Background: C-type lectin receptors, including Dectin-2, are pattern recognition receptors on monocytes and macrophages that mainly recognize sugars and sugar-like structures present on fungi.... Show moreBackground: C-type lectin receptors, including Dectin-2, are pattern recognition receptors on monocytes and macrophages that mainly recognize sugars and sugar-like structures present on fungi. Activation of C-type lectin receptors induces downstream CARD9 signalling, leading to the production of cytokines. We hypothesized that under hyperglycaemic conditions, as is the case in diabetes mellitus, glycosylated protein (sugar-like) structures activate C-type lectin receptors, leading to immune cell activation and increased atherosclerosis development. Methods: Low-density lipoprotein receptor-deficient mice were lethally irradiated and transplanted with bone marrow from control wild-type, Dectin-2(-/-) or Card9(-/-) mice. After 6 weeks of recovery, mice received streptozotocin injections (50 mg/g BW; 5 days) to induce hyperglycaemia. After an additional 2 weeks, mice were fed a Western-type diet (0.1% cholesterol) for 10 weeks. Results and Conclusion: Deletion of haematopoietic Dectin-2 reduced the number of circulating Ly6C(hi) monocytes, increased pro-inflammatory cytokine production, but did not affect atherosclerosis development. Deletion of haematopoietic CARD9 tended to reduce macrophage and collagen content in atherosclerotic lesions, again without influencing the lesion size. Deletion of haematopoietic Dectin-2 did not influence atherosclerosis development under hyperglycaemic conditions, despite some minor effects on inflammation. Deletion of haematopoietic CARD9 induced minor alterations in plaque composition under hyperglycaemic conditions, without affecting lesion size. Show less
Cardiovascular diseases are the primary cause of death in the world with atherosclerosis as primary underlying cause. Atherosclerosis is characterized by cholesterol accumulation in the vessel wall... Show moreCardiovascular diseases are the primary cause of death in the world with atherosclerosis as primary underlying cause. Atherosclerosis is characterized by cholesterol accumulation in the vessel wall and inflammation of the vessel wall of medium to large size arteries. Both cholesterol accumulation and inflammation are pathogenic in the context of atherosclerosis. Current treatment regimens are tailored to reduce cholesterol levels in the blood. However, even a successful lowering of cholesterol is in many patients not sufficient to prevent a major cardiovascular event due to unresolved inflammation. Therefore, the immune system provides an interesting therapeutic target for the treatment of atherosclerosis. In this thesis we have explored the effect on atherosclerosis of several immunomodulatory strategies in pre-clinical models.As cholesterol is not soluble in water, cholesterol is transported in the bloodstream in particles called lipoproteins. The low-density lipoprotein (LDL) carries the highest concentration of cholesterol and accumulates in the vessel wall where a pathogenic specific immune response against LDL is instigated. In this thesis we have used several strategies to modulate the specific immune response against LDL, inducing LDL-specific regulatory T cells, antibodies, and cytotoxic T cells. Through immunoproteasomal inhibition we assessed the effect of general immune inhibition on atherosclerosis. Show less
This thesis explores different avenues to develop insurmountable antagonists for CC Chemokine Receptors, such as CCR1, CCR2 and CCR5. These receptors, which belong to the large family of G protein... Show moreThis thesis explores different avenues to develop insurmountable antagonists for CC Chemokine Receptors, such as CCR1, CCR2 and CCR5. These receptors, which belong to the large family of G protein-coupled receptors (GPCRs), are implicated in a variety of inflammatory and immune diseases, including atherosclerosis, rheumatoid arthritis and cancer. Thus, numerous drug candidates have been developed over the years to target them. Despite promising preclinical data, most of these candidates have failed in clinical trials due to lack of efficacy, making necessary the development of novel tools and concepts to better study and target these receptors. Thus, throughout this thesis we have explored different mechanisms to achieve insurmountable inhibition, which include intracellular allosteric modulation, covalent inhibition and long residence time. Moreover, the crystal structure presented in this thesis provides a new template for the rational design of future antagonists. Finally, with the identification of several selective or multitarget intracellular ligands for CCR1, CCR2 and CCR5, we are expanding the toolbox to further modulate chemokine receptors. Overall, the results of this thesis may contribute to the development of novel chemokine receptor antagonists, and GPCRs in general, with improved in vivo efficacy. Show less
BACKGROUND: South Asians are more prone to develop atherosclerotic cardiovascular disease (ASCVD) compared with white Caucasians, which is not fully explained by classical risk factors. We recently... Show moreBACKGROUND: South Asians are more prone to develop atherosclerotic cardiovascular disease (ASCVD) compared with white Caucasians, which is not fully explained by classical risk factors. We recently reported that the presence of aggregation-prone low-density lipoprotein (LDL) in the circulation is associated with increased ASCVD mortality.OBJECTIVE: We hypothesized that LDL of South Asians is more prone to aggregate, which may be explained by differences in their LDL lipid composition.METHODS: In this cross-sectional hypothesis-generating study, LDL was isolated from plasma of healthy South Asians (n = 12) and age- and BMI-matched white Caucasians (n = 12), and its aggregation susceptibility and lipid composition were analyzed.RESULTS: LDL from South Asians was markedly more prone to aggregate compared with white Caucasians. Among all measured lipids, sphingomyelin 24:0 and triacylglycerol 56:8 showed the highest positive correlation with LDL aggregation. In addition, LDL from South Asians was enriched in arachidonic acid containing phosphatidylcholine 38:4 and had less phosphatidylcholines and cholesteryl esters containing monounsaturated fatty acids. Interestingly, body fat percentage, which was higher in South Asians (+26%), positively correlated with LDL aggregation and highly positively correlated with triacylglycerol 56:8, sphingomyelin 24:0, and total sphingomyelin.CONCLUSIONS: LDL aggregation susceptibility is higher in healthy young South Asians compared with white Caucasians. This may be partly explained by the higher body fat percentage of South Asians, leading to sphingomyelin enrichment of LDL. We anticipate that the presence of sphingomyelin-rich, aggregation -prone LDL particles in young South Asians may increase LDL accumulation in the arterial wall and thereby contribute to their increased risk of developing ASCVD later in life. (C) 2019 National Lipid Association. Published by Elsevier Inc. Show less
Dijk, L.J.D. van; Harki, J.; Noord, D. van; Verhagen, H.J.M.; Kolkman, J.J.; Geelkerken, R.H.; ... ; Dutch Mesenteric Ischemia Study Gr 2019
Background: Chronic mesenteric ischemia (CMI) is the result of insufficient blood supply to the gastrointestinal tract and is caused by atherosclerotic stenosis of one or more mesenteric arteries... Show moreBackground: Chronic mesenteric ischemia (CMI) is the result of insufficient blood supply to the gastrointestinal tract and is caused by atherosclerotic stenosis of one or more mesenteric arteries in > 90% of cases. Revascularization therapy is indicated in patients with a diagnosis of atherosclerotic CMI to relieve symptoms and to prevent acute-on-chronic mesenteric ischemia, which is associated with high morbidity and mortality. Endovascular therapy has rapidly evolved and has replaced surgery as the first choice of treatment in CMI. Bare-metal stents (BMS) are standard care currently, although retrospective studies suggested significantly higher patency rates for covered stents (CS). The Covered stents versus Bare-metal stents in chronic atherosclerotic Gastrointestinal Ischemia (CoBaGI) trial is designed to prospectively assess the patency of CS versus BMS in patients with atherosclerotic CMI.Methods/design: The CoBaGI trial is a randomized controlled, parallel-group, patient-and investigator-blinded, superiority, multicenter trial conducted in six centers of the Dutch Mesenteric Ischemia Study group (DMIS). Eighty-four patients with a consensus diagnosis of atherosclerotic CMI are 1:1 randomized to either a balloon-expandable BMS (Palmaz Blue with rapid-exchange delivery system, Cordis Corporation, Bridgewater, NJ, USA) or a balloon-expandable CS (Advanta V12 over-the-wire, Atrium Maquet Getinge Group, Hudson, NH, USA). The primary endpoint is the primary stent-patency rate at 24 months assessed with CT angiography. Secondary endpoints are primary stent patency at 6 and 12 months and secondary patency rates, freedom from restenosis, freedom from symptom recurrence, freedom from re-intervention, quality of life according the EQ-5D-5 L and SF-36 and cost-effectiveness at 6, 12 and 24 months.Discussion: The CoBaGI trial is designed to assess the patency rates of CS versus BMS in patients treated for CMI caused by atherosclerotic mesenteric stenosis. Furthermore, the CoBaGI trial should provide insights in the quality of life of these patients before and after stenting and its cost-effectiveness. The CoBaGI trial is the first randomized controlled trial performed in CMI caused by atherosclerotic mesenteric artery stenosis. Show less
Hermans, M.; Roeters van Lennep, J.E.; Daele, P. van; Bot, I. 2019
Mast cells are pluripotent leukocytes that reside in the mucosa and connective tissue. Recent studies show an increased prevalence of cardiovascular disease among patients with mastocytosis, which... Show moreMast cells are pluripotent leukocytes that reside in the mucosa and connective tissue. Recent studies show an increased prevalence of cardiovascular disease among patients with mastocytosis, which is a hematological disease that is characterized by the accumulation of mast cells due to clonal proliferation. This association suggests an important role for mast cells in cardiovascular disease. Indeed, the evidence establishing the contribution of mast cells to the development and progression of atherosclerosis is continually increasing. Mast cells may contribute to plaque formation by stimulating the formation of foam cells and causing a pro-inflammatory micro-environment. In addition, these cells are able to promote plaque instability by neo-vessel formation and also by inducing intraplaque hemorrhage. Furthermore, mast cells appear to stimulate the formation of fibrosis after a cardiac infarction. In this review, the available data on the role of mast cells in cardiovascular disease are summarized, containing both in vitro research and animal studies, followed by a discussion of human data on the association between cardiovascular morbidity and diseases in which mast cells are important: Kounis syndrome, mastocytosis and allergy. 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
Purpose of Review Coronary computed tomography angiography (CCTA) is the optimal non-invasive test to rule out coronary artery disease (CAD). Decisions to perform coronary revascularization have... Show morePurpose of Review Coronary computed tomography angiography (CCTA) is the optimal non-invasive test to rule out coronary artery disease (CAD). Decisions to perform coronary revascularization have traditionally been based upon ischemia testing. This review summarizes the latest observations and trials evaluating the suitability of CCTA to select patients for invasive coronary angiography (ICA) and subsequent revascularization.Recent FindingsRecent data shows that beyond stenosis, whole-heart quantification and characterization of coronary atherosclerotic plaque improves the estimation of myocardial ischemia. This comprehensive evaluation of the coronary artery tree has greater diagnostic accuracy for invasive fractional flow reserve (FFR) than conventional stress tests. Further, clinical trials have demonstrated that the performance of CCTA in patients with a clinical indication for ICA results in more effective patient care and significantly lower costs.SummaryBesides the excellent ability to rule out CAD, recent data shows that quantification and characterization of the coronary artery tree results in high accuracy for ischemia and that CCTA-guided care to select patients for ICA and revascularization is effective. Trials evaluating revascularization based on CCTA findings may be needed. Show less
The presence of mast cells in human atherosclerotic plaques has been associated with adverse cardiovascular events. Mast cell activation, through the classical antigen sensitized-IgE binding to... Show moreThe presence of mast cells in human atherosclerotic plaques has been associated with adverse cardiovascular events. Mast cell activation, through the classical antigen sensitized-IgE binding to their characteristic Fcε-receptor, causes the release of their cytoplasmic granules. These granules are filled with neutral proteases such as tryptase, but also with histamine and pro-inflammatory mediators. Mast cells accumulate in high numbers within human atherosclerotic tissue, particularly in the shoulder region of the plaque. These findings are largely based on immunohistochemistry, which does not allow for the extensive characterization of these mast cells and of the local mast cell activation mechanisms. In this study, we thus aimed to develop a new flow-cytometry based methodology in order to analyze mast cells in human atherosclerosis. We enzymatically digested 22 human plaque samples, collected after femoral and carotid endarterectomy surgery, after which we prepared a single cell suspension for flow cytometry. We were able to identify a specific mast cell population expressing both CD117 and the FcεR, and observed that most of the intraplaque mast cells were activated based on their CD63 protein expression. Furthermore, most of the activated mast cells had IgE fragments bound on their surface, while another fraction showed IgE-independent activation. In conclusion, we are able to distinguish a clear mast cell population in human atherosclerotic plaques, and this study establishes a strong relationship between the presence of IgE and the activation of mast cells in advanced atherosclerosis. Our data pave the way for potential therapeutic intervention through targeting IgE-mediated actions in human atherosclerosis. Show less
Geest, R. van der; Sluis, R.J. van der; Groen, A.K.; Eck, M. van; Hoekstra, M. 2019
Chronic glucocorticoid overexposure predisposes to the development of atherosclerotic cardiovascular disease in humans. Cholestatic liver disease is associated with increased plasma glucocorticoid... Show moreChronic glucocorticoid overexposure predisposes to the development of atherosclerotic cardiovascular disease in humans. Cholestatic liver disease is associated with increased plasma glucocorticoid levels. Here we determined, in a preclinical setting, whether the chronic presence of cholestatic liver disease also induces a concomitant negative impact on atherosclerosis susceptibility. Hereto, regular chow diet-fed atherosclerosis-susceptible hypercholesterolemic apolipoprotein E (APOE) knockout mice were treated with the bile duct toxicant alpha‑naphthylisothiocyanate (ANIT) for 8 weeks. ANIT exposure induced the development of fibrotic cholestatic liver disease as evident from collagen deposits and compensatory bile duct hyperproliferation within the liver and the rise in plasma levels of bilirubin (+60%; P<0.01) and bile acids (10-fold higher; P<0.01). Adrenal weights (+22%; P<0.01) and plasma corticosterone levels (+72%; P<0.01) were increased in ANIT-treated mice. In contrast, atherosclerosis susceptibility was not increased in response to ANIT feeding, despite the concomitant increase in plasma free cholesterol (+30%; P<0.01) and cholesteryl ester (+42%; P<0.001) levels. The ANIT-induced hypercorticosteronemia coincided with marked immunosuppression as judged from the 50% reduction (P<0.001) in circulating lymphocyte numbers. However, hepatic glucocorticoid signaling was not enhanced after ANIT treatment. It thus appears that the immunosuppressive effect of glucocorticoids is uncoupled from their metabolic effect under cholestatic disease conditions. In conclusion, we have shown that cholestatic liver disease-associated endogenous glucocorticoid overexposure does not increase atherosclerosis susceptibility in APOE knockout mice. Our studies provide novel preclinical evidence for the observations that the hypercholesterolemia seen in cholestatic human subjects does not translate into a higher risk for atherosclerotic cardiovascular disease. 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 nuclear receptor liver X receptor (LXR) impacts on cholesterol metabolism as well as hepatic lipogenesis via transcriptional regulation. It is proposed that inhibition of the protein arginine... Show moreThe nuclear receptor liver X receptor (LXR) impacts on cholesterol metabolism as well as hepatic lipogenesis via transcriptional regulation. It is proposed that inhibition of the protein arginine methyltransferase 3 (PRMT3) uncouples these two transcriptional pathways in vivo by acting as a specific lipogenic coactivator of LXR. Here we validated the hypothesis that treatment with the allosteric PRMT3 inhibitor SGC707 will diminish the hepatic steatosis extent, while leaving global cholesterol metabolism, important in cholesterol-driven pathologies like atherosclerosis, untouched. For this purpose, 12-week old hyperlipidemic apolipoprotein E knockout mice were fed a Western-type diet for six weeks to induce both hepatic steatosis and atherosclerosis. The mice received 3 intraperitoneal injections with SGC707 or solvent control per week. Mice chronically treated with SGC707 developed less severe hepatic steatosis as exemplified by the 51% reduced (P < 0.05) liver triglyceride levels. In contrast, the extent of in vivo macrophage foam cell formation and aortic root atherosclerosis was not affected by SGC707 treatment. Interestingly, SGC707-treated mice gained 94% less body weight (P < 0.05), which was paralleled by changes in white adipose tissue morphology, i.e. reduction in adipocyte size and browning. In conclusion, we have shown that through PRMT3 inhibitor treatment specific functions of LXR involved in respectively the development of fatty liver disease and atherosclerosis can be uncoupled, resulting in an overall diminished hepatic steatosis extent without a negative impact on atherosclerosis susceptibility. As such, our studies highlight that PRMT3 inhibition may constitute a novel therapeutic approach to limit the development of fatty liver disease in humans. 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
Meeuwsen, J.A.L.; Vries, J.J. de; Duijvenvoorde, A. van; Velden, S. van der; Laan, S.W. van der; Koeverden, I.D. van; ... ; Jager, S.C.A. de 2019
future AbstractMouse studies have established distinct monocyte subtypes that participate in the process of atherosclerotic lesion formation. The pro-inflammatory Ly6Chigh monocyte subtype actively... Show morefuture AbstractMouse studies have established distinct monocyte subtypes that participate in the process of atherosclerotic lesion formation. The pro-inflammatory Ly6Chigh monocyte subtype actively contributes to murineplaque progression and destabilization. Also in humans, different peripheral monocyte subtypes have been identified, of which the CD14+CD16− classical monocyte is suggested to display similar pro-atherosclerotic properties as the murine Ly6Chigh subtype. We aimed to investigate if circulating CD14+CD16− classical monocytes associate with characteristics of a vulnerable carotid atherosclerotic plaque and if they associate with the risk of secondary adverse manifestations of atherosclerotic disease.We enrolled 175 carotid endarterectomy patients of the Athero-Express biobank in our study. Just prior to surgical procedure, blood was collected and peripheral blood mononuclear cells were isolated. Characterization of monocyte subsets was performed by flow cytometry. Plaque characteristics were semi-quantitatively scored for the presence of fat, collagen, intraplaque hemorrhage and calcification. Vessel density, smooth muscle cells and macrophages were assessed quantitatively on a continuous scale. All features of a vulnerable plaque phenotype, including low amounts of collagen and smooth muscle cells, and increased fat content, vessel density, intraplaque hemorrhage and plaque macrophages were not significantly associated with differential levels of peripheral classical CD14+CD16− monocytes or other monocyte subsets. Using Cox regression models to evaluate the prognostic value of circulating monocyte subtypes, we found that total counts of peripheral monocytes, as well as CD14+CD16− classical and other monocyte subtypes were not associated with the risk of secondary cardiovascular events during 3 years follow-up.Circulating classical CD14+CD16− monocytes do not associate with specific vulnerable plaque characteristics. In addition, they do not predict secondary adverse manifestations. This suggests that in patients with established carotid artery disease, the circulating monocytes do not reflect plaque characteristics and have no value in identifying patients at risk for future cardiovascular events. Show less
Duijn, J. van; Elsas, M. van; Benne, N.; Depuydt, M.; Wezel, A.; Smeets, H.; ... ; Slütter, B. 2019
CD8+T-cells have been attributed both atherogenic and atheroprotective properties, butanalysis of CD8+T-cells has mostly been restricted to the circulation and secondary lymphoid organs.... Show moreCD8+T-cells have been attributed both atherogenic and atheroprotective properties, butanalysis of CD8+T-cells has mostly been restricted to the circulation and secondary lymphoid organs. Theatherosclerotic lesion, however, is a complex microenvironment containing a plethora of inflammatory signals,which may affect CD8+T-cell activation. Here, we address how this environment affects the functionality ofCD8+T-cells. We compared the cytokine production of CD8+T-cells derived from spleens and en-zymatically digested aortas ofapoE−/−mice with advanced atherosclerosis byflow cytometry. Aortic CD8+T-cells produced decreased amounts of IFN-γand TNF-αcompared to their systemic counterparts. The observeddysfunctional phenotype of the lesion-derived CD8+T-cells was not associated with classical exhaustion mar-kers, but with increased expression of the ectonucleotidase CD39. Indeed, pharmacological inhibition of CD39 inapoE−/−mice partly restored cytokine production by CD8+T-cells. Using a bone-marrow transplantation ap-proach, we show that TCR signaling is required to induce CD39 expression on CD8+T-cells in atheroscleroticlesions. Importantly, analysis of human endarterectomy samples showed a strong microenvironment specificupregulation of CD39 on CD8+T-cells in the plaques of human patients compared to matched blood samples. Our results suggest that the continuous TCR signaling in the atherosclerotic environment in thevessel wall induces an immune regulatory CD8+T-cell phenotype that is associated with decreased cytokineproduction through increased CD39 expression in both a murine atherosclerotic model and in atherosclerosispatients. This provides a new understanding of immune regulation by CD8+T-cells in atherosclerosis. Show less
