Background: There is room for improvement of prevention of venous thromboembolism (VTE) after lower-leg cast application or knee arthroscopy. Information about the mechanism of clot formation in... Show moreBackground: There is room for improvement of prevention of venous thromboembolism (VTE) after lower-leg cast application or knee arthroscopy. Information about the mechanism of clot formation in these patients may be useful to identify new prophylaxis targets. We aimed to study the effect of 1) lower-leg injury and 2) knee arthroscopy on thrombin generation. Methods: A cross-sectional study was conducted using plasma samples of POT-(K)CAST trials to measure ex vivo thrombin generation (Calibrated Automated Thrombography [CAT]) and plasma levels of prothrombin fragment 1 + 2 (F1 + 2), thrombin-antithrombin (TAT), fibrinopeptide A (FPA). Plasma was obtained shortly after lower-leg trauma or before and after (< 4 h) knee arthroscopy. Participants were randomly selected from those who did not develop VTE. For aim 1, samples of 88 patients with lower-leg injury were compared with 89 control samples (i.e., preoperative samples of arthroscopy patients). Linear regression was used to obtain mean differences (or ratios if ln-retransformed because of skewedness) adjusted for age, sex, body mass index, comorbidities. For aim 2, pre- and postoperative samples of 85 arthroscopy patients were compared, for which mean changes were obtained. Results: In patients with lower-leg injury (aim 1), endogenous thrombin potential, thrombin peak, velocity index, FPA and TAT were increased as compared with controls. In arthroscopy patients (aim 2), pre- and postoperative levels were similar for all parameters. Conclusion: Lower-leg trauma increases thrombin generation both ex vivo and in vivo, in contrast to knee arthroscopy. This may imply that the pathogenesis of VTE is different in both situations. Show less
Veneuze trombose is een ziekte gekenmerkt door het ontstaan van een ongewenst bloedstolsel. Om inzichten te verkrijgen in de pathofysiologie van dit ziektebeeld zijn voorheen genoomstudies... Show moreVeneuze trombose is een ziekte gekenmerkt door het ontstaan van een ongewenst bloedstolsel. Om inzichten te verkrijgen in de pathofysiologie van dit ziektebeeld zijn voorheen genoomstudies uitgevoerd. Deze studies hebben een nieuwe erfelijke factor voor veneuze trombose geïdentificeerd, namelijk het SLC44A2 gen. Dit was een opmerkelijke bevinding, aangezien SLC44A2 nooit eerder gekoppeld was aan de bloedstolling. Het onderzoek beschreven in dit proefschrift heeft als doel het mechanisme, onderliggend aan deze associatie, te ontrafelen. Er is hiervoor gebruik gemaakt van muizen die dit gen niet meer hebben, zogenaamde SLC44A2 knock-out muizen. Dierstudies maakten het mogelijk om de complexiteit van stromend bloed, de bloedvaatwand en het ontstaan van veneuze trombose nader te onderzoeken. We hebben aangetoond dat de afwezigheid van SLC44A2 de normale bloedstolling ongemoeid laat. De vorming van veneuze trombose in SLC44A2 knock-out muizen is echter afwijkend, met mogelijk betrokkenheid van neutrofielen en von Willebrand factor (VWF), een eiwit met een rol in veneuze trombose. Studies verricht aan SLC44A2 op de neutrofielen van mensen, met aandacht voor de twee verschillende vormen van SLC44A2 die bij mensen voorkomen, geven goede aanwijzingen dat SLC44A2 een rol speelt in de binding van neutrofielen aan VWF. Er werd ook geobserveerd dat de erfelijke variant van SLC44A2 op neutrofielen welke zwak bindt aan VWF, ook degene is die samengaat met een mindere kans op het krijgen van VT. Door deze studies begrijpen we beter hoe veneuze trombose ontstaat, met hopelijk in de nabije toekomst concrete aanknopingspunten voor alternatieve, betere en veiligere behandelingsstrategieën voor veneuze trombose. Show less
A prominent feature of severe streptococcal infections is the profound inflammatory response that contributes to systemic toxicity. In sepsis the dysregulated host response involves both... Show moreA prominent feature of severe streptococcal infections is the profound inflammatory response that contributes to systemic toxicity. In sepsis the dysregulated host response involves both immunological and nonimmunological pathways. Here, we report a fatal case of an immunocompetent healthy female presenting with toxic shock and purpura fulminans caused by group B streptococcus (GBS; serotype III, CC19). The strain (LUMC16) was pigmented and hyperhemolytic. Stimulation of human primary cells with hyperhemolytic LUMC16 and STSS/NF-HH strains and pigment toxin resulted in a release of proinflammatory mediators, including tumor necrosis factor, interleukin (IL)-1 beta, and IL-6. In addition, LUMC16 induced blood clotting and showed factor XII activity on its surface, which was linked to the presence of the pigment. The expression of pigment was not linked to a mutation within the CovR/S region. In conclusion, our study shows that the hemolytic lipid toxin contributes to the ability of GBS to cause systemic hyperinflammation and interferes with the coagulation system. Show less
The aim of this thesis is to identify emerging risk factors for VTE. To achieve this goal, we describe the supposedly causal role of statin and glucocorticoid use (i.e. two drugs that can influence... Show moreThe aim of this thesis is to identify emerging risk factors for VTE. To achieve this goal, we describe the supposedly causal role of statin and glucocorticoid use (i.e. two drugs that can influence inflammation) with changes in hemostasis and VTE risk. Systemic glucocorticoid use increases the relative risk of first VTE by more than three-fold and confers an 5% absolute risk of recurrent VTE per year. On the other hand, rosuvastatin use may reduce the risk of first VTE by 40%. Although the mechanisms behind this association are not fully elucidated, this thesis shows that rosuvastatin is capable of decreasing the thrombin generation potential by 10% in patients with a prior VTE. This thesis has shown that both statins and systemic glucocorticoids can affect the risk of VTE, improving the knowledge on the influence of these two commonly prescribed drugs on VTE pathophysiology. These findings have the potential to further refine the assessment of VTE risk since they highlight that the use of these drugs should be considered when evaluating the risk of VTE. Finally, this thesis provides insight into new therapeutic approaches since the results underscore that treatment strategies on VTE prevention in patients already taken statins, which may be sufficient for VTE prevention, are lacking. Treatment strategies to prevent glucocorticoid-associated VTE are also needed. Show less
Purpose Recombinant human erythropoietin (rHuEPO) is known to increase thrombotic risk in patients and might have similar effects in athletes abusing the drug. rHuEPO is prohibited by anti-doping... Show morePurpose Recombinant human erythropoietin (rHuEPO) is known to increase thrombotic risk in patients and might have similar effects in athletes abusing the drug. rHuEPO is prohibited by anti-doping legislation, but this risk has not been investigated thoroughly. This analysis was designed to evaluate whether rHuEPO impacts hemostatic profile and endothelial and platelet activation markers in trained subjects, and whether the combination with exercise affects exercise induced alterations. Methods This double-blind, randomized, placebo-controlled trial enrolled healthy, trained male cyclists aged 18-50 years. Participants were randomly allocated (1:1) to receive subcutaneous injections of rHuEPO (epoetin-beta; mean dose 6000 IU per week) or placebo (0.9% NaCl) for 8 weeks. Subjects performed five maximal exercise tests and a road race, coagulation and endothelial/platelet markers were measured at rest and directly after each exercise effort. Results rHuEPO increased P-selectin (+ 7.8% (1.5-14.5),p = 0.02) and E-selectin (+ 8.6% (2.0-15.7),p = 0.01) levels at rest. Maximal exercise tests significantly influenced all measured coagulation and endothelial/platelet markers, and in the rHuEPO group maximal exercise tests led to 15.3% ((7.0-24.3%),p = 0.0004) higher E-selectin and 32.1% ((4.6-66.8%),p = 0.0207) higher Platelet factor 4 (PF4) levels compared to the placebo group. Conclusion In conclusion, rHuEPO treatment resulted in elevated E- and P-selectin levels in trained cyclists, indicating enhanced endothelial activation and/or platelet reactivity. Exercise itself induces hypercoagulability, and the combination of rHuEPO and exercise increased E-selectin and PF4 levels more than either intervention alone. Based on this, exercise potentially increases thrombotic risk, a risk that might be enhanced in combination with rHuEPO use. Show less
Willems, A.; Patte, P.; Groote, F. de; Linden, P. van der 2019
Atherothrombotic events such as myocardial infarction and ischemic stroke are a major cause of morbidity and mortality worldwide. Understanding the molecular and cellular mechanisms of... Show moreAtherothrombotic events such as myocardial infarction and ischemic stroke are a major cause of morbidity and mortality worldwide. Understanding the molecular and cellular mechanisms of atherosclerotic plaque destabilization or erosion, and developing new therapeutics to prevent acute cardiovascular events is important for vascular biology research and clinical cardiovascular medicine. However, basic research on plaque destabilization, rupture and erosion is hampered by the lack of appropriate animal models of atherothrombosis. Unprovoked atherothrombosis is very scarce in commonly used mouse models for atherosclerosis, the low-density lipoprotein receptor knockout and apolipoprotein E knockout mice. Therefore, specific interventions are required to induce atherothrombosis in these models. Two strategies can be employed to induce atherothrombosis: 1) plaque destabilization and 2) induction of blood hypercoagulability. Although the individual strategies yield atherothrombosis at low incidence, it appears that the combination of both plaque destabilization and an increase in blood coagulability is the most promising strategy to induce atherothrombosis on a larger scale. In this review, we summarize the recent developments on mouse models for the investigation of atherothrombosis. Show less
This thesis reports on studies that have investigated the role of several factors on the risk of arterial thrombosis. The thesis is organised in two sections. The first section (Chapters 2-5)... Show moreThis thesis reports on studies that have investigated the role of several factors on the risk of arterial thrombosis. The thesis is organised in two sections. The first section (Chapters 2-5) deals with risk factors for the first arterial thrombotic event whereas the second section (Chapters 6 and 7) concerns risk factors for recurrence. The investigations touch several aspects of epidemiology, and make use of several observational study designs, encompassing case control, cohort and meta-analysis. Several statistical models were also applied ranging from logistic regression models, Cox proportional hazards time to event regression models as well as non-parametric statistics. Because of the heterogeneous nature, each investigation had specific problems in study design, data collection and analyses. A common line, however, is the haemostatic balance and its markers. Taken together, the findings of this thesis lead to the conclusion that there are differences in the aetiology of the two main forms of arterial thrombosis. Indeed, they support the hypothesis that hypercoagulability plays a greater role in the pathogenesis of ischaemic stroke than in that of myocardial infarction. Show less
Atherothrombosis is a complication of atherosclerosis that causes acute cardiovascular events such as myocardial infarction and stroke. Circulating lipid levels are highly correlated with... Show moreAtherothrombosis is a complication of atherosclerosis that causes acute cardiovascular events such as myocardial infarction and stroke. Circulating lipid levels are highly correlated with atherosclerotic plaque development. In addition, experimental evidence suggests that lipids also directly influence thrombosis and influence the risk and the outcome of acute cardiovascular events. Plasma lipoproteins influence three aspects important to atherothrombosis: endothelial function, platelet aggregation (primary coagulation) and secondary coagulation. Overall, VLDL, LDL and oxLDL promote thrombus formation, whereas HDL shows antithrombotic actions. In this review we will address the current knowledge about modulation of atherothrombosis by lipoproteins, summarizing findings from in vitro and in vivo animal studies, as well as from observational and interventional studies in humans. We will conclude with future perspectives for lipid modulation in the prevention of atherothrombosis. Show less
Tissue Factor (TF) is a membrane protein that is responsible for the initiation of the coagulation. In addition to its coagulant activity, it can also signal through a member of G-protein coupled... Show moreTissue Factor (TF) is a membrane protein that is responsible for the initiation of the coagulation. In addition to its coagulant activity, it can also signal through a member of G-protein coupled receptor family, PARs, thus play a role in breast cancer growth and angiogenesis. The switch between signaling and coagulant TF regulated by the oxidation/reduction of an allosteric disulfide bond which resides in TF antigen. A decade ago, it was discovered that TF RNA can be alternatively spliced to form a soluble protein called Alternatively Spliced Tissue Factor (asTF). This protein is non-coagulant. However, it plays a major role in breast cancer growth via inducing cancer cell proliferation. The mechanism lying behind behind this phenomenon is asTF's capability to ligate integrins thus it can initiate integrin signaling. Moreover, both TF and asTF can synergize with estrogen pathway thus providing a complex regulation of breast cancer progression. Show less
The venom of the Australian brown snake Pseudonaja textilis contains a prothrombinase-like initiator of blood coagulation, which has evolved into a potent weapon through several gainof-function... Show moreThe venom of the Australian brown snake Pseudonaja textilis contains a prothrombinase-like initiator of blood coagulation, which has evolved into a potent weapon through several gainof-function adaptations. Here we examined the functional implications of a disulfide bond exclusively found in the factor (F)Va-like cofactor component, ptFV. We found that this remarkable structural feature is not required for the procoagulant properties of ptFV. The nearly identical liver-derived plasma ptFV that lacks this disulfide link displayed a similar procoagulant profile. Whether the unique disulfide bond imposes conformational constraints essential to other aspects of the venom FV life cycle remains to be determined. Show less
Woei-A-Jin, F.J.S.H.; Starre, W.E. van der; Tesselaar, M.E.T.; Rodriguez, P.G.; Nieuwkoop, C. van; Bertina, R.M.; ... ; Osanto, S. 2014
Myocardial infarction and ischaemic stroke are both forms of arterial thrombosis. It is unclear to what extent hypercoagulability is a causal factor of these diseases and whether this effect might... Show moreMyocardial infarction and ischaemic stroke are both forms of arterial thrombosis. It is unclear to what extent hypercoagulability is a causal factor of these diseases and whether this effect might be different for myocardial infarction and ischaemic stroke. Several measures of hypercoagulability were investigated in the RATIO study, a nationwide population based case-control study which includes 248 women with myocardial infarction, 203 women with ischaemic stroke and 925 control women, all under 50 years of age. Chapter 2 describes the relationship of a positive family history of arterial thrombosis and the risk of either myocardial infarction or ischaemic stroke. Chapters 3-6 focus on the intrinsic coagulation proteins. Chapters 7-9 describe a genetic approach that focuses on the role of fibrinogen and coagulation factor XIII. Chapter 10 discusses the role of the fibrinolytic capacity, chapter 11 discusses VWF and ADAMTS13, and chapter 12 discusses the risk of myocardial infarction and ischaemic stroke associated with the presence of markers of the antiphospholipid syndrome. Chapter 13 provides a summary and discussion of these results. These results suggest that hypercoagulability is a cause of ischaemic stroke, whereas it does not have a major effect on the risk of myocardial infarction in young women. Show less
The studies presented in this thesis explored several pathogenic mechanisms underlying von Willebrand disease that is characterized by a quantitative or functional deficiency of von Willebrand... Show moreThe studies presented in this thesis explored several pathogenic mechanisms underlying von Willebrand disease that is characterized by a quantitative or functional deficiency of von Willebrand factor, in particular with respect to intracellular storage in Weibel-Palade body and regulated secretion of von Willebrand factor. By using molecular biology, confocal and electron microscopic techniques, storage and secretion of von Willebrand factor were analyzed for von Willebrand disease variants identified in the patients. These studies advanced our understanding of von Willebrand disease at the molecular and cellular levels. HEK293 cells and endothelial cells derived from patients__ peripheral blood were established as two useful model-systems for examining von Willebrand factor structure-function relationships in the context of von Willebrand disease. Using these model-systems we have demonstrated that von Willebrand factor mutations may impair its storage and secretion and thus lead to a quantitative deficiency of this factor in the patients. Furthermore, we demonstrated that alteration in the structure of von Willebrand factor, by natural mutations that occur in von Willebrand disease patients, modulates von Willebrand factor string formation and function. We propose that alteration in von Willebrand factor string formation and function may be another new mechanism that contributes to the bleeding tendency in von Willebrand disease. Show less
Due to a lack of patient materials and ethical reasons animal models of BPD are critical for characterization the pathophysiology of BPD and testing of potential treatment options. In chapter 2 of... Show moreDue to a lack of patient materials and ethical reasons animal models of BPD are critical for characterization the pathophysiology of BPD and testing of potential treatment options. In chapter 2 of this thesis we characterize a rat model for experimental BPD, induced in neonatal pups by prolonged exposure to hyperoxia, by investigating histopathology and differential gene expression profiles in the lung and demonstrate its significance for studying BPD in premature infants. In chapter 3 we describe the spatial and temporal expression of surfactant proteins in this experimental BPD model. Since inflammation and unbalanced coagulation and fibrinolysis, leading to extravascular fibrin deposition in the lung, are two interrelated processes that play a pivotal role in the pathophysiology of inflammatory lung disease, we investigated whether the pathophysiology of experimental BPD could be improved by interrupting the vicious cycle of inflammation and coagulation. Fibrin deposition can be prevented directly via inhibition of the coagulation cascade and/or stimulation of the fibrinolytic cascade or indirectly via inhibition of the inflammatory response, thereby preventing activated leucocytes to perform their procoagulant and antifibrinolytic activity. In chapters 4 and 5 intervention studies in experimental BPD are described which study the potential therapeutic effect of agents with anti-inflammatory and/or anticoagulant activity for premature infants who are at risk of developing BPD. The role of pentoxifylline, a methylxantine derivative and weak non-selective phosphodiesterase inhibitor with anti-inflammatory and anticoagulant properties, and with positive effects on capillary blood flow in experimental BPD is presented in chapter 4. The role of nitric oxide, a gas that is involved in multiple (patho)physiological processes in the injured lung, including pulmonary vasodilatation, inflammation and plasma exudation, is presented in chapter 5. In chapter 6 the presented studies of chapters 2-5 and the future perspectives are discussed. In chapter 7 a summary is given of this thesis. Due to a lack of patient materials and ethical reasons animal models of BPD are critical for characterization the pathophysiology of BPD and testing of potential treatment options. In chapter 2 of this thesis we characterize a rat model for experimental BPD, induced in neonatal pups by prolonged exposure to hyperoxia, by investigating histopathology and differential gene expression profiles in the lung and demonstrate its significance for studying BPD in premature infants. In chapter 3 we describe the spatial and temporal expression of surfactant proteins in this experimental BPD model. Since inflammation and unbalanced coagulation and fibrinolysis, leading to extravascular fibrin deposition in the lung, are two interrelated processes that play a pivotal role in the pathophysiology of inflammatory lung disease, we investigated whether the pathophysiology of experimental BPD could be improved by interrupting the vicious cycle of inflammation and coagulation. Fibrin deposition can be prevented directly via inhibition of the coagulation cascade and/or stimulation of the fibrinolytic cascade or indirectly via inhibition of the inflammatory response, thereby preventing activated leucocytes to perform their procoagulant and antifibrinolytic activity. In chapters 4 and 5 intervention studies in experimental BPD are described which study the potential therapeutic effect of agents with anti-inflammatory and/or anticoagulant activity for premature infants who are at risk of developing BPD. The role of pentoxifylline, a methylxantine derivative and weak non-selective phosphodiesterase inhibitor with anti-inflammatory and anticoagulant properties, and with positive effects on capillary blood flow in experimental BPD is presented in chapter 4. The role of nitric oxide, a gas that is involved in multiple (patho)physiological processes in the injured lung, including pulmonary vasodilatation, inflammation and plasma exudation, is presented in chapter 5. In chapter 6 the presented studies of chapters 2-5 and the future perspectives are discussed. In chapter 7 a summary is given of this thesis. Due to a lack of patient materials and ethical reasons animal models of BPD are critical for characterization the pathophysiology of BPD and testing of potential treatment options. In chapter 2 of this thesis we characterize a rat model for experimental BPD, induced in neonatal pups by prolonged exposure to hyperoxia, by investigating histopathology and differential gene expression profiles in the lung and demonstrate its significance for studying BPD in premature infants. In chapter 3 we describe the spatial and temporal expression of surfactant proteins in this experimental BPD model. Since inflammation and unbalanced coagulation and fibrinolysis, leading to extravascular fibrin deposition in the lung, are two interrelated processes that play a pivotal role in the pathophysiology of inflammatory lung disease, we investigated whether the pathophysiology of experimental BPD could be improved by interrupting the vicious cycle of inflammation and coagulation. Fibrin deposition can be prevented directly via inhibition of the coagulation cascade and/or stimulation of the fibrinolytic cascade or indirectly via inhibition of the inflammatory response, thereby preventing activated leucocytes to perform their procoagulant and antifibrinolytic activity. In chapters 4 and 5 intervention studies in experimental BPD are described which study the potential therapeutic effect of agents with anti-inflammatory and/or anticoagulant activity for premature infants who are at risk of developing BPD. The role of pentoxifylline, a methylxantine derivative and weak non-selective phosphodiesterase inhibitor with anti-inflammatory and anticoagulant properties, and with positive effects on capillary blood flow in experimental BPD is presented in chapter 4. The role of nitric oxide, a gas that is involved in multiple (patho)physiological processes in the injured lung, including pulmonary vasodilatation, inflammation and plasma exudation, is presented in chapter 5. In chapter 6 the presented studies of chapters 2-5 and the future perspectives are discussed. In chapter 7 a summary is given of this thesis. Due to a lack of patient materials and ethical reasons animal models of BPD are critical for characterization the pathophysiology of BPD and testing of potential treatment options. In chapter 2 of this thesis we characterize a rat model for experimental BPD, induced in neonatal pups by prolonged exposure to hyperoxia, by investigating histopathology and differential gene expression profiles in the lung and demonstrate its significance for studying BPD in premature infants. In chapter 3 we describe the spatial and temporal expression of surfactant proteins in this experimental BPD model. Since inflammation and unbalanced coagulation and fibrinolysis, leading to extravascular fibrin deposition in the lung, are two interrelated processes that play a pivotal role in the pathophysiology of inflammatory lung disease, we investigated whether the pathophysiology of experimental BPD could be improved by interrupting the vicious cycle of inflammation and coagulation. Fibrin deposition can be prevented directly via inhibition of the coagulation cascade and/or stimulation of the fibrinolytic cascade or indirectly via inhibition of the inflammatory response, thereby preventing activated leucocytes to perform their procoagulant and antifibrinolytic activity. In chapters 4 and 5 intervention studies in experimental BPD are described which study the potential therapeutic effect of agents with anti-inflammatory and/or anticoagulant activity for premature infants who are at risk of developing BPD. The role of pentoxifylline, a methylxantine derivative and weak non-selective phosphodiesterase inhibitor with anti-inflammatory and anticoagulant properties, and with positive effects on capillary blood flow in experimental BPD is presented in chapter 4. The role of nitric oxide, a gas that is involved in multiple (patho)physiological processes in the injured lung, including pulmonary vasodilatation, inflammation and plasma exudation, is presented in chapter 5. In chapter 6 the presented studies of chapters 2-5 and the future perspectives are discussed. In chapter 7 a summary is given of this thesis. Show less
Von Willebrand factor (VWF) plays an important role in both primary and secondary hemostasis as a molecular glue between platelets and subendothelial structures, and as a carrier of FVIII.... Show moreVon Willebrand factor (VWF) plays an important role in both primary and secondary hemostasis as a molecular glue between platelets and subendothelial structures, and as a carrier of FVIII. Mutations in VWF may cause von Willebrand disease (VWD), which is the most common bleeding disorder. It is characterized by symptoms ranging from very mild to severe bleeding. Mutations may influence the level of VWF (quantitative defect; type 1 or type 3) or may affect the function of VWF. Especially important for the generation of functional VWF is the formation of disulfide linked bonds. Firstly, intrachain linking is essential for the monomer structure. Secondly, interchain linking is necessary for both dimerization and multimerization of VWF. All 169 cysteine residues in the mature VWF subunit (8.2%) participate in these intra- or interchain disulfide bonds. The interaction between proVWF dimers ultimately yields high-molecular weight VWF that is active in primary hemostasis in the bloodstream.The main aims of the studies reported in this thesis were to examine how loss of cysteines located in different domains of VWF results in quantitative and qualitative VWF defects; how these mutations interfere with dimerization and multimerization; and how they influence intracellular routing, secretion and clearance of VWF. Show less
