tbuckley/cabot-search huggingface dataset:
Abstract 5300: Targeting Ongoing Arterial Thrombosis With Platelet-Specific Microparticles
Authors: Zaverio M Ruggeri, Jennifer N Orje, Samir Mitragorti, Jeffrey Smith
Journal: Circulation (2009)

In the arterial circulation with rapid blood flow, initial platelet adhesion at sites of vascular injury depends on the interaction between the amino terminal domain of platelet glycoprotein Ib (GPIb-NH2) and the A1 domain of von Willebrand Factor (VWF-A1) immobilized onto the vessel wall. Moreover, platelet aggregation responsible for subsequent thrombus growth is mediated by binding of soluble plasma VWF to GPIb on the platelet membrane. Thus, microparticles (MPs) presenting on their surface GPIb-NH2 or VWF-A1 should be capable of homing to sites of ongoing thrombus formation by mimicking platelets either without or with bound VWF, respectively. To test this hypothesis, we coated fluorescent MPs with recombinant VWF-A1 (residues 445–733 of the mature human VWF subunit) or GPIb-NH2 (residues -2–290). Both proteins were expressed as dimers in the attempt to mimic the corresponding native functional conformations. When added to a washed human red cell suspension and perfused over the appropriate substrate (i.e. MPs coated with VWF-A1 over surface-immobilized GPIb-NH2; or vice versa), both kinds of MPs adhered in equal number at shear rate as high as 10,000 s-1. This response was markedly decreased when MPs were coated with VWF-A1 carrying the loss-of-function mutation G561S. In vivo, derivatized MPs were used in mouse models of thrombosis in the carotid and femoral arteries and in the femoral vein in which a thrombogenic lesion was induce by superfusion of ferric chloride or with a pulsed nitrogen laser. Upon injection during the early stages of platelet response to injury, MPs coated with either VWF-A1 or GPIb-NH2 specifically adhered to the lesion, indicating that both GPIb and VWF were present on the surface of the forming thrombus. In contrast, MPs coated with VWF-A1 were remarkably more efficient than those coated with GPIb-NH2 in targeting nearly occluding thrombi, indicating that the surface of the latter presents GPIb (platelets) but not accessible VWF. These findings show that MPs derivatized with specific adhesive domains may be used to target areas of vascular injury with developing thrombi for diagnostic or therapeutic purposes, as well as to interrogate thrombus composition.
Abstract 5312: Deletion of Microsomal Prostaglandin E <sub>2</sub> Synthase-1 Modulates the Response to Vascular Injury in Mice
Authors: Miao Wang, Mathieu C Tamby, Kaori Ihida-Stansbury, Zhou Yu, Yan Cheng, Peter L Jones, Garret A FitzGerald
Journal: Circulation (2009)

Microsomal (m) prostaglandin (PG) E 2 synthase(S)-1 catalyzes the isomerization of the cyclooxygenase (COX) product, PGH 2 , into PGE 2 . Previous studies in mice suggest that targeting of mPGES-1 may less likely cause hypertension or thrombosis than COX-2 selective inhibitors in vivo . Indeed, deletion of mPGES-1 retards atherogenesis and angiotensin II induced aortic aneurysm formation. To address the role of mPGES-1 in the response to vascular injury, the effect of enzyme deletion on neointimal formation four weeks after wire injury of the femoral artery was assessed. mPGES-1 suppressed urinary excretion of the major metabolite of PGE 2 , while augmented that of prostacyclin (PGI 2 ), a prostanoid that restrains vascular proliferation after the injury. Both maximal neointimal area and vascular stenosis were reduced significantly in mPGES-1 knock out mice compared to wild type controls (65.6±5.7 vs 37.7±5.1×10 3 pixel area and 70.5±13.4% vs 47.7±17.4%, respectively; in both cases, p &lt; 0.01). Neointimal Tenascin C, a promoter of vascular smooth muscle cell (VSMC) proliferation is upregulated in response to vascular injury, and this was suppressed by mPGES-1 deletion. VSMCs isolated from mPGES-1 deficient mice exhibited delayed attachment and less coordinate migratory morphology when cultured on fibrillar type I collagen. Deletion of mPGES-1 impairs VSMC mobility and attenuates neointimal formation in response to vascular injury. Inhibition of mPGES-1 has therapeutic potential for the prevention of restenosis. This research has received full or partial funding support from the American Heart Association, National Center.
Abstract 5302: Glutathione Peroxidase-3 Deficiency Promotes Platelet-dependent Thrombosis and Thrombotic Stroke <i>in vivo</i>
Authors: Richard C Jin, Christopher E Mahoney, Ying-Yi Zhang, Diane E Handy, Joseph Loscalzo
Journal: Circulation (2009)

Plasma glutathione peroxidase (GPx-3) is a selenocysteine-containing protein with antioxidant activity. GPx-3 plays an important role in plasma by scavenging reactive oxygen species. We have previously shown that a heritable deficiency of this enzyme is associated with platelet-dependent thrombotic stroke in patients. We recently developed a GPx-3 knockout mouse to assess platelet function and platelet-dependent thrombosis in models of vascular injury. We hypothesized that GPx-3 deficiency promotes platelet-dependent thrombus formation in vivo . GPx-3 (−/−) mice showed an attenuated bleeding time compared with wild-type mice (94.5±28.8 s versus 153.4±32.3, P&lt;0.05). We also noted an increase in the plasma levels of soluble P-selectin, a marker of platelet activation and prothrombotic activity, in GPx-3 (−/−) mice compared with wild-type mice (137.8±12.3 ng/ml plasma versus 101.5±8.8, P&lt;0.05). Using a no-flow ischemia-reperfusion stroke model, we found that GPx-3 (−/−) mice had significantly larger cerebral infarctions compared with wild-type mice (117.5±7.9 mm 3 versus 17.2±2.7, P&lt;0.001) as well as higher neurological deficit scores (3.33±0.33 versus 1.3±0.33, P=0.02). To investigate the effect of platelet inhibition on stroke size in GPx-3 deficiency, GPx-3 deficient mice were pre-treated with clopidogrel prior to producing the stroke. We found that clopidogrel treatment reduced stroke size significantly compared with vehicle-treated controls (4.42±3.0 mm 3 versus 105.1±15.2, P=0.003) as well as lowered neurological deficit scores (0.4±0.2 versus 2.83±0.44, P=0.018). These findings demonstrate that GPx-3 deficiency promotes platelet activation resulting in a prothrombotic state. These data illustrate the importance of this plasma antioxidant enzyme in regulating platelet activity, platelet-dependent thrombosis, and vascular thrombotic propensity.
Abstract 5304: Ectonucleoside Triphosphate Diphosphohydrolase-1 (ENTDP-1/CD39) Over-Expression Delays <i>in vivo</i> Carotid Arterial Thrombosis in Mice
Authors: Michael S Nickoli, Michael W Milks, Debra G Wheeler, Karen M Dwyer, Peter J Cowan, Simon C Robson, Anthony J d’Apice, Richard J Gumina
Journal: Circulation (2009)

Background: Vascular injury results in release adenosine diphosphate (ADP), activating platelets leading to further release of ADP from platelet granules. ADP release results in platelet aggregation and cross-linking. Ectonucleoside Triphosphate Diphosphohydrolase-1 (ENTDP-1/ CD39), an endothelial cell-expressed diphosphonucleotidase, rapidly converts ATP and ADP to AMP which is further degraded by ecto-5′-nucleotidase (CD73) to adenosine, an anti-thrombotic, vasodilatory and cardioprotective compound. We hypothesized that transgenic CD39 over-expression would increase the time to thrombosis in an in vivo ferric chloride-induced carotid artery thrombosis model. Methods: Mice, 8 –12 week old human CD39 overexpressing (hCD39-OE) and wildtype littermates, were anesthetized using 55 mg/kg ketamine and 15 mg/kg xylazine, intubated, and ventilated with room air using a mouse respirator (Harvard Apparatus). A midline incision was made and the left carotid artery was exposed. Baseline carotid blood flow was obtained using a Doppler flow probe (Model 0.5 VB, Transonics Systems). Thrombosis was induced by placing filter paper saturated with 10% FeCl3 on the carotid artery for 3 minutes. Carotid blood flow was monitored continuously and time to cessation of flow analyzed. Results: In response to FeCl3 induced injury, wild-type mice demonstrated a consistent time to occlusion of 8±1 minute. In contrast, in animals overexpressing hCD39, the time to occlusion following FeCl3 induced injury was profoundly increased to 60±2 minutes (&gt;7-fold). (Figure ). Conclusion: CD39 over-expression significantly delays the time to arterial thrombosis.
Abstract 5276: Insulin-like Growth Factor I Downregulates Vascular Smooth Muscle and Macrophage 12/15-Lipoxygenase Expression: Potential Mechanism for Igf-1-induced Atheroprotection.
Authors: Charlotte Vaughn, Sergiy Sukhanov, Shaw-Yung Shai, Yusuke Higashi, Patrick Delafontaine
Journal: Circulation (2009)

We have shown that IGF-1 infusion in ApoE−/− mice reduces atherosclerosis. To define mechanisms we performed RT-PCR gene arrays and found that IGF-1 (1.8 mg/kg/d, i.p., 1w, n=6) markedly reduces aortic 12/15-lipoxygenase (LOX) expression (64±6% decrease, P&lt;0.05). LOX plays a major role in oxidation of native LDL to its pro-atherogenic form (OxLDL) and is expressed in vascular smooth muscle cells (SMC) and macrophages (MΦ). DHE staining in situ revealed increased superoxides in atherosclerotic plaque of ApoE−/− mice (77±6% increase vs. adjacent media, P&lt;0.05) correlating with increased MΦ infiltration and LOX expression. A LOX-specific inhibitor baicalin (50 μ M) dramatically suppressed plaque superoxides (59±8% inhibition, P&lt;0.01), consistent with LOX being a major source of superoxides. IGF-1 infusion in ApoE−/− mice (1.5 mg/kg/d, 12 w, western diet, n=12) markedly reduced aortic plaque LOX immunopositivity (74±9% decrease, P&lt;0.05), superoxide levels (84±7%, P&lt;0.05) and atherosclerotic lesion size (IGF-1: 0.259±0.018 μ m2 saline: 0.356±0.331 μ m2, 28% decrease, P&lt;0.05). To obtain insight into the relative role of SMC vs. MΦ LOX in IGF-1 induced atheroprotection we generated SMP8/ApoE−/− mice in which IGF-1 is overexpressed in SMC. SMP8/ApoE−/− mice (western diet, 12w) had decreased aortic LOX expression (71% decrease vs. ApoE−/− mice, P&lt;0.05, n=5) but no reduction in atherosclerosis suggesting that the ability of increased circulating IGF-1 to reduce atherosclerosis was primarily mediated via its effect on MΦ LOX. To further define mechanisms and to model in vivo conditions, SMC or THP-1 derived MΦ were exposed to OxLDL (80ug/mL, 16h) with/without IGF-1. OxLDL markedly increased LOX activity in MΦ and SMC (18-fold vs. nLDL), however, pre-treatment with IGF-1 completely abolished OxLDL-induced LOX activation only in MΦ. In summary, IGF-1 infusion markedly reduces plaque LOX levels and decreases atherosclerotic plaque burden, but SMC-specific IGF-1 over expression reduces LOX but does not alter atherosclerosis. Taken together with our finding that IGF-1 markedly inhibits OxLDL-induced LOX activation in MΦ in vitro our data suggests that IGF-1 downregulation of MΦ LOX activity plays an important role in reducing atherosclerotic plaque burden.
Abstract 5301: Fractalkine Desensitizes Platelets to Platelet Inhibition by the Endogenous Platelet Inhibitor Prostacyclin
Authors: Andreas Schaefer, Ulrike Flierl, Johann Bauersachs
Journal: Circulation (2009)

Background: Fractalkine plays a pivotal role in atherogenesis. Platelet activation is a central factor in atherosclerosis progression. We previously reported that fractalkine induces platelet degranulation and P-selectin expression facilitating platelet-leukocyte adhesion. Fractalkine attenuates the bioavailability of the important endogenous platelet inhibitor nitric oxide. Methods: The influence of preincubation of platelets with fractalkine (1 μ g/ml) on platelet inhibition by the platelet inhibitor prostaglandin E1 (PGE1) was assessed by two assays: first, the ability to prevent PGE1-induced attenuation of ADP-induced platelet aggregation, and second, the capability to decrease PGE1-induced vasodilator-stimulated phosphoprotein (VASP)-phosphorylation determined by flow-cytometry. Samples were preincubated with fractalkine and stimulated with different concentrations of PGE1. Results: PGE1 significantly inhibited ADP-induced platelet aggregation. In samples pre-treated with fractalkine, prevention of ADP-induced platelet aggregation by PGE1was abrogated. While secondary platelet aggregation was prevented by PGE1 (1 μ M), preincubation with fractalkine for 10 minutes reestablished secondary platelet aggregation. These results indicate that fractalkine desensitized platelets to PGE1. PGE1-induced VASP-phosphorylation was significantly attenuated by preincubation with fractalkine in a time- and concentration-dependent pattern, whereby a maximum effect was achieved after preincubation of platelets with fractalkine for 10 minutes, which reduced PGE1 (1 μ M)-induced VASP-phosphorylation by ~25% (p&lt;0.01 vs. PGE1 without fractalkine). Conclusion: Fractalkine desensitizes platelets to PGE1 suggesting that platelet inhibition by the endogenous platelet inhibitor prostacyclin is affected by fractalkine. These results indicate a new pathomechanism by which this atherogenic chemokine facilitates relevant steps leading to platelet activation and leukocyte recruitment, namely rendering platelets less responsive to endogenous platelet inhibition.
Abstract 5325: Inherited Human Nox2 Deficiency is Associated With Impaired Isoprostane Formation and Reduced Platelet Recruitment
Authors: Pasquale Pignatelli, Roberto Carnevale, Serena Di Santo, Simona Bartimoccia, Annarita Panarelli, Valerio Sanguigni, Andrea Finocchi, Alessandro Plebani, Francesco Violi
Journal: Circulation (2009)

Platelet isoprostane PGF2 α -III, a pro-aggregating molecule, is believed to derive from non enzymatic oxidation of arachidonic acid. We assessed the hypothesis that PGF2 α -III derives also from gp91phox activation and contributes to the phenomenon of platelet recruitment. We studied PGF2 α -III in platelets from 8 male patients with hereditary deficiency of gp91phox (Nox2) the catalytic subunit of NADPH oxidase, and 8 male controls. Gp91phox deficency is a very rare human disease(prevalence 1:1000.000) characterized by life-threatening infections. Patients were a subgroup from a multicentre study in collaboration with the Italian Primary Immunodeficiency Network (IPINET). Upon stimulation platelets from healthy subjects produced PGF2 α -III, that was inhibited 8% by aspirin and 43% by an inhibitor of gp91phox. Also, in platelets incubated with a gp91phox inhibitor or with SQ29548, a thromboxane A2 receptors inhibitor, platelet recruitment, an in vitro model of thrombus growth, was reduced by 52% and 84% respectively; a lower effect (−13%) was seen with aspirin. Incubation of normal platelets with PGF2 α -III dose-dependently(1–100 pM) increased platelet recruitment by mobilizing platelet Ca2+ and activating gpIIb/IIIa. Platelets from patients with gp91phox hereditary deficiency had normal thromboxane A2 formation and 75% PGF2 α -III reduction compared to controls. In gp91phox-deficient patients agonist-induced platelet aggregation was within the normal range while platelet recruitment was reduced compared to controls. Incubation of gp91phox-deficient platelets with PGF2 α -III (1–100 pM) partially restored platelet recruitment. In conclusion this study provides the first evidence that platelet PGF2 α -III maximally derives from Nox2 activation and contributes to platelet recruitment via activation of gpIIb/IIIa.
Abstract 5305: Intracoronary Upregulation of Platelet P-selectin and Platelet-monocyte Aggregation Correlate With Coronary Lesion Stenosis Severity Despite Aspirin and Clopidogrel Use
Authors: Andy S Yong, Gabrielle Pennings, Tommy Chung, David Brieger, Martin K Ng, Harry C Lowe
Journal: Circulation (2009)

Background: In vitro studies suggest that platelets are activated by shear stress as they travel through areas of significant coronary stenosis. However, it is unknown whether coronary stenoses cause platelet activation in the presence of dual anti-platelet therapy with aspirin and clopidogrel. We hypothesized that platelet P-selectin, a key regulator of platelet-leukocyte interactions and inflammation, is upregulated as platelets cross coronary plaques despite dual anti-platelet therapy, and this upregulation is directly associated with stenosis severity. Methods: Prior to PCI, blood was collected in sequence from the coronary sinus (CS, in left coronary target lesions), coronary artery distal (DA) and proximal (PA) to target lesion, and CS a second time immediately after intracoronary sampling. Quantitative coronary angiography was used to measure target lesion percentage area stenosis. Percentage platelet P-selectin (CD62P) expression, GPIIb/IIIa conformational change (PAC-1), and platelet-monocyte aggregate formation were quantified by flow cytometry. Results: In total, 15 consecutive patients pre-treated with dual anti-platelet therapy undergoing elective percutaneous coronary intervention (PCI) to a single target lesion were recruited. Mean age was 67.5y, and 88% were male. Mean percentage lesion area stenosis was 80.8±8.2%. Percentage area stenosis correlated with trans-lesion gradients (DA-PA) for CD62P (r=0.62, p=0.01) and platelet-monocyte aggregation (r=0.76, p&lt;0.01), but not for PAC-1 (r=0.03, p=0.90). CS samples were significantly more activated than PA for CD62P (p=0.03) but CS samples and trans-cardiac gradients (CS-PA) did not correlate with lesion stenosis. There were no significant differences between first and second CS samples, indicating no artificial activation caused by sampling. Conclusions: We provide evidence of a direct relationship between coronary stenosis severity and intracoronary platelet P-selectin expression and platelet-monocyte aggregation despite dual anti-platelet therapy. Upregulation of P-selectin by shear stress and/or other mechanical factors under conditions where IIb/IIIa is not, appears to be resistant to current conventional anti-platelet therapy.
Abstract 5322: Donepezil, an Acetylcholinesterase Inhibitor, Attenuates Atherogenesis in Apolipoprotein E Knockout Mice Through Antioxidative and Anti-inflammatory Effects
Authors: Keita Inanaga, Toshihiro Ichiki, Kotaro Takeda, Kenji Sunagawa
Journal: Circulation (2009)

Objective Donepezil, a reversible acetylcholinesterase inhibitor, improves cognitive function of Alzheimer’s disease. Vagus nerve stimulation is known to attenuate inflammatory responses in mice with lipopolysaccharide-induced sepsis, which is designated cholinergic anti-inflammatory system. We investigated whether the pharmacological stimulation of cholinergic system by donepezil affects atherogenesis in apolipoprotein (Apo) E-knockout (KO) mice. Methods and Results Male ApoE-KO mice (10-week-old) were fed a high fat diet (HFD) and received infusion of angiotensin (Ang) II (1.9 mg/kg/day). Oral administration of donepezil (5 mg/kg/day) or infusion of physostigmine (2mg/kg/day), another acetylcholinesterase inhibitor, for 4 weeks did not change hemodynamics or cholesterol level, but significantly reduced Oil Red O-positive area of en face aorta (Control 3.8±0.4%, AngII + HFD 13.6±2.2%, AngII + HFD and donepezil 6.9±0.9%*, AngII + HFD and physostigmine 8.2±0.6%*, *P&lt;0.05 vs AngII + HFD) and macrophage infiltration into the aortic root (p&lt;0.05). Donepezil also decreased monocyte chemoattractant protein (MCP)-1-positive area by 45% (p&lt;0.05) in the aortic sinus. Donepezil administration also attenuated atherogenesis in ApoE-KO mice fed a HFD for 8 weeks without AngII infusion. Quantitative RT-PCR revealed that administration of donepezil to ApoE-KO mice treated with AngII and a HFD significantly suppressed expression of MCP-1 and tumor necrosis factor-alpha 52% and 70% reduction, respectively, P&lt;0.05) in the aorta. Donepezil significantly suppressed NADPH oxidase activity (43% reduction, P&lt;0.05) and production of reactive oxygen species in the aorta. Preincubation with acetylcholine completely inhibited AngII-induced NADPH oxidase 1 expression in cultured vascular smooth muscle cells (P&lt;0.05). Conclusion The present study revealed a novel anti-atherosclerotic effect of pharmacological stimulation of cholinergic system by donepezil. Donepezil may increase acetylcholine availability and downregulate NADPH oxidase followed by suppression of inflammatory cytokine production and atherogenesis. Cholinergic stimulation may be a novel therapeutic strategy for atherosclerotic cardiovascular diseases.
Abstract 5327: Circulating Leukocyte Telomere Length Reflects the Burden of Oxidative Stress and Inflammation in Patients With Acute Myocardial Infarction
Authors: Sébastien Saliques, Marianne Zeller, Catherine Vergely, Sebastien Amoureux, Pierre Sicard, Jean-Eric Wolf, Julie Lorin, Anne-Cécile Lagrost, Juliane Berchoud, Anne Javouhey-Donzel, Yves Cottin, Jean-Raymond Teyssier, Luc Rochette
Journal: Circulation (2009)

Objectives: Recent data suggest that leukocyte telomere length (TL) may be a possible reliable marker in human-aging diseases and cardiovascular illness such as coronary artery disease (CAD) and heart failure. The main outcome of our study was to identify the possible correlation between TL and biomarkers of oxidative and inflammatory status. in patients with acute myocardial infarction (MI). Materials and Methods : The TL was determined prospectively by quantitative Polymerase Chain Reaction method from circulating leukocytes of consecutive patients admitted &lt;24 h in intensive care unit for an acute MI, as well as leukocyte expression of c-Fos, gene involved in cellular proliferation and oxidative stress. Left ventricular ejection fraction (LVEF) was assessed by echocardiography &lt;3 days after admission. Results: Among the 69 patients included in the study, mean age was 66±2 and 78% were male, and TL was 1.34±0.01. A negative correlation was found between leukocyte TL and age (r=−0.37, p=0.002), cFos gene expression (r=−0.46, p&lt;0.001), logNT-proBNP (r=−0.30, p=0.019) and CRP (r=−0.29, p=0.018). In contrast, creatinine clearance (r= +0.30, p=0.02), and LVEF (r= +0.26, p=0.04) were positively correlated with TL. Leukocyte count was not related with TL (p=0.54). Age-adjusted TL was significantly reduced in male vs. women (p=0.001), and in patients with hypertension (p=0.023), family history of CAD (p=0.006), smokers (p&lt;0.001), or clinical heart failure on admission (p=0.009). Backward multivariable linear regression analysis identified cFos ( β =0.51, p&lt;0.001), smoking ( β =0.25, p=0.031) and prior CAD ( β =−0.266, p=−0.011) as factors independently associated with LT (R 2 =0.43). Conclusion : Our study suggests that in patients with acute MI, circulating leukocyte TL reflects increased oxidative stress and inflammation, while the independent influence of age is limited. Considering the relevance of these findings, definitive question is if telomere attrition is a primary cause or a consequence of the development of the illness, encouraging further studies in this field.