A strong correlation exists between abdominal aortopathy and atherosclerosis. In thoracic aortopathy however, the prevalence of atherosclerosis and its role in the etiology of thoracic aortopathy... Show moreA strong correlation exists between abdominal aortopathy and atherosclerosis. In thoracic aortopathy however, the prevalence of atherosclerosis and its role in the etiology of thoracic aortopathy remained unknown. This thesis therefore studied the cardiovascular disease burden within this patient group. These results showed that the prevalence of atherosclerosis (i.e. cardiovascular disease burden), in contrast to abdominal aortopathy, is not increased within the thoracic aortopathy population. Show less
Acute cardiovascular syndromes, including myocardial infarction or stroke, are the principal cause of death in the Western society. The main underlying pathology of cardiovascular diseases is... Show moreAcute cardiovascular syndromes, including myocardial infarction or stroke, are the principal cause of death in the Western society. The main underlying pathology of cardiovascular diseases is atherosclerosis, which is caused by the accumulation of lipids and inflammatory cells in the vessel wall, in so-called atherosclerotic plaques. Current therapies mainly target the disturbed lipid homeostasis, but recent clinical trials have shown a clear benefit in treating patients with anti-inflammatory drugs. However, more specific targeting is required to avoid unwanted side effects. In this thesis, we have generated a detailed atlas of all the cells present in human atherosclerotic plaques using a novel state-of-the-art technique called single-cell RNA sequencing. This data set can be applied as a powerful tool to select potential drug targets with a functional relevance for atherosclerosis. We showed that the majority of the immune cells in the human atherosclerotic plaque consisted of T cells. Subsequently, we identified a pro-inflammatory population of T cells that likely responds to a plaque-derived antigen, suggesting that atherosclerosis has an autoimmune-like component. Finally, we have applied our single-cell atlas to define and validate targets to intervene with the recruitment and activation of mast cells and other immune cells in atherosclerosis. Show less
There is an increasing number of adults who suffer from cardiovascular diseases (CVD). These patients would benefit from a healthy lifestyle, as this improves the prognosis of CVD. However, even... Show moreThere is an increasing number of adults who suffer from cardiovascular diseases (CVD). These patients would benefit from a healthy lifestyle, as this improves the prognosis of CVD. However, even though improving one’s health and lifestyle is the focus of cardiac rehabilitation, CVD patients need support to also maintain a healthy lifestyle after their rehabilitation has ended. Even though the support of a healthcare professional seems to be an important factor in successful lifestyle change, there are barriers that hinder professionals from providing lifestyle support, such as a lack of time or expertise. Since the involvement of healthcare professionals is also not always possible or desirable, it is important to further investigate possibilities to provide patients with a self-help eHealth intervention. In such self-help eHealth interventions, feedback is automatically provided, making the interference of a healthcare professional no longer needed. However, self-help eHealth interventions can suffer from a low uptake and a low level of adherence. This PhD dissertation therefore focuses on (1) mapping out the needs and wishes of both healthcare professionals and CVD patients with regard to (human-supported and self-help) eHealth lifestyle interventions, and (2) investigating if and how self-help eHealth lifestyle interventions could be optimised. Show less
Two types of financial incentives can help improve healthy lifestyles: carrots (a reward where one can gain something) and sticks (a deposit contract where one can lose something). In a deposit... Show moreTwo types of financial incentives can help improve healthy lifestyles: carrots (a reward where one can gain something) and sticks (a deposit contract where one can lose something). In a deposit contract, participants deposit own money and can lose or earn it back depending on lifestyle changes. We studied the potential of deposit contracts to stimulate a healthy lifestyle.A smartphone app was developed together with the Swiss university ETH Zurich to conduct experimental research into the effects of deposit contracts. In addition, we collaborated with the American company WayBetter to observe the effects of commercially available deposit contracts. Finally, the opinion of people with cardiovascular disease and healthcare professionals regarding financial incentives and deposit contracts for lifestyle change was investigated.The results show that deposit contracts can have strong effects on exercise behavior (daily step counts) in the short term. The results also show that voluntary participation in deposit contracts is limited, but can be increased by doubling the amount deposited and by allowing participants to determine the amount themselves. Finally, healthcare providers think it is a good idea to use financial incentives, but people with cardiovascular disease themselves are skeptical about the use of deposit contracts. Show less
Cardiovascular diseases are the leading cause of death worldwide, with atherosclerosis as most common underlying pathology. Atherosclerosis is characterized by arterial narrowing due to cholesterol... Show moreCardiovascular diseases are the leading cause of death worldwide, with atherosclerosis as most common underlying pathology. Atherosclerosis is characterized by arterial narrowing due to cholesterol and lipid accumulation. Despite available effective cholesterol lowering medication, considerable risk for recurrent vascular events remains. This residual risk is at least in part explained by high blood lipid levels. The research described in this thesis revealed novel therapeutic strategies that improve lipid metabolism and reduce atherosclerosis development in mice. Inhibition of the endocannabinoid system was found to be an effective strategy, as well as concomitant activation of two incretin hormone receptors, namely those for GIP and GLP1. For combined GIP/GLP1 receptor agonism we additionally showed strongly attenuated hepatic steatosis. We were also able to identify additional targets to attenuate hyperlipidemia by studying the mechanisms underlying the strong day-night rhythm of brown adipose tissue, which is a lipid combusting tissue. In this thesis, I also stress the importance of the choice in animal model when studying lipid-modifying interventions, and describe the development of the software tool RandoMice which can be used to improve the quality of preclinical studies by creating well-balanced experimental groups. Show less
The prevalence of cardiovascular diseases has increased in the last decennia. This thesis studied the potential relationship between oxidative stress and cardiovascular diseases. The first part of... Show moreThe prevalence of cardiovascular diseases has increased in the last decennia. This thesis studied the potential relationship between oxidative stress and cardiovascular diseases. The first part of the thesis focused on anti-oxidants, which are scavengers that protect against oxidative damage. We studied the association between several lifestyle factors, diet, physical activity, sleep, alcohol intake and smoking, and antioxidant levels both in blood and urine. Subsequently, we investigated whether a higher concentration of antioxidants leads to a decrease in ischaemic stroke occurrence. Next, we aimed to study a possible cause of oxidative damage and its effect on cardiovascular disease. Mitochondrial dysfunction is one of the mechanisms that may underly this effect. Mitochondria are an important source of Reactive Oxygen Species (ROS), as an inevitable byproduct of their essential role in energy production. A disbalance in ROS production and scavenging might result in oxidative damage. Thus, we investigated the causal association between mitochondrial dysfunction and stroke using the Mendelian Randomization method. Finally, we studied how socio-demographic traits could modify the causal association between CVD risk factors and coronary artery disease. Show less
Cardiovascular disease is the leading cause of death in the world. Therefore, there is an increasing need for accurate and efficient cardiovascular risk assessment to optimize cardiovascular... Show moreCardiovascular disease is the leading cause of death in the world. Therefore, there is an increasing need for accurate and efficient cardiovascular risk assessment to optimize cardiovascular treatment. The aorta plays a central role in the cardiovascular system, transporting blood to various organ systems while absorbing the pulsatile pressure of the cardiac output. Aortic stiffness is a marker of vascular aging and has shown to be an independent marker for cardiovascular risk. Additionally, enlarged aortic dimensions are linked to an increased risk of rupture. MRI is capable of providing accurate information on aortic morphology, stiffness and blood flow patterns.In this thesis we expanded the potential clinical utility of MRI-based measures of aortic morphology and function in the assessment of cardiovascular risk and further unravelled complex cardiovascular systemic interactions using MRI. We provided standardized methods and reference values for fundamental MRI-based measures of aortic morphology and function, explored new methods to make PWV more accessible, evaluated the prognostic value of MRI-based measures of aortic morphology and function and explored systemic interactions of cardiovascular function with obesity as well as the brain. These studies contribute to more accurate and accessible cardiovascular risk assessment, which eventually can lead to improved cardiovascular treatment. Show less
Cardiovascular disease (CVD) is a major cause of death worldwide. The underlying cause of most CVD is atherosclerosis. Atherosclerosis is characterized by progressive plaque build-up in the... Show moreCardiovascular disease (CVD) is a major cause of death worldwide. The underlying cause of most CVD is atherosclerosis. Atherosclerosis is characterized by progressive plaque build-up in the arterial wall.Noncoding RNAs (ncRNAs) are RNAs that are not translated into protein. This thesis focuses on two types: microRNAs and small nucleolar RNAs (snoRNAs). MicroRNAs inhibit the production of proteins and act on multiple proteins simultaneously. In CVD, many different proteins are involved. Changing expression of one microRNA can therefore have a major impact.Numerous snoRNAs have been associated with diseases, including CVD. The function of half of the human C/D box snoRNAs, however, is unknown.The first aim of this thesis is to investigate inhibition of microRNA-494-3p in advanced atherosclerosis. The second aim is to elucidate the function of SNORD113-6, a snoRNA that is involved in CVD.The thesis shows that inhibition of microRNA-494-3p halts plaque progression and increases stability of advanced plaques. This reduces the risk of e.g. a myocardial infarction.Furthermore, SNORD113-6 influences the function of fibroblasts, scar cells, and thus plays a role in maintaining function of our blood vessels.These insights may open up new therapeutic possibilities in future treatment of CVD. Show less
This thesis investigates the effectiveness and safety of treatments in patients with cardiovascular and kidney disease. Routinely collected healthcare data provide an immense opportunity to... Show moreThis thesis investigates the effectiveness and safety of treatments in patients with cardiovascular and kidney disease. Routinely collected healthcare data provide an immense opportunity to investigate such questions in populations underrepresented in clinical trials, such as patients with advanced chronic kidney disease (CKD).The first part of this thesis deals with how to appropriately use routinely collected data to answer causal questions. It illustrates what study designs eliminate commonly occurring biases, namely immortal time and prevalent user bias, and how to use propensity scores to correctly adjust for confounding in the setting of time-fixed and time-varying treatments.The second part investigates the effectiveness and safety of various treatments. For instance, the effectiveness of beta-blockers in patients with heart failure and advanced CKD is investigated. Renin-angiotensin system inhibitors (RASi) are an especially widely used medication class in CKD patients. The relationship between the magnitude of renal function decline - which is commonly observed after initiation of these drugs - with mortality and cardiorenal outcomes is investigated. In addition, comparative effectiveness study of RASi and calcium channel blockers among patients with advanced CKD is performed. In the last two chapters, a target trial is explicitly emulated to investigate the effect of stopping or continuing RASi and the optimal timing to start dialysis in patients with advanced chronic kidney disease. Show less
Throughout evolution, humans have lived in synchrony with the natural light-dark cycle. Our bodies were used to going to sleep a few hours after dark, and waking up just before dawn. However, in... Show moreThroughout evolution, humans have lived in synchrony with the natural light-dark cycle. Our bodies were used to going to sleep a few hours after dark, and waking up just before dawn. However, in modern society the unambiguous availability of artificial light has desynchronized our biological clock from the naturally occurring day and night, with large consequences for metabolic health. This thesis sheds light on the negative health consequences of a disturbed biological clock, and elucidates novel approaches to prevent disease associated with chronic rhythm disruption, as occurs in shift work. We have identified important mechanisms through which rhythm disruption contributes to (cardio)metabolic disease, namely by exacerbating vascular inflammation and by deregulating rhythm in glucocorticoid hormone, thereby affecting the metabolic activity of tissues such as brown fat and bone. We continued by investigating two main approaches to prevent diseases associated with circadian disturbances: (1) by limiting disruption of the circadian timing system, and (2) by directly targeting the affected tissues. We found that timed feeding (1) and stimulation of the metabolic activity of brown fat (2) are both promising strategies to prevent and/or reduce (cardio)metabolic disease risk in the ever-increasing population of individuals who suffer from circadian disturbances. Show less
14q32 microRNAs are known to play a role in various forms of vascular remodelling. This thesis elucidated that snoRNAs of the 14q32 locus are also involved in vascular remodelling processes. The... Show more14q32 microRNAs are known to play a role in various forms of vascular remodelling. This thesis elucidated that snoRNAs of the 14q32 locus are also involved in vascular remodelling processes. The expression of both noncoding RNA types in the human vasculature has been found to be vascular location and vessel type specific and are therefore promising targets for future implementation in clinical practice.The second part of this thesis focuses on three different types of 14q32 microRNA expression regulation in order to affect various vascular remodelling processes. 14q32 DNA methylation, myostatin and CIRBP were tested for their effect on 14q32 microRNA expression and the (subsequent) effect on vein graft disease and tissue ischemia, restenosis and angiogenesis, respectively. DNA methylation is not correlated with 14q32 microRNA expression, but directly interacts with vascular remodelling process status. Myostatin negatively affects 14q32 microRNA expression in vascular smooth muscle cells, but not in inflammatory cells involved in restenosis. Due to this latter finding, overall restenosis was not inhibited by myostatin. Inhibition of CIRBP inhibited 14q32 microRNA expression post-transcriptionally and therefore increased in vitro angiogenesis. These promising findings provide novel indirect regulators of vascular remodelling processes and future research will elucidate the potential for clinical application. Show less
This thesis examines how both genetic and more conventional epidemiological endeavors may complement research into effects of statin therapy. These include a pharmacogenetic GWAS meta-analysis... Show moreThis thesis examines how both genetic and more conventional epidemiological endeavors may complement research into effects of statin therapy. These include a pharmacogenetic GWAS meta-analysis on statin-induced HDL-C response by the Genomic Investigation of consortium, which identified CETP as a loci of interest, and two-sample Mendelian randomization studies utilizing summary level data from the GIST and other GWAS consortia on fasted blood lipids and type 2 diabetes. We additionally examine the issue of survival bias in Mendelian randomization studies. Finally, we show that intra-individual lipid variability associates with worse neurocognitive outcomes in older individuals at high risk for vascular disease, discuss its interplay with lipid-lowering treatment, and describe the literature regarding genetic factors of possible interest. Show less
Atherosclerosis is the main underlying pathology of cardiovascular disease. Atherosclerosis is caused by an immune response which is directed against (modified) lipoproteins which accumulate in the... Show moreAtherosclerosis is the main underlying pathology of cardiovascular disease. Atherosclerosis is caused by an immune response which is directed against (modified) lipoproteins which accumulate in the vessel wall. Over time, this accumulation of lipids and immune cells induce morphological abnormalities in the vessel wall which cause the vessel lumen to narrow. This narrowing of the lumen (stenosis) causes ischemia in the downstream tissue. Prolonged ischemia causes myocardial ischemia and/or stroke. The research described in my thesis examines a well-recognized risk factor of atherosclerosis, being dyslipidemia, from an entirely new perspective. More specifically, it describes how dyslipidemia affects intrinsic metabolic processes in T cells, the conductors of the immune response characterizing atherosclerosis, and how this affects their function. My research has contributed to knowledge on the pathophysiology of atherosclerosis and might one day pave the way for the development of novel therapeutic approaches to treat cardiovascular disease. Show less
Metabolic disease has become pandemic in the developed world. Given our lack of understanding of its molecular pathology, we are often unable to diagnose patients before they reach an... Show moreMetabolic disease has become pandemic in the developed world. Given our lack of understanding of its molecular pathology, we are often unable to diagnose patients before they reach an irreversible state of diabetes or cardiovascular disease. Much research has been done on the role of insulin signaling in metabolic disease, as well as the resultant disturbed lipid homeostasis present in cardiovascular disease and atherosclerosis. Here we add to existing work by developing new tools and sketching out the pathology of dysregulated adipose insulin signaling. We discuss the mechanism of lipodystrophy by using adipocytes differentiated from patient-derived iPSCs. These cells mimic the clinical phenotype and hint at mechanism that reduced patients’ adipose tissue mass. In mice we find that if we knock out the adipose insulin receptor, there is disrupted adipose and liver metabolism. There is a protection from diet-induced obesity, but a dramatically reduced lifespan. We also establish a relationship between obesity and inflammation by transcriptomically assessing obese human adipocytes. We find that an immune factor is responsible for lipid droplet formation and content. Lastly, we develop a new differentiation and purification strategy for iPSC-derived hepatocytes, which we employ to in vitro model a SNP that protects against cardiovascular disease. Show less
Cardiovascular disease (CVD) is the leading cause of death in women in the Western world. In this thesis, several studies are presented examining the association between recurrent miscarriage and... Show moreCardiovascular disease (CVD) is the leading cause of death in women in the Western world. In this thesis, several studies are presented examining the association between recurrent miscarriage and cardiovascular disease. Main aim of this thesis was to assess whether miscarriages are independently associated with an increased risk of cardiovascular disease later in life. And, if this was true, to identify cardiovascular risk factors and predict long term cardiovascular disease risk in women with a history of recurrent miscarriage. We found an increased risk of ischemic heart disease in women with a history of two (multivariate analysis HR 1.82) and three or more miscarriages (HR 3.18), irrespective whether consecutive or not (chapter 2). Women with a history of recurrent miscarriage have significantly higher 10- and 30-year cardiovascular risk scores compared to women with a history of no miscarriage. These results indicate an opportunity for the early identification of women prone to cardiovascular disease later in life. Women with a history of two or more miscarriages must be made aware of their increased cardiovascular risk and appropriate risk factor modifications will have to be offered, for example life style advises; weight management and smoking control. Show less
Atherosclerotic changes of the carotid artery are associated with elevated cardiovascular risk. Non-invasive imaging studies of the artery can provide information on the presence or absence of... Show moreAtherosclerotic changes of the carotid artery are associated with elevated cardiovascular risk. Non-invasive imaging studies of the artery can provide information on the presence or absence of abnormalities. Although the techniques are extensively used in clinical research their implementation in common practice is not widespread. In this thesis the potential benefits and challenges of carotid imaging in clinical practice are studied. Ultrasound and magnetic resonance imaging are the two modalities of interest. The findings suggest that ultrasound can be performed by the clinician in a routine outpatient setting. Clinicians are able to detect atherosclerotic plaques but not intima-media thickness. Plaques are highly prevalent in asymptomatic primary prevention patients. Magnetic resonance imaging is a new highly reproducible modality but requires further clinical validation. Its utility in individual patient risk assessment is unclear and ultrasound validity cannot be extrapolated to magnetic resonance. The use of a combination of the two imaging modalities may allow for estimation of the lamina adventitia in vivo. Finally, interpretation of the imaging parameters must be done in conjunction with all cardiovascular risk factors and treatment decision should not be based on imaging results alone. Show less
Cardiovascular syndromes are the major cause of death in Western societies. The main underlying pathology is atherosclerosis, a chronic disease affecting the arteries. During atherosclerosis... Show moreCardiovascular syndromes are the major cause of death in Western societies. The main underlying pathology is atherosclerosis, a chronic disease affecting the arteries. During atherosclerosis progression, LDL, or “bad” cholesterol, accumulates in the arterial wall, resulting in the formation of a lipid-rich atherosclerotic plaque. This event activates the immune system, which increases plaque inflammation. Mast cells are components of the immune system known for their role in allergy. However, it has been established that mast cells are also important in atherosclerosis. In this PhD dissertation, we explored the interaction of mast cells with other immune cells. We examined the interrelation between mast cells and T-lymphocytes and discovered that mast cells can function as antigen presenting cells in atherosclerosis and, enhance the development of an atherosclerotic plaque via a direct interaction. Nonetheless, mast cells can also act on the Natural Killer T-cells, resulting in a protective function against atherosclerosis. Importantly, we used a relatively novel technical approach to explore the characteristics of mast cells inside human atherosclerotic plaques. We found that mast cells are highly activated and thus possibly promote disease progression. In conclusion, mast cells possess both protective and harmful effects, acting as regulators of the immune response in atherosclerosis. Show less
Cardiovascular diseases (CVD) are the leading cause of death worldwide, and disturbances in day-night rhythms have recently been implicated as a novel risk factor for CVD. We investigated the... Show moreCardiovascular diseases (CVD) are the leading cause of death worldwide, and disturbances in day-night rhythms have recently been implicated as a novel risk factor for CVD. We investigated the effects of modulating circadian rhythms on energy metabolism using animal models and by studying plasma metaoblites and lipids in humans. Using animal studies we observed that brown adipose tissue (BAT) is strongly regulated by the biological clock, possibly via circadian glucocorticoid rhythms, and attenuated BAT activity through prolonged light exposure increases adiposity. Research focusing on the rhythm in human BAT, and regulation thereof, is necessary to confirm the translational value of our findings. We also observed that mistimed light exposure enhances atherosclerosis development, which may provide a mechanistic link between the known association between shift work and CVD. We anticipate that living according to the natural circadian rhythms presumably contributes to cardiometabolic health. Since disturbances in day-night rhythms are inevitable in modern society, in the future we may advise individuals at risk for development of CVD refrain from shift work and short sleep duration. In addition, data in this thesis may be useful to design strategies to avoid the disadvantageous metabolic effects of shift work. Show less
In this thesis we observe that prescription rates of lipid-lowering drugs and antithrombotic medication in secondary prevention in old age are low. According to focus-group discussions with general... Show moreIn this thesis we observe that prescription rates of lipid-lowering drugs and antithrombotic medication in secondary prevention in old age are low. According to focus-group discussions with general practitioners highly individualized care with the ultimate aim to improve quality of life, might largely explain these low prescription rates; however, improvements might be expected from structured follow up, and tailored, age-specific guidelines, reflecting the heterogeneity of clinical practice. In very old age we observed that the severity of the cardiovascular disease history is associated with unfavourable prognosis, not only with regard to (recurrent) cardiovascular disease/mortality, but also with regard to future disability and cognitive decline. Of four newer cardiovascular risk markers N-terminal pro B-type natriuretic peptide (NT-proBNP) was the strongest predictor of cardiovascular events/mortality in secondary cardiovascular prevention in very old age. NT-proBNP was also associated with cognitive and functional decline. Finally NT-proBNP predicted treatment effect of pravastatin. In order to improve patient care in older age, the following actions are recommended: vigorous ICPC coding and pro-active follow-up of all older patients with a history of cardiovascular disease. Finally, optimisation of secondary cardiovascular prevention is advised by individualised risk prediction and consciously weighing all pros and cons of preventive treatment. Show less
During this research project we studied circulating cells in the blood of people with cardiovascular disease, we investigated if these cells could be used as biomarkers for future cardiovascular... Show moreDuring this research project we studied circulating cells in the blood of people with cardiovascular disease, we investigated if these cells could be used as biomarkers for future cardiovascular incidents. We specifically looked at circulating immune cells such as monocytes, T cells and neutrophils. It was shown that both specific subsets of monocytes as well as neutrophils could be used to predict cardiovascular events in patients with cardiovascular disease. Surprisingly it was shown that different cell subsets were predictive for cardiovascular events in men and women. Investigating the difference between men and women further we show that the acute immune response in during cardiovascular disease is different between men and women. While the response in males was skewed towards a monocyte response, in women the acute response was skewed towards a T cell response. The research presented in this thesis shows that our knowledge of the gender specific immune response in cardiovascular disease is limited and further research is necessary. Show less
