Abstract 646: The Paradoxical Role of TREM-Like 1 in Atherosclerosis

Atherosclerosis is a chronic inflammatory process of the vessel wall driven by an inflammatory state caused by the involvement of different cell populations, including platelets. The receptor Triggering Receptor Expressed on Myeloid Cells (TREM)-like transcript (TLT)-1 is prepacked in platelet α-granules and brought to the surface upon activation. TLT-1 has both membrane-bound and soluble forms (sTLT-1) and the latter has been found to enhance platelet activation as well as platelet-endothelial cell interactions. TLT-1 null mice (treml1-/-) have reduced platelet aggregation, are significantly more susceptible to lipopolysaccharide challenge compared to their wild type counterparts, and accordingly, hemorrhage in response to an acute inflammatory challenge. These results suggest that TLT-1 is a key regulatory molecule in the interface between hemostatic and inflammatory mechanisms and in light of this, we hypothesized that TLT-1 plays an important role in atherosclerosis progression. To address this, we generated apoE-/-/treml1-/- double knockout mice [DKO]. We found that DKO mice fed an atherogenic diet (HFD) showed significantly increased weight gain when compared to apoE-/-. Accordingly, DKO mice showed increased total cholesterol and triglycerides compared to controls. Surprisingly, assessment of lesion size revealed that DKO mice have significantly smaller lesions in the aortic sinus at four and 12 weeks after HFD compared to apoE-/-. At 20 weeks, lesion differences are no longer significant, but compositional analysis revealed that DKO atherosclerotic lesions are less vulnerable as seen by decreased lesion calcification and increased smooth muscle cell content. Furthermore, q-rtPCR analysis of atherosclerosis-related genes revealed that TLT-1 differentially affects genes related to lipid metabolism (apo AI and B) and vascular inflammation (thrombospondin 4, PAI-1 and VGFR-2). While our data suggests that the smaller lesion size may be explained by lower platelet reactivity, differences in cholesterol levels suggest altered lipid metabolism which is supported by our metabolomics studies (González, M. et.al). Taken together TLT-1 plays a dual role in the progression of atherosclerosis.

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Abstract 623: Role Of Cd73-derived Adenosine In Atherosclerosis

Circulation ◽

10.1161/circ.116.suppl_16.ii_114 ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Anja Buchheiser ◽

Barbara Emde ◽

Jens W Fischer ◽

Jürgen Schrader

Keyword(s):

Thoracic Aorta ◽

Double Mutant ◽

Vascular Inflammation ◽

Mutant Mice ◽

Matrix Composition ◽

Atherosclerotic Plaques ◽

Chow Diet ◽

Double Knockout ◽

Aortic Sinus ◽

Atherosclerotic Lesions

We recently reported that mice with targeted deletion of ecto-5′-nucleotidase (CD73) are characterized by enhanced platelet activation and increased adherence of monocytes to the endothelium. Wire-induced injury of the carotid artery resulted in enhanced neointima formation associated with increased macrophage content and VCAM-1 expression in CD73−/−mice. In order to study a possible modulation of atherogenesis and vascular inflammation by CD73-derived adenosine, we generated ApoE−/−/CD73−/− double mutant mice. Quantification and characterisation of atherosclerotic lesions was performed in WT, ApoE−/−, and ApoE−/− / CD73−/− mice on chow diet after 6 and 12 month, respectively, by macroscopic analysis of the descending thoracic aorta after oil red staining and by histological stainings for cholesterol, hyaloronic acid, and collagen in cryo sections of the aortic sinus. Immunohistological analysis of lesion morphology included primary antibodies for ICAM-1, VCAM-1, CD4, CD73, and CD11b. Determination of the plaque score by oil red staining revealed enhanced development of atherosclerotic lesions over the entire thoracic aorta after 6 month in the double mutant compared with ApoE−/− (2.5-fold increased, n=8, P<0.05). Atherosclerotic plaques in the aortic sinus were substantially enlarged as compared to ApoE−/− mice. Changes in extracellular matrix composition were not detected. However, we found enhanced VCAM-1 expression in ApoE−/−/CD73−/− mice after 6 month, which was accompanied by an increased infiltration of monocytes and macrophages but unchanged T-cells. We also noted that in atherosclerotic plaques of ApoE−/− mice the expression and activity of CD73 was significantly increased compared to WT. Measurements of cytokines in plasma support the notion of an increased inflammatory state in the double knockout. Interestingly, after 12 months all double mutant mice showed multiple scattered myocardial infarcts associated with myocardial hypertrophy and fibrosis. Our findings demonstrate that CD73-derived adenosine acts as an endogenous modulator protecting against chronic vascular inflammation and monocyte recruitment. Thus in the murine model, extracellular adenosine appears to limit the progression of atherosclerosis.

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Spontaneous Atherosclerotic Lesions in TREM-Like Transcript-1 Deficient Mice

Blood ◽

10.1182/blood.v120.21.3312.3312 ◽

2012 ◽

Vol 120 (21) ◽

pp. 3312-3312

Author(s):

Marieli Gonzalez ◽

Fiorella Reyes ◽

Deborah Marrero ◽

A. Valance Washington

Keyword(s):

Vessel Wall ◽

Inflammatory Responses ◽

Conflicts Of Interest ◽

Atherogenic Diet ◽

Chow Diet ◽

Aortic Sinus ◽

Platelet Surface ◽

Atherosclerosis Progression ◽

Atherosclerotic Lesions ◽

Cholesterol Levels

Abstract Abstract 3312 It is well known that platelets, aside from regulating hemostasis, play an important role in inflammation-associated conditions like sepsis, viral infections, and atherosclerosis. In the latter, platelets not only form occlusive thrombi at lesions, but also play a role in the initiation of the disease by depositing activating molecules such as cytokines on the developing plaque. Although the mechanism by which platelet aggregation leads to occlusion is well-defined, the role of platelets in lesion initiation and progression is poorly understood and thus remains a gap in our knowledge. TLT-1 (Triggering Receptor Expressed in Myeloid cells (TREM)-like transcript-1) is a receptor exclusively found on megakarocytes and platelets that has a demonstrated effect in inflammatory responses. Upon platelet activation, TLT-1 is moved to the platelet surface along with p-selectin from the α-granules. Studies using the treml1−/− mouse demonstrated a predisposition to hemorrhage after an acute inflammatory challenge suggesting that TLT-1 may be a key regulatory molecule in the interface between hemostatic and inflammatory mechanisms and therefore should play a role in the development of atherosclerosis. Our original hypothesis was that evaluation of atherosclerosis lesions in the treml1−/− mouse would demonstrate fewer lesions and hence, a similar phenotype as the psel−/− mouse. Evaluation of 50 week old mice fed a chow diet surprisingly revealed spontaneous lesions in C57Bl/6 treml1−/− mice. Subsequent evaluation of cholesterol levels in treml1−/−mice on an atherogenic diet for four weeks demonstrated that they have significantly higher cholesterol levels when compared to WT mice. To evaluate atherosclerosis progression in TLT-1 deficiency, we developed the apoE−/−/treml1−/− double knockout mice and assessed lesion development after a four weeks atherogenic diet. Our results demonstrate that double null mice have exacerbated lesions when compared to the apoE −/− mice. Accordingly, 50 week old double null mice fed a chow diet also have larger atherosclerotic lesions in the aortic sinus than apoE −/− mice. These results clearly support a role for TLT-1 in dampening the progression of atherosclerosis. Current data from our laboratory suggest that TLT-1 may affect leukocyte function, therefore based on our model that TLT-1 deficiency leads to a heighted inflammatory state we hypothesized that treml1−/− mice will demonstrate greater leukocyte recruitment into the injured vessel wall, leading to greater deposition of factors that recruit more platelets and macrophages that later become foam cells. To delineate the mechanism by which TLT-1 affects atherosclerosis progression, we have evaluated neutrophil and monocyte infiltration into the vessel wall of the aortic sinus after four weeks atherogenic diet. The current state of our investigation is reported here. Disclosures: No relevant conflicts of interest to declare.

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Abstract 3917: Role of Endothelial Cell-Selective Adhesion Molecule in the Progression of Atherosclerosis

Circulation ◽

10.1161/circ.118.suppl_18.s_502-c ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Michihiko Inoue ◽

Tatsuro Ishida ◽

Tetsuya Hara ◽

Cangara M Husni ◽

Li Sun ◽

...

Keyword(s):

Endothelial Cells ◽

Endothelial Cell ◽

Adhesion Molecule ◽

Lesion Size ◽

Macrophage Infiltration ◽

Immunoglobulin Superfamily ◽

Double Knockout ◽

Aortic Sinus

Backgrounds : Endothelial cell-selective adhesion molecule (ESAM) is a new member of the immunoglobulin superfamily, which is expressed in vascular endothelial cells. Although ESAM has been shown to mediate homohilic adhesion between endothelial cells, the interaction of ESAM and hematopoietic cells has not been ingestigated. Also, the role of ESAM in atherosclerosis remains unclear. In this study, we assessed the role of ESAM in monocyte/ macarophage infiltration, and examined effects of ESAM inactivation in the development atherosclerosis using a murine model of atherosclerosis. Methods and Results : ESAM−/− mice were bred with apoE−/− mice to generate the double knockout mice, and the lesion size of aortic sinus was evaluated histologically between ESAM+/+ apoE−/− and ESAM−/− apoE+/+ mice. Plasma lipid profile was not affected by ESAM deficiency. However, the lesion size was markedly attenuated in ESAM−/− apoE−/− mice compared to ESAM+/+apoE−/− mice. The percentage of MOMA-2-stained area in the aortic sinus lesions was significantly smaller in ESAM-/-apoE−/− mice than in ESAM+/+apoE−/− mice, suggesting that ESAM deficiency reduced the macrophage infiltration in the atheroma. To clarify the mechanism for the reduced macrophage content in the plaque, in vitro adhesion- and transendothelial migration assays were performed between cultured endothelial monolayers and monocyte/macrophage cell line THP-1 cells utilizing siRNA-mediated knockdown of ESAM. These assays revealed that ESAM deficiency in endothelial cells resulted in decreases in monocyte adhesion to the endothelial cells as well as transendothelialmigration. THP-1 cells did not express ESAM, but directly bound to the recommbinant ESAM protein-coated culture plates. Conclusion : ESAM modulates macrophage infiltration into the atheroma through interaction with unidentified ligand(s) on monocytes. ESAM inactivation can reduce susceptibility to atherosclerosis.

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CFTR protects against vascular inflammation and atherogenesis in apolipoprotein E-deficient mice

Bioscience Reports ◽

10.1042/bsr20170680 ◽

2017 ◽

Vol 37 (4) ◽

Cited By ~ 8

Author(s):

Zhengzhang Li ◽

Zhe Shen ◽

Haoping Xue ◽

Shi Cheng ◽

Qun Ji ◽

...

Keyword(s):

Cystic Fibrosis ◽

Apolipoprotein E ◽

Inflammatory Responses ◽

Vascular Inflammation ◽

Peritoneal Macrophages ◽

M2 Macrophage ◽

Aortic Sinus ◽

Cell Content

Atherosclerosis is a chronic inflammatory disease of the vascular wall. Dysfunction of cystic fibrosis transmembrane conductance regulator (CFTR) has been shown to result in inflammatory responses in cystic fibrosis (CF) patients. However, little is known about the role of CFTR in vascular inflammation and atherogenesis. Our results showed that CFTR was dominantly expressed in macrophages of atherosclerotic plaque and reduced in aorta and aortic sinus from atherosclerotic apolipoprotein E-deficient (apoE−/−) mice. In vivo administration of adenovirus encoding CFTR (Ad-CFTR) with apoE−/− mice fed on high-fat diet (HFD) improved plaque stability by decreasing lipid accumulation and necrotic area and increasing smooth muscle cell content and collagen. The Ad-CFTR-treated mice also displayed reduced proinflammatory cytokines levels in aorta and peritoneal macrophages, whereas the anti-inflammatory M2 macrophage markers were increased. Confocal microscopy revealed that the infiltration of T lymphocytes, neutrophils, and macrophages in aortic sinus was markedly attenuated in Ad-CFTR-treated apoE−/− mice. Moreover, in vitro experiments showed that overexpression of CFTR inhibited ox-LDL-induced the migration of peritoneal macrophages. Finally, it was observed that CFTR up-regulation suppressed NFκB and MAPKs activity induced by ox-LDL. Inhibition of JNK or ERK abrogated CFTR down-regulation induced NFκB activation, whereas NFκB inhibitor had no effect on JNK or ERK activation. Taken together, these results demonstrate that CFTR prevents inflammation and atherogenesis via inhibition of NFκB and MAPKs activation. Our data suggest that CFTR may present a potential therapeutic target for the treatment of vascular inflammation and development of atherosclerotic disease.

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Circulating Endothelial Microparticles: A Key Hallmark of Atherosclerosis Progression

Scientifica ◽

10.1155/2016/8514056 ◽

2016 ◽

Vol 2016 ◽

pp. 1-9 ◽

Cited By ~ 19

Author(s):

Keshav Raj Paudel ◽

Nisha Panth ◽

Dong-Wook Kim

Keyword(s):

Vascular Function ◽

Cell Activation ◽

Vascular Inflammation ◽

Rho Kinase ◽

Disease Status ◽

Endothelial Microparticles ◽

Atherosclerosis Progression ◽

Mitogen Activated Protein ◽

Circulating Microparticles ◽

Ros Formation

The levels of circulating microparticles (MPs) are raised in various cardiovascular diseases. Their increased level in plasma is regarded as a biomarker of alteration in vascular function. The prominent MPs present in blood are endothelial microparticles (EMPs) described as complex submicron (0.1 to 1.0 μm) vesicles like structure, released in response to endothelium cell activation or apoptosis. EMPs possess both physiological and pathological effects and may promote oxidative stress and vascular inflammation. EMPs release is triggered by inducer like angiotensin II, lipopolysaccharide, and hydrogen peroxide leading to the progression of atherosclerosis. However, there are multiple physiological pathways for EMPs generation like NADPH oxidase derived endothelial ROS formation, Rho kinase pathway, and mitogen-activated protein kinases. Endothelial dysfunction is a key initiating event in atherosclerotic plaque formation. Atheroemboli, resulting from ruptured carotid plaques, is a major cause of stroke. Increasing evidence suggests that EMPs play an important role in the pathogenesis of cardiovascular disease, acting as a marker of damage, either exacerbating disease progression or triggering a repair response. In this regard, it has been suggested that EMPs have the potential to act as biomarkers of disease status. This review aims to provide updated information of EMPs in relation to atherosclerosis pathogenesis.

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Lessons from the Monitored Atherosclerosis Regression Study (MARS) and beyond: atherosclerosis progression/regression responses to therapy depend on lesion size and composition

Developments in Cardiovascular Medicine - Lipid-Lowering Therapy and Progression of Coronary Atherosclerosis ◽

10.1007/978-94-009-0143-8_12 ◽

1996 ◽

pp. 131-141

Author(s):

D. M. Kramsch

Keyword(s):

Lesion Size ◽

Atherosclerosis Progression

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Alirocumab, evinacumab, and atorvastatin triple therapy regresses plaque lesions and improves lesion composition in mice

The Journal of Lipid Research ◽

10.1194/jlr.ra119000419 ◽

2019 ◽

Vol 61 (3) ◽

pp. 365-375 ◽

Cited By ~ 8

Author(s):

Marianne G. Pouwer ◽

Elsbet J. Pieterman ◽

Nicole Worms ◽

Nanda Keijzer ◽

J. Wouter Jukema ◽

...

Keyword(s):

Triple Therapy ◽

Atherosclerotic Lesion ◽

Lesion Size ◽

Lipid Lowering ◽

Atherosclerosis Progression ◽

Cholesterol Levels ◽

Baseline Group ◽

Current Therapies ◽

Triple Treatment ◽

Lesion Severity

Atherosclerosis-related CVD causes nearly 20 million deaths annually. Most patients are treated after plaques develop, so therapies must regress existing lesions. Current therapies reduce plaque volume, but targeting all apoB-containing lipoproteins with intensive combinations that include alirocumab or evinacumab, monoclonal antibodies against cholesterol-regulating proprotein convertase subtilisin/kexin type 9 and angiopoietin-like protein 3, may provide more benefit. We investigated the effect of such lipid-lowering interventions on atherosclerosis in APOE*3-Leiden.CETP mice, a well-established model for hyperlipidemia. Mice were fed a Western-type diet for 13 weeks and thereafter matched into a baseline group (euthanized at 13 weeks) and five groups that received diet alone (control) or with treatment [atorvastatin; atorvastatin and alirocumab; atorvastatin and evinacumab; or atorvastatin, alirocumab, and evinacumab (triple therapy)] for 25 weeks. We measured effects on cholesterol levels, plaque composition and morphology, monocyte adherence, and macrophage proliferation. All interventions reduced plasma total cholesterol (37% with atorvastatin to 80% with triple treatment; all P < 0.001). Triple treatment decreased non-HDL-C to 1.0 mmol/l (91% difference from control; P < 0.001). Atorvastatin reduced atherosclerosis progression by 28% versus control (P < 0.001); double treatment completely blocked progression and diminished lesion severity. Triple treatment regressed lesion size versus baseline in the thoracic aorta by 50% and the aortic root by 36% (both P < 0.05 vs. baseline), decreased macrophage accumulation through reduced proliferation, and abated lesion severity. Thus, high-intensive cholesterol-lowering triple treatment targeting all apoB-containing lipoproteins regresses atherosclerotic lesion area and improves lesion composition in mice, making it a promising potential approach for treating atherosclerosis.

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Inhibition of Atherosclerosis Progression, Intimal Hyperplasia, and Oxidative Stress by Simvastatin and Ivabradine May Reduce Thoracic Aorta’s Stiffness in Hypercholesterolemic Rabbits

Journal of Cardiovascular Pharmacology and Therapeutics ◽

10.1177/1074248415617289 ◽

2015 ◽

Vol 21 (4) ◽

pp. 412-422 ◽

Cited By ~ 3

Author(s):

Ioanna Koniari ◽

Dimosthenis Mavrilas ◽

Efstratios Apostolakis ◽

Evangelia Papadimitriou ◽

Helen Papadaki ◽

...

Keyword(s):

Oxidative Stress ◽

Intimal Hyperplasia ◽

Aortic Stiffness ◽

Neointimal Hyperplasia ◽

Atherogenic Diet ◽

Diet Group ◽

Atherosclerosis Progression ◽

Stiffness Reduction ◽

Group I ◽

And Oxidative Stress

Aims: This study aims to evaluate atherosclerosis, oxidative stress, and arterial stiffness attenuation by simvastatin and ivabradine in hyperlipidemic rabbits. Methods and Results: Forty rabbits were randomly divided into 4 groups: atherogenic diet (group C), atherogenic diet plus simvastatin (group S), atherogenic diet plus ivabradine (group I), and atherogenic diet plus simvastatin and ivabradine (group S + I). After 9 weeks, rabbits were euthanized and descending aortas excised for mechanical testing. Atherogenic diet induced the development of significant atherosclerotic lesions in group C animals but in none of groups S, I, and S + I. RAM-11 and HHF-35–positive cells were significantly reduced in groups S, I, and S + I compared with group C ( P < .001). A significant neointimal hyperplasia and intima–media ratio reduction was demonstrated in groups S ( P = .015 and P < .001), I ( P = .021 and P < .001), and S + I ( P = .019 and P < .001) compared with group C. Protein nitrotyrosine levels were significantly decreased in group S compared with group C ( P = .009), and reactive oxygen species levels were decreased in group I compared with group C ( P = .011). Aortic stiffness was significantly reduced in groups S, I, and S + I compared with group C ( P = .003, P = .011, and P = .029). Conclusion: Simvastatin and ivabradine significantly inhibited intimal hyperplasia and oxidative stress contributing to aortic stiffness reduction in hyperlipidemic rabbits.

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