Accumulation Of Macrophages In Atherosclerotic Lesions Research Articles

Dual-energy CT imaging of atherosclerotic plaque using novel ultrasmall superparamagnetic iron oxide in hyperlipidemic rabbits.

A study using magnetic resonance imaging (MRI) revealed that ultra-small superparamagnetic iron oxide is phagocytosed by macrophages. However, MRI has limitations in obtaining clear images due to its poor spatial and temporal resolutions. To examine whether the use of dual-energy computed tomography (DECT) facilitated the visualization of carboxymethyl-diethylaminoethyl dextran magnetite ultra-small superparamagnetic iron oxide (CMEADM-U) accumulation in arteriosclerotic lesions using hyperlipidemic rabbits. CMEADM-U at 0.5 mmol Fe/kg was administered to Watanabe hereditary atherosclerotic (WHHL) rabbits (n = 6, 24 sections) and New Zealand white (NZW) rabbits (n = 2, 6 sections). After 72 h, DECT was performed to prepare virtual monochromatic images (35 keV, 70 keV) and an iron-based map. Subsequently, the aorta was collected along with hematoxylin and eosin staining, Berlin blue (BB) staining, and RAM11 immunostaining. In the WHHL rabbits, CMEADM-U accumulation was not observed at 70 keV. However, CMEADM-U accumulation consistent with an arteriosclerotic lesion was observed at 35 keV and the iron-based map. On the other hand, in the NZW rabbits, there was no accumulation of CMEADM-U in any images. Further, there were significant differences in the iron-based map value at the site of accumulation among the grades of expression on BB staining and RAM11 immunostaining. In addition, there was a good correlation at 35 kev and iron-based map value (r = 0.42; P < 0.05). DECT imaging for CMEADM-U facilitated the assessment of macrophage accumulation in atherosclerotic lesions in an in vivo study using a rabbit model of induced aortic atherosclerosis.

Leptin treatment has vasculo-protective effects in lipodystrophic mice

Lipodystrophy syndromes (LDs) are characterized by loss of adipose tissue, metabolic complications such as dyslipidemia, insulin resistance, and fatty liver disease, as well as accelerated atherosclerosis. As a result of adipose tissue deficiency, the systemic concentration of the adipokine leptin is reduced. A current promising therapeutic option for patients with LD is treatment with recombinant leptin (metreleptin), resulting in reduced risk of mortality. Here, we investigate the effects of leptin on endothelial to mesenchymal transition (EndMT), which impair the functional properties of endothelial cells and promotes atherogenesis in LD. Leptin treatment reduced inflammation and TGF-β2-induced expression of mesenchymal genes and prevented impairment of endothelial barrier function. Treatment of lipodystrophic- and atherosclerosis-prone animals (Ldlr-/-; aP2-nSrebp1c-Tg) with leptin reduced macrophage accumulation in atherosclerotic lesions, vascular plaque protrusion, and the number of endothelial cells with mesenchymal gene expression, confirming a reduction in EndMT in LD after leptin treatment. Treatment with leptin inhibited LD-mediated induction of the proatherosclerotic cytokine growth/differentiation factor 15 (GDF15). Inhibition of GDF15 reduced EndMT induction triggered by plasma from patients with LD. Our study reveals that in addition to the effects on adipose tissue function, leptin treatment exerts beneficial effects protecting endothelial function and identity in LD by reducing GDF15.

Assessment of Albumin ECM Accumulation and Inflammation as Novel In Vivo Diagnostic Targets for Multi-Target MR Imaging.

Simple SummaryAtherosclerosis is an inflammatory disease associated with extracellular matrix remodeling. It is characterized by endothelial dysfunction with albumin influx into the vessel wall and macrophage accumulation in atherosclerotic lesions. Non-invasive magnetic resonance imaging (MRI) allows for the assessment of the molecular components of the plaque and vessel wall by using two different target-specific MRI contrast agents in one imaging session. Therefore, multi-target MRI is a promising method to improve diagnosis and treatment monitoring in patients with atherosclerosis.Atherosclerosis is a progressive inflammatory vascular disease characterized by endothelial dysfunction and plaque burden. Extracellular matrix (ECM)-associated plasma proteins play an important role in disease development. Our magnetic resonance imaging (MRI) study investigates the feasibility of using two different molecular MRI probes for the simultaneous assessment of ECM-associated intraplaque albumin deposits caused by endothelial damage and progressive inflammation in atherosclerosis. Male apolipoprotein E-deficient (ApoE-/-)-mice were fed a high-fat diet (HFD) for 2 or 4 months. Another ApoE-/--group was treated with pravastatin and received a HFD for 4 months. T1- and T2*-weighted MRI was performed before and after albumin-specific MRI probe (gadofosveset) administration and a macrophage-specific contrast agent (ferumoxytol). Thereafter, laser ablation inductively coupled plasma mass spectrometry and histology were performed. With advancing atherosclerosis, albumin-based MRI signal enhancement and ferumoxytol-induced signal loss areas in T2*-weighted MRI increased. Significant correlations between contrast-to-noise-ratio (CNR) post-gadofosveset and albumin stain (R2 = 0.78, p < 0.05), and signal loss areas in T2*-weighted MRI with Perls’ Prussian blue stain (R2 = 0.83, p < 0.05) were observed. No interference of ferumoxytol with gadofosveset enhancement was detectable. Pravastatin led to decreased inflammation and intraplaque albumin. Multi-target MRI combining ferumoxytol and gadofosveset is a promising method to improve diagnosis and treatment monitoring in atherosclerosis.

Deficiency of histone lysine methyltransferase SETDB2 in hematopoietic cells promotes vascular inflammation and accelerates atherosclerosis.

Epigenetic modifications of the genome, including DNA methylation, histone methylation/acetylation, and noncoding RNAs, have been reported to play a fundamental role in regulating immune response during the progression of atherosclerosis. SETDB2 is a member of the KMT1 family of lysine methyltransferases, and members of this family typically methylate histone H3 Lys9 (H3K9), an epigenetic mark associated with gene silencing. Previous studies have shown that SETDB2 is involved in innate and adaptive immunity, the proinflammatory response, and hepatic lipid metabolism. Here, we report that expression of SETDB2 is markedly upregulated in human and murine atherosclerotic lesions. Upregulation of SETDB2 was observed in proinflammatory M1 but not antiinflammatory M2 macrophages. Notably, we found that genetic deletion of SETDB2 in hematopoietic cells promoted vascular inflammation and enhanced the progression of atherosclerosis in BM transfer studies in Ldlr-knockout mice. Single-cell RNA-Seq analysis in isolated CD45+ cells from atherosclerotic plaques from mice transplanted with SETDB2-deficient BM revealed a significant increase in monocyte population and enhanced expression of genes involved in inflammation and myeloid cell recruitment. Additionally, we found that loss of SETDB2 in hematopoietic cells was associated with macrophage accumulation in atherosclerotic lesions and attenuated efferocytosis. Overall, these studies identify SETDB2 as an important inflammatory cell regulator that controls macrophage activation in atherosclerotic plaques.

Anti-Inflammatory Actions of Soluble Ninjurin-1 Ameliorate Atherosclerosis.

Macrophages produce many inflammation-associated molecules, released by matrix metalloproteinases, such as adhesion molecules, and cytokines, as well, which play a crucial role in atherosclerosis. In this context, we investigated the relationship between Ninjurin-1 (Ninj1 [nerve injury-induced protein]), a novel matrix metalloproteinase 9 substrate, expression, and atherosclerosis progression. Ninj1 expression and atherosclerosis progression were assessed in atherosclerotic aortic tissue and serum samples from patients with coronary artery disease and healthy controls, and atheroprone apolipoprotein e-deficient (Apoe-/-) and wild-type mice, as well. Apoe-/- mice lacking systemic Ninj1 expression (Ninj1-/-Apoe-/-) were generated to assess the functional effects of Ninj1. Bone marrow transplantation was also used to generate low-density lipoprotein receptor-deficient (Ldlr-/-) mice that lack Ninj1 specifically in bone marrow-derived cells. Mice were fed a Western diet for 5 to 23 weeks, and atherosclerotic lesions were investigated. The anti-inflammatory role of Ninj1 was verified by treating macrophages and mice with the peptides Ninj11-56 (ML56) and Ninj126-37 (PN12), which mimic the soluble form of Ninj1 (sNinj1). Our in vivo results conclusively showed a correlation between Ninj1 expression in aortic macrophages and the extent of human and mouse atherosclerotic lesions. Ninj1-deficient macrophages promoted proinflammatory gene expression by activating mitogen-activated protein kinase and inhibiting the phosphoinositide 3-kinase/Akt signaling pathway. Whole-body and bone marrow-specific Ninj1 deficiencies significantly increased monocyte recruitment and macrophage accumulation in atherosclerotic lesions through elevated macrophage-mediated inflammation. Macrophage Ninj1 was directly cleaved by matrix metalloproteinase 9 to generate a soluble form that exhibited antiatherosclerotic effects, as assessed in vitro and in vivo. Treatment with the sNinj1-mimetic peptides, ML56 and PN12, reduced proinflammatory gene expression in human and mouse classically activated macrophages, thereby attenuating monocyte transendothelial migration. Moreover, continuous administration of mPN12 alleviated atherosclerosis by inhibiting the enhanced monocyte recruitment and inflammation characteristics of this disorder in mice, regardless of the presence of Ninj1. Ninj1 is a novel matrix metalloproteinase 9 substrate in macrophages, and sNinj1 is a secreted atheroprotective protein that regulates macrophage inflammation and monocyte recruitment in atherosclerosis. Moreover, sNinj1-mediated anti-inflammatory effects are conserved in human macrophages and likely contribute to human atherosclerosis.

Pravastatin attenuates atherosclerosis after myocardial infarction by inhibiting inflammatory Ly6Chigh monocytosis in apolipoprotein E knockout mice.

ObjectiveTo evaluate the protective effect of pravastatin on atherosclerotic development and inflammatory monocyte subset in atherosclerotic apolipoprotein E (ApoE)−/− mice after myocardial infarction (MI).MethodsMale ApoE−/− mice (8 weeks old) were fed a high-fat diet for 14 weeks throughout the experiment. A MI model was produced using 18-week-old ApoE−/− mice. They were randomly divided into three groups: sham group, MI group, and MI+Pra group (40 mg/kg/day pravastatin). After 4 weeks (at the end of the study period), the mice were sacrificed and cardiac function was evaluated by echocardiography. Aortic lesion areas were evaluated using oil red O staining. Plaque macrophage in aortic sinus was analyzed by immunofluorescence staining. Flow cytometry was used to explore the proportions of monocyte subsets in the blood, spleen, and bone marrow．ResultsPravastatin improved cardiac function and reduced lesion areas. It also attenuated the supply of monocytes in spleen, especially the inflammatory Ly6Chigh monocyte subset. Pravastatin also subsequently reduced macrophage accumulation in atherosclerotic lesions.ConclusionsMI accelerated chronic atherosclerosis progress. Pravastatin suppressed atherosclerotic development and inhibited inflammatory monocytosis after MI in ApoE−/− mice.

Abstract 184: Hyperglycemia Enhances Pro-inflammatory Properties of Macrophage-derived Exosomes to Drive Hematopoiesis in Apolipoprotein E-deficient Mouse

Background and Purpose: Diabetes is recognized to enhance the frequency and severity of atherosclerosis and cardiovascular disease. Recent studies have shown that hyperglycemia is associated with enhanced hematopoiesis and macrophage accumulation in atherosclerotic lesions. We explored whether high glucose concentrations can enhance intercellular communication between mature macrophages and hematopoietic progenitors via exosomes to promote inflammation and diabetic atherosclerosis. Methods: Bone marrow derived macrophages (BMDM) from C57BL/6 mice were cultured with normal (5mM) or high glucose concentrations (25mM). Exosomes were isolated with our cushioned-density gradient ultracentrifugation method followed by nanoparticle tracking and western blot analysis. Pro-inflammatory properties of high glucose exosomes (HGexo) were tested in vitro by exposing them to BMDM cultured in normal low glucose. The capacity for BMDM-derived exosomes to alter systemic and vascular inflammation were next tested by infusing 25-30 weeks-old ApoE -/- mice fed a chow diet with 3 x 10 10 exosomes three times a week, for four weeks. Results: Our data show that HGexo can stimulate the expression of inflammatory cytokines (IL-6, IL-1ß) as well as NADPH oxidases (Nox-1 and Nox-4) in cultured BMDM. Furthermore, our findings show that intraperitoneally injected exosomes distribute to numerous organs and tissues including the bone marrow and the spleen. Lastly, HGexo enhance the expansion of multipotent and lineage committed hematopoietic progenitors. Conclusions: We identify that exosomes derived from cultured BMDM exposed to high glucose have the capacity to exert intercellular communication in vitro , and in vivo. Our findings suggest that exosomes produced by macrophages exposed to hyperglycemia could represent an unsuspected source of inflammation to accelerate atherosclerosis in diabetes.

Abstract 423: Telomerase Deficiency in Hematopoietic Stem Cells Decreases Atherosclerosis by Silencing STAT3-Dependent Inflammation in Macrophages

Objective: Telomerase Reverse Transcriptase (TERT), the catalytic subunit of telomerase, supports critical cellular responses required for tissue remodeling. Previous studies established that TERT expression is induced in activated macrophages and during experimental and human atherosclerosis formation. In the present study, we investigated the role of TERT for atherosclerosis development and macrophage inflammation. Approach and Results: TERT-deficient mice were crossbred with LDL-receptor-deficient (LDLr-/-) mice to generate first generation G1TERT-/-LDLr-/- offsprings, which were then further intercrossed to obtain third generation G3TERT-/-LDLr-/- mice. G1TERT-/-LDLr-/- mice revealed no telomere shortening while severe telomere attrition was evident in G3TERT-/-LDLr-/- mice. When fed an atherogenic diet, G1TERT-/-LDLr-/- and G3TERT-/-LDLr-/- mice were both protected from atherosclerosis formation compared to their wildtype controls, indicating that genetic TERT-deletion prevents atherosclerosis, and formation of the disease is not affected by telomere attrition. Similarly, atherosclerosis development was decreased in chimeric LDLr-/- mice with TERT deletion in hematopoietic stem cells after bone marrow transplantation. TERT deficiency reduced macrophage accumulation in atherosclerotic lesions and altered chemokine expression, including CXC1/2/3, CCL3, CCL5, CCL21, CCR7, IL-6, and IL-1α. In isolated macrophages, sequence analysis of silenced inflammatory gene promoters indicated that TERT deletion altered signal transducer and activator of transcription 3 (STAT3)-dependent chemokine expression and recruitment of phosphorylated STAT3 to its target promoters. Mechanistically, TERT expression was necessary and sufficient to maintain STAT3 phosphorylation. Finally, we demonstrate that TERT deletion induces transcription of PIAS and SOCS3, both are endogenous inhibitors of STAT3 pathway. Conclusions: We propose that genetic TERT deficiency decreases atherosclerosis formation by silencing inflammatory chemokine transcription through inactivation of the STAT3 signaling pathway.

Abstract 11773: N-3 Polyunsaturated Fatty Acids Inhibit Inflammatory Responses in Macrophages by the Reduction of Toll-like Receptor 4 Expression in Lipid Rafts, Leading to the Suppression of Atherogenesis in Apolipoprotein E Deficient Mice

Introduction: Macrophages promote inflammatory responses, contributing to the development of atherosclerosis. Lipid rafts in macrophages facilitate inflammatory responses by gathering inflammatory molecules such as toll-like receptor 4 (TLR4). Whereas, n-3 polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), incorporated into the plasma membrane cause functional alteration of lipid rafts. Here, we tested the hypothesis that n-3 PUFAs decrease macrophage activation by the reduction of TLR4 expression in lipid rafts and attenuate atherogenesis in apolipoprotein E knockout (ApoE KO) mice. Methods and Results: ApoE KO mice were fed western-type diets supplemented with 2.5% EPA, 5% omega-3-acid ethyl esters which include 2.3% EPA and 1.9% DHA (EPA+DHA), or none of n-3 PUFAs (control group) from 8-week-old for 20 weeks. Blood pressure and plasma total cholesterol level did not differ in these groups. En face Sudan IV staining of the aorta revealed that n-3 PUFAs treatment significantly attenuated atherogenesis compared with control group, and the effect was enhanced in EPA+DHA group (P&lt; 0.05). Histological or quantitative RT-PCR analyses demonstrated that EPA+DHA treatment decreased lipid deposition, MMP-9 expression, and macrophage accumulation in atherosclerotic lesions in the aorta compared with control group (P&lt;0.05, P&lt;0.01 and P&lt;0.01, respectively). In vitro experiment using RAW264.7, a murine macrophage cell line, demonstrated that n-3 PUFAs attenuated the up-regulation of MMP-9 and MCP-1 induced by LPS. Isolation of lipid rafts from RAW264.7 by sucrose gradient ultracentrifugation demonstrated that n-3 PUFAs suppressed LPS-induced TLR4 expression in lipid rafts. Lipid raft disruption by methyl-β-cyclodextrin, the membrane cholesterol depleting agent, suppressed LPS-induced up-regulation of MMP-9 and MCP-1 in this cell type. Conclusions: N-3 PUFAs inhibited inflammatory responses in macrophages by the reduction of TLR4 expression in lipid rafts, leading to the suppression of atherogenesis in ApoE KO mice. Our results suggested that lipid rafts in macrophages may serve as a potential therapeutic target for atherosclerosis.

Chemokines and microRNAs in atherosclerosis.

The crucial role of chemokines in the initiation and progression of atherosclerosis has been widely recognized. Through essential functions in leukocyte recruitment, chemokines govern the infiltration with mononuclear cells and macrophage accumulation in atherosclerotic lesions. Beyond recruitment, chemokines also provide homeostatic functions supporting cell survival and mediating the mobilization and homing of progenitor cells. As a new regulatory layer, several microRNAs (miRNAs) have been found to modulate the function of endothelial cells (ECs), smooth muscle cells and macrophages by controlling the expression levels of chemokines and thereby affecting different stages in the progression of atherosclerosis. For instance, the expression of CXCL1 can be down-regulated by miR-181b, which inhibits nuclear factor-κB activation in atherosclerotic endothelium, thus attenuating the adhesive properties of ECs and exerting early atheroprotective effects. Conversely, CXCL12 expression can be induced by miR-126 in ECs through an auto-amplifying feedback loop to facilitate endothelial regeneration, thus limiting atherosclerosis and mediating plaque stabilization. In contrast, miR-155 plays a pro-atherogenic role by promoting the expression of CCL2 in M1-type macrophages, thereby enhancing vascular inflammation. Herein, we will review novel aspects of chemokines and their regulation by miRNAs during atherogenesis. Understanding the complex cross-talk of miRNAs controlling chemokine expression may open novel therapeutic options to treat atherosclerosis.

Effects of fasudil on early atherosclerotic plaque formation and established lesion progression in apolipoprotein E-knockout mice

Rho kinases have been shown to be involved in the pathogenesis of atherosclerosis. This study examined the effects of fasudil, a specific Rho kinase inhibitor, on plaque development and progression in atherosclerotic mice. Sixty apolipoprotein E-knockout (apoE-KO) mice were fed a high-fat diet. Mice started to receive fasudil at the same time as fat feeding (early treatment), or after 12 weeks of fat feeding (delayed treatment). In each administrative schedule, mice were divided into three groups: low dose fasudil group (30 mg/kg/day), high dose fasudil group (100 mg/kg/day) and control group (tap water) ( n = 10, respectively). Plaque size was determined by using ultrasound biomicroscopy (UBM) and histological examinations. Brachiocephalic artery UBM analysis showed that in early treatment, both doses of fasudil significantly reduced lesion size compared with the controls ( P < 0.05). In delayed-fasudil treatment, plaque area was reduced by 54% ( P < 0.05) after 12 weeks of treatment at a high dose of fasudil (100 mg/kg/day). The UBM findings were confirmed by histological studies at the corresponding arterial sites. The beneficial effect was also observed in the left common carotid arteries that delayed-fasudil treatment reduced the plaque size in a dose-dependent manner. The arterial intima-medial thickness (IMT) and maximal flow velocity of both arteries were lower in fasudil-treated group (100 mg/kg/day) in comparison with the control mice. Furthermore, fasudil treatment (100 mg/kg/day) reduced the macrophage accumulation in atherosclerotic lesions. However, fasudil had no effects on blood pressure and plasma lipid concentrations in both studies. In conclusion, our studies showed that blocking Rho kinase reduced both the early development and later progression of atherosclerotic plaques in apoE-KO mice by using a novel micro-ultrasound approach.

Disruption of Tissue-Specific Fucosyltransferase VII, an Enzyme Necessary for Selectin Ligand Synthesis, Suppresses Atherosclerosis in Mice

A hallmark feature of atherosclerosis is that circulating mononuclear cells adhere to the endothelium and migrate into the subendothelial space. This adhesion is mediated by molecules such as selectins that are expressed on the surfaces of both leukocytes and endothelial cells. In this study, we have determined the role of tissue-specific fucosyltransferase VII (FucT-VII), an enzyme necessary for selectin ligand synthesis, in the development of atherosclerosis. We adopted a scheme of transplanting either FucT-VII(-/-)GFP(+) bone marrow into lethally irradiated low-density lipoprotein receptor low density lipoprotein receptor mice or FucT-VII(+/+) GFP(+) bone marrow into FucT-VII(-/-), low density lipoprotein receptor double-mutant mice to evaluate the roles of E- and P-selectin ligands versus L-selectin ligands, respectively, in diet-induced atherosclerosis. GFP was used to track the transplanted cells. Our results indicate that, compared with controls, selective disruption of E- and P-selectin ligand synthesis resulted in a significant reduction in atherosclerosis. Selective disruption of L-selectin ligand production did not reduce atherosclerosis as robustly as disruption of E- and P-selectin ligands. In both groups, however, there was a significant reduction in the accumulation of macrophages in the lesion. These studies indicate that selectin ligands, particularly those for E- and P-selectins, play an important role in the pathogenesis of atherosclerosis by regulating macrophage accumulation in atherosclerotic lesions.

More good reasons for adherence to statin therapy during acute coronary syndromes

During the last decade, the evidence that statins have potent effects in reducing death and myocardial infarction in patients following acute coronary syndromes has become overwhelming, both in patients with elevated cholesterol levels and in those with normal cholesterol levels.1,2 Beyond their intended impact on blood cholesterol levels, statins are also known to have multiple non-lipid effects that contribute to the reduction of cardiovascular morbidity and mortality.3,4 Statins may prevent acute thrombus formation at the site of plaque rupture by inhibiting platelet function and inhibiting platelet deposition on damaged vessels. They have also been shown to contribute to plaque stabilization, not only through a reduction in lipids but also as a result of reduced macrophage accumulation in atherosclerotic lesions and inhibition of expression of matrix metalloproteinases. Statins have anti-inflammatory properties; they reduce levels of high sensitivity C-reactive protein and, through attenuation of P-selectin expression, protect the ischaemic myocardium. Statins restore endothelial function before any significant reduction in cholesterol levels may have occurred. In the context of acute coronary syndromes, the statin-mediated improvement of vascular function by inhibiting the production of harmful intermediates of the cholesterol biosynthetic pathway appears to play a major role. Therefore, the effects of statins include an increase in nitric oxide bioavailability, reduced expression of endothelin-1, and increased expression of tissue plasminogen activator. Ongoing clinical trials with highly potent statins are now expected to provide valuable information about the most appropriate agents and doses to improve the treatment of patients with acute coronary syndromes.5 Despite these demonstrated beneficial effects of statins and the low incidence of undesired effects, the use of statins is still highly variable in daily clinical routine. Up to 30% of prescriptions are discontinued during the first year. … *Corresponding author. Tel: +49 89 7095 3438, Fax: +49 89 7095 6433, Email: christopher.heeschen{at}med.uni-muenchen.de

ED-B fibronectin (ED-B) can be targeted using a novel single chain antibody conjugate and is associated with macrophage accumulation in atherosclerotic lesions

It has been shown that ED-B fibronectin (ED-B) is a potential target for plaque imaging. The aim of this study was to test a novel modified single chain anti-ED-B antibody (scFv) conjugated for near infrared fluorescence imaging (NIRF) with tetrasulfonated carbocyanine-maleimide (TSC-scFv) and to examine the association of ED-B with the presence of macrophages in a murine model of atherosclerosis. Expression of ED-B was observed in plaque areas in apolipoprotein E-deficient (apoE(-/-)) mice which increased with age and plaque load. Robust imaging was possible after explantation of the aorta and demonstrated a strong NIRF signal intensity in focal aortic and brachiocephalic plaque lesions, whereas no signals were found in undiseased areas. Plaque lesion ED-B was expressed by smooth muscle cell and was closely associated to macrophage infiltrates. Although not expressed by the same cell type, there was a significant correlation (p<0.01) between ED-B and macrophage immunoreactivity. In vitro human coronary and mouse smooth muscle cells significantly increased ED-B expression after angiotensin II and TNF-alpha treatment. This study demonstrates that plaque NIRF imaging is feasible with a novel single chain antibody and that ED-B expression is closely associated with inflammation in experimental atherosclerosis.

Homozygous disruption of Pctp modulates atherosclerosis in apolipoprotein E-deficient mice

Phosphatidylcholine transfer protein (PC-TP) is a cytosolic phospholipid binding protein and a member of the steroidogenic acute regulatory-related transfer domain superfamily. Its tissue distribution includes liver and macrophages. PC-TP regulates hepatic lipid metabolism, and its absence in cholesterol-loaded macrophages is associated with reduced ATP binding cassette transporter A1-mediated lipid efflux and increased susceptibility to apoptosis induced by unesterified cholesterol. To explore a role for PC-TP in atherosclerosis, we prepared PC-TP-deficient/apolipoprotein E-deficient (Pctp(-/-)/Apoe(-/-)) mice and littermate Apoe(-/-) controls. At 16 weeks, atherosclerosis was increased in chow-fed male, but not female, Pctp(-/-)/Apoe(-/-) mice. This effect was associated with increases in plasma lipid concentrations. By contrast, no differences in atherosclerosis were observed between male or female Pctp(-/-)/Apoe(-/-) mice and Apoe(-/-) controls fed a Western-type diet for 16 weeks. At 24 weeks, atherosclerosis in chow-fed male Pctp(-/-)/Apoe(-/-) mice tended to be reduced in proportion to plasma cholesterol. The attenuation of atherosclerosis in female Pctp(-/-)/Apoe(-/-) mice fed chow or the Western-type diet for 24 weeks was not attributable to changes in plasma cholesterol or triglyceride concentrations. These findings suggest that PC-TP modulates the development of atherosclerosis, in part by regulating plasma lipid concentrations.