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Daeichin V, Sluimer JC, van der Heiden K, Skachkov I, Kooiman K, Janssen A, Janssen B, Bosch JG, de Jong N, Daemen MJAP, van der Steen AFW. Live Observation of Atherosclerotic Plaque Disruption in Apolipoprotein E-Deficient Mouse. Ultrasound Int Open 2016; 1:E67-71. [PMID: 27689156 DOI: 10.1055/s-0035-1565092] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
AIM The actual occurrence of spontaneous plaque rupture in mice has been a matter of debate. We report on an in vivo observation of the actual event of possible plaque disruption in a living ApoE(-/-) mouse. METHODS AND RESULTS During live contrast-enhanced ultrasonography of a 50-week-old ApoE(-/-) male mouse, symptoms suggesting plaque disruption in the brachiocephalic artery were observed. Histological analysis confirmed the presence of advanced atherosclerotic lesions with dissections and intraplaque hemorrhage in the affected brachiocephalic trunk, pointing towards plaque rupture as the cause of the observed event. However, we did not detect a luminal thrombus or cap rupture, which is a key criterion for plaque rupture in human atherosclerosis. CONCLUSION This study reports the real-time occurrence of a possible plaque rupture in a living ApoE(-/-) mouse.
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Daeichin V, Kooiman K, Skachkov I, Bosch JG, Theelen TL, Steiger K, Needles A, Janssen BJ, Daemen MJAP, van der Steen AFW, de Jong N, Sluimer JC. Quantification of Endothelial αvβ3 Expression with High-Frequency Ultrasound and Targeted Microbubbles: In Vitro and In Vivo Studies. ULTRASOUND IN MEDICINE & BIOLOGY 2016; 42:2283-2293. [PMID: 27302657 DOI: 10.1016/j.ultrasmedbio.2016.05.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 05/03/2016] [Accepted: 05/04/2016] [Indexed: 06/06/2023]
Abstract
Angiogenesis is a critical feature of plaque development in atherosclerosis and might play a key role in both the initiation and later rupture of plaques. The precursory molecular or cellular pro-angiogenic events that initiate plaque growth and that ultimately contribute to plaque instability, however, cannot be detected directly with any current diagnostic modality. This study was designed to investigate the feasibility of ultrasound molecular imaging of endothelial αvβ3 expression in vitro and in vivo using αvβ3-targeted ultrasound contrast agents (UCAs). In the in vitro study, αvβ3 expression was confirmed by immunofluorescence in a murine endothelial cell line and detected using the targeted UCA and ultrasound imaging at 18-MHz transmit frequency. In the in vivo study, expression of endothelial αvβ3 integrin in murine carotid artery vessels and microvessels of the salivary gland was quantified using targeted UCA and high-frequency ultrasound in seven animals. Our results indicated that endothelial αvβ3 expression was significantly higher in the carotid arterial wall containing atherosclerotic lesions than in arterial segments without any lesions. We also found that the salivary gland can be used as an internal positive control for successful binding of targeted UCA to αvβ3 integrin. In conclusion, αvβ3-targeted UCA allows non-invasive assessment of the expression levels of αvβ3 on the vascular endothelium and may provide potential insights into early atherosclerotic plaque detection and treatment monitoring.
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Mandell DM, Mossa-Basha M, Qiao Y, Hess CP, Hui F, Matouk C, Johnson MH, Daemen MJAP, Vossough A, Edjlali M, Saloner D, Ansari SA, Wasserman BA, Mikulis DJ. Intracranial Vessel Wall MRI: Principles and Expert Consensus Recommendations of the American Society of Neuroradiology. AJNR Am J Neuroradiol 2016; 38:218-229. [PMID: 27469212 DOI: 10.3174/ajnr.a4893] [Citation(s) in RCA: 397] [Impact Index Per Article: 49.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Intracranial vessel wall MR imaging is an adjunct to conventional angiographic imaging with CTA, MRA, or DSA. The technique has multiple potential uses in the context of ischemic stroke and intracranial hemorrhage. There remain gaps in our understanding of intracranial vessel wall MR imaging findings and research is ongoing, but the technique is already used on a clinical basis at many centers. This article, on behalf of the Vessel Wall Imaging Study Group of the American Society of Neuroradiology, provides expert consensus recommendations for current clinical practice.
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Bronzwaer ASGT, Verbree J, Stok WJ, van Buchem MA, Daemen MJAP, van Osch MJP, van Lieshout JJ. Cardiovascular Response Patterns to Sympathetic Stimulation by Central Hypovolemia. Front Physiol 2016; 7:235. [PMID: 27378944 PMCID: PMC4913112 DOI: 10.3389/fphys.2016.00235] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 05/30/2016] [Indexed: 11/30/2022] Open
Abstract
In healthy subjects, variation in cardiovascular responses to sympathetic stimulation evoked by submaximal lower body negative pressure (LBNP) is considerable. This study addressed the question whether inter-subject variation in cardiovascular responses coincides with consistent and reproducible responses in an individual subject. In 10 healthy subjects (5 female, median age 22 years), continuous hemodynamic parameters (finger plethysmography; Nexfin, Edwards Lifesciences), and time-domain baroreflex sensitivity (BRS) were quantified during three consecutive 5-min runs of LBNP at −50 mmHg. The protocol was repeated after 1 week to establish intra-subject reproducibility. In response to LBNP, 5 subjects (3 females) showed a prominent increase in heart rate (HR; 54 ± 14%, p = 0.001) with no change in total peripheral resistance (TPR; p = 0.25) whereas the other 5 subjects (2 females) demonstrated a significant rise in TPR (7 ± 3%, p = 0.017) with a moderate increase in HR (21 ± 9%, p = 0.004). These different reflex responses coincided with differences in resting BRS (22 ± 8 vs. 11 ± 3 ms/mmHg, p = 0.049) and resting HR (57 ± 8 vs. 71 ± 12 bpm, p = 0.047) and were highly reproducible over time. In conclusion, we found distinct cardiovascular response patterns to sympathetic stimulation by LBNP in young healthy individuals. These patterns of preferential autonomic blood pressure control appeared related to resting cardiac BRS and HR and were consistent over time.
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Denswil NP, van der Wal AC, Ritz K, de Boer OJ, Aronica E, Troost D, Daemen MJAP. Atherosclerosis in the circle of Willis: Spatial differences in composition and in distribution of plaques. Atherosclerosis 2016; 251:78-84. [PMID: 27288902 DOI: 10.1016/j.atherosclerosis.2016.05.047] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 04/26/2016] [Accepted: 05/27/2016] [Indexed: 10/21/2022]
Abstract
BACKGROUND AND AIMS Intracranial atherosclerosis is one of the main causes of ischemic stroke. However, the characteristics of intracranial arteries and atherosclerosis have rarely been studied. Therefore, we systematically investigated atherosclerotic changes in all arteries of the Circle of Willis (CoW). METHODS Sixty-seven CoWs obtained at autopsy from randomly chosen hospital patients (mean age, 67.3 ± 12.5 years), of which a total of 1220 segments were collected from 22 sites. Atherosclerotic plaques were classified according to the revised American Heart Association classification and were related to local vessel characteristics, such as the presence of an external and internal elastic lamina and the elastic fibre density of the media. RESULTS 181 out of the 1220 segments had advanced plaques (15%), which were mainly observed in large arteries such as the internal carotid, middle cerebral, basilar and vertebral artery. Only 11 out of 1220 segments (1%) showed complicated plaques (p < 0.001). Six of these were intraplaque hemorrhages (IPH) and observed only in patients who had cardiovascular-related events (p = 0.015). The frequency of characteristics such as the external elastic lamina and a high elastin fibre density in the media was most often associated with the vertebral artery. Only 3% (n = 33) of the CoW arteries contained calcification (p < 0.001), which were mostly observed in the vertebral artery (n = 13, 12%). CONCLUSIONS Advanced atherosclerotic plaques in the CoW are relatively scarce and mainly located in the 4 large arteries, and mostly characterized by an early and stable phenotype, a low calcific burden, and a low frequency of IPH.
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van Hoof RHM, Hermeling E, Truijman MTB, van Oostenbrugge RJ, Daemen JWH, van der Geest RJ, van Orshoven NP, Schreuder AH, Backes WH, Daemen MJAP, Wildberger JE, Kooi ME. Phase-based vascular input function: Improved quantitative DCE-MRI of atherosclerotic plaques. Med Phys 2016; 42:4619-28. [PMID: 26233189 DOI: 10.1118/1.4924949] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
PURPOSE Quantitative pharmacokinetic modeling of dynamic contrast-enhanced (DCE)-MRI can be used to assess atherosclerotic plaque microvasculature, which is an important marker of plaque vulnerability. Purpose of the present study was (1) to compare magnitude- versus phase-based vascular input functions (m-VIF vs ph-VIF) used in pharmacokinetic modeling and (2) to perform model calculations and flow phantom experiments to gain more insight into the differences between m-VIF and ph-VIF. METHODS Population averaged m-VIF and ph-VIFs were acquired from 11 patients with carotid plaques and used for pharmacokinetic analysis in another 17 patients. Simulations, using the Bloch equations and the MRI scan geometry, and flow phantom experiments were performed to determine the effect of local blood velocity on the magnitude and phase signal enhancement. RESULTS Simulations and flow phantom experiments revealed that flow within the lumen can lead to severe underestimation of m-VIF, while this is not the case for the ph-VIF. In line, the peak concentration of the m-VIF is significantly lower than ph-VIF (p < 0.001), in vivo. Quantitative model parameters for m- and ph-VIF differed in absolute values but were moderate to strongly correlated with each other [K(trans) Spearman's ρ > 0.93 (p < 0.001) and vp Spearman's ρ > 0.58 (p < 0.05)]. CONCLUSIONS m-VIF is strongly influenced by local blood velocity, which leads to underestimation of the contrast medium concentration. Therefore, it is advised to use ph-VIF for DCE-MRI analysis of carotid plaques for accurate quantification.
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Marsch E, Demandt JAF, Theelen TL, Tullemans BME, Wouters K, Boon MR, van Dijk TH, Gijbels MJ, Dubois LJ, Meex SJR, Mazzone M, Hung G, Fisher EA, Biessen EAL, Daemen MJAP, Rensen PCN, Carmeliet P, Groen AK, Sluimer JC. Deficiency of the oxygen sensor prolyl hydroxylase 1 attenuates hypercholesterolaemia, atherosclerosis, and hyperglycaemia. Eur Heart J 2016; 37:2993-2997. [PMID: 27125949 PMCID: PMC5081036 DOI: 10.1093/eurheartj/ehw156] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 03/04/2016] [Accepted: 03/23/2016] [Indexed: 12/22/2022] Open
Abstract
AIMS Normalization of hypercholesterolaemia, inflammation, hyperglycaemia, and obesity are main desired targets to prevent cardiovascular clinical events. Here we present a novel regulator of cholesterol metabolism, which simultaneously impacts on glucose intolerance and inflammation. METHODS AND RESULTS Mice deficient for oxygen sensor HIF-prolyl hydroxylase 1 (PHD1) were backcrossed onto an atherogenic low-density lipoprotein receptor (LDLR) knockout background and atherosclerosis was studied upon 8 weeks of western-type diet. PHD1-/-LDLR-/- mice presented a sharp reduction in VLDL and LDL plasma cholesterol levels. In line, atherosclerotic plaque development, as measured by plaque area, necrotic core expansion and plaque stage was hampered in PHD1-/-LDLR-/- mice. Mechanistically, cholesterol-lowering in PHD1 deficient mice was a result of enhanced cholesterol excretion from blood to intestines and ultimately faeces. Additionally, flow cytometry of whole blood of these mice revealed significantly reduced counts of leucocytes and particularly of Ly6Chigh pro-inflammatory monocytes. In addition, when studying PHD1-/- in diet-induced obesity (14 weeks high-fat diet) mice were less glucose intolerant when compared with WT littermate controls. CONCLUSION Overall, PHD1 knockout mice display a metabolic phenotype that generally is deemed protective for cardiovascular disease. Future studies should focus on the efficacy, safety, and gender-specific effects of PHD1 inhibition in humans, and unravel the molecular actors responsible for PHD1-driven, likely intestinal, and regulation of cholesterol metabolism.
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Marsch E, Theelen TL, Janssen BJA, Briede JJ, Haenen GR, Senden JMG, van Loon LJC, Poeze M, Bierau J, Gijbels MJ, Daemen MJAP, Sluimer JC. The effect of prolonged dietary nitrate supplementation on atherosclerosis development. Atherosclerosis 2015; 245:212-21. [PMID: 26724532 DOI: 10.1016/j.atherosclerosis.2015.11.031] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 11/13/2015] [Accepted: 11/26/2015] [Indexed: 12/29/2022]
Abstract
BACKGROUND Short term dietary nitrate or nitrite supplementation has nitric oxide (NO)-mediated beneficial effects on blood pressure and inflammation and reduces mitochondrial oxygen consumption, possibly preventing hypoxia. As these processes are implicated in atherogenesis, dietary nitrate was hypothesized to prevent plaque initiation, hypoxia and inflammation. AIMS Study prolonged nitrate supplementation on atherogenesis, hypoxia and inflammation in low density lipoprotein receptor knockout mice (LDLr(-/-)). METHODS LDLr(-/-) mice were administered sodium-nitrate or equimolar sodium-chloride in drinking water alongside a western-type diet for 14 weeks to induce atherosclerosis. Plasma nitrate, nitrite and hemoglobin-bound nitric oxide were measured by chemiluminescence and electron parametric resonance, respectively. RESULTS Plasma nitrate levels were elevated after 14 weeks of nitrate supplementation (NaCl: 40.29 ± 2.985, NaNO3: 78.19 ± 6.837, p < 0.0001). However, prolonged dietary nitrate did not affect systemic inflammation, hematopoiesis, erythropoiesis and plasma cholesterol levels, suggesting no severe side effects. Surprisingly, neither blood pressure, nor atherogenesis were altered. Mechanistically, plasma nitrate and nitrite were elevated after two weeks (NaCl: 1.0 ± 0.2114, NaNO3: 3.977 ± 0.7371, p < 0.0001), but decreased over time (6, 10 and 14 weeks). Plasma nitrite levels even reached baseline levels at 14 weeks (NaCl: 0.7188 ± 0.1072, NaNO3: 0.9723 ± 0.1279 p = 0.12). Also hemoglobin-bound NO levels were unaltered after 14 weeks. This compensation was not due to altered eNOS activity or conversion into peroxynitrite and other RNI, suggesting reduced nitrite formation or enhanced nitrate/nitrite clearance. CONCLUSION Prolonged dietary nitrate supplementation resulted in compensation of nitrite and NO levels and did not affect atherogenesis or exert systemic side effects.
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van Hinsbergh VWM, Eringa EC, Daemen MJAP. Neovascularization of the atherosclerotic plaque: interplay between atherosclerotic lesion, adventitia-derived microvessels and perivascular fat. Curr Opin Lipidol 2015; 26:405-11. [PMID: 26241102 DOI: 10.1097/mol.0000000000000210] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
PURPOSE OF REVIEW Neovascularization is a prominent feature in advanced human atherosclerotic plaques. This review surveys recent evidence for and remaining uncertainties regarding a role of neovascularization in atherosclerotic plaque progression. Specific emphasis is given to hypoxia, angiogenesis inhibition, and perivascular adipose tissue (PVAT). RECENT FINDINGS Immunohistochemical and imaging studies showed a strong association between hypoxia, inflammation and neovascularization, and the progression of the atherosclerotic plaque both in humans and mice. Whereas in humans, a profound invasion of microvessels from the adventitia into the plaque occurs, neovascularization in mice is found mainly (peri)adventitially. Influencing neovascularization in mice affected plaque progression, possibly by improving vessel perfusion, but supportive clinical data are not available. Whereas plaque neovascularization contributes to monocyte/macrophage accumulation in the plaque, lymphangiogenesis may facilitate egress of cells and waste products. A specific role for PVAT and its secreted factors is anticipated and wait further clinical evaluation. SUMMARY Hypoxia, inflammation, and plaque neovascularization are associated with plaque progression as underpinned by recent imaging data in humans. Recent studies provide new insights into modulation of adventitia-associated angiogenesis, PVAT, and plaque development in mice, but there is still a need for detailed information on modulating human plaque vascularization in patients.
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van Dijk AC, Truijman MTB, Hussain B, Zadi T, Saiedie G, de Rotte AAJ, Liem MI, van der Steen AFW, Daemen MJAP, Koudstaal PJ, Nederkoorn PJ, Hendrikse J, Kooi ME, van der Lugt A. Intraplaque Hemorrhage and the Plaque Surface in Carotid Atherosclerosis: The Plaque At RISK Study (PARISK). AJNR Am J Neuroradiol 2015; 36:2127-33. [PMID: 26251429 DOI: 10.3174/ajnr.a4414] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 03/14/2015] [Indexed: 12/21/2022]
Abstract
BACKGROUND AND PURPOSE An important characteristic of vulnerable plaque, intraplaque hemorrhage, may predict plaque rupture. Plaque rupture can be visible on noninvasive imaging as a disruption of the plaque surface. We investigated the association between intraplaque hemorrhage and disruption of the plaque surface. MATERIALS AND METHODS We selected the first 100 patients of the Plaque At RISK study, an ongoing prospective noninvasive plaque imaging study in patients with mild-to-moderate atherosclerotic lesions in the carotid artery. In carotid artery plaques, disruption of the plaque surface (defined as ulcerated plaques and/or fissured fibrous cap) and intraplaque hemorrhage were assessed by using MDCTA and 3T MR imaging, respectively. We used a χ(2) test and multivariable logistic regression to assess the association between intraplaque hemorrhage and disrupted plaque surface. RESULTS One hundred forty-nine carotid arteries in 78 patients could be used for the current analyses. Intraplaque hemorrhage and plaque ulcerations were more prevalent in symptomatic compared with contralateral vessels (hemorrhage, 38% versus 11%; P < .001; and ulcerations, 27% versus 7%; P = .001). Fissured fibrous cap was more prevalent in symptomatic compared with contralateral vessels (13% versus 4%; P = .06). After adjustment for age, sex, diabetes mellitus, and degree of stenosis, intraplaque hemorrhage was associated with disrupted plaque surface (OR, 3.13; 95% CI, 1.25-7.84) in all vessels. CONCLUSIONS Intraplaque hemorrhage is associated with disruption of the plaque surface in patients with a carotid artery stenosis of <70%. Serial studies are needed to investigate whether intraplaque hemorrhage indeed increases the risk of plaque rupture and subsequent ischemic stroke during follow-up.
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Theelen TL, Lappalainen JP, Sluimer JC, Gurzeler E, Cleutjens JP, Gijbels MJ, Biessen EAL, Daemen MJAP, Alitalo K, Ylä-Herttuala S. Angiopoietin-2 blocking antibodies reduce early atherosclerotic plaque development in mice. Atherosclerosis 2015; 241:297-304. [PMID: 26062989 PMCID: PMC4549395 DOI: 10.1016/j.atherosclerosis.2015.05.018] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 05/04/2015] [Accepted: 05/20/2015] [Indexed: 12/17/2022]
Abstract
OBJECTIVE Angiopoietin-2 (Ang-2) blocking agents are currently undergoing clinical trials for use in cancer treatment. Ang-2 has also been associated with rupture-prone atherosclerotic plaques in humans, suggesting a role for Ang-2 in plaque stability. Despite the availability of Ang-2 blocking agents, their clinical use is still lacking. Our aim was to establish if Ang-2 has a role in atheroma development and in the transition of subclinical to clinically relevant atherosclerosis. We investigated the effect of antibody-mediated Ang-2 blockage on atherogenesis after in a mouse model of atherosclerosis. METHODS Hypercholesterolemic (low-density lipoprotein receptor(-/-) apolipoprotein B(100/100)) mice were subjected to high-cholesterol diet for eight weeks, one group with and one group without Ang-2 blocking antibody treatment during weeks 4-8.To enhance plaque development, a peri-adventitial collar was placed around the carotid arteries at the start of antibody treatment. Aortic root, carotid arteries and brachiocephalic arteries were analyzed to evaluate the effect of Ang-2 blockage on atherosclerotic plaque size and stable plaque characteristics. RESULTS Anti-Ang-2 treatment reduced the size of fatty streaks in the brachiocephalic artery (-72%, p < 0.05). In addition, antibody-mediated Ang-2 blockage reduced plasma triglycerides (-27%, p < 0.05). In contrast, Ang-2 blockage did not have any effect on the size or composition (collagen content, macrophage percentage, adventitial microvessel density) of pre-existing plaques in the aortic root or collar-induced plaques in the carotid artery. CONCLUSIONS Ang-2 blockage was beneficial as it decreased fatty streak formation and plasma triglyceride levels, but had no adverse effect on pre-existing atherosclerosis in hypercholesterolemic mice.
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Abstract
Formation of foam cell macrophages, which sequester extracellular modified lipids, is a key event in atherosclerosis. How lipid loading affects macrophage phenotype is controversial, with evidence suggesting either pro- or anti-inflammatory consequences. To investigate this further, we compared the transcriptomes of foamy and non-foamy macrophages that accumulate in the subcutaneous granulomas of fed-fat ApoE null mice and normal chow fed wild-type mice in vivo. Consistent with previous studies, LXR/RXR pathway genes were significantly over-represented among the genes up-regulated in foam cell macrophages. Unexpectedly, the hepatic fibrosis pathway, associated with platelet derived growth factor and transforming growth factor-β action, was also over-represented. Several collagen polypeptides and proteoglycan core proteins as well as connective tissue growth factor and fibrosis-related FOS and JUN transcription factors were up-regulated in foam cell macrophages. Increased expression of several of these genes was confirmed at the protein level in foam cell macrophages from subcutaneous granulomas and in atherosclerotic plaques. Moreover, phosphorylation and nuclear translocation of SMAD2, which is downstream of several transforming growth factor-β family members, was also detected in foam cell macrophages. We conclude that foam cell formation in vivo leads to a pro-fibrotic macrophage phenotype, which could contribute to plaque stability, especially in early lesions that have few vascular smooth muscle cells.
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Daeichin V, Akkus Z, Skachkov I, Kooiman K, Needles A, Sluimer J, Janssen B, Daemen MJAP, van der Steen AFW, de Jong N, Bosch JG. Quantification of bound microbubbles in ultrasound molecular imaging. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2015; 62:1190-1200. [PMID: 26067053 DOI: 10.1109/tuffc.2015.006264] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Molecular markers associated with diseases can be visualized and quantified noninvasively with targeted ultrasound contrast agent (t-UCA) consisting of microbubbles (MBs) that can bind to specific molecular targets. Techniques used for quantifying t-UCA assume that all unbound MBs are taken out of the blood pool few minutes after injection and only MBs bound to the molecular markers remain. However, differences in physiology, diseases, and experimental conditions can increase the longevity of unbound MBs. In such conditions, unbound MBs will falsely be quantified as bound MBs. We have developed a novel technique to distinguish and classify bound from unbound MBs. In the post-processing steps, first, tissue motion was compensated using block-matching (BM) techniques. To preserve only stationary contrast signals, a minimum intensity projection (MinIP) or 20th-percentile intensity projection (PerIP) was applied. The after-flash MinIP or PerIP was subtracted from the before-flash MinIP or PerIP. In this way, tissue artifacts in contrast images were suppressed. In the next step, bound MB candidates were detected. Finally, detected objects were tracked to classify the candidates as unbound or bound MBs based on their displacement. This technique was validated in vitro, followed by two in vivo experiments in mice. Tumors (n = 2) and salivary glands of hypercholesterolemic mice (n = 8) were imaged using a commercially available scanner. Boluses of 100 μL of a commercially available t-UCA targeted to angiogenesis markers and untargeted control UCA were injected separately. Our results show considerable reduction in misclassification of unbound MBs as bound ones. Using our method, the ratio of bound MBs in salivary gland for images with targeted UCA versus control UCA was improved by up to two times compared with unprocessed images.
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Huveneers S, Daemen MJAP, Hordijk PL. Between Rho(k) and a hard place: the relation between vessel wall stiffness, endothelial contractility, and cardiovascular disease. Circ Res 2015; 116:895-908. [PMID: 25722443 DOI: 10.1161/circresaha.116.305720] [Citation(s) in RCA: 133] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Vascular stiffness is a mechanical property of the vessel wall that affects blood pressure, permeability, and inflammation. As a result, vascular stiffness is a key driver of (chronic) human disorders, including pulmonary arterial hypertension, kidney disease, and atherosclerosis. Responses of the endothelium to stiffening involve integration of mechanical cues from various sources, including the extracellular matrix, smooth muscle cells, and the forces that derive from shear stress of blood. This response in turn affects endothelial cell contractility, which is an important property that regulates endothelial stiffness, permeability, and leukocyte-vessel wall interactions. Moreover, endothelial stiffening reduces nitric oxide production, which promotes smooth muscle cell contraction and vasoconstriction. In fact, vessel wall stiffening, and microcirculatory endothelial dysfunction, precedes hypertension and thus underlies the development of vascular disease. Here, we review the cross talk among vessel wall stiffening, endothelial contractility, and vascular disease, which is controlled by Rho-driven actomyosin contractility and cellular mechanotransduction. In addition to discussing the various inputs and relevant molecular events in the endothelium, we address which actomyosin-regulated changes at cell adhesion complexes are genetically associated with human cardiovascular disease. Finally, we discuss recent findings that broaden therapeutic options for targeting this important mechanical signaling pathway in vascular pathogenesis.
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Starmans LWE, Moonen RPM, Aussems-Custers E, Daemen MJAP, Strijkers GJ, Nicolay K, Grüll H. Evaluation of iron oxide nanoparticle micelles for magnetic particle imaging (MPI) of thrombosis. PLoS One 2015; 10:e0119257. [PMID: 25746677 PMCID: PMC4352001 DOI: 10.1371/journal.pone.0119257] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 01/12/2015] [Indexed: 11/19/2022] Open
Abstract
Magnetic particle imaging (MPI) is an emerging medical imaging modality that directly visualizes magnetic particles in a hot-spot like fashion. We recently developed an iron oxide nanoparticle-micelle (ION-Micelle) platform that allows highly sensitive MPI. The goal of this study was to assess the potential of the ION-Micelles for MPI-based detection of thrombi. To this aim, an in vivo carotid artery thrombosis mouse model was employed and ex vivo magnetic particle spectrometer (MPS) measurements of the carotid arteries were performed. In addition, we studied the effect of functionalization of the ION-Micelle nanoplatform with fibrin-binding peptides (FibPeps) with respect to nanoparticle thrombus uptake and hence thrombus detection. In vivo quantitative MR imaging pre- and post-ION-Micelle injection was performed as reference for visualization of ION-micelle uptake. ION-Micelles significantly decreased T2 values in the thrombi with respect to pre-injection T2 values (p < 0.01) and significantly increased ex vivo MPS thrombus signal with respect to the noninjured, contralateral carotid (p < 0.01). Functionalization of the ION-Micelles with the FibPep peptides did not result in an increased MPS thrombus signal with respect to the non-fibrin binding ION-Micelles. The lack of a significant increased thrombus uptake for the FibPep-ION-Micelles indicates that (non-fibrin-specific) entrapment of nanoparticles in the mesh-like thrombi is the key contributor to thrombus nanoparticle uptake. Therefore, (nontargeted) ION-Micelles might be of value for noninvasive MPI-based diagnosis, characterization and treatment monitoring of thrombosis.
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van der Kolk AG, Zwanenburg JJM, Denswil NP, Vink A, Spliet WGM, Daemen MJAP, Visser F, Klomp DWJ, Luijten PR, Hendrikse J. Imaging the intracranial atherosclerotic vessel wall using 7T MRI: initial comparison with histopathology. AJNR Am J Neuroradiol 2014; 36:694-701. [PMID: 25477359 DOI: 10.3174/ajnr.a4178] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 08/30/2014] [Indexed: 12/28/2022]
Abstract
BACKGROUND AND PURPOSE Several studies have attempted to characterize intracranial atherosclerotic plaques by using MR imaging sequences. However, dedicated validation of these sequences with histology has not yet been performed. The current study assessed the ability of ultra-high-resolution 7T MR imaging sequences with different image contrast weightings to image plaque components, by using histology as criterion standard. MATERIALS AND METHODS Five specimens of the circle of Wills were imaged at 7T with 0.11 × 0.11 mm in-plane-resolution proton attenuation-, T1-, T2-, and T2*-weighted sequences (through-plane resolution, 0.11-1 mm). Tissue samples from 13 fiducial-marked locations (per specimen) on MR imaging underwent histologic processing and atherosclerotic plaque classification. Reconstructed MR images were matched with histologic sections at corresponding locations. RESULTS Forty-four samples were available for subsequent evaluation of agreement or disagreement between plaque components and image contrast differences. Of samples, 52.3% (n = 23) showed no image contrast heterogeneity; this group comprised solely no lesions or early lesions. Of samples, 25.0% (n = 11, mostly advanced lesions) showed good correlation between the spatial organization of MR imaging heterogeneities and plaque components. Areas of foamy macrophages were generally seen as proton attenuation-, T2-, and T2*- hypointense areas, while areas of increased collagen content showed more ambiguous signal intensities. Five samples showed image-contrast heterogeneity without corresponding plaque components on histology; 5 other samples showed contrast heterogeneity based on intima-media artifacts. CONCLUSIONS MR imaging at 7T has the image contrast capable of identifying both focal intracranial vessel wall thickening and distinguishing areas of different signal intensities spatially corresponding to plaque components within more advanced atherosclerotic plaques.
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Marsch E, Theelen TL, Demandt JAF, Jeurissen M, van Gink M, Verjans R, Janssen A, Cleutjens JP, Meex SJR, Donners MM, Haenen GR, Schalkwijk CG, Dubois LJ, Lambin P, Mallat Z, Gijbels MJ, Heemskerk JWM, Fisher EA, Biessen EAL, Janssen BJ, Daemen MJAP, Sluimer JC. Reversal of hypoxia in murine atherosclerosis prevents necrotic core expansion by enhancing efferocytosis. Arterioscler Thromb Vasc Biol 2014; 34:2545-53. [PMID: 25256233 DOI: 10.1161/atvbaha.114.304023] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
OBJECTIVE Advanced murine and human plaques are hypoxic, but it remains unclear whether plaque hypoxia is causally related to atherogenesis. Here, we test the hypothesis that reversal of hypoxia in atherosclerotic plaques by breathing hyperoxic carbogen gas will prevent atherosclerosis. APPROACH AND RESULTS Low-density lipoprotein receptor-deficient mice (LDLR(-/-)) were fed a Western-type diet, exposed to carbogen (95% O2, 5% CO2) or air, and the effect on plaque hypoxia, size, and phenotype was studied. First, the hypoxic marker pimonidazole was detected in murine LDLR(-/-) plaque macrophages from plaque initiation onwards. Second, the efficacy of breathing carbogen (90 minutes, single exposure) was studied. Compared with air, carbogen increased arterial blood pO2 5-fold in LDLR(-/-) mice and reduced plaque hypoxia in advanced plaques of the aortic root (-32%) and arch (-84%). Finally, the effect of repeated carbogen exposure on progression of atherosclerosis was studied in LDLR(-/-) mice fed a Western-type diet for an initial 4 weeks, followed by 4 weeks of diet and carbogen or air (both 90 min/d). Carbogen reduced plaque hypoxia (-40%), necrotic core size (-37%), and TUNEL(+) (terminal uridine nick-end labeling positive) apoptotic cell content (-50%) and increased efferocytosis of apoptotic cells by cluster of differentiation 107b(+) (CD107b, MAC3) macrophages (+36%) in advanced plaques of the aortic root. Plaque size, plasma cholesterol, hematopoiesis, and systemic inflammation were unchanged. In vitro, hypoxia hampered efferocytosis by bone marrow-derived macrophages, which was dependent on the receptor Mer tyrosine kinase. CONCLUSIONS Carbogen restored murine plaque oxygenation and prevented necrotic core expansion by enhancing efferocytosis, likely via Mer tyrosine kinase. Thus, plaque hypoxia is causally related to necrotic core expansion.
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Kwak BR, Bäck M, Bochaton-Piallat ML, Caligiuri G, Daemen MJAP, Davies PF, Hoefer IE, Holvoet P, Jo H, Krams R, Lehoux S, Monaco C, Steffens S, Virmani R, Weber C, Wentzel JJ, Evans PC. Biomechanical factors in atherosclerosis: mechanisms and clinical implications. Eur Heart J 2014; 35:3013-20, 3020a-3020d. [PMID: 25230814 DOI: 10.1093/eurheartj/ehu353] [Citation(s) in RCA: 297] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Blood vessels are exposed to multiple mechanical forces that are exerted on the vessel wall (radial, circumferential and longitudinal forces) or on the endothelial surface (shear stress). The stresses and strains experienced by arteries influence the initiation of atherosclerotic lesions, which develop at regions of arteries that are exposed to complex blood flow. In addition, plaque progression and eventually plaque rupture is influenced by a complex interaction between biological and mechanical factors-mechanical forces regulate the cellular and molecular composition of plaques and, conversely, the composition of plaques determines their ability to withstand mechanical load. A deeper understanding of these interactions is essential for designing new therapeutic strategies to prevent lesion development and promote plaque stabilization. Moreover, integrating clinical imaging techniques with finite element modelling techniques allows for detailed examination of local morphological and biomechanical characteristics of atherosclerotic lesions that may be of help in prediction of future events. In this ESC Position Paper on biomechanical factors in atherosclerosis, we summarize the current 'state of the art' on the interface between mechanical forces and atherosclerotic plaque biology and identify potential clinical applications and key questions for future research.
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Verbree J, Bronzwaer ASGT, Ghariq E, Versluis MJ, Daemen MJAP, van Buchem MA, Dahan A, van Lieshout JJ, van Osch MJP. Assessment of middle cerebral artery diameter during hypocapnia and hypercapnia in humans using ultra-high-field MRI. J Appl Physiol (1985) 2014; 117:1084-9. [PMID: 25190741 DOI: 10.1152/japplphysiol.00651.2014] [Citation(s) in RCA: 226] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In the evaluation of cerebrovascular CO2 reactivity measurements, it is often assumed that the diameter of the large intracranial arteries insonated by transcranial Doppler remains unaffected by changes in arterial CO2 partial pressure. However, the strong cerebral vasodilatory capacity of CO2 challenges this assumption, suggesting that there should be some changes in diameter, even if very small. Data from previous studies on effects of CO2 on cerebral artery diameter [middle cerebral artery (MCA)] have been inconsistent. In this study, we examined 10 healthy subjects (5 women, 5 men, age 21-30 yr). High-resolution (0.2 mm in-plane) MRI scans at 7 Tesla were used for direct observation of the MCA diameter during hypocapnia, -1 kPa (-7.5 mmHg), normocapnia, 0 kPa (0 mmHg), and two levels of hypercapnia, +1 and +2 kPa (7.5 and 15 mmHg), with respect to baseline. The vessel lumen was manually delineated by two independent observers. The results showed that the MCA diameter increased by 6.8 ± 2.9% in response to 2 kPa end-tidal P(CO2) (PET(CO2)) above baseline. However, no significant changes in diameter were observed at the -1 kPa (-1.2 ± 2.4%), and +1 kPa (+1.4 ± 3.2%) levels relative to normocapnia. The nonlinear response of the MCA diameter to CO2 was fitted as a continuous calibration curve. Cerebral blood flow changes measured by transcranial Doppler could be corrected by this calibration curve using concomitant PET(CO2) measurements. In conclusion, the MCA diameter remains constant during small deviations of the PET(CO2) from normocapnia, but increases at higher PET(CO2) values.
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Thomas AC, Eijgelaar WJ, Daemen MJAP, Hayes EM, Bevan LA, Johnson JL, White SJ, Newby AC. P730Foam cell macrophages increase fibrosis: a new paradox. Cardiovasc Res 2014. [DOI: 10.1093/cvr/cvu098.151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Theelen TL, Marsch E, Demandt J, Dinjens C, Cleutjens JP, Gijbels MJ, Carmeliet P, Daemen MJAP, Sluimer JC. P477Myeloid PHD-2 deficiency leads to enlarged and fibrotic atherosclerotic plaques in mice. Cardiovasc Res 2014. [DOI: 10.1093/cvr/cvu091.153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Marsch E, Demandt J, Theelen T, Gijbels MJ, Rensen PCN, Carmeliet P, Fisher EA, Biessen EAL, Daemen MJAP, Sluimer JC. 13PHD1 deficiency promotes an atheroprotective metabolic phenotype. Cardiovasc Res 2014. [DOI: 10.1093/cvr/cvu075.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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van Geemen D, Smeets MWJ, van Stalborch AMD, Woerdeman LAE, Daemen MJAP, Hordijk PL, Huveneers S. F-actin-anchored focal adhesions distinguish endothelial phenotypes of human arteries and veins. Arterioscler Thromb Vasc Biol 2014; 34:2059-67. [PMID: 25012130 DOI: 10.1161/atvbaha.114.304180] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
OBJECTIVE Vascular endothelial-cadherin- and integrin-based cell adhesions are crucial for endothelial barrier function. Formation and disassembly of these adhesions controls endothelial remodeling during vascular repair, angiogenesis, and inflammation. In vitro studies indicate that vascular cytokines control adhesion through regulation of the actin cytoskeleton, but it remains unknown whether such regulation occurs in human vessels. We aimed to investigate regulation of the actin cytoskeleton and cell adhesions within the endothelium of human arteries and veins. APPROACH AND RESULTS We used an ex vivo protocol for immunofluorescence in human vessels, allowing detailed en face microscopy of endothelial monolayers. We compared arteries and veins of the umbilical cord and mesenteric, epigastric, and breast tissues and find that the presence of central F-actin fibers distinguishes the endothelial phenotype of adult arteries from veins. F-actin in endothelium of adult veins as well as in umbilical vasculature predominantly localizes cortically at the cell boundaries. By contrast, prominent endothelial F-actin fibers in adult arteries anchor mostly to focal adhesions containing integrin-binding proteins paxillin and focal adhesion kinase and follow the orientation of the extracellular matrix protein fibronectin. Other arterial F-actin fibers end in vascular endothelial-cadherin-based endothelial focal adherens junctions. In vitro adhesion experiments on compliant substrates demonstrate that formation of focal adhesions is strongly induced by extracellular matrix rigidity, irrespective of arterial or venous origin of endothelial cells. CONCLUSIONS Our data show that F-actin-anchored focal adhesions distinguish endothelial phenotypes of human arteries from veins. We conclude that the biomechanical properties of the vascular extracellular matrix determine this endothelial characteristic.
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Starmans LWE, van Duijnhoven SMJ, Rossin R, Aime S, Daemen MJAP, Nicolay K, Grüll H. SPECT imaging of fibrin using fibrin-binding peptides. CONTRAST MEDIA & MOLECULAR IMAGING 2013; 8:229-37. [PMID: 23606426 DOI: 10.1002/cmmi.1521] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Revised: 11/01/2012] [Accepted: 11/12/2012] [Indexed: 01/24/2023]
Abstract
Noninvasive detection of fibrin in vivo using diagnostic imaging modalities may improve clinical decision-making on possible therapeutic options in atherosclerosis, cancer and thrombus-related pathologies such as pulmonary embolism and deep venous thrombosis. The aim of this study was to assess the potential of a novel (111)In-labeled fibrin-binding peptide (FibPep) to visualize thrombi in mice noninvasively using single-photon emission computed tomography (SPECT). FibPep and a negative control peptide (NCFibPep) were synthesized and their fibrin-binding properties were assessed in vitro. FibPep showed enhanced binding compared with NCFibPep to both fibrin and blood clots. FibPep bound to fibrin with a dissociation constant (K(d)) of 0.8 μ m, whereas NCFibPep displayed at least a 100-fold lower affinity towards fibrin. A FeCl3 -injury carotid artery thrombosis mouse model was used to evaluate the peptides in vivo. FibPep and NCFibPep displayed rapid blood clearance and were eliminated via the renal pathway. In vivo SPECT imaging using FibPep allowed clear visualization of thrombi. Ex vivo biodistribution showed significantly increased uptake of FibPep in the thrombus-containing carotid in comparison to the noninjured carotid (5.7 ± 0.7 and 0.6 ± 0.4% injected dose per gram (%ID g(-1)), respectively; p < 0.01; n = 4), whereas nonspecific NCFibPep did not (0.4 ± 0.2 and 0.3 ± 0.0%ID g(-1), respectively; n = 4). In conclusion, FibPep displayed high affinity towards fibrin in vitro and rapid blood clearance in vivo, and allowed sensitive detection of thrombi using SPECT imaging. Therefore, this particular imaging approach may provide a new tool to diagnose and monitor diseases such as atherosclerosis and cancer.
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