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
Invasive lobular carcinoma (ILC) is the second most common type of breast cancer. Hallmarks of ILC include disruption of adherens junctions and hyperactivation of phosphoinositide 3-kinase (PI3K)... Show moreInvasive lobular carcinoma (ILC) is the second most common type of breast cancer. Hallmarks of ILC include disruption of adherens junctions and hyperactivation of phosphoinositide 3-kinase (PI3K)-mTOR signaling. The tumor suppressor PTEN regulates PI3K signaling. We present a preclinical mouse model of ILC metastasis, based on inactivation of the adherens junction protein E-cadherin and the tumor suppressor p53 and surgical excision of primary tumors. In this model, pharmacological mTOR inhibition blocks growth of primary tumors as well as metastatic disease, and this response is partially dependent on the adaptive immune system. Loss of E-cadherin mouse mammary epithelium leads to apoptosis, and PTEN activation alone results in squamous metaplastic mammary tumors, but a combination of these events leads to ILC formation, indicating a causal role of PI3K signaling together with E-cadherin loss in ILC. Combined somatic loss of the adherens junction molecule p120 and p53 in the mouse mammary gland leads to metaplastic mammary tumors, and loss of p120 in breast cancer cell lines promotes anoikis resistance through hypersensitization of growth factor receptor (GFR) signaling. Combined inactivation of E-cadherin, p120 and p53 induces basal-like tumors, with an epithelial-to- mesenchymal-transition (EMT) phenotype, and no ILC formation. Show less
One of the pathological hallmarks of Alzheimer's disease is amyloid‑β accumulation in the parenchymal brain tissue. Amyloid‑β is also found in the vessel wall of patients with cerebral amyloid... Show moreOne of the pathological hallmarks of Alzheimer's disease is amyloid‑β accumulation in the parenchymal brain tissue. Amyloid‑β is also found in the vessel wall of patients with cerebral amyloid angiopathy (CAA). These pathological accumulations of the amyloid‑β peptide are referred to as amyloidosis. Both patients with AD and CAA also commonly show cerebrovascular dysfunction. The aim of this thesis was to improve our understanding of the relation between cerebrovascular dysfunction and amyloidosis. To that end, cerebrovascular function measurements were designed and carried out in mouse models of cerebral amyloidosis. Chapter 2 and 3 show improvements of the current techniques to measure cerebrovascular function in mice. Surprisingly however, no difference was found in cerebrovascular function in two different models of amyloidosis, as shown in chapter 4 and 5. Possible explanations of the negative findings are further discussed in chapter 6. Despite the negative connotation of the outcome this thesis, this work is another small step towards a better understanding of the exact relationship between cerebrovascular dysfunction and amyloid‑β deposition in AD and CAA patients. Ultimately, this will help in the design of highly needed novel therapies for AD and CAA. Show less
Using a variety of relevant preclinical mouse models, this thesis not only showed several ways to improve antibody-based cancer immunotherapy but also demonstrates the importance of the choice of... Show moreUsing a variety of relevant preclinical mouse models, this thesis not only showed several ways to improve antibody-based cancer immunotherapy but also demonstrates the importance of the choice of the model for the translational relevance of the preclinical observations. Show less
Autosomal Dominant Polycystic Kidney Disease (ADPKD) progression involves a complex interaction of different molecular pathways, ultimately leading to cyst growth and loss of kidney function. The... Show moreAutosomal Dominant Polycystic Kidney Disease (ADPKD) progression involves a complex interaction of different molecular pathways, ultimately leading to cyst growth and loss of kidney function. The exact mechanism behind cyst formation is still not clearly understood. Moreover, we know some of the molecular pathways involved in cyst initiation and progression, but we do not know at which stage of the disease they play a role. In this thesis, we investigated the molecular pathways involved in renal injury-repair mechanisms and ADPKD. According to the currently available literature, injury-repair and ADPKD are two extremely intertwined mechanisms, which not only are characterised by activation of similar molecular pathways but are also able to influence each other. In fact, injury is able to accelerate cyst formation and progression, and cyst growth can cause injury to the surrounding tissue. Thus, the introduction of injury in the context of ADPKD can help to characterize the steps of disease progression, particularly in the early phases of cyst initiation, and direct future research to new possible therapeutic targets. 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
The research in this thesis is aimed at the elucidation of the role of the glucocorticoid receptor (GR) in hippocampal neuroplasticity and functioning. To achieve this, we have developed a novel... Show moreThe research in this thesis is aimed at the elucidation of the role of the glucocorticoid receptor (GR) in hippocampal neuroplasticity and functioning. To achieve this, we have developed a novel method to specifically knockdown GR in a discrete cell population of the mouse brain. In this thesis I report silencing of GR expression selectively in a population of neuronal progenitors and immature neurons of the dentate gyrus, using RNA-interference (RNAi) delivered by a lentiviral vector. Characterization of these cells resulted in the discovery that GR knockdown causes a striking modulation of hippocampal neurogenesis and remodelling of hippocampal circuitry. Functional studies further revealed consequences of GR knockdown for contextual memory performance and behavioural coping strategies during stressful conditions. The results demonstrate the feasibility to apply RNAi in discrete cell populations for study of the action mechanism of glucocorticoids underlying control of neuroplasticity and behaviour. Show less
Activation of the complement system provides an important mechanism of defense of an organism against invading pathogens. In the healthy individual this defense is finely regulated to prevent... Show moreActivation of the complement system provides an important mechanism of defense of an organism against invading pathogens. In the healthy individual this defense is finely regulated to prevent attack of the complement system against cells and tissues of the host, however in abnormal situations this regulation can be out of balance. In the present thesis we look at a mouse model where the classical pathway of complement, in conjunction with anti-C1q autoantibodies, is shown to be involved in the development of renal disease (Chapter 2). In Chapter 3, a novel mouse model of complement-mediated glomerulonephritis is described. This model seems to be dependent on the alternative pathway of complement activation as well as on Fc receptors, and provides a novel tool to dissect the contribution of different effector systems in renal inflammation.Then the natural complement-inhibitory properties of the defensin Human Neutrophil Peptide-1 and the extracellular matrix molecules decorin and biglycan are investigated, which are presented to play a role in the regulation of complement in vitro, which hopefully can be extended to in vivo situations of health and disease in the near future (Chapter 4 & 5). The thesis is concluded with a general discussion in Chapter 6. Show less
In a murine model for rheumatoid arthritis, we wished to investigated whether it was possible to skew the immune response with a cellular vaccin to protect the mice against the induction and/or... Show moreIn a murine model for rheumatoid arthritis, we wished to investigated whether it was possible to skew the immune response with a cellular vaccin to protect the mice against the induction and/or progeression of arthritis. the model that was used for this purpose was Collagen-Induced Arthritis (CIA). As dendritic cells (DCs) are the main antigen-presenting cells and key players in setting immune responses and connecting innate witth adaptive immunity, it is favorable to use these cells to manipulate the immune system to circumvent autoimmunity, in this case CIA. Because CIA is still implicated as a Th1-mediated disease, the aim was to skew the immune system towards a more Th2-like phenotype or to induce a T cell with a regulatory capacity. Therefore, several ways to stimulate DCs and subsequently the evolving T cell response were selected, to analyze whether Th2 cells or regulatory T cells were activated, resulting in the inhibition of arthritis. Show less
This thesis examines different risk factors, in relation to restenosis after Percutaneous coronary interventions (PCI), with its main focus on genetic markers. Restenosis is the main drawback of... Show moreThis thesis examines different risk factors, in relation to restenosis after Percutaneous coronary interventions (PCI), with its main focus on genetic markers. Restenosis is the main drawback of PCI. Genetic variance poses an opportunity to enhance stratification of individuals who will be more prone to develop restenosis. Restenosis is a multifactorial process, therefore only limited part of the number of candidate genes that are potentially involved in restenosis can be described. Since the inflammatory reaction is known to be highly important in restenosis, our study has its main focus on inflammatory markers. To examine various candidate genes and their polymorphisms we made use of the GENetic DEterminants of Restenosis (GENDER) study, a multicenter follow-up study, including 3,104 consecutive patients, who were successfully treated with PCI. In the different chapters we describe the study population and the clinical and genetic factors investigated. Furthermore, we made use of a mouse model to improve our understanding of restenosis. Our results have contributed to a better understanding of the restenotic process, they could provide novel therapeutic targets as well as contribute to development of improved risk stratification of patients who are scheduled for elective PCI, thereby creating the opportunity to individualize treatment in the future. Show less
