Obesity, type 2 diabetes and cardiovascular diseases are major public health problems. South Asians are specifically at risk for the development of (cardio)metabolic diseases, due to a... Show moreObesity, type 2 diabetes and cardiovascular diseases are major public health problems. South Asians are specifically at risk for the development of (cardio)metabolic diseases, due to a combination of known and unknown risk factors. Since effective long-term treatment strategies are currently lacking, the search for additional risk factors and development of targeted treatment strategies to combat these (cardio)metabolic diseases is warranted. An attractive approach seems to be activation of energy-combusting brown adipose tissue (BAT), which can result in increased energy expenditure and improvement in glucose and lipid metabolism. In this thesis, we aimed to address two key objectives: 1) unravelling the underlying mechanisms that could explain the increased predisposition for metabolic disease in the South Asian population, and 2) identifying novel pharmacological strategies that activate BAT and increase energy expenditure in risk populations, including South Asians and individuals with overweight and prediabetes. The studies described in this thesis have highlighted some novel factors, such as endocannabinoids and angiopoitein-like-protein-4, that might in part explain to unbeneficial metabolic phenotype of South Asians. In addition, novel potential therapeutic strategies were identified to combat metabolic disease, such as treatment with a β3-adrenergic receptor agonist and a dipeptidyl-peptidase-4 inhibitor. Show less
Cardiovascular disease is the number one cause of death worldwide. The most important risk factor for developing this disease is high cholesterol levels in the blood. Other risk factors... Show moreCardiovascular disease is the number one cause of death worldwide. The most important risk factor for developing this disease is high cholesterol levels in the blood. Other risk factors contributing to cardiovascular disease can develop in individuals which are overweight. The clinical consequences of being overweight are clustered in the medical term: metabolic syndrome. Included in the metabolic syndrome are high blood pressure, dyslipidemia and glucose intolerance. At present, most cardiovascular disease patients are treated with statins which lower blood cholesterol levels. However, this treatment is not as effective in all patients and can cause some adverse drug reactions. Therefore, it is essential that novel therapeutic targets for the treatment of cardiovascular disease are identified. In this thesis, potential novel therapeutic targets in cardiovascular disease and metabolic syndrome are validated. In total, three potential targets were investigated: proteoglycan 4, protein arginine methyltransferase 3 and stabilin 1. Our studies showed the involvement of two of these targets in the development of cardiovascular disease and metabolic syndrome. Moreover, our results stress (1) that cardiovascular disease and metabolic syndrome are complex, multifactorial diseases with overlapping mechanisms and (2) that integration of research into both diseases can benefit therapeutic target identification and validation. Show less
Worldwide, there is an strong rise of cardiometabolic disorders, which mainly comprise obesity, cardiovascular disease (CVD) and type 2 diabetes. Therefore, the development and improvement of... Show moreWorldwide, there is an strong rise of cardiometabolic disorders, which mainly comprise obesity, cardiovascular disease (CVD) and type 2 diabetes. Therefore, the development and improvement of preventive and curative strategies for cardiometabolic disease is eagerly warranted. With the studies describes in this thesis, we aimed to disentangle the interwoven physiological, environmental and genetic factors that determine cholesterol and energy metabolism to increase our understanding of their contribution to cardiometabolic disease risk. The first part of this thesis focussed on the cholesteryl ester transfer protein (CETP). The lipid transfer properties of CETP induce a proatherogenic lipoprotein profile. Therefore, CETP inhibitory molecules have been developed and tested in clinical trials for their capability to improve the lipoprotein profile and reduce CVD risk. To fully understand the role of CETP in CVD, its physiology and biological function should be fully unravelled. The focus of the second part of this thesis was on the role of energy metabolism in cardiometabolic health. Specifically, we aimed to study the association of environmental and genetic factors, which were previously described to influence brown adipose tissue (BAT) activity, with energy expenditure and disease outcomes. Show less
Weighing the strengths and limitations of our studies, we believe our results contribute to the unraveling of causal pathways between obesity and lung function impairment. The main conclusion of... Show moreWeighing the strengths and limitations of our studies, we believe our results contribute to the unraveling of causal pathways between obesity and lung function impairment. The main conclusion of the first part of this thesis is that visceral fat is associated with lung function impairment in men with the metabolic syndrome. Furthermore, we conclude that in the general population there is no causal association between insulin resistance and lung function, nor an association between visceral fat and exhaled nitric oxide. In the second part of this thesis we showed that vitamin D is associated with lung function and nitric oxide in obese participants.In the study presented in this thesis antimicrobial peptides levels were lower in allergic asthmatics than in healthy controls. Unfortunately, we were not able to conclude if vitamin D supplementation influences these antimicrobial peptide levels. Larger studies are needed to investigate whether vitamin D also increases antimicrobial peptides in the lung.In summary, obesity is a global burden that influences lung function. Future research should reveal if obesity, and in particular visceral fat, causes lung inflammation and thereby impairs lung function.Large randomized trials are necessary to establish the effect of vitamin D therapy on infections in vitamin deficient patients. Show less
Immunometabolism focusses on the interplay between immunological and metabolic processes, both at a systemic and a cellular level. This thesis is divided into two parts based on these two... Show moreImmunometabolism focusses on the interplay between immunological and metabolic processes, both at a systemic and a cellular level. This thesis is divided into two parts based on these two levels. The first part focusses on the infrapatellar fat pad (IFP), an adipose tissue located in the knee, and the potential role in the pathophysiology of osteoarthritis. Therefore, we characterized the IFP based on a cellular and molecular level and found that the inflammatory state of the joint does affect the cellular load of the IFP, however, the secretory profile of the IFP does not seem to be affected. Furthermore, obesity-related changes normally found in adipose tissue were not present in the IFP. When characterizing the IFP we found two interesting cell populations, IL-6-secreting T cells and macrophages with an anti-inflammatory phenotype secreting pro-inflammatory cytokines. Both populations could be involved in the pathophysiology of the osteoarthritic joint. Furthermore, in the second part we focussed on cellular metabolism where we determined the mechanism by which fatty acids exert their effect on T cells. We found that fatty acids are not served as energy, however, whether it is used for daughter cells or influencing cell signalling remains to be elucidated. Show less
