Acute cardiovascular clinical events such as myocardial infarction and cerebral stroke represent the major cause of death in Western societies. These pathologies are primarily resulting from... Show moreAcute cardiovascular clinical events such as myocardial infarction and cerebral stroke represent the major cause of death in Western societies. These pathologies are primarily resulting from atherosclerosis, a progressive condition characterized by the accumulation of lipids, immune cells, and fibrous elements in large arteries. The pathogenesis of atherosclerosis involves complex interactions between a wide variety of cells, including monocytes, macrophages, neutrophils, and lymphocytes. It is essential to identify novel targets for therapeutic application in order to reduce the residual atherosclerotic cardiovascular disease risk in current and future patients. Recent studies have suggested that members of the protein arginine methyltransferase (PRMT) family can potentially serve as novel therapeutic targets for atherosclerosis because of their regulatory role in inflammation and metabolism. To validate the contribution of PRMTs in the progression of atherosclerosis, in the studies presented in this thesis we have investigated the effect of inhibition of PRMT functionality on atherosclerosis susceptibility in established atherosclerotic mouse models.To address the role of PRMTs in atherosclerosis, we therefore made use of specific PRMT inhibitors, i.e. TC-E 5003 for PRMT1 inhibition, TP-064 for PRMT4 inhibition, and GSK3326595 for PRMT5 inhibition, that thus far have primarily been applied in vivo in the context of cancer treatment. Show less
The vascular system delivers oxygen and nutrients through the entire body. In addition, it enables distribution of hormones and immune cells. A proper functioning vascular system is important in... Show moreThe vascular system delivers oxygen and nutrients through the entire body. In addition, it enables distribution of hormones and immune cells. A proper functioning vascular system is important in preventing cardiovascular disease (CVD). In recent years, several risk factors, e.g. smoking and obesity, have been described. Also genetic variants have been shown to influence vascular function and thereby the risk on developing CVD.In this thesis the role of Neuroimmune Guidance Cues (NGCs) in the development of atherosclerosis, one of the main causes of CVD is investigated. The development of atherosclerosis is characterized by the deposition of fatty acids and immune cells in the vessel wall. With several experiments we have shown that NGCs play an important role in the vessel wall and regulate atherosclerosis-related processes. We show that PLXNA4 regulates endothelial permeability, while the Eph receptor B2 regulates migration of monocytes through the vessel. In addition, we have shown that genetic variants in Eph receptor B4, EphrinB2 and Netrin-1 can modulate atherosclerosis-related processes and thereby could influence the development of CVD.The results shown here give us new insights in the function of the vascular system and provide novel targets to treat and/or prevent CVD. Show less
Cardiometabolic diseases including atherosclerotic cardiovascular disease (CVD) and non-alcoholic fatty liver disease (NAFLD) are the leading cause of preventable death worldwide.... Show moreCardiometabolic diseases including atherosclerotic cardiovascular disease (CVD) and non-alcoholic fatty liver disease (NAFLD) are the leading cause of preventable death worldwide. Hypercholesterolemia and inflammation are common major risk factors for atherosclerotic CVD as well as NAFLD. The studies described in this thesis aimed to get insight in strategies how to further improve cholesterol metabolism and inflammation, by exploring the therapeutic potential of brown fat activation and transcription factors involved in both processes. The results described in this thesis have increased our insight into regulation of cholesterol metabolism and inflammation by brown fat and nuclear receptors, respectively, and provided promising leads for innovative treatment of cardiometabolic diseases including brown fat activation, Δ24-dehydrocholesterol reductase inhibition, and farnesoid X receptor activation. Show less
The aim of this thesis was to unravel a selection of a multitude of potential causal pathways that may underlie the association between excess body fat and cardiovascular disease, such as... Show moreThe aim of this thesis was to unravel a selection of a multitude of potential causal pathways that may underlie the association between excess body fat and cardiovascular disease, such as adipokines, inflammation, HDL-cholesterol and postprandial triglyceride response, and cholesteryl ester transfer protein (CETP). We showed that hs-CRP and GlycA as measures of inflammation, adiponectin, and leptin are not associated with clinical and subclinical cardiovascular disease in the general population. However, all may be relevant markers of disease risk. Also, postprandial triglyceride excursions, genetically-determined CETP and HDL-cholesterol, while not related with subclinical atherosclerosis in the general population, may be interesting targets to pursue in women and men separately, and in subgroups of individuals at high-cardiovascular risk. Show less
During my PhD we have investigated different approaches to block intraplaque angiogenesis in atherosclerosis. Intraplaque angiogenesis is a physiological response to the increased oxygen demand in... Show moreDuring my PhD we have investigated different approaches to block intraplaque angiogenesis in atherosclerosis. Intraplaque angiogenesis is a physiological response to the increased oxygen demand in the plaque but also has adverse effects by facilitating intraplaque hemorrhage and influx of inflammatory mediators, resulting in plaque instability and consequent rupture. To study this phenomenon we used in vitro assays as well as the accelerated atherosclerosis vein graft model in ApoE3*Leiden mice, a unique model in which the formed plaque shows characteristics that highly resemble human atherosclerotic lesions, including intraplaque angiogenesis and hemorrhage and a high inflammatory cell content. We focused on different approaches to restore plaque stability via improving intraplaque oxygen levels as well as via blocking different growth factors signaling. Moreover we studied the effects of our treatments on the interaction between angiogenesis and inflammation both in vitro and in vivo. Show less
Despite the available treatment options and sophisticated imaging technologies for monitoring lesion development, the morbidity and mortality from acute cardiovascular events remain unacceptably... Show moreDespite the available treatment options and sophisticated imaging technologies for monitoring lesion development, the morbidity and mortality from acute cardiovascular events remain unacceptably high.While cholesterol-lowering, anti-inflammatory and anti-platelet therapies benefits can increase survival as a primary or secondary prevention, they are not sufficient for plaque rupture prevention. Moreover, the most advance imaging technologies to detect high-risk atherosclerotic patients fail to visualize and explore cellular events in small preclinical models. Therefore, there is a clear need for the development of new therapies and the application of high-resolution imaging modalities.In the current thesis, we evaluated new possibilities to inhibit and image intraplaque angiogenesis. Show less
Cardiovascular disease is a major global burden and atherosclerosis is the main underlying pathological process. Despite better management of cholesterol levels, there remains a significant... Show moreCardiovascular disease is a major global burden and atherosclerosis is the main underlying pathological process. Despite better management of cholesterol levels, there remains a significant residual risk of developing atherosclerosis and cardiovascular events. Hence, novel pathways and targets should be identified to optimize atherosclerosis therapy. Despite dyslipidemia, the immune system is also heavily involved in the pathophysiology of atherosclerosis. Protective immune responses in the acute setting of increased cholesterol levels eventually turn into debilitating responses when the immune system is chronically stimulated. Hence, we aimed to identify new therapeutic targets to dampen the immune response in atherosclerosis. More specifically, we focused our efforts on modulating the B lymphocyte response, for which there was a scarcity of data. In this thesis we describe novel ways to modulate the B cell response in atherosclerosis. We have found that there are specific B cell subsets that have different effects on the progress of atherosclerosis. For instance, removal of TIM-1+ B cells resulted in increased atherosclerosis, while removal of BTLA+ follicular B cells reduced atherosclerosis. In conclusion, this thesis provides promising immunological targets for the treatment of atherosclerosis. Show less
Within this thesis, several diseases central in the field of cardiovascular disease will be outlined. First, the central dogma of molecular biology, RNA biology in general, RNA (alternative... Show moreWithin this thesis, several diseases central in the field of cardiovascular disease will be outlined. First, the central dogma of molecular biology, RNA biology in general, RNA (alternative)splicing and the role of RNA-binding proteins within these processes will be discussed to enhance the accessibility to non-molecular biologists. Subsequently, the current literature and insights into the RNA-binding protein Quaking will be outlined. Thereafter, a brief summary of the role of many distinct RNA-binding proteins (RBPs) in the cardiovascular system is provided, detailing their importance in the heart and cells of the blood vessels. This review provides some historical and biological perspectives, while simultaneously highlighting many recent advances in our understanding of RBP function in cardiovascular health and disease. By harnessing established and novel techniques, including RNA-sequencing, this thesis will describe the role of Quaking in vascular stenosis, atherosclerosis, inflammation and endothelial barrier function. Collectively, Quaking can be described as a genome-wide governor of RNA-processing that results in the proper translation into functional proteins. This thesis describes which RNA transcripts are under control of Quaking, which alternative transcripts are being generated through modulation by Quaking, while also describing the unique role for this protein in health and cardiovascular and renal disease. Show less
The worldwide prevalence of obesity is steadily increasing. Obesity leads to insulin resistance and atherosclerosis, which are the pathologies underlying type 2 diabetes and cardiovascular disease,... Show moreThe worldwide prevalence of obesity is steadily increasing. Obesity leads to insulin resistance and atherosclerosis, which are the pathologies underlying type 2 diabetes and cardiovascular disease, respectively. Inflammation is an important factor connecting obesity to these disorders, but the exact mechanisms connecting obesity, the immune system, type 2 diabetes and cardiovascular disease are still under investigation. The research described in this thesis was performed 1) to gain more insight into the role of the immune system in obesity, dyslipidemia, insulin resistance and atherosclerosis, 2) to study whether inflammation contributes to the disadvantageous metabolic phenotype of a human population with a particularly high risk to develop type 2 diabetes and cardiovascular disease, and 3) to study the therapeutic potential of decreasing inflammation by pharmacological strategies to reduce obesity and improve glucose and lipid metabolism in pre-clinical models. The studies described in this thesis have increased our understanding of the role of inflammation in adipose tissue function and lipid metabolism during the development of type 2 diabetes and cardiovascular disease. Moreover, novel potential therapeutic strategies were identified to combat obesity, metabolic inflammation and associated metabolic disorders, such as treatment with interferons, salsalate and GPR120 agonists. Show less
Non-alcoholic fatty liver disease (NAFLD) has rapidly become the most common cause of chronic liver disease, and its worldwide prevalence continues to increase in parallel of the obesity epidemic.... Show moreNon-alcoholic fatty liver disease (NAFLD) has rapidly become the most common cause of chronic liver disease, and its worldwide prevalence continues to increase in parallel of the obesity epidemic. NAFLD comprises a wide spectrum of liver damage ranging fat accumulation (steatosis) to steatosis with inflammation (non-alcoholic steatohepatitis, NASH), which can further progress to fibrosis. In particular patients with NASH have increased risk to develop other metabolic complications, such as cardiovascular disease.NAFLD is a complex disease, in which the origin and molecular mechanisms controlling the progression of simple steatosis to NASH remain poorly understood. Nevertheless, it is thought that inflammation is a critical component of NAFLD progression. This inflammation may be triggered by metabolic surplus (excess of energy or nutrients) and is also referred to as “metabolic inflammation”. White adipose tissue (WAT) is assumed to be largely involved in the development of metabolic inflammation. The studies described in this thesis contributed to the understanding of the role of WAT in the development of NAFLD and provide insight into the molecular processes that cause metabolic inflammation. Show less
The brain is increasingly recognized as the regulator of body homeostasis and as possible treatment target for cardiovascular disease. This thesis further reveals the role of the autonomic nervous... Show moreThe brain is increasingly recognized as the regulator of body homeostasis and as possible treatment target for cardiovascular disease. This thesis further reveals the role of the autonomic nervous system (ANS) in the control of lipid metabolism and inflammation, and identified pathological consequences of disturbed regulation. Part I focuses on regulation of lipid metabolism by the ANS, with special attention for brown adipose tissue (BAT) as an emerging pharmacological target for therapy. We describe novel targets that modulate BAT, both directly (e.g. CB1R) and via the brain (e.g. MC4R, GLP-1R) to show that BAT activation improves dyslipidemia, glucose tolerance and T2D and even atherosclerosis. In addition, we identified the biological clock as an important regulator of BAT function and showed the consequences of disturbed circadian rhythmicity for lipid metabolism. Part II of this thesis describes studies on the regulation of inflammation by the ANS, with focus on the anti-inflammatory reflex. During this reflex, binding of acetylcholine to _7nAChR and subsequent intracellular signaling results in transcriptional repression of pro-inflammatory genes. We investigated the effects of hematopoietic _7nAChR deficiency and the consequences of selective parasympathetic and sympathetic denervation of the spleen for this reflex, and for inflammation and atherosclerotic plaque development. Show less
Atherosclerosis, restenosis and cardiac remodeling after myocardial infarction can cause serious clinical problems that greatly contribute to both high morbidity and mortality. In all these... Show moreAtherosclerosis, restenosis and cardiac remodeling after myocardial infarction can cause serious clinical problems that greatly contribute to both high morbidity and mortality. In all these processes, the inflammatory responses caused by activation of the immune system play a very prominent role. This thesis elaborates on the role of specific components of the immune system and the therapeutic possibilities that lay hidden therein. This was done by focussing on the pathophysiological process in which Damage Associated Molecular Patterns (DAMPs) are released upon cell stress and cell death or other tissue damage, and may play an important role via different mechanisms. The data in this thesis illustrates specific involvement of DAMPs recognizing factors such as Toll-like Receptors in vascular remodeling and the therapeutic potential that lies within these findings. We show that endogenous activation of the immune s ystem plays an important role in the post-interventional vascular remodeling process. Multiple DAMPs such as HMGB1 are absent before intervention however they were found highly up regulated locally in the vessel wall after intervention indicating a specific relation with the intervention procedure. The presence and involvement of a variety of Toll Like Receptors in different models of vascular remodeling is interesting since these receptors are considered to be important recognizers of the DAMPs locally found in the vessel wall. Different intracellular signalling pathways and TLR accessory molecules seem to mediate the outcome of the specific DAMP-TLR interactions on vascular remodeling majorly. Protective effects of TLR3 and different outcomes of RP105 deficiency on vascular remodeling processes indicate the complexity of the underlying pathophysiological processes. These results can be partly explained by downstream TLR signalling and involvement of specific cell subtypes. The exploration of these underlying mechanisms offers new opportunities for biomarker selection and therapy development. Show less
Vein graft surgery to treat occlusive arterial disease is a common applied procedure. Each year more than two million vein graft surgeries are performed worldwide. The major drawback of vein... Show moreVein graft surgery to treat occlusive arterial disease is a common applied procedure. Each year more than two million vein graft surgeries are performed worldwide. The major drawback of vein grafting is that within 10 years after vein graft surgery 50-60 % of the vein grafts suffer from patency loss due to thrombosis, intimal hyperplasia formation, accelerated atherosclerosis and rupture. Endogenous factors orchestrate the development and failure of vein grafts. Investigating the role of endogenous constituents on vein graft remodeling can enhance our basic knowledge of the involvement of these factors in vein graft remodeling. By interfering in the function of endogenous factors, as we showed in this thesis, vein graft remodeling can be negatively or positively influenced depending on the factor and strategy used. New therapeutic strategies can be developed based on this knowledge. In this thesis we investigate the role of innate immune components, complement system factors, toll like receptors, mast cells and NK cells and the role of Annexin A5 in vein graft remodeling. Furthermore we explored the role of plaque stability, plaque neovascularization and extracellular matrix remodeling in a hypercholersterolemic mouse vein graft model. Show less
Cardiovascular diseases remain the major cause of death throughout the world and can be primarily attributed to atherosclerotic vascular disease leading to stroke and coronary heart disease (CHD).... Show moreCardiovascular diseases remain the major cause of death throughout the world and can be primarily attributed to atherosclerotic vascular disease leading to stroke and coronary heart disease (CHD). Improved primary prevention and the introduction and subsequent optimization of percutaneous coronary interventions (PCI) for myocardial ischemia due to obstructive CHD have significantly improved patient outcome and reduced morbidity and mortality. The insight into disease pathology has however expanded tremendously over the past decade and continuing research has shifted the focus of interest towards post-interventional accelerated atherosclerosis development due to a dysfunctional (auto) immune inflammatory response, responsible for vascular remodeling, re-occlusion and recurrence of symptoms. The aim of this thesis therefore was to investigate the role of the immune system in this pathophysiological process that ultimately results in post-interventional atherosclerotic vascular remodeling and apply this insight for the development of new immune-modulatory therapies in a preclinical setting. Show less
In this thesis, the role of the liver and lungs in atherosclerosis development were studied. The liver plays an important role in lipid metabolism and inflammation, the two main processes involved... Show moreIn this thesis, the role of the liver and lungs in atherosclerosis development were studied. The liver plays an important role in lipid metabolism and inflammation, the two main processes involved in atherogenesis. We show that continuous enhanced inflammation in hepatocytes increased the hepatic production of VLDL and aggravated atherosclerosis development in hyperlipidemic APOE*3-Leiden (E3L) mice as compared to control E3L mice. Poor lung function, most commonly caused by chronic obstructive pulmonary disease (COPD), is a risk factor for atherosclerosis development. To this end, we investigated whether elastase-induced alveolar wall destruction, a model for COPD, would worsen atherosclerosis development in E3L mice. No difference in atherosclerotic lesion size was observed between mice after elastase or vehicle instillation, indicating that alveolar destruction per se is not responsible for the increased risk for atherosclerosis in COPD patients. Furthermore, we studied the anti-atherosclerotic effects of resveratrol which can be found in red wine and Asian medicinal herbs. Hyperlipidemic E3L.CETP mice were fed a diet without (control) or with resveratrol, atorvastatin, or both. Resveratrol protected against atherosclerosis development, but did not add to the anti-atherogenic effects of atorvastatin. Finally, the clinical implications and future perspectives of these results are discussed. Show less
Overgewicht en obesitas kunnen leiden tot insulineresistentie (type 2 diabetes mellitus) en hyperlipidemie, een risicofactor voor atherosclerose (aderverkalking). Obesitas gaat ook gepaard met de... Show moreOvergewicht en obesitas kunnen leiden tot insulineresistentie (type 2 diabetes mellitus) en hyperlipidemie, een risicofactor voor atherosclerose (aderverkalking). Obesitas gaat ook gepaard met de ontwikkeling van een chronische ontsteking in vetweefsel en lever. Met dit promotieonderzoek laten we met behulp van onderzoek in muizen zien dat ontsteking een belangrijke rol speelt in het metabolisme en transport van vetten. We bekijken ook welk effect dit heeft op de ontwikkeling van atherosclerose en type 2 diabetes. In het eerste deel van dit promotieonderzoek laten we zien dat ontsteking een belangrijke rol speelt in vetmetabolisme en atherosclerose. De ontstekingsremmer aspirine zorgde voor een verlaging van de hoeveelheid vet in het bloed. Activatie van een onsteking in de lever leidde juist tot een verhoging van vet in het bloed, wat de ontwikkeling van atherosclerose in de vaatwand verergerde. In het tweede deel van dit promotieonderzoek bestuderen we het belang van het inflammasoom/caspase-1 complex (betrokken bij ontstekingsprocessen) in obesitas, insulineresistentie en vetmetabolisme. We laten zien dat muizen die een deel van dit eiwit-complex missen, beschermt zijn tegen de ontwikkeling van obesitas en insulineresistentie. Het inflammasoom/caspase-1 complex lijkt daarmee een potentieel target voor de behandeling van obesitas, insulineresistentie en type 2 diabetes. Show less
The aim of this thesis is to evaluate the effect of doxycycline on the proteolytic and inflammatory processes in abdominal aneurysms. This data is essential for the development of pharmaceutical... Show moreThe aim of this thesis is to evaluate the effect of doxycycline on the proteolytic and inflammatory processes in abdominal aneurysms. This data is essential for the development of pharmaceutical strategies for the stabilization of an AAA. Such an approach could reduce the need for elective surgery and endovascular repair. It has repeatedly been shown that AAA progression and rupture is related to the failure of collagen in the aortic wall. Yet the exact mechanism underlying this failure remains unknown. Furthermore, the precise mechanism of activation of collagenases and their inflammatory mediators that are responsible for the collagen turnover of AAA are unknown. In this thesis we attempt to determine how collagen metabolism is balanced in aneurysmal diseases and contribute to the knowledge which collagenases and inflammatory mediators are involved in the destruction of the collagen network in AAA disease. Moreover, we evaluate some of the effects of doxycycline on the proteases and inflammatory mediators in AAA. Analyses showed that doxycycline inhibits specific MMPs and inflammatory pathways that are involved in the collagen balance and aneurysm growth. Together, these observations provide a rationale for a randomized clinical trial studying the effect of doxycycline on aneurysm growth. Show less
Een effectieve diagnose voor hart- en vaatziekten kan op dit moment pas gesteld worden als de ziekte zich al in een vergevorderd stadium bevindt of als er klinische symptomen (beroerte) zijn... Show moreEen effectieve diagnose voor hart- en vaatziekten kan op dit moment pas gesteld worden als de ziekte zich al in een vergevorderd stadium bevindt of als er klinische symptomen (beroerte) zijn opgetreden. Tijdens mijn promotieonderzoek heb ik in samenwerking met de farmaceutische industrie (Guerbet) aandacht besteed aan het synthetiseren en valideren van kleine eiwitten die specifiek binden en opgenomen worden door receptoren waarvan aangetoond is dat deze verhoogd tot expressie komen of een specifieke rol spelen in atherosclerose. Dit heeft geleid tot de synthese van 2 kleine eiwitten (PP1 en NP31) die specifiek gericht zijn tegen respectievelijk de scavenger receptor en de CD40 receptor. De scavenger receptor komt verhoogd tot expressie op macrofagen en zorgt voor de verwijdering van slecht cholesterol uit de bloedbaan en vaatwand. De CD40 receptor speelt een belangrijke rol bij de initiatie en in standhouding van de ontstekingsreactie bij atherosclerose. Het onderzoek beschreven in dit proefschrift geeft nieuwe inzichten in mogelijke toepassingen van synthetisch eiwitten die specifiek binden aan receptoren die belangrijk zijn tijdens de ontwikkeling van hart- en vaatziekten. De verschillende synthetische liganden kunnen gezien worden als potenti_le kandidaat-eiwitten voor verbeterde beeldvormingtechnieken van atherosclerotische plaques. Show less
The studies described in this thesis show that inflammation and CETP are both important factors in lipid metabolism and atherosclerosis. In the first part of this thesis we showed that high dietary... Show moreThe studies described in this thesis show that inflammation and CETP are both important factors in lipid metabolism and atherosclerosis. In the first part of this thesis we showed that high dietary cholesterol can induce hepatic inflammation via disturbed cholesterol homeostasis and ER stress, revealing new targets for the treatment of metabolic inflammation. Next, we demonstrated that intervention in both systemic and vascular inflammation can reduce atherosclerosis progression and/ or induce regression, highlighting the importance of developing drugs targeting the inflammatory component of atherosclerotic disease. In the second part of this thesis we showed that CETP inhibition per se may be anti-atherogenic, but that combination therapy of the CETP inhibitor torcetrapib with atorvastatin may have obscured its atheroprotective effect. Furthermore, we showed that the VLDL-increasing effect of CETP largely explains its atherogenic effect, at least in APOE*3-Leiden.CETP mice, and that CETP inhibition may negatively affect lesion stability. Our data suggest that CETP inhibition may not be the most optimal strategy to increase HDL-C levels and thereby reduce atherosclerosis. We anticipate that strategies improving HDL functionality, rather than raising the HDL level, are more likely to effectively reduce CVD. Show less
In this thesis the role of several apoptosis regulating proteins in the development of atherosclerosis and atherosclerotic plaque stability is investigated. Apoptosis of different cell types in... Show moreIn this thesis the role of several apoptosis regulating proteins in the development of atherosclerosis and atherosclerotic plaque stability is investigated. Apoptosis of different cell types in atherosclerotic plaques, such as macrophages and smooth muscle cells may inhibit or promote plaque development or stability depending on the stage of atherosclerosis. As many of these apoptosis regulating proteins also display immune-modulating features, we have particularly investigated effects of modulation of apoptosis regulating proteins on plaque and systemic inflammation. We performed a number of studies in mouse models of atherosclerosis. First gene expression profiles of stable and unstable atherosclerotic plaques were compared in order to identify genes or pathways that are associated with plaque vulnerability. We further developed transgenic mice partially or wholly lacking genes involved in apoptosis and/or inflammation such as Bcl-2 family members and focal adhesion kinase, both systemically or in the leukocyte subset. The studies described in this thesis show amongst other things that Bim and Mcl-1, both members of the Bcl-2 family of apoptosis regulators, regulate specific cell death and inflammatory processes relevant to atherosclerosis. Show less
