assumed main vein thrombosis (TMV) localization), as well as the main veins of the extremities. Conclusions. The multifactorial nature of TMV development in ICU patients requires increased alertness to this complication, which necessitates ultrasound monitoring of the great veins in patients in intensive care units with installed CVCs. It should be noted that, despite the ongoing prophylaxis of TMV (including the use of anticoagulants), there is still a high risk of their development.

MORPHOLOGICAL PREDICTORS OF VEIN THROMBOSIS DEVELOPMENT UNDER CONDITIONS OF ONCOPATHOLOGY

Nowadays pulmonary embolism is the second most common cause of death for cancer patients. The reason for this is activation of the blood coagulation system, depression of the coagulation system and fibrinolysis, decrease in the linear velocity of blood flow, phlebohypertension, as well as varicose reorganization of the vascular wall, its valves and endothelial cells. However, structural changes of veins as predictors of vein thrombosis in cancer patients are not sufficiently covered. At the same time, knowledge of these changes is important for understanding pathogenesis and prevention of thromboembolic complications. Objective: to find out the peculiarities of the restructuring of the structural components of the venous wall as a source of possible primary formation of intravascular thrombosis under conditions of oncogenic pathology. Material and methods. Histologic, submicroscopic and polarization data of the study of hind limb veins of 12 sexually mature non-linear rats - males weighing 170-180 g for 30 days of chronic neoplastic intoxication and vein fragments of 12 patients with colon cancer complicated by thrombosis were analyzed. Chronic neoplastic intoxication was simulated by subcutaneously injecting 7.2 mg / kg (based on the active substance) subcutaneously into the interscapular area once a week for 30 weeks, according to the weight of the animal at the rate of 0.1 ml of dimethylhydrazine hydrochloride solution (DMH). 10 grams of the body weight of rat 1,2-DMH (from SIGMA-ALDRICH CHEMIE, made in Japan, series D161802) pre-diluted with isotonic sodium chloride solution. Results and Discussion. Morphological studies of hind limb veins in experimental neoplastic intoxication mainly concerned submicroscopic reorganization of the endothelial cells and their desquamation, as well as platelet sweetening, which may be one of the links in pathogenesis of thrombus formation. Histological and electron microscopic examination of biopsy of the veins of patients with colon cancer found disorders of laminar intima, desquamation of endothelial cells, sclerosis of all membranes of the deep vein and neoplasm of vessels in the middle membrane. Patients with cancer are considred to have dystrophic-necrotic changes of skeletal muscle, which is one of the links in pathogenesis of hemodynamic disorders in the venous system of the lower extremities. Conclusions. The features of restructuring of the structural components of the venous wall, as a source of possible primary formation of intravascular thrombosis under conditions of oncogenic pathology include focal loss of integrity of the endothelial layer, endothelial dysfunction, sweetening of platelets, fibrotic remodeling of tunica intima, tunica media, tunica adventitia, neovascularization of tunica media, dystrophic and sclerotic changes of the skeletal muscle.

Recent Advances in the Understanding of Thrombosis.

Recent Advances in the Understanding of Thrombosis.

Patients with atrial fibrillation undergoing percutaneous coronary intervention. Current concepts and concerns: part I

Atrial fibrillation (AF) and coronary artery disease (CAD) often coexist. Both conditions confer an increased risk of acute thrombotic complications. However, the pathogenesis of thrombus development in AF and CAD is different. Coagulation activation is the main pathway in AF, and platelet activation is the hallmark of coronary thrombosis. Antithrombotic prophylaxis is essential in both conditions. In patients with AF undergoing percutaneous coronary intervention (PCI), a combination of oral anticoagulation and antiplatelet therapy is required, which elevates the risk of major bleeding. This has to be balanced against the risk of stroke and stent thrombosis. In the first part of the present review, the prerequisites for antithrombotic management in AF patients undergoing PCI are discussed. We cover the epidemiology of concomitant presentation of AF and CAD as well as differences in the pathogenesis of thrombus formation in both conditions. We evaluate data regarding a variety of antithrombotic regimens including triple therapy in line with stroke and bleeding risk assessment. Overall, triple therapy is often warranted but should be for the shortest possible duration. Although much of the current guidance comes from observational data, well designed, adequately powered randomized clinical trials are emerging to further inform practice in this challenging area.

Utility of Noninvasive Endothelial Function Test for Prediction of Deep Vein Thrombosis After Total Hip or Knee Arthroplasty

Venous thromboembolism (VTE) is a common and sometimes lethal postoperative complication of arthroplasty. Endothelial dysfunction is important in the pathogenesis of thrombus formation. Reactive hyperemia-peripheral arterial tonometry (RH-PAT) can noninvasively evaluate endothelial function. This study investigated the predictive value of RH-PAT for deep vein thrombosis (DVT) after lower limb arthroplasty. A prospective observational study of 126 osteoarthritic patients who underwent total knee arthroplasty (TKA) or hip arthroplasty (THA) was conducted. The RH-PAT index (RHI) was measured on the day before surgery, and presence of DVT was checked by ultrasonography or phlebography before and after surgery. Following arthroplasty, DVT was diagnosed in 51 patients (40.5%). RHI in the DVT group (0.58±0.25) was significantly lower than in the non-DVT group (0.71±0.25, P=0.004). RHI was a significant and independent predictor of postoperative DVT in multivariate logistic regression analyses and improved a net reclassification index (23.8%, P=0.022). Subgroup analyses according to operation site with adjustment for Qthrombosis score demonstrated that RHI significantly predicted postoperative DVT in the THA group (odds ratio per 0.1, 0.77; 95% confidence interval 0.60-0.98; P=0.03), but did not reach statistical significance in the TKA group. Low RHI was significantly associated with DVT after lower limb arthroplasty. Endothelial dysfunction, as assessed by RH-PAT, is potentially useful for identifying patients at high risk for VTE especially after THA.

Bone morphogenic protein-4: A potential novel target for preventing vein graft failure in coronary revascularization

Coronary artery bypass surgery is an effective and durable therapy in both acute coronary syndrome and chronic coronary stenotic disease refractory to pharmacological treatment. Despite rapid development in operation-specific technologies and secondary prevention measures, the benefits of surgical revascularization are largely limited by inadequate patency of one of the most commonly used conduits, namely the autologous saphenous vein. However, apart from antiplatelet and lipid-lowering drugs, no other pharmacologic agent has hitherto proven clinically effective in preventing short- and long-term vein graft failure. Aiming at a large number of known biomolecules, multiple promising strategies failed to translate their beneficial effects observed in animal models into the clinical settings. Bone morphogenic protein-4 (BMP4), originally identified as a mediator in bone formation, has been recently demonstrated to participate in the process of arterial post-injury remodeling. Existing evidence has demonstrated that BMP4 is closely involved in the pathogenesis of thrombus formation, neointimal hyperplasia and superimposed atherosclerosis, all of which significantly contribute to arterial stenotic lesions. Although the post-injury responses inherent to arterial and venous vessel are unique, they share common elements and present with similar physiologic characteristics and clinical sequelae. Therefore, with regard to the multifaceted effects of BMP4 in regulating arterial wall remodeling, we hypothesize that BMP4 may play an important role in mediating the pathological responses of the venous wall to the arterial circulation. If our hypothesis is demonstrated correct, BMP4 inhibition could presumably serve as a novel strategy for preventing vein graft failure in coronary revascularization.

Thrombosis Therapy: Focus on Antiplatelet Agents

Platelet adhesion, activation and aggregation to the injured vessel wall are crucially involved in the pathogenesis of thrombus formation. Agents in theory thwarting these phases would have significant clinical value. The current antiplatelet drugs used in daily clinical practice include COX-1 inhibitor aspirin, ADP P2Y12 receptor antagonist clopidogrel, and the GPIIb-IIIa antagonists (abciximab, eptifibatide and tirofiban). However, confined curative ratio along with unforeseen bleeding risk remains a major puzzle of antiplatelet therapy. With advances in understanding of the molecular basis of platelet in thrombosis, newer antiplatelet agents that targets different stage of thrombus formation have been recently developed, mostly including agents targeting platelet adhesion (GPIV, vWF), activation (GPVI, P2Y12, TPα, PAR1, phosphodiesterase, cyclooxygenase), and aggregation (GPIIb/IIIa). In this article, we will review the advantages and limitations of various antiplatelet agents that have been approved by the US Food and Drug Administration (FDA) or under development.

Frequency and clinical outcomes of platelet membrane glycoprotein polymorphisms in antiphospholipid syndrome

AbstractAbstract 3171 Introduction:The pathogenesis of thrombus formation in antiphospholipid syndrome (APS) is not clear. Therefore, it is difficult to estimate thrombus formation time in APS. Platelet membrane glycoprotein (GP) receptors play important roles in the development of thrombosis. Our study aimed to understand the relationship between thrombosis and polymorphisms in GPIb alpha variable number of tandem repeats (VNTR), Kozak, and GPIa C807T in patients with APS. Methods:The study group consisted of 60 APS patients (50 females, 10 males) and 63 controls (44 females, 19 males). Thirty patients with APS had thrombosis (nine arterial and venous, 10 arterial, 11 venous), and the remaining 30 were positive for antiphospholipid antibodies without thrombosis. C807T polymorphism was determined with real-time polymerase chain reaction (PCR). Genotyping was performed with melting curve analysis. Melting temperature was 66°C for C allele and 59°C for T allele. Kozak and VNTR polymorphisms were determined by conventional PCR. PCR product of Kozak polymorphism was digested with AvaII restriction enzyme to produce three bands (125, 157, and 175 bp), two bands (125 and 332 bp), or four bands (125, 157, 175, and 332 bp) from T/T homozygotes, C/C homozygotes, and heterozygotes respectively. PCR product for VNTR was 239 bp for allele A, 200 bp for allele B, 161 bp for allele C, and 122 bp for allele D. Results:Frequency of thrombocytopenia and pregnancy morbidity in APS were not related to the studied polymorphisms. Genotype distribution and allele frequencies of the polymorphisms are shown in Tables 1 and 2. Frequency of mutant TT genotype of C807T polymorphism was significantly higher in APS with thrombosis than without thrombosis (p=0.023). Frequency of TT genotype for C807T polymorphism was significantly higher in APS with multiple thrombi than APS without thrombi (p=0.023). This is the first study investigating the relationship between thrombosis and Kozak polymorphism in APS. Neither comparison of APS versus controls nor APS with thrombosis versus APS without thrombosis exhibited any differences in the distribution of Kozak polymorphism genotype. TC genotype was more frequent in APS with arterial thrombosis than in APS with venous thrombosis, controls, and APS without thrombosis (p=0.03, p=0.0007, and p=0.0024, respectively). D allele frequency and D allele carrier state of VNTR polymorphism were significantly less in APS than in controls (p=0.0018 and p=0.0046, respectively).Table 1C807T, Kozak allele and genotype frequencies in APS and controlsC807TCC, n (%)CT, n (%)TT, n (%)C, n (%)T, n (%)Thrombosis (n=30)18 (60)6 (20)6 (20)42/60 (70)18/60 (30)Without thrombosis (n=30)19 (63.3)11 (36.7)049/60 (81.7)11/60 (18.3)Controls (n=63)43 (68.2)18 (28.6)2 (3.2)104/126 (82.5)22/126 (17.5)KozakTT, n (%)TC, n (%)CC, n (%)T, n (%)C, n (%)Thrombosis (n=30)15 (50)15 (50)045/60 (75)15/60 (25)Without thrombosis (n=30)21 (70)7 (23.3)2 (6.7)49/60 (81.7)11/60 (18.3)Controls (n=63)47 (74.6)14 (22.2)2 (3.2)108/126 (85.7)18/126 (14.3)Table 2VNTR allele and genotype frequencies in APS and controlsVNTRThrombosis (n=30)Without thrombosis (n=30)Controls (n=63)AC, n(%)001 (1.6)BB, n(%)1 (3.3)01 (1.6)BC, n(%)7 (23.3)5 (16.7)12 (19)BD, n(%)01 (3.3)2 (3.2)CC, n(%)22 (73.4)23 (76.7)36 (57.1)CD, n(%)01 (3.3)9 (14.3)DD, n(%)002 (3.2)A allele, n(%)001/126 (0.8)B allele, n(%)9/60 (15)6/60 (10)16/126 (12.7)C allele, n(%)51/60 (85)52/60 (86.7)94/126 (74.6)D allele, n(%)02/60 (3.3)15/126 (11.9) Conclusions:Our findings demonstrated the relationship between TT genotype of C807T polymorphism and the risk of thrombosis as well as the increased tendency to development of multiple thrombi. Frequency of TC genotype of Kozak polymorphism was significantly higher in APS with arterial thrombosis. This may indicate that TC genotype predisposes to arterial thrombosis. Lower frequency of VNTR D allele and D allele carrier state in APS suggest a protective role for D allele. Detection of these polymorphisms may be useful for thrombotic risk assesment in APS. Specific inhibition of platelets GPIa and GPIb alpha may be an alternative for treating recurrent thrombosis despite appropriate anticoagulant or antiaggregant therapy. Disclosures:No relevant conflicts of interest to declare.

Increased Serum Levels of Leptin in Retinal Vein Occlusion

Retinal vein occlusion is an important cause of visual loss. Several ocular and systemic conditions have been reported for retinal vein occlusion. The pathogenesis of thrombus formation in the retinal vein, which results in retinal vein occlusion, is unclear. The aim of this study was to investigate the correlation between increased serum leptin levels and the occurrence of retinal vein occlusion (RVO). The study group consisted of 40 patients with RVO (58.1 +/- 6 years old; 17 males and 23 females): 15 patients with central RVO, 23 with branch RVO, and 2 with hemispheric RVO. The patients who had any ocular or systemic pathology were not included in the study. The control group consisted of 40 healthy individuals of similar gender, age, date and type of health survey, and geographic region. The blood samples of the RVO patients (n = 40) and controls (n = 40) were obtained antecubitally. Leptin levels were measured by an enzyme-linked immunosorbent assay (ELISA) method, and Student's t-test was used to determine differences between the groups. The mean serum leptin levels were 12.5 +/- 1.64 ng/ml in patients with RVO and 8.4 +/- 1.22 ng/ml in the control subjects; namely, the mean serum leptin levels were significantly higher in the patients with RVO (p < 0.001). These results suggest that leptin may be involved in the pathogenesis of venous thrombosis in the retina probably through its effects on homeostasis of the vessel wall.

Stroke prevention in atrial fibrillation – things can only get better

Stroke prevention in atrial fibrillation – things can only get better

Paclitaxel Enhances Thrombin-Induced Endothelial Tissue Factor Expression via c-Jun Terminal NH 2 Kinase Activation

Paclitaxel is used on drug-eluting stents because it inhibits proliferation of vascular cells. Stent thrombosis remains a concern with this compound, particularly with higher dosages. This study investigates the effect of paclitaxel on tissue factor (TF) expression in human endothelial cells. Paclitaxel enhanced thrombin-induced endothelial TF protein expression in a concentration- and time-dependent manner. A concentration of 10(-5) mol/L elicited a 2.1-fold increase in TF protein and a 1.6-fold increase in TF surface activity. The effect was similar after a 1 hour as compared with a 25-hour pretreatment period. Real-time polymerase chain reaction revealed that paclitaxel increased thrombin-induced TF mRNA expression. Paclitaxel potently activated c-Jun terminal NH2 kinase (JNK) as compared with thrombin alone, whereas the thrombin-mediated phosphorylation of p38 and extracellular signal-regulated kinase remained unaffected. Similar to paclitaxel, docetaxel enhanced both TF expression and JNK activation as compared with thrombin alone. The JNK inhibitor SP600125 reduced thrombin-induced TF expression by 35%. Moreover, SP600125 blunted the effect of paclitaxel and docetaxel on thrombin-induced TF expression. Paclitaxel increases endothelial TF expression via its stabilizing effect on microtubules and selective activation of JNK. This observation provides novel insights into the pathogenesis of thrombus formation after paclitaxel-eluting stent deployment and may have an impact on drug-eluting stent design.

CENTRAL RETINAL VEIN OCCLUSION

The clinical and histopathologic features of 29 eyes from 28 patients with central retinal vein occlusion (CRVO) are reported. A fresh or a recanalized thrombus was observed in each eye. This study considers the temporal aspects of the cases, and it notes the different morphologic features of the occlusion. These observations explain most of the variability of the changes observed in previous reports. We believe these different features representthe various stages in the natural evolution of such a thrombus. The interval between CRVO and histopathologic study in our series ranged from six hours to more than ten years. Local and systemic factors were reviewed and were found to be important in the pathogenesis of thrombus formation. Local diseases with a predisposing effect on CRVO included: glaucoma, papilledema, subdural hemorrhage, optic nerve hemorrhage, and drusen of the optic nerve head. Associated systemic diseases included: hypertension, cardiovascular and cerebrovascular disease, diabetes mellitus, and leukemia with thrombocytopenia. A fresh thrombus in the CRVO was observed in three (10.3%), and a recanalized thrombus in 26 eyes (89.7%). Endothelial-cell proliferation was a conspicuous feature in 14 (48.3%) of the eyes. Chronic inflammation in the area of the thrombus and/or vein wall or perivenular area was observed in 14 (48.3%) of the eyes. Arterial occlusive disease was observed in seven eyes (24.6%). Cystoid macular edema was found in 26 (89.7%) of the eyes.

Increased coronary vasomotor tone in acute myocardial infarction patients with spontaneous coronary recanalization.

To clarify the role of coronary spasm or dynamic coronary obstruction in the development of acute myocardial infarction (AMI) with spontaneous recanalization (SR), symptoms in 296 patients with AMI admitted within 24 h after the onset of chest pain were analyzed just before and after onset, and coronary angiograms were analyzed soon after onset. Patients were divided into 3 groups according to the initial angiographic findings in the infarct-related coronary artery (IRCA): group 1 comprised 172 patients with total occlusion (TIMI O); group 2 comprised 57 patients with subtotal occlusion (TIMI 1,2); and group 3 comprised 67 patients with SR (TIMI 3). The incidence of SR was 20.3% at 0-4 h after onset, 22.2% at 4-6 h, 19.7% at 6-12 h, 24.0% at 12-24 h, and 36.0% at 24 h or later. The incidence of SR did not increase significantly as time elapsed. The incidence of angina at rest and variable-threshold angina before the onset of infarction was only 16.2% in group 1, but was significantly higher in groups 2 (64.3%) and 3 (61.9%). The incidence of intermittent chest pain at onset in group 1 (8.4%) was significantly lower than in groups 2 (54.5%) and 3 (38.8%). Vasodilation of the proximal normal segment adjacent to the stenotic site of the IRCA induced by intracoronary nitroglycerin was significantly higher in groups 2 (11.7 +/- 1.2%) and 3 (20.7 +/- 2.6%) than in group 1 (4.0 +/- 0.6%). These results suggest that coronary spasm or dynamic obstruction may be involved in the pathogenesis of thrombus formation or coronary obstruction causing AMI in many Japanese patients.

Induction of tissue factor-like activity in monocytes by anti-cardiolipin antibodies.

Anti-cardiolipin Abs (ACLA) are present in the sera of patients with antiphospholipid syndrome (APLS) and are associated with high incidence of thromboembolic phenomena, fetal loss, thrombocytopenia, and prolongation of the phospholipid-dependent coagulation assays (lupus anticoagulant). Recently, it has been shown that APLS can be induced experimentally by using ACLA. However, the pathophysiology of thrombus formation in this syndrome is unknown. Monocytes generate a potent procoagulant activity (PCA) after stimulation with various substances. Increased PCA has been found in monocytes from patients with diseases that are associated with high incidence of thromboembolic phenomena. In the present study, we report that the monoclonal ACLA that were shown previously by us to induce APLS stimulate mononuclear cells to generate a potent PCA. The PCA resembled tissue factor (TF) in that it accelerated clotting through the extrinsic coagulation pathway, was abolished by phospholipase C, and was inhibited by anti-TF mAbs. The induction of TF-like activity by ACLA in monocytes was dose- and time-dependent. It was induced in monocytes and monocytic cell lines, but not in lymphoid or myeloid cells, and did not require T lymphocytes for expression. The generation of PCA was dependent on protein synthesis inasmuch as it was prevented by adding puromycin to the system and was not affected by cytarabine. The TF-like activity that is induced by ACLA in monocytes may activate coagulation and thereby play a major role in the pathogenesis of thrombus formation in APLS.

Mural Thrombi in Coronary Artery Disease

Detection of ventricular mural thrombi has been facilitated by the introduction of echocardiography, nuclear angiography, and radioactive labeling of platelets. Most of the data regarding the incidence of mural thrombi, pathogenesis of thrombus formation, and predisposing factors for systemic emboli after myocardial infarction that were reported on postmortem studies in the past can now be reexamined in the living patient with these noninvasive methods. The data accumulated from such investigations are now available and the results are reviewed herein. A critique of the usefulness of echocardiography and nuclear methods is also presented.