Lipid signaling is an essential biological event/process in a plethora of pathophysiological conditions. The underlying idea of this thesis is that many of the roles and the complex interplay of... Show moreLipid signaling is an essential biological event/process in a plethora of pathophysiological conditions. The underlying idea of this thesis is that many of the roles and the complex interplay of the individual signaling lipids in inflammatory processes and related conditions in health and disease is not well known, and therefore has to be studied integrally as a complex network. In order to study this complex interplay, an improved broad analytical method is necessary to analyze a wide range of different signaling lipid classes such as oxylipins, (nitro) free fatty acids, endocannabinoids, bile acids and different subclasses of lysophospholipids. Therefore, the aim of this thesis is to develop a better method to study signaling lipids, and to apply it to study the role of these molecules in several relevant biological questions for a better understanding of inflammation related pathophysiology including autoimmune diseases, neurodegeneration and regulatory effect of exercise training. Show less
To increase clinical success rate of drugs, a better understanding of drug action mechanism and disease dynamics is required. Metabolomics, which studies small molecules involved in biochemical... Show moreTo increase clinical success rate of drugs, a better understanding of drug action mechanism and disease dynamics is required. Metabolomics, which studies small molecules involved in biochemical processes in organisms, has shown to be a useful tool for this better understanding. In this thesis, we focus on the endocannabinoid system (ECS) and profiling its related metabolic pathways using liquid chromatography - mass spectrometry (LC-MS) based metabolomics techniques. The endocannabinoid system (ECS) is a signaling system involved in multiple physiological and pathological processes. Due to its wide distribution and complex network of metabolic interactions, the development of drugs targeting the ECS has seen high failure rates. To get a better understanding of the behavior of the ECS and related pathways, LC-MS platforms with wide coverage of the major ECS-related metabolites, or with high sensitivity that reaches low levels of metabolites, were developed and optimized. Furthermore, these metabolomics platforms were applied in clinical studies looking into cardiometabolic health, and revealed correlations between endogenous metabolite signaling, cardiometabolic health and the benefits of exercise. Show less
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 external tissues of plants and animals are colonized by microbial communities termed microbiota. When organisms are exposed to environmental pollutants, these substances will therefore... Show moreThe external tissues of plants and animals are colonized by microbial communities termed microbiota. When organisms are exposed to environmental pollutants, these substances will therefore encounter microbiota at the exposure interface. Many antimicrobial substances have been found to disturb beneficial interactions between microbiota and the host, thereby impairing host health. Nanomaterials exhibit nanoscale properties that could affect host health in two additional, understudied, microbiota-dependent ways. Firstly, owing to their large surface area, adsorption interactions between nanomaterials, microbial metabolites and microbes could alter the identity and colloidal stability of nanomaterials, and may influence the dispersal of microbes. Secondly, the immuno-modulatory effects of microbiota could affect the sensitivity of hosts to immunotoxic nanomaterials. In this dissertation, we use a combination of computational techniques and zebrafish larvae experiments to unravel and quantify these interactions. We predict the affinity of microbial metabolites to carbon and metal nanomaterials, and show that titanium dioxide nanoparticles can affect the dispersal of microbes through aquatic ecosystems, and across different life stages of oviparous animals. Additionally, we provide insight into microbiota-dependent signaling pathways that affect the sensitivity of zebrafish larvae to particle-specific, immunotoxic effects of silver nanoparticles. Altogether, these results contribute to mechanistic pathways for microbiota-inclusive nanomaterial safety assessment. Show less
This thesis focuses on the role of chemokine receptors CXCR3 and CCR2 in the inflammatory process and infection control using the zebrafish model. It describes the regulatory interplay between an... Show moreThis thesis focuses on the role of chemokine receptors CXCR3 and CCR2 in the inflammatory process and infection control using the zebrafish model. It describes the regulatory interplay between an atypical and a conventional chemokine receptor during chemotaxis in macrophages, the role of chemotactic signaling in cell polarization and explores an in vivo screening workflow for human anti-inflammatory drugs using zebrafish. 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
Despite recent clinical advances, breast cancer still remains one of the main causes of cancer-related death in women. The majority of these deaths are caused by metastatic disease, which is... Show moreDespite recent clinical advances, breast cancer still remains one of the main causes of cancer-related death in women. The majority of these deaths are caused by metastatic disease, which is still poorly understood and incurable. Recent clinical and experimental studies have shown that the role of the immune system in cancer progression and therapy responsiveness is paradoxical. While some immune cells are able to attack and kill cancer cells, other populations counteract anti-tumor immune responses and promote cancer progression. To provide optimal treatment options for patients with disseminated cancer, we need to gain a better understanding of the delicate balance between pro- and anti-tumor immunity. This thesis describes the complex interactions between innate and adaptive immune cells that facilitate metastatic spread in a mouse model of spontaneous invasive breast cancer. Moreover, this thesis describes that the use of chemo-immunotherapy as a therapeutic strategy can enhance anti-tumor immunity to fight breast cancer. 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
Inflammation is an immune reaction of the body to the external stimuli such as toxins or pathogens, and is characterized by redness, swelling, pain, and heat. The process of inflammation is... Show moreInflammation is an immune reaction of the body to the external stimuli such as toxins or pathogens, and is characterized by redness, swelling, pain, and heat. The process of inflammation is regulated by several pro-inflammatory and antiinflammatory cytokines. Tumor necrosis factor-_ (TNF-_) is a major pro-inflammatory cytokine involved in the inflammatory response.Elevated TNF-_ expression has been found to be associated with the development of diabetes, atherosclerosis, septic shock, and tumorigenesis. Thus inhibition of TNF-_ at any step of inflammatory pathways provides an attractive treatment for inflammatory diseases as well as for series of other common diseases.Plants provide an alternative sources of medicines used traditionally by people worldwide since thousands of years ago. The aim of this thesis was to develop methods for the rapid identification of active compounds in plant extracts by correlating NMR metabolomics and bioassay results by means of multivariate data analysis. This work demonstrates the great potential of NMR spectroscopy in combination with chemometrics for the screening of large set of crude extracts, to study the effects of different variables on the activity, and identifying sets of active compounds in complex mixtures like plant extracts. Show less
In the last decade the study of the innate immune system has gained renewed scientific momentum as a result of the discovery of essential receptor families, such as the Toll-like receptor (TLR)... Show moreIn the last decade the study of the innate immune system has gained renewed scientific momentum as a result of the discovery of essential receptor families, such as the Toll-like receptor (TLR) family, that are required for pathogen recognition. These receptors detect specific molecular structures of microorganisms and in turn are able to trigger host immune responses. The work described in this thesis focuses on the use of the zebrafish embryo as a model to study the vertebrate immune system in order to gain new insights into the mechanisms of innate immune defence against bacterial infections and TLR signalling. Making use of a Salmonella infection model in combination with microarray technology and gene knock-down studies we were able to thoroughly characterize the embryonic host transcriptome response to a bacterial infection. Furthermore, we have demonstrated important functions for key signalling molecules in the innate immune response, including Tlr5, MyD88 and Traf6 and discovered new downstream targets of the TLR signalling pathway. The data presented here will enable in-depth functional follow-up studies that will provide new insights into the mechanisms of innate immune defence systems. This, in combination with future applications of zebrafish embryo infection models in high-throughput compound screens, holds much promise for the discovery of novel anti-microbial and anti-inflammatory drugs. 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
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
