Mouse Model Of Advanced Atherosclerosis Research Articles

α-Tocopherol inhibits atherogenesis and improves cardiac function in mice independently of its antioxidant properties.

The impact of α-tocopherol on atherosclerosis is unclear and controversial. While some studies suggest potential benefits, such as antioxidant properties that may reduce oxidative stress, other studies indicate no significant preventive effects. The intricate interplay of various factors, including dosage, individual differences, and study methodologies, contributes to the ongoing uncertainty surrounding α-tocopherol's role in atherosclerosis. Further research is needed to clarify its impact and establish clearer guidelines. Therefore, we aimed to evaluate the impact of α-tocopherol on atherogenesis in ApoE-/- fibrillin (Fbn)1C1039G/+ mice, which is a unique mouse model of advanced atherosclerosis with typical features, such as large necrotic cores, high levels of inflammation, and intraplaque neovascularization, that resemble the unstable phenotype of human plaques. ApoE-/- Fbn1C1039G+/- mice were fed a western-type diet (WD) supplemented with a high dose of α-tocopherol (500 mg/kg diet), while control mice were fed a WD containing a low dose of α-tocopherol (50 mg/kg diet). The high dose of α-tocopherol reduced plaque thickness and necrotic core area in the right common carotid artery (RCCA) after 24 weeks WD. Moreover, α-tocopherol decreased plaque formation and intraplaque neovascularization in the RCCA. In addition to its antiatherogenic effect, chronic supplementation of α-tocopherol improved cardiac function in ApoE-/- Fbn1C1039G/+ mice. However, chronic supplementation of α-tocopherol did not decrease lipid peroxidation. On the contrary, α-tocopherol acted as a prooxidant by increasing plasma levels of oxidized LDL and plaque malondialdehyde, an end product of lipid peroxidation. Our data indicate that α-tocopherol inhibits atherogenesis and improves cardiac function independent of its antioxidant properties.

The impact of RIPK1 kinase inhibition on atherogenesis

Background and Aims : RIPK1 (receptor-interacting serine/threonine-protein kinase 1) enzymatic activity drives both apoptosis and necroptosis, a regulated form of necrosis. Because necroptosis is involved in necrotic core development in atherosclerotic plaques, we investigated the effect of a RIPK1S25D/S25D mutation, which prevents the activation of RIPK1 kinase, on atherogenesis in ApoE-/- mice. Furthermore, we pharmacologically inhibited RIPK1 kinase activity by administering GSK’547 to ApoE-/- Fbn1C1039G+/- mice, a mouse model of advanced atherosclerosis.

Acetylsalicylic Acid Reduces Passive Aortic Wall Stiffness and Cardiovascular Remodelling in a Mouse Model of Advanced Atherosclerosis.

Acetylsalicylic acid (ASA) is widely used in secondary prevention of cardiovascular (CV) disease, mainly because of its antithrombotic effects. Here, we investigated whether ASA can prevent the progression of vessel wall remodelling, atherosclerosis, and CV complications in apolipoprotein E deficient (ApoE−/−) mice, a model of stable atherosclerosis, and in ApoE−/− mice with a mutation in the fibrillin-1 gene (Fbn1C1039G+/−), which is a model of elastic fibre fragmentation, accompanied by exacerbated unstable atherosclerosis. Female ApoE−/− and ApoE−/−Fbn1C1039G+/− mice were fed a Western diet (WD). At 10 weeks of WD, the mice were randomly divided into four groups, receiving either ASA 5 mg/kg/day in the drinking water (ApoE−/− (n = 14), ApoE−/−Fbn1C1039G+/− (n = 19)) or plain drinking water (ApoE−/− (n = 15), ApoE−/−Fbn1C1039G+/− (n = 21)) for 15 weeks. ApoE−/−Fbn1C1039G+/− mice showed an increased neutrophil–lymphocyte ratio (NLR) compared to ApoE−/− mice, and this effect was normalised by ASA. In the proximal ascending aorta wall, ASA-treated ApoE−/−Fbn1C1039G+/− mice showed less p-SMAD2/3 positive nuclei, a lower collagen percentage and an increased elastin/collagen ratio, consistent with the values measured in ApoE−/− mice. ASA did not affect plaque progression, incidence of myocardial infarction and survival of ApoE−/−Fbn1C1039G+/− mice, but systolic blood pressure, cardiac fibrosis and hypertrophy were reduced. In conclusion, ASA normalises the NLR, passive wall stiffness and cardiac remodelling in ApoE−/−Fbn1C1039G+/− mice to levels observed in ApoE−/− mice, indicating additional therapeutic benefits of ASA beyond its classical use.

LDL-Based Lipid Nanoparticle Derived for Blood Plasma Accumulates Preferentially in Atherosclerotic Plaque.

Apolipoprotein-based drug delivery is a promising approach to develop safe nanoparticles capable of targeted drug delivery for various diseases. In this work, we have synthesized a lipid-based nanoparticle (NPs) that we have called “Aposomes” presenting native apolipoprotein B-100 (apoB-100), the primary protein present in Low-Density Lipoproteins (LDL) on its surface. The aposomes were synthesized from LDL isolated from blood plasma using a microfluidic approach. The synthesized aposomes had a diameter of 91 ± 4 nm and a neutral surface charge of 0.7 mV ± mV. Protein analysis using western blot and flow cytometry confirmed the presence of apoB-100 on the nanoparticle’s surface. Furthermore, Aposomes retained liposomes’ drug loading capabilities, demonstrating a prolonged release curve with ∼80% cargo release at 4 hours. Considering the natural tropism of LDL towards the atherosclerotic plaques, we evaluated the biological properties of aposomes in a mouse model of advanced atherosclerosis. We observed a ∼20-fold increase in targeting of plaques when comparing aposomes to control liposomes. Additionally, aposomes presented a favorable biocompatibility profile that showed no deviation from typical values in liver toxicity markers (i.e., LDH, ALT, AST, Cholesterol). The results of this study demonstrate the possibilities of using apolipoprotein-based approaches to create nanoparticles with active targeting capabilities and could be the basis for future cardiovascular therapies.

Pleiotropic Effects of Atorvastatin Result in a Downregulation of the Carboxypeptidase U System (CPU, TAFIa, CPB2) in a Mouse Model of Advanced Atherosclerosis.

Statins (hydroxymethyl-glutaryl-CoA-reductase inhibitors) lower procarboxypeptidase U (proCPU, TAFI, proCPB2). However, it is challenging to prove whether this is a lipid or non-lipid-related pleiotropic effect, since statin treatment decreases cholesterol levels in humans. In apolipoprotein E-deficient mice with a heterozygous mutation in the fibrillin-1 gene (ApoE−/−Fbn1C1039G+/−), a model of advanced atherosclerosis, statins do not lower cholesterol. Consequently, studying cholesterol-independent effects of statins can be achieved more straightforwardly in these mice. Female ApoE −/−Fbn1C1039G+/− mice were fed a Western diet (WD). At week 10 of WD, mice were divided into a WD group (receiving WD only) and a WD + atorvastatin group (receiving 10 mg/kg/day atorvastatin +WD) group. After 15 weeks, blood was collected from the retro-orbital plexus, and the mice were sacrificed. Total plasma cholesterol and C-reactive protein (CRP) were measured with commercially available kits. Plasma proCPU levels were determined with an activity-based assay. Total plasma cholesterol levels were not significantly different between both groups, while proCPU levels were significantly lower in the WD + atorvastatin group. Interestingly proCPU levels correlated with CRP and circulating monocytes. In conclusion, our results confirm that atorvastatin downregulates proCPU levels in ApoE−/−Fbn1C1039G+/− mice on a WD, and evidence was provided that this downregulation is a pleiotropic effect of atorvastatin treatment.

P.57 Acetylsalicylic Acid Reduces Passive Aortic Wall Stiffness and Cardiac Remodelling in a Mouse Model of Advanced Atherosclerosis

BackgroundAcetylsalicylic acid (ASA) is used in secondary prevention of cardiovascular disease (CVD) because of its antithrombotic effects. We investigated whether ASA has additional therapeutic value by preventing the progression of inflammation and cardiovascular remodelling in mice with stable atherosclerosis (ApoE−/−) and in a model of arterial stiffness with advanced unstable atherosclerotic plaques (ApoE−/−Fbn1C1039G+/− mice).MethodsFemale ApoE−/− and ApoE−/−Fbn1C1039G+/− mice were fed a Western diet (WD). At 10 weeks WD, the mice were divided in 2 groups receiving ASA (5 mg/kg/day) via the drinking water or plain water (control) for a period of 15 weeks. Echocardiograms were performed at 10, 17 and 25 weeks WD. At the end, blood pressure was measured via tail-cuff and blood samples were taken. The aorta and heart were collected for histology.ResultsApoE−/−Fbn1C1039G+/− mice showed an increased neutrophil-lymphocyte ratio (NLR), an important inflammatory biomarker, which was decreased by ASA treatment (Table 1). Wall thickness of the proximal ascending aorta was reduced and elastin/collagen ratio was increased in ASA-treated ApoE−/−Fbn1C1039G+/− mice, resembling values measured in ApoE−/− mice (Table 1). Systolic blood pressure, cardiac fibrosis and hypertrophy (Table 1, Figure 1) were reduced after ASA treatment in ApoE−/−Fbn1C1039G+/− mice.ConclusionWe showed that ASA is able to decrease the NLR, passive aortic wall stiffness and cardiac remodelling in mice with advanced atherosclerosis to levels observed in mice with smaller and more stable atherosclerotic plaques. These data point towards an additional benefit of ASA in the prevention of CVD beyond its classical use.Table 1Summary of main resultsApoE−/−ApoE−/−FbnlC1039G+/−ControlASAControlASAMean ± SEMNMean ± SEMNMean ± SEMNMean ± SEMNBloodNeutrophils (%)10.7 ± 2.1159.1 ± 1.51226.4 ± 6.2**1013.2 ± 2.1§7Lymphocytes (%)79.2 ± 3.01580.0 ± 4.31358.2 ± 7.9**1086.4 ± 2.4§§7NLR0.12 ± 0.02140.12 ± 0.02120.45 ± 0.13***90.16 ± 0.03§§7Proximal aortaWall thickness (µm)64.9 ± 1.5961.7 ± 1.81070.0 ± 2.41360.3 ± 2.9§§15Elastin wall (%)24.1 ± 1.2928.0 ± 1.21019.9 ± 1.1*1322.8 ± 1.515Collagen wall (%)44.4 ± 4.5939.4 ± 3.21063.9 ± 3.9**1347.1 ± 3.3§§15Elastin/collagen ratio (%)58.8 ± 5.9975.1 ± 6.9*1032.5 ± 2.6***1349.5 ± 2.1§§§15HeartHeart weight/body weight (%)0.50 ± 0.02150.49 ± 0.02141.16 ± 0.12***100.76 ± 0.05§§§8Total fibrosis (%)5.7 ± 0.2156.1 ± 0.4149.0 ± 0.7***166.1 ± 0.5§§§15BPSystolic BP (mmHg)88 ± 41580 ± 41283 ± 6767 ± 4§8Diastolic BP (mmHg)63 ± 41556 ± 31259 ± 6747 ± 482-way ANOVA followed by a simple main effects analysis including a Bonferroni correction for multiple comparisons: *p < 0.05, **p < 0.01, ***p < 0.001 vs. ApoE-/- control and §p < 0.05, §§p < 0.01, §§§p < 0.001 vs. ApoE−/−FbnlC1039G+/− control. NLR, neutrophillymphocyte ratio; BP, blood pressure.

Three-Dimensional Imaging of Intraplaque Neovascularization in a Mouse Model of Advanced Atherosclerosis

Multiple lines of evidence suggest that intraplaque (IP) neovascularization promotes atherosclerotic plaque growth, destabilization, and rupture. However, pharmacological inhibition of IP neovascularization remains largely unexplored due to the limited number of animal models that develop IP neovessels and the lack of reliable methods for visualizing IP angiogenesis. Here, we applied 3D confocal microscopy with an optimized tissue-clearing process, immunolabeling-enabled three-dimensional imaging of solvent-cleared organs, to visualize IP neovessels in apolipoprotein E-deficient (ApoE^−/−) mice carrying a heterozygous mutation (C1039+/−) in the fibrillin-1 gene. Unlike regular ApoE^−/− mice, this mouse model is characterized by the presence of advanced plaques with evident IP neovascularization. Plaques were stained with antibodies against endothelial marker CD31 for 3 days, followed by incubation with fluorescently labeled secondary antibodies. Subsequent tissue clearing with dichloromethane (DCM)/methanol, DCM, and dibenzyl ether allowed easy visualization and 3D reconstruction of the IP vascular network while plaque morphology remained intact.

Therapeutic ultrasound combined with microbubbles improves atherosclerotic plaque stability by selectively destroying the intraplaque neovasculature.

Objective: The current antiangiogenic therapy for atherosclerotic plaques was mainly achieved by the use of antiangiogenic drugs, but serious side effects have limited the clinical application. The present study investigated whether therapeutic ultrasound (TUS) treatment with appropriate pressure could selectively deplete the neovasculature in vulnerable plaques to improve its stability with no side effects on the body; the underlying mechanisms were also explored.Methods and Results: A mouse model of advanced atherosclerosis was generated by maintaining apolipoprotein E-deficient (ApoE-/-) mice on a hypercholesterolemic diet (HCD). Plaque, skeletal muscle, mesentery and skin tissue from 114 atheroma-bearing mice were subjected to sham therapy, an ultrasound application combined with microbubbles at four different ultrasound pressures (1.0, 2.0, 3.0, 5.0 MPa), or ultrasound at 5.0 MPa alone. Microvessel density (MVD) was assessed by immunofluorescence and immunohistochemical methods. The plaque necrotic center/fiber cap (NC/FC) ratio and vulnerability index were calculated to evaluate plaque vulnerability. Twenty-four hours after TUS treatment at 3.0 MPa, the MVD in the plaque was substantially decreased by 84% (p < 0.05), while there was almost no change in MVD and neovessel density (NVD) in normal tissues, including skeletal muscle, mesentery and skin. Additionally, a marked reduction in the number of immature vessels was observed in the plaques (reduced by 90%, p < 0.05), whereas the number of mature vessels was not significantly decreased. Furthermore, TUS treatment at 3.0 MPa significantly improved plaque stability, as reflected by the NC/FC ratio and vulnerability index, which may be due to the selective destruction of intraplaque neovascularization by TUS treatment, thereby decreasing the extravasation of erythrocytes and leading to vascular inflammation alleviation and thin-cap fibroatheroma reduction.Conclusions: TUS treatment at 3.0 MPa selectively depleted plaque neovessels and improved the stability of vulnerable plaques through a reduction in erythrocyte extravasation and inflammatory mediator influx, with no significant effect on normal tissue.

Everolimus depletes plaque macrophages, abolishes intraplaque neovascularization and improves survival in mice with advanced atherosclerosis

Background and aimsInhibition of the mechanistic target of rapamycin (mTOR) is a promising approach to halt atherogenesis in different animal models. This study evaluated whether the mTOR inhibitor everolimus can stabilize pre-existing plaques, prevent cardiovascular complications and improve survival in a mouse model of advanced atherosclerosis. MethodsApoE−/-Fbn1C1039G+/− mice (n = 24) were fed a Western diet (WD) for 12 weeks. Subsequently, mice were treated with everolimus (1.5 mg/kg daily) or vehicle for another 12 weeks while the WD continued. ResultsDespite hypercholesterolemia, everolimus treatment was associated with a reduction in circulating Ly6Chigh monocytes (15 vs. 28% of total leukocytes, p = 0.046), a depletion of plaque macrophages (2.1 vs. 4.1%, p = 0.040) and an abolishment of intraplaque neovascularization, which are all indicative of a more stable plaque phenotype. Moreover, everolimus reduced hypoxic brain damage and improved cardiac function, which led to increased survival (100 vs. 67% of animals, p = 0.038). ConclusionsEverolimus enhances features of plaque stability and counters cardiovascular complications in ApoE−/-Fbn1C1039G+/− mice, even when administered at a later stage of the disease.

Activation of Bone Marrow-Derived Cells Angiotensin (Ang) II Type 1 Receptor by Ang II Promotes Atherosclerotic Plaque Vulnerability.

Angiotensin (Ang) II triggers vulnerable atherosclerotic plaque development. Bone marrow (BM)-derived cells are key players in atherogenesis but whether Ang II induces plaque vulnerability directly through Ang II type 1 receptor (AT1R) activation on these cells remains to be clarified. In the present study, we investigated whether a lack of AT1R on BM-derived cells might affect Ang II-mediated vulnerable plaque development. The 2-kidney, 1-clip (2K1C) model (Ang II-dependent mouse model of advanced atherosclerosis and vulnerable plaques) was generated in ApoE−/− mice transplanted with AT1aR−/− or AT1aR+/+ BM. Plasma cholesterol as well as hepatic mRNA expression levels of genes involved in cholesterol metabolism were significantly lower in 2K1C mice transplanted with AT1aR−/− BM than in controls. Atherosclerotic lesions were significantly smaller in AT1aR−/− BM 2K1C mice (−79% in the aortic sinus and −71% in whole aorta compared to controls). Plaques from AT1aR−/− BM 2K1C mice exhibited reduced lipid core/fibrous cap and macrophage/smooth muscle cells ratios (−82% and −88%, respectively), and increased collagen content (+70%), indicating a more stable phenotype. Moreover, aortic mRNA levels of pro-inflammatory cytokines IL-12p35, IL-1β, and TNF-α were significantly reduced in AT1aR−/− BM 2K1C mice. No significant differences in either the number of circulating Ly6Chigh inflammatory monocytes and Ly6Clow resident anti-inflammatory monocyte subsets, or in mRNA levels of aortic M1 or M2 macrophage markers were observed between the two groups. No significant differences were observed in splenic mRNA levels of T cell subsets (Th1, Th2, Th17 and Treg) markers between the two groups. In conclusion, direct AT1R activation by Ang II on BM-derived cells promotes hepatic mRNA expression of cholesterol-metabolism-related genes and vascular mRNA expression of pro-inflammatory cytokines that may lead to plaque instability.

CD163+ macrophages promote angiogenesis and vascular permeability accompanied by inflammation in atherosclerosis.

Intake of hemoglobin by the hemoglobin-haptoglobin receptor CD163 leads to a distinct alternative non-foam cell antiinflammatory macrophage phenotype that was previously considered atheroprotective. Here, we reveal an unexpected but important pathogenic role for these macrophages in atherosclerosis. Using human atherosclerotic samples, cultured cells, and a mouse model of advanced atherosclerosis, we investigated the role of intraplaque hemorrhage on macrophage function with respect to angiogenesis, vascular permeability, inflammation, and plaque progression. In human atherosclerotic lesions, CD163+ macrophages were associated with plaque progression, microvascularity, and a high level of HIF1α and VEGF-A expression. We observed irregular vascular endothelial cadherin in intraplaque microvessels surrounded by CD163+ macrophages. Within these cells, activation of HIF1α via inhibition of prolyl hydroxylases promoted VEGF-mediated increases in intraplaque angiogenesis, vascular permeability, and inflammatory cell recruitment. CD163+ macrophages increased intraplaque endothelial VCAM expression and plaque inflammation. Subjects with homozygous minor alleles of the SNP rs7136716 had elevated microvessel density, increased expression of CD163 in ruptured coronary plaques, and a higher risk of myocardial infarction and coronary heart disease in population cohorts. Thus, our findings highlight a nonlipid-driven mechanism by which alternative macrophages promote plaque angiogenesis, leakiness, inflammation, and progression via the CD163/HIF1α/VEGF-A pathway.

Inhibition of VEGF receptor signaling attenuates intraplaque angiogenesis and plaque destabilization in a mouse model of advanced atherosclerosis

Aim: Intraplaque (IP) microvessels have a major causative effect on atherosclerotic plaque development. An increase in microvessel density in ruptured versus nonruptured human plaques suggests that VEGF and other angiogenic factors promote atherosclerosis and potentially destabilize plaques. Because apolipoprotein deficient mice with a heterozygous mutation (C1039G+/-) in the fibrillin-1 gene (ApoE-/-Fbn1C1039G+/-) manifest substantial IP neovascularization, they represent a unique tool to investigate angiogenesis and its role in atherosclerosis. Here, we examined whether administration of axitinib (inhibitor of VEGF receptor-1,-2 and -3) inhibits IP neovascularization and stabilizes atherosclerotic plaques.

Everolimus attenuates atherosclerotic plaque progression, intraplaque neovascularization, myocardial infarction and sudden death in a mouse model of advanced atherosclerosis

Aim: Inhibition of the mechanistic target of rapamycin (mTOR) is a promising approach to halt atherogenesis in different animal models. This study aims to elucidate mechanisms involved in the anti-atherosclerotic effects of the mTOR inhibitor everolimus using ApoE-/- mice with a heterozygous mutation in the fibrillin-1 gene (Fbn1C1039G+/-), representing a novel model of advanced atherosclerosis.

Inhibition of glycolysis reduces intraplaque angiogenesis in a mouse model of advanced atherosclerosis

Inhibition of glycolysis reduces intraplaque angiogenesis in a mouse model of advanced atherosclerosis

Ticagrelor promotes atherosclerotic plaque stability in a mouse model of advanced atherosclerosis.

ObjectiveThere is increasing evidence supporting the role of platelets in atherosclerotic vascular disease. The G-protein-coupled receptor P2Y12 is a central mediator of platelet activation and aggregation but has also been linked to platelet-independent vascular disease. Ticagrelor is an oral P2Y12 antagonist that is used as a standard treatment in patients after acute myocardial infarction. However, the effects of ticagrelor on advanced atherosclerosis have not been investigated.Materials and methodsTwenty-week-old apolipoprotein-E-deficient mice received standard chow or standard chow supplemented with 0.15% ticagrelor (approximately 270 mg/kg/day) for 25 weeks. The lesion area was evaluated in the aortic sinus by Movat’s pentachrome staining and lesion composition, thickness of the fibrous cap, and size of the necrotic core evaluated by morphometry. RAW 264.7 macrophages were serum starved and treated with ticagrelor in vitro for the detection and quantification of apoptosis. In addition, oxLDL uptake in RAW 264.7 macrophages was evaluated.ResultsA trend toward the reduction of total lesion size was detected. However, data did not reach the levels of significance (control, n=11, 565,881 μm2 [interquartile range {IQR} 454,778–603,925 μm2] versus ticagrelor, n=13, 462,595 μm2 [IQR 379,740–546,037 μm2]; P=0.1). A significant reduction in the relative area of the necrotic core (control, n=11, 0.46 [IQR 0.4–0.51] versus ticagrelor, n=13, 0.34 [IQR 0.31–0.39]; P=0.008), and a significant increase in fibrous caps thickness (control, n=11, 3.7 μm [IQR 3.4–4.2 μm] versus ticagrelor, n=13, 4.7 [IQR 4.3–5.5 μm], P=0.04) were seen in ticagrelor-treated mice. In vitro studies demonstrated a reduction in apoptotic RAW 264.7 macrophages (control 0.07±0.03 versus ticagrelor 0.03±0.03; P=0.0002) when incubated with ticagrelor. Uptake of oxLDL in RAW 264.7 was significantly reduced when treated with ticagrelor (control 9.2 [IQR 5.3–12.9] versus ticagrelor 6.4 [IQR 2.5–9.5], P=0.02).ConclusionThe present study demonstrates for the first time a plaque-stabilizing effect of ticagrelor in a model of advanced vascular disease, potentially induced by a reduction of oxLDL uptake or an inhibition of apoptosis as seen in vitro.

(Re)solving atherosclerosis.

Delivery of nanoparticles with arterial tropism containing the annexin A1 fragment Ac2-26 reduces signs of lesion instability in a mouse model of advanced atherosclerosis (Fredman et al., this issue).

Detection of high-risk atherosclerotic plaques with ultrasound molecular imaging of glycoprotein IIb/IIIa receptor on activated platelets.

Objective: Ultrasound molecular imaging (UMI) of glycoprotein (GP) IIb/IIIa receptor on activated platelets offers a unique means of identifying high-risk atherosclerosis. We hypothesized that contrast-enhanced ultrasound with microbubbles (MBs) targeted to GP IIb/IIIa could be used to detect and quantify activated platelets on the surface of advanced plaques.Methods and Results: A mouse model of advanced atherosclerosis was generated by maintaining apolipoprotein E-deficient (ApoE-/-) mice on a hypercholesterolemic diet (HCD). The three other experimental groups consisted of ApoE-/- and wild-type (C57BL/6) mice fed a normal chow diet and C57BL/6 mice on an HCD diet. Plaque formation was confirmed by histological and immunohistochemical methods using light, fluorescence, and electron microscopy. Mice were injected with a lipid MB-conjugated cyclic Arg-Gly-Asp peptide or nonspecific control peptide, and the abdominal aorta was examined by UMI. The accumulation of GP IIb/IIIa and activated platelets on the surface of atherosclerotic plaques was highest in the ApoE-/-+HCD group, followed by ApoE-/-+chow, C57BL/6+HCD, and C57BL/6+chow groups (P<0.05). Notably, GP IIb/IIIa expression was associated with the vulnerability index and necrotic center/fiber cap ratio (P<0.05), and contrast video intensity from adhered cyclic Arg-Gly-Asp-modified MBs (MB-cRGDs) was correlated with GP IIb/IIIa expression on the plaque surface (P<0.05).Conclusion: GP IIb/IIIa of activated platelets on the atherosclerotic endothelium is a biomarker for high-risk plaques that can be quantified by UMI using MB-cRGDs, providing a noninvasive means for detecting high-risk plaques and preventing acute cardiovascular events.

GDF-15 protects from macrophage accumulation in a mousemodel of advanced atherosclerosis

BackgroundThe cytokine growth differentiation factor-15 (GDF-15), a member of the TGF beta superfamily, has recently been discovered to play an important role in cardiovascular diseases. It is mostly expressed in macrophages of atherosclerotic lesions, but its impact on advanced atherosclerosis is still unknown. This study was performed to evaluate the effects of GDF-15 in an established mouse model of advanced atherosclerosis.MethodsThirty-eight LDL receptor deficient mice received a lethal body radiation. Half of the group was transplanted with bone marrow of GDF-15 deficient mice. Nineteen mice were transplanted with bone marrow from wild-type controls. After 24 weeks on an atherogenic diet, animals were euthanized and sections of the aortic sinus were prepared. Lesion size and lesion composition, as well as macrophage content,were evaluated.ResultsWhile demonstrating no difference in lesion size, LDL-receptor knockout mice transplanted with bone marrow from GDF-15 deficient mice showed enhanced macrophage accumulation and features of atherosclerotic plaque destabilization, such as thinning of fibrous caps. Immunostaining against intercellular adhesion molecule-1 further revealed an increased expression in mice receiving GDF-15-deficient bone marrow.ConclusionsThis is the first study that demonstrates a protective role of GDF-15 in advanced atherosclerosis and macrophage accumulation, possibly due to the reduced expression of adhesion molecules.

Abstract 5672: Deletion of Bone Marrow Derived Receptor for Advanced Glycation End-products (RAGE) Does Not Attenuate Plaque Formation but Inhibits Plaque Progression in a Mouse Model of Advanced Atherosclerosis

Background and Hypothesis: The multiligand receptor for advanced glycation end products (RAGE) of the immunoglobulin superfamily is expressed on multiple cell types implicated in the immune-inflammatory response and in atherosclerosis. We sought to determine the role that bone marrow derived RAGE plays in different stages of atherosclerotic lesion development in apolipoprotein E deficient (apoE −/− ) mice. Methods and Results: 7 and 23 week apoE −/− mice were lethally irradiated and given bone marrow from RAGE null (RAGE −/− //apoE −/− ) or RAGE −/−/ /apoE −/− mice to create double knock out chimeras. After 16 weeks on a standard chow diet the mice were sacrificed and atherosclerotic lesion development was evaluated. Plaques in the aortic root of the young mice showed no significant difference in maximum plaque size (217 470±17 480 μ m 2 for the RAGE −/− //apoE −/− mice compared to 244 764±45 840 μ m 2 ) whereas plaques from the older innominate artery of Rage −/− /apoE −/− mice had significantly smaller maximum plaque area compared to the Rage −/−/ apoE −/− mice (83 384±17 981 μ m 2 compared to 136 041±13604 μ m 2 , p&lt;.05) as well as reduced average necrotic core area (35 582±4 797 μ m 2 compared to 55 604±6 523 μ m 2 , p&lt;.05). Reduced plaque size and more stable plaque morphology was associated with significant decreases in the expression of important atherogenic mediators including VCAM-1, ICAM-1, and MCP-1. Accumulation of the RAGE ligand HMGB-1 was also significantly reduced within the lesions of the Rage −/− /apoE −/− mice. Conclusions: This study demonstrates that bone marrow derived RAGE is an important factor in the progression of atherosclerotic plaque development by causing increased expression of pro-atherosclerotic mediators. It provides evidence that RAGE could be a potential target for clinical treatment of advanced atherosclerosis.

153 MR vessel wall imaging of the descending aorta using an elastin-binding contrast agent in an ApoE-/- TFDeltact double knockout mouse model of advanced atherosclerosis

153 MR vessel wall imaging of the descending aorta using an elastin-binding contrast agent in an ApoE-/- TFDeltact double knockout mouse model of advanced atherosclerosis