The research described in this thesis shows that hypercholesterolemia, a well-established risk factor for atherosclerosis, can impact skin lipid pool and barrier function already at young age. In... Show moreThe research described in this thesis shows that hypercholesterolemia, a well-established risk factor for atherosclerosis, can impact skin lipid pool and barrier function already at young age. In the field of atherosclerosis, we showed that the small peptide Lyp-1 can be used as a targeting molecule in liposomal formulations to deliver liver X receptor agonist to plaque resident foam cells/lipid-rich macrophages. Elucidation of the mechanisms underlying the intercommunication between plasma lipids and skin lipids may also bring valuable opportunities to prevent and treat dermatological pathologies in dyslipidemic patients; perhaps in combination with anti-atherogenic therapies. Thus, by deepening our knowledge we may improve our advice to the patients and ultimately improve their quality of life. Show less
Hart- en vaatziekten zijn wereldwijd de belangrijkste doodsoorzaak, waarvan het grootste deel kan worden toegeschreven aan coronairlijden. De belangrijkste veroorzaker hiervan is atherosclerose... Show moreHart- en vaatziekten zijn wereldwijd de belangrijkste doodsoorzaak, waarvan het grootste deel kan worden toegeschreven aan coronairlijden. De belangrijkste veroorzaker hiervan is atherosclerose ofwel aderverkalking, wat een op zichzelf staande complexe lipide-gedreven chronische inflammatoire ontstekingsziekte is. Na een hartinfarct is tijdige reperfusie door een acute dotterbehandeling het belangrijkste doel om verdere schade aan de hartspier te beperken. Echter, het herstel van de coronaire perfusie zelf induceert myocardiale reperfusieschade. Gedurende vele jaren heeft translationeel onderzoek zicht gericht op immunomodulatie van deze post-ischemische inflammatierespons. Dit proefschrift omvat pre-klinisch onderzoek waarin gunstige modulatie van de post-ischemische inflammatierespons door farmacologische interventies met annexine A5 en phosphorylcholine antilichamen wordt aangetoond. Remming van bijvoorbeeld cytokine IL-6 en afweercellen als monocyten, macrofagen en leukocyten, resulteert na een hartinfarct in minder schade aan de hartspier met een verbetering van de resterende hartfunctie. Daarnaast werd onderzocht hoe een pre-klinisch experimenteel onderzoeksmodel kan worden geoptimaliseerd door rekening te houden met zowel ischemie-reperfusie schade als hypercholesterolemie, een belangrijke risicofactor voor hart- en vaatziekten. Door gebruik te maken van klinisch relevantere onderzoeksmodellen kunnen in de toekomst hopelijk meer veelbelovende pre-klinische onderzoeksresultaten succesvol worden vertaald naar de dagelijkse klinische praktijk. Ter introductie worden deze onderzoeksresultaten voorafgegaan door een state-of-the-art review waarin een overzicht wordt gegeven van alle fases die deze post-ischemische inflammatierespons omvat. Hierbij worden de meest toonaangevende onderzoeksresultaten betreffende modulatie van deze inflammatierespons beschreven. Na recente succesvolle grote klinische trials, zal in de toekomst een belangrijke rol zijn weggelegd voor modulatie van deze afweerreactie bij zowel atherosclerose als na een hartinfarct. Show less
Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition, by increasing hepatic low density lipoprotein (LDL) receptor (LDLR) levels, has emerged as a strategy to reduce atherosclerosis by... Show moreProprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition, by increasing hepatic low density lipoprotein (LDL) receptor (LDLR) levels, has emerged as a strategy to reduce atherosclerosis by lowering circulating very low density lipoprotein (VLDL)-cholesterol. We hypothesized that the therapeutic effectiveness of PCSK9 inhibition can be increased by accelerating the generation of VLDL remnants, which typically have a high affinity for the LDLR. Therefore, we aimed to investigate whether accelerating lipolytic processing of VLDL by brown fat activation can further lower (V)LDL and reduce atherosclerosis on top of PCSK9 inhibition. APOE*3-Leiden.CETP mice were fed a Western-type diet and treated with the anti-PCSK9 antibody alirocumab or saline. After 2 weeks, both groups of mice were randomized to receive either the selective beta 3-adrenergic receptor (AR) agonist CL316,243 to activate brown fat or saline for 3 additional weeks to evaluate VLDL clearance or 12 additional weeks to analyze atherosclerosis development. beta 3-AR agonism and alirocumab combined decreased (V)LDL-cholesterol compared to alirocumab alone, which was explained by an accelerated plasma clearance of VLDL-cholesteryl esters that were mainly taken up by the liver. In addition, the combination promoted the transfer of VLDL-phospholipids to HDL to a higher extent than alirocumab alone, accompanied by higher plasma HDL-cholesterol levels and increased cholesterol efflux capacity. Consequently, combination treatment largely reduced atherosclerotic lesion area compared to vehicle. Together, beta 3-AR agonism enhances the lipoprotein-modulating effects of alirocumab to further improve dyslipidemia and non-significantly further attenuate atherosclerosis development. Our findings demonstrate that brown fat activation may enhance the therapeutic effects of PCSK9 inhibition in dyslipidemia. Show less
Cardiovascular disease is the leading cause of death worldwide. The primary underlying pathology of cardiovascular disease is atherosclerosis. Atherosclerosis is a chronic, multifactorial disease... Show moreCardiovascular disease is the leading cause of death worldwide. The primary underlying pathology of cardiovascular disease is atherosclerosis. Atherosclerosis is a chronic, multifactorial disease in which lipid accumulates in the arterial wall, leading to a local inflammatory reaction and atherosclerotic plaque formation. Atherosclerotic disease develops largely asymptomatic over a lifetime. However, plaque rupture or erosion can cause the formation of a superimposed thrombus, blocking the flow of blood, and cause acute cardiovascular events such as myocardial infarction or ischemic stroke. Defects in cholesterol metabolism and hypercholesterolemia, which are major risk factors for atherosclerosis, have been shown to affect hematopoiesis, immune cell production and platelet counts and reactivity. Therefore, bone marrow cholesterol handling is an interesting target in the battle against cardiovascular disease, and acute cardiovascular events in particular. This thesis describes novel interactions between cholesterol metabolism and the production of immune cells and platelets, and its effects on atherosclerosis and atherothrombosis development. Show less
The most important risk factor for atherosclerotic cardiovascular disease is increased levels of LDL-C. Statins have long been the most potent LDL-C lowering drugs on the market. However,... Show moreThe most important risk factor for atherosclerotic cardiovascular disease is increased levels of LDL-C. Statins have long been the most potent LDL-C lowering drugs on the market. However, statin treatment is complicated by the fact that a considerable number of patients is unable to tolerate full therapeutic doses, or can be classified as statin low or non-responders. In >25% of patients at (very) high risk for cardiovascular disease, statin efficacy is too limited to achieve current guideline-mandated LDL-C target goals, and aggressive statin therapy decreases relative risk for ASCD by only 30-35%, leaving an unacceptable residual relative risk of 65-70% for life-threatening events. It is clear that on-treatment LDL-C levels and on-treatment measures of systemic inflammation are of equal importance in this residual risk. Both for residual cholesterol risk and residual inflammatory risk, effective drug therapy has been lacking for decades. In this thesis, we describe the first clinical studies with novel compounds based on increased LDL-C levels and inflammation (including the required methodology), and present the methodology that may be useful to develop future compounds based on dysfunctional endothelial barrier function resulting in subendothelial cholesterol accumulation and subsequent atheroma formation. Show less
Cholestatic liver disease is characterized by a disruption of bile flow, bile acid toxicity, liver injury, and hypercholesterolemia. Relatively high secretion of glucocorticoids by the adrenals has... Show moreCholestatic liver disease is characterized by a disruption of bile flow, bile acid toxicity, liver injury, and hypercholesterolemia. Relatively high secretion of glucocorticoids by the adrenals has been observed under cholestatic conditions. Here we investigated a contribution of the rise in endogenous glucocorticoids to initial stage cholestasis pathology. Adrenalectomized or sham-operated control C57BL/6 mice were given an oral dose of alpha-naphthylisothiocyanate to induce cholestasis. Adrenalectomy effectively lowered plasma corticosterone levels (18 ± 5 ng/ml vs 472 ± 58 ng/ml; P < 0.001) and disrupted the metabolic and anti-inflammatory glucocorticoid function. Adrenal removal did not exacerbate the cholestasis extent. In contrast, the cholestasis-associated liver injury was markedly lower in adrenalectomized mice as compared to controls as evidenced by a 84%–93% decrease in liver necrosis and plasma alanine aminotransferase and bile acid levels (P < 0.001 for all). Gene expression analysis on livers from adrenalectomized mice suggested the absence of bile acid toxicity-associated farnesoid X receptor signaling in the context of a 44% (P < 0.01) and 82% (P < 0.001) reduction in sodium/bile acid cotransporter member 1 transcript level as compared to respectively control and non-diseased mice. Adrenalectomy reduced the expression of the cholesterol synthesis gene HMG-CoA reductase by 70% (P < 0.05), which translated into a 73% lower plasma total cholesterol level (P < 0.05). Treatment of C57BL/6 mice with the glucocorticoid receptor antagonist RU-486 recapitulated the protective effect of adrenalectomy on indices of liver injury and hypercholesterolemia.In conclusion, we have shown that endogenous glucocorticoids exacerbate the liver injury and hypercholesterolemia associated with acute cholestasis in mice. Show less
This thesis focuses on the potential of cell-based therapy in ischemic heart disease and the role of the inflammatory response after myocardial infarction (MI). Chapter 2 reviews the specific... Show moreThis thesis focuses on the potential of cell-based therapy in ischemic heart disease and the role of the inflammatory response after myocardial infarction (MI). Chapter 2 reviews the specific myocardial inflammatory events that occur following MI and explores the potential role of cell therapy, in specific of the mesenchymal stromal cell (MSC), to positively influence this process. In chapter 3 we studied the usefulness of a clinically relevant transient ischemia MI model in immunodeficient mice to investigate the potential of human stem cell therapy and compared this to the commonly used animal MI model via permanent ischemia. Next, in chapter 4 we aimed to extend our previous research regarding the positive therapeutic effects of MSC therapy after MI by injecting MSCs stimulated with the pro-inflammatory cytokine interferon-γ, since pro-inflammatory priming has shown additional beneficial effects in several experimental disease models. Chapter 5 evaluates the short-term effect of human cardiomyocyte progenitor cell infusion on cardiac function in an animal MI model. Chapter 6 discusses the effect of diet-induced hypercholesterolemia on both cardiac function and inflammation after myocardial ischemia-reperfusion injury. Finally, chapter 7 provides an overview of the results described in this thesis, and discusses future perspectives. Show less
Cardiovascular disease (CVD) is the leading cause of death worldwide despite the successful development of several pharmaceutical interventions of which statin therapy is the dominating lipid... Show moreCardiovascular disease (CVD) is the leading cause of death worldwide despite the successful development of several pharmaceutical interventions of which statin therapy is the dominating lipid-lowering treatment option. Atherosclerosis, a chronic inflammatory disease of multifactorial origin, is a dominant contributor to the development of CVD. The research described in this thesis provides evidence for anti-atherogenic effects of several innovative pharmaceutical interventions that are currently being investigated in clinical trials, targeting hypertension and hypercholesterolemia, more specifically high low-density lipoprotein-cholesterol (LDL-C) and low high-density lipoprotein-cholesterol (HDL-C), as risk factors for CVD. Our results further support additional benefit of these treatment strategies in combination with statin treatment which is currently the __gold standard__ therapy for the treatment of CVD. Most of these lipid-modifying treatment strategies affect both LDL-C and HDL-C and we demonstrate that the beneficial effects of these treatment strategies predominantly derive from their non-HDL-C/LDL-C-lowering abilities. Nonetheless, results from preclinical studies and clinical trials support the notion that treatment strategies aimed at improving HDL function and raising apolipoprotein A-I may also inhibit the development of atherosclerosis and reduce the prevalence of CVD. Show less
In summary, in this thesis it becomes clear that the intrauterine environment created by the mother during pregnancy not only has beneficial effects on the developing embryo / fetus. Although it is... Show moreIn summary, in this thesis it becomes clear that the intrauterine environment created by the mother during pregnancy not only has beneficial effects on the developing embryo / fetus. Although it is too early to draw definite conclusions, the first results of this research line show that maternal apoE-deficiency, in contrast to maternal Ldlr-deficiency, adversely affects the offspring, not only in late fetal stages but also in adult life. Our data indicate that the inflammatory status of the mother and the lack of maternal apoE itself may attribute to the increased cardiovascular disease risk observed in the adult offspring. Hypercholesterolemia and oxidative stress possibly play a more regulatory role. In a first attempt to elucidate the underlying mechanism we show that maternal apoE-deficiency leads to changes in the histone triple-methylation modifications in the vascular wall of the offspring. Thi s can be considered an important lead that needs to be investigated further. It does not mean, however, that we are close to complete elucidation of the underlying mechanism. A lot of research is needed to accomplish this and it is needed. Why? The fact that a hit so early in life exerts negative effects on cardiovascular disease risk in adulthood is worrisome. If we could succeed in elucidating the exact role of epigenetics in this process and are able to translate these data to the human situation, possibly we could reduce the incidence of cardiovascular disease. Show less
