RESUMEN
BACKGROUND: Cerebral infarcts distal to carotid stenoses are thought to be caused by emboli from inflamed, destabilized plaques. We hypothesized that microembolic signals (MES) on transcranial Doppler will be associated with carotid plaque inflammation on (18)F fluorodeoxyglucose positron-emission tomography (FDG PET) in recently symptomatic patients. METHODS AND RESULTS: Sixteen patients presenting with recent (47 ± 31 days) anterior circulation transient ischemic attack or minor stroke and 50% to 99% stenosis of the ipsilateral carotid bifurcation underwent FDG PET, high-resolution black-blood carotid MRI, and transcranial Doppler for detection of MES. Patients with potential cardiac sources of emboli or contralateral MES were excluded. Regions of interest defined on the coregistered MRI were used to measure FDG standardized uptake values (with Rousset partial volume correction) from the index and contralateral carotid plaques and artery. Ipsilateral MES were detected in 7 patients (MES+ group) and absent in 8 (MES- group). There was a significant difference in index-to-contralateral plaque standardized uptake value ratio between MES+ (median, 1.05; first to third quartile, 0.96 to 1.32) and MES- (median, 0.76; first to third quartile, 0.62 to 0.94) patients (P=0.005). The interval from symptom onset to PET and percent index carotid stenosis were not different between the 2 groups (P=0.68 and P=0.48, respectively). CONCLUSIONS: In this sample of recently symptomatic patients with carotid stenosis, an association was found between in vivo measures of plaque inflammation detected by FDG PET and the presence of transcranial Doppler MES. These findings strengthen the notion that embolic events distal to carotid stenoses are related to plaque inflammation, and FDG PET may be useful in the investigation of culprit carotid lesions.
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Estenosis Carotídea/complicaciones , Inflamación/complicaciones , Embolia Intracraneal/etiología , Ataque Isquémico Transitorio/etiología , Accidente Cerebrovascular/etiología , Anciano , Anciano de 80 o más Años , Estenosis Carotídea/diagnóstico por imagen , Femenino , Fluorodesoxiglucosa F18 , Humanos , Inflamación/diagnóstico por imagen , Embolia Intracraneal/diagnóstico por imagen , Ataque Isquémico Transitorio/diagnóstico por imagen , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Proyectos Piloto , Tomografía de Emisión de Positrones , Valor Predictivo de las Pruebas , Radiofármacos , Accidente Cerebrovascular/diagnóstico por imagen , Factores de Tiempo , Ultrasonografía Doppler TranscranealRESUMEN
The presence of activated macrophages is an important predictor of atherosclerotic plaque rupture. In this study, our aim was to determine the accuracy of (18)F- fluorodeoxyglucose (FDG) microPET imaging for quantifying aortic wall macrophage content in a rabbit model of atherosclerosis. Rabbits were divided into a control group and two groups post aortic balloon injury: 6 months high-cholesterol diet (HC); and 3 months HC followed by 3 months low-cholesterol diet plus statin (LCS). In vivo and ex vivo microPET, ex vivo well counting and histological quantification of the atherosclerotic aortas were performed for all groups. Macrophage density was greater in the HC group than the LCS group (5.1 +/- 1.4% vs. 0.6 +/- 0.7%, P < 0.001) with a trend towards greater macrophage density in LCS compared to controls (P = 0.08). There was a strong correlation across all groups between macrophage density and standardized uptake value (SUV) derived from ex vivo microPET (r = 0.95, P < 0.001) and well counting (r = 0.96, P < 0.001). Ex vivo FDG SUV was significantly different between the three groups (P < 0.001). However, the correlation between in vivo microPET FDG SUV and macrophage density was insignificant (r = 0.16, P = 0.57) with no statistical differences in FDG SUV seen between the three groups. This study confirms that in an animal model of inflamed and non-inflamed atherosclerosis, significant differences in FDG SUV allow differentiation of highly inflamed atherosclerotic aortas from those stabilized by statin therapy and low cholesterol diet and controls.
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Aorta/diagnóstico por imagen , Aterosclerosis/diagnóstico por imagen , Fluorodesoxiglucosa F18 , Inflamación/diagnóstico por imagen , Tomografía de Emisión de Positrones , Radiofármacos , Animales , Aorta/efectos de los fármacos , Aterosclerosis/tratamiento farmacológico , Aterosclerosis/etiología , Atorvastatina , Cateterismo , Colesterol en la Dieta , Diagnóstico Diferencial , Modelos Animales de Enfermedad , Ácidos Heptanoicos/farmacología , Inhibidores de Hidroximetilglutaril-CoA Reductasas/farmacología , Inflamación/tratamiento farmacológico , Inflamación/etiología , Macrófagos/diagnóstico por imagen , Masculino , Valor Predictivo de las Pruebas , Pirroles/farmacología , ConejosRESUMEN
BACKGROUND AND PURPOSE: Inflammation is a major risk factor for atherosclerotic plaque rupture and clinical events. Previous studies have shown that plaque [(18)F]fluorodeoxyglucose (FDG) uptake correlates with macrophage content. In this study we examined the reproducibility of 3 methods of quantifying plaque FDG uptake in the carotid arteries using positron emission tomography (PET). The correlation between 2 simplified uptake parameters (standardized uptake value [SUV], vessel wall-to-blood ratio [VBR]) and a gold standard technique (influx rate [K(i)]) was also determined. We used MRI to correct carotid plaque FDG uptake for partial volume error. METHODS: Seven patients with a recent carotid territory transient ischemic attack underwent imaging twice within 8 days using MR and FDG-PET. MR coregistered to PET was used to delineate regions of interest, and to facilitate partial volume correction (PVC). RESULTS: SUV was the most reproducible parameter irrespective of whether it was normalized by body surface area (BSA), lean body mass, or weight (intraclass correlation coefficient=0.85, 0.88, and 0.90, respectively). VBR correlated better to K(i) than SUV (r=0.58 VBR, r=0.46 SUV(BSA)). PVC improved these correlations to r=0.81 VBR and r=0.76 SUV(BSA), and only slightly degraded the reproducibility of SUV (intraclass correlation coefficient=0.83-0.85). CONCLUSIONS: MR-guided FDG-PET is a highly reproducible technique in the carotid artery and the excellent anatomic detail provided by MR facilitates PVC. Of the methods examined, SUV(BSA)(PVC) appears to represent the best compromise between reproducible and accurate determination of FDG metabolism in carotid artery vessel wall.
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Arteritis/diagnóstico por imagen , Arteritis/patología , Estenosis Carotídea/diagnóstico por imagen , Estenosis Carotídea/patología , Imagen por Resonancia Magnética/métodos , Tomografía de Emisión de Positrones/métodos , Anciano , Arteritis/fisiopatología , Artefactos , Arterias Carótidas/diagnóstico por imagen , Arterias Carótidas/patología , Arterias Carótidas/fisiopatología , Estenosis Carotídea/fisiopatología , Quimiotaxis de Leucocito/inmunología , Femenino , Fluorodesoxiglucosa F18 , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Ataque Isquémico Transitorio/diagnóstico por imagen , Ataque Isquémico Transitorio/patología , Ataque Isquémico Transitorio/fisiopatología , Macrófagos/patología , Masculino , Persona de Mediana Edad , Potasio/metabolismo , Valor Predictivo de las Pruebas , Reproducibilidad de los ResultadosRESUMEN
Emery-Dreifuss muscular dystrophy (EDMD) is a heterogeneous late-onset disease involving skeletal muscle wasting and heart defects caused, in a minority of cases, by mutations in either of two genes encoding the inner nuclear membrane (INM) proteins, emerin and lamins A/C. Nesprin-1 and -2 are multi-isomeric, spectrin-repeat proteins that bind both emerin and lamins A/C and form a network in muscle linking the nucleoskeleton to the INM, the outer nuclear membrane, membraneous organelles, the sarcomere and the actin cytoskeleton. Thus, disruptions in nesprin/lamin/emerin interactions might play a role in the muscle-specific pathogenesis of EDMD. Screening for DNA variations in the genes encoding nesprin-1 (SYNE1) and nesprin-2 (SYNE2) in 190 probands with EDMD or EDMD-like phenotypes identified four heterozygous missense mutations. Fibroblasts from these patients exhibited nuclear morphology defects and specific patterns of emerin and SUN2 mislocalization. In addition, diminished nuclear envelope localization of nesprins and impaired nesprin/emerin/lamin binding interactions were common features of all EDMD patient fibroblasts. siRNA knockdown of nesprin-1 or -2 in normal fibroblasts reproduced the nuclear morphological changes and mislocalization of emerin and SUN2 observed in patient fibroblasts. Taken together, these data suggest that EDMD may be caused, in part, by uncoupling of the nucleoskeleton and cytoskeleton because of perturbed nesprin/emerin/lamin interactions.
Asunto(s)
Proteínas de Microfilamentos/genética , Distrofia Muscular de Emery-Dreifuss/genética , Proteínas del Tejido Nervioso/genética , Proteínas Nucleares/genética , Secuencia de Aminoácidos , Secuencia de Bases , Línea Celular , Proteínas del Citoesqueleto , ADN/genética , Análisis Mutacional de ADN , Femenino , Fibroblastos/metabolismo , Fibroblastos/ultraestructura , Heterocigoto , Humanos , Laminas/genética , Laminas/metabolismo , Masculino , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Proteínas de Microfilamentos/metabolismo , Microscopía Electrónica de Transmisión , Datos de Secuencia Molecular , Músculo Esquelético/metabolismo , Distrofia Muscular de Emery-Dreifuss/etiología , Distrofia Muscular de Emery-Dreifuss/metabolismo , Mutación Missense , Proteínas del Tejido Nervioso/metabolismo , Membrana Nuclear/metabolismo , Proteínas Nucleares/metabolismo , Linaje , ARN Interferente Pequeño/genética , Homología de Secuencia de AminoácidoRESUMEN
INTRODUCTION: The peripheral benzodiazepine receptor (PBR) has shown considerable potential as a clinical marker of neuroinflammation and tumour progression. [(11)C]DAA1106 ([(11)C]N-(2,5-dimethoxybenzyl)-N-(5-fluoro-2-phenoxyphenyl)-acetamide) is a promising positron emission tomography (PET) radioligand for imaging PBRs. METHODS: A four-step synthetic route was devised to prepare DAA1123, the precursor for [(11)C]DAA1106. Two robust, high yielding methods for radiosynthesis based on [(11)C]-O-methylation of DAA1123 were developed and implemented on a nuclear interface methylation module, producing [(11)C]DAA1106 with up to 25% radiochemical yields at end-of-synthesis based on [(11)C]CH(3)I trapped. Evaluation of [(11)C]DAA1106 for in vivo imaging was performed in a rabbit model with microPET, and the presence of PBR receptor in the target organ was further corroborated by immunohistochemistry. RESULTS: The standard solution method produced 2.6-5.2 GBq (n=19) of [(11)C]DAA1106, whilst the captive solvent method produced 1.6-6.3 GBq (n=10) of [(11)C]DAA1106. Radiochemical purities obtained were 99% and specific radioactivity at end-of-synthesis was up to 200 GBq/micromol for both methods. Based on radiochemical product, shorter preparation times and simplicity of synthesis, the captive solvent method was chosen for routine productions of [(11)C]DAA1106. In vivo microPET [(11)C]DAA1106 scans of rabbit kidney demonstrated high levels of binding in the cortex. The subsequent introduction of nonradioactive DAA1106 (0.2 micromol) produced considerable displacement of the radioactive signal in this region. The presence of PBR in kidney cortex was further corroborated by immunohistochemistry. CONCLUSIONS: A robust, high yielding captive solvent method of [(11)C]DAA1106 production was developed which enabled efficacious in vivo imaging of PBR expressing tissues in an animal model.
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Acetamidas/síntesis química , Éteres Fenílicos/síntesis química , Tomografía de Emisión de Positrones/métodos , Radiofármacos/síntesis química , Receptores de GABA-A/metabolismo , Acetamidas/farmacocinética , Animales , Automatización , Cromatografía Líquida de Alta Presión , Humanos , Inmunohistoquímica , Indicadores y Reactivos , Marcaje Isotópico/métodos , Corteza Renal/diagnóstico por imagen , Corteza Renal/metabolismo , Metilación , Éteres Fenílicos/farmacocinética , Conejos , Radiofármacos/farmacocinética , SolventesRESUMEN
Migration of adventitial fibroblasts contributes to vascular remodeling after angioplasty. This study has used perivascular gene transfer of a truncated platelet-derived growth factor PDGF receptor (PDGFXR) to investigate whether antagonism of PDGF signaling alters adventitial cell migration after balloon injury in rat carotid arteries. Adenoviruses coordinating expression of beta-galactosidase (LacZ) and PDGFXR or LacZ and green fluorescent protein (GFP) were applied to the perivascular surface of arteries and balloon injury performed 4 days later. Vessels were excised at 3, 7, and 14 days to determine morphology and gene expression. Uninjured arteries only expressed LacZ positive cells in the adventitial compartment; however, after injury in LacZ and GFP transfected arteries, LacZ positive cells contributed to the population of cells within the media and neointima at 7-14 days. Overexpression of PDGFXR and LacZ resulted in a significant reduction in the number of LacZ labeled cells in the neointima after vascular injury, concomitant with reduced remodeling, collagen content, expression of matrix metalloproteinase-2, and increased levels of tissue inhibitors of metalloproteinase-1 and -2. We provide evidence that perivascular antagonism of PDGF attenuates remodeling and contribution of adventitial fibroblasts to neointima formation after balloon angioplasty. Perivascular gene transfer may represent a therapeutic strategy to reduce the incidence of restenosis.
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Traumatismos de las Arterias Carótidas/terapia , Movimiento Celular , Factor de Crecimiento Derivado de Plaquetas/antagonistas & inhibidores , Receptores del Factor de Crecimiento Derivado de Plaquetas/administración & dosificación , Transfección , Angioplastia de Balón/efectos adversos , Animales , Arteriopatías Oclusivas/prevención & control , Traumatismos de las Arterias Carótidas/patología , Fibroblastos/fisiología , Proteínas Fluorescentes Verdes/administración & dosificación , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/farmacocinética , Operón Lac/genética , Ratas , Receptores del Factor de Crecimiento Derivado de Plaquetas/genética , Eliminación de Secuencia , Distribución TisularRESUMEN
The endothelin (ET) receptor system has been shown to play a role in a number of vascular diseases. We have synthesized 18F-and 11C-labeled radioligands to enable in vivo imaging of the fundamental processes involved in ET receptor pharmacology in normal and diseased tissue using positron emission tomography (PET). One aim is to elucidate the proposed role of the ET(B) subtype as clearing receptor, removing ET-1 from the circulation, and whether this is an important mechanism to limit the detrimental effects caused by upregulated ET-1 in disease. To image ET(B) receptors we have labeled the selective agonist BQ3020 with 18F. In vitro characterization verified that [18F]-BQ3020 bound with a single subnanomolar affinity (K(D) = 0.34 +/- 0.10 nM, B(max) = 9.23 +/- 3.70 fmol/mg protein) to human left ventricle. Binding of [18F]-BQ3020 to human kidney was inhibited by ET-1 and unlabeled BQ3020 but not by the ET(A) selective antagonist FR139317, confirming that selectivity for the ET(B) receptor was retained. In vitro autoradiography revealed, as expected, high levels of ET(B) receptor densities in lung and kidney medulla, whereas kidney cortex and heart showed lower levels of ET(B) receptor densities. Furthermore, a high level of [18F]-BQ3020 binding was found to colocalize to macrophages in atherosclerotic coronary arteries. MicroPET studies demonstrated high uptake of [18F]-BQ3020 in ET(B) receptor-rich tissue, including lung, liver and kidney. The in vivo biodistribution of [18F]-BQ3020 was comparable to that previously obtained for [18F]-ET-1, supporting our hypothesis that the ET(B) receptor plays a significant role in the uptake of ET-1. In conclusion, [18F]-BQ3020 has retained high affinity and selectivity, allowing imaging of ET(B) receptor distributions in vitro and in vivo in human and animal tissue. Furthermore, in vitro data suggest that [18F]-BQ3020 potentially can be used to image atherosclerotic lesions in vivo using PET.
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Endotelina-1/farmacología , Endotelinas/farmacología , Fragmentos de Péptidos/farmacología , Tomografía de Emisión de Positrones , Receptor de Endotelina B/metabolismo , Animales , Unión Competitiva/efectos de los fármacos , Vasos Coronarios/diagnóstico por imagen , Vasos Coronarios/metabolismo , Vasos Coronarios/patología , Relación Dosis-Respuesta a Droga , Antagonistas de los Receptores de la Endotelina B , Radioisótopos de Flúor , Ventrículos Cardíacos/diagnóstico por imagen , Ventrículos Cardíacos/metabolismo , Humanos , Técnicas In Vitro , Riñón/diagnóstico por imagen , Riñón/metabolismo , Corteza Renal/diagnóstico por imagen , Corteza Renal/metabolismo , Médula Renal/diagnóstico por imagen , Médula Renal/metabolismo , Pulmón/diagnóstico por imagen , Pulmón/metabolismo , Conejos , Ensayo de Unión Radioligante , Distribución TisularRESUMEN
Imaging of atheromatous plaques has traditionally centered on assessing the degree of luminal stenosis. More recently it has become clear that the vulnerable atherosclerotic plaques responsible for the majority of life-threatening syndromes are characterized by high numbers of inflammatory cells and proteins. This has highlighted the urgent need for suitable imaging techniques that can identify and quantify levels of inflammation within atheromatous lesions. Positron emission tomography and single-photon emission computed tomography imaging hold promise in this regard. Tracer compounds capable of assessing macrophage recruitment, foam cell generation, matrix metalloproteinase production, macrophage apoptosis, and macrophage metabolism have been developed and tested in the carotid and peripheral circulation. The identification of inflamed lesions within the coronary circulation, however, remains elusive owing to small plaque size, cardiac and respiratory motion, and lack of a suitable specific nuclear tracer.
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Aterosclerosis/diagnóstico por imagen , Animales , Apoptosis , Aterosclerosis/inmunología , Aterosclerosis/patología , Fluorodesoxiglucosa F18 , Células Espumosas , Humanos , Inflamación , Macrófagos , Metaloproteinasas de la Matriz , Monocitos , Fagocitosis , Tomografía de Emisión de Positrones , RadiofármacosRESUMEN
BACKGROUND AND PURPOSE: Carotid endarterectomy is currently guided by angiographic appearance on the assumption that the most stenotic lesion visible at angiography is likely to be the lesion from which future embolic events will arise. However, risk of plaque rupture, the most common cause of atherosclerosis-related thromboembolism, is dictated by the composition of the plaque, in particular the degree of inflammation. Angiography may, therefore, be an unreliable method of identifying vulnerable plaques. In this study, plaque inflammation was quantified before endarterectomy using the combination of 18F fluorodeoxyglucose positron (FDG)-emission tomography (PET) and high-resolution MRI (HRMRI). METHODS: Twelve patients, all of whom had suffered a recent transient ischemic attack, had a severe stenosis in the ipsilateral carotid artery, and were awaiting carotid endarterectomy underwent FDG-PET and HRMRI scanning. A semiquantitative estimate of plaque inflammation was calculated for all of the lesions identified on HRMRI. RESULTS: In 7 of 12 patients (58%), high FDG uptake was seen in the lesion targeted for endarterectomy. In the remaining 5 patients, FDG uptake in the targeted lesion was low. In these 5 patients, 3 had nonstenotic lesions identified on HRMRI that exhibited a high level of FDG uptake. All 3 of the highly inflamed nonstenotic lesions were located in a vascular territory compatible with the patients' presenting symptoms. CONCLUSIONS: Our data suggest that angiography may not always identify the culprit lesion. Combined FDG-PET and HRMRI can assess the degree of inflammation in stenotic and nonstenotic plaques and could potentially be used to identify lesions responsible for embolic events.
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Estenosis Carotídea/diagnóstico , Ataque Isquémico Transitorio/diagnóstico , Placa Amiloide/metabolismo , Anciano , Anciano de 80 o más Años , Estenosis Carotídea/complicaciones , Femenino , Fluorodesoxiglucosa F18/farmacocinética , Humanos , Aumento de la Imagen , Ataque Isquémico Transitorio/complicaciones , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Tomografía de Emisión de PositronesRESUMEN
Vascular calcification predicts an increased risk for cardiovascular events/mortality in atherosclerosis, diabetes, and ESRD. Serum concentrations of alpha(2)-Heremens-Schmid glycoprotein, commonly referred to as fetuin-A, are reduced in ESRD, a condition associated with an elevated circulating calcium x phosphate product. Mice that lack fetuin-A exhibit extensive soft tissue calcification, which is accelerated on a mineral-rich diet, suggesting that fetuin-A acts to inhibit calcification systemically. Western blot and immunohistochemistry demonstrated that serum-derived fetuin-A co-localized with calcified human vascular smooth muscle cells (VSMC) in vitro and in calcified arteries in vivo. Fetuin-A inhibited in vitro VSMC calcification, induced by elevated concentrations of extracellular mineral ions, in a concentration-dependent manner. This was achieved in part through inhibition of apoptosis and caspase cleavage. Confocal microscopy and electron microscopy-immunogold demonstrated that fetuin-A was internalized by VSMC and concentrated in intracellular vesicles. Subsequently, fetuin-A was secreted via vesicle release from apoptotic and viable VSMC. Vesicles have previously been identified as the nidus for mineral nucleation. The presence of fetuin-A in vesicles abrogated their ability to nucleate basic calcium phosphate. In addition, fetuin-A enhanced phagocytosis of vesicles by VSMC. These observations provide evidence that the uptake of the serum protein fetuin-A by VSMC is a key event in the inhibition of vesicle-mediated VSMC calcification. Strategies aimed at maintaining normal circulating levels of fetuin-A may prove beneficial in patients with ESRD.
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Proteínas Sanguíneas/fisiología , Calcinosis , Músculo Liso Vascular/citología , Calcinosis/prevención & control , Células Cultivadas , Humanos , Músculo Liso Vascular/patología , alfa-2-Glicoproteína-HSRESUMEN
Although conventional intraarterial digital subtraction angiography remains the gold standard method for imaging the vertebral artery, noninvasive modalities such as ultrasound, multislice computed tomographic angiography and magnetic resonance angiography are constantly improving and are playing an increasingly important role in diagnosing vertebral artery pathology in clinical practice. This paper reviews the current state of vertebral artery imaging from an evidence-based perspective. Normal anatomy, normal variants and a number of pathological entities such as vertebral atherosclerosis, arterial dissection, arteriovenous fistula, subclavian steal syndrome and vertebrobasilar dolichoectasia are discussed.
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Trastornos Cerebrovasculares/diagnóstico , Diagnóstico por Imagen , Arteria Vertebral/patología , Angiografía de Substracción Digital , Arteriosclerosis/diagnóstico , Fístula Arteriovenosa/diagnóstico , Humanos , Imagen por Resonancia Magnética , Síndrome del Robo de la Subclavia/diagnóstico , Tomografía Computarizada por Rayos X , Arteria Vertebral/anatomía & histología , Disección de la Arteria Vertebral/diagnóstico , Insuficiencia Vertebrobasilar/diagnósticoRESUMEN
Nesprins are a recently discovered family of ubiquitously expressed intracellular proteins. Through alternative transcriptional initiation, termination and splicing, two genes - nesprin-1 and nesprin-2 (also known as syne-1 and syne-2) - give rise to many protein isoforms that vary markedly in size. The largest of these isoforms comprise a C-terminal transmembrane domain (the KLS domain) linked by a spectrin-repeat rod domain to an N-terminal paired, actin-binding, calponin-homology domain. This structure suggests that they are well suited to orchestrate signalling between cell membranes and the cytoskeleton. Other isoforms have variable lengths of this rod domain linked to either end of the protein. Smaller isoforms with the KLS domain are localised at the inner nuclear membrane, where they bind lamin A/C and emerin. Larger nesprin isoforms link the outer nuclear membrane with intracellular organelles and the actin cytoskeleton and are thought to regulate nuclear anchorage and organelle migration. Thus, nesprins might have a variety of fundamental roles in cells, particularly muscle cells where they are highly expressed. We speculate that nesprin mutations might contribute to a broad range of human disease syndromes, including laminopathies.
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Proteínas Nucleares/metabolismo , Animales , Caenorhabditis elegans/metabolismo , Membrana Celular/metabolismo , Citoesqueleto/metabolismo , Drosophila melanogaster/metabolismo , Humanos , Lamina Tipo A/metabolismo , Células Musculares/metabolismo , Distrofia Muscular de Emery-Dreifuss/metabolismo , Mutación , Proteínas Nucleares/química , Proteínas Nucleares/genética , Isoformas de Proteínas/química , Isoformas de Proteínas/metabolismo , Estructura Terciaria de ProteínaRESUMEN
OBJECTIVE: Migration of adventitial fibroblasts contributes to arterial remodeling after angioplasty. This study used vascular gene transfer of smad7 to investigate whether antagonism of transforming growth factor-beta1 signaling alters luminal loss and adventitial cell migration after balloon injury in rat carotid arteries. METHODS AND RESULTS: Adenoviruses coordinating expression of beta-galactosidase (beta-gal) and smad7 or beta-gal and green fluorescent protein (GFP) were applied to the perivascular surface of common carotid arteries. Balloon injury was performed 4 days after gene transfer, and animals were killed at 3, 7, and 14 days after injury. Uninjured arteries only expressed adventitial beta-gal positive cells; however, after balloon injury in beta-gal- and GFP-transfected arteries, beta-gal-positive cells were observed within the medial layer of vessels and contributed to the population of cells within the neointima at 7 to 14 days. Overexpression of smad7 and beta-gal resulted in a significant reduction in the number of beta-gal-labeled cells in the neointima, concomitant with reduced luminal loss and decreased adventitial collagen content. CONCLUSIONS: We provide the first evidence that vascular smad7 overexpression attenuates remodeling and contribution of adventitial fibroblasts to neointima formation after balloon angioplasty. Smad7 may represent a novel therapeutic target to reduce the incidence of restenosis.
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Angioplastia de Balón/efectos adversos , Traumatismos de las Arterias Carótidas/terapia , Estenosis Carotídea/terapia , Terapia Genética/métodos , Proteína smad7/genética , Actinas/genética , Animales , Arterias Carótidas/patología , Arterias Carótidas/fisiopatología , Traumatismos de las Arterias Carótidas/patología , Traumatismos de las Arterias Carótidas/fisiopatología , Estenosis Carotídea/patología , Estenosis Carotídea/fisiopatología , Movimiento Celular/fisiología , Colágeno/metabolismo , Técnicas de Transferencia de Gen , Masculino , Ratas , Ratas Sprague-Dawley , Prevención Secundaria , Transducción de Señal/fisiología , Proteína smad7/metabolismo , Factor de Crecimiento Transformador beta/metabolismo , Factor de Crecimiento Transformador beta1RESUMEN
The majority of acute ischemic events relating to atherosclerosis are caused by plaque rupture and ensuing thrombosis. The risk of plaque rupture is dictated in part by plaque morphology, which in turn is influenced by pathophysiologic mechanisms at the cellular and molecular level. Anatomic imaging modalities such as intravascular ultrasound, high-resolution magnetic resonance imaging, and multislice computed tomography can identify morphologic features of the vulnerable plaque, such as a large lipid core and thin fibrous cap, but give little or no information regarding molecular and cellular mechanisms, such as endothelial function, macrophage activation, lipid transport and metabolism, and cell death. Recent studies suggest that nuclear imaging may be able to provide images of sufficient quality to identify and quantify some of these molecular and cellular pathophysiologic processes. In the future this could allow for the early identification and noninvasive monitoring of vulnerable plaque.
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Arteriosclerosis/diagnóstico por imagen , Isquemia Miocárdica/diagnóstico por imagen , Isquemia Miocárdica/etiología , Cintigrafía/métodos , Cintigrafía/tendencias , Medición de Riesgo/métodos , Animales , Arteriosclerosis/complicaciones , Estenosis Carotídea/complicaciones , Estenosis Carotídea/diagnóstico por imagen , Ensayos Clínicos como Asunto , Humanos , Medicina Nuclear/métodos , Medicina Nuclear/tendencias , Guías de Práctica Clínica como Asunto , Pautas de la Práctica en Medicina , Factores de Riesgo , Disfunción Ventricular Izquierda/diagnóstico por imagen , Disfunción Ventricular Izquierda/etiologíaRESUMEN
Rupture of so-called vulnerable or unstable atherosclerotic lesions is responsible for a significant proportion of myocardial infarcts and strokes. However, timely identification of such plaques, in order to allow for aggressive local and systemic therapy, remains problematic. In order to address this problem, there is a need to develop techniques that can image the cellular, biochemical, and molecular components that typify the vulnerable plaque. In this article, both techniques that are in current clinical use and those being evaluated in clinical trials are reviewed with regard to their ability to identify unstable lesions at risk of rupture.
Asunto(s)
Enfermedad de la Arteria Coronaria/diagnóstico , Rotura Espontánea/diagnóstico , Angiografía Coronaria , Enfermedad de la Arteria Coronaria/diagnóstico por imagen , Enfermedad de la Arteria Coronaria/fisiopatología , Humanos , Pronóstico , Medición de Riesgo , Rotura Espontánea/diagnóstico por imagen , Termografía , UltrasonografíaRESUMEN
Nesprin-2 is a multi-isomeric, modular protein composed of variable numbers of spectrin-repeats linked to a C-terminal transmembrane domain and/or to N-terminal paired calponin homology (CH) domains. The smaller isoforms of nesprin-2 co-localize with and bind lamin A and emerin at the inner nuclear envelope (NE). In SW-13 cells, which lack lamin A/C, nesprin-2 epitopes and emerin were both mislocalized and formed aggregates in the endoplasmic reticulum (ER). The larger isoforms and other CH-domain-containing isoforms co-localize with heterochromatin within the nucleus and are also present at the outer NE and in multiple cytoplasmic compartments. Nesprin-2 isoforms relocalize during in vitro muscle differentiation of C2C12 myoblasts to the sarcomere of myotubes. Immunogold electron microscopy using antibodies specific for three different epitopes detected nesprin-2 isoforms at multiple locations including intranuclear foci, both membranes of the NE, mitochondria, sarcomeric structures and plasma membrane foci. In adult skeletal muscle, confocal immunolocalization studies demonstrated that nesprin-2 epitopes were present at the Z-line and were also associated with the sarcoplasmic reticulum (SR) in close apposition to SERCA2. These data suggest that nesprin-2 isoforms form a linking network between organelles and the actin cytoskeleton and thus may be important for maintaining sub-cellular spatial organisation. Moreover, its association at the NE with lamin and emerin, the genes mutated in Emery-Dreifuss muscular dystrophy, suggests a mechanism to explain how disruption of the NE leads to muscle dysfunction.
Asunto(s)
Laminas/metabolismo , Proteínas de la Membrana/metabolismo , Músculo Esquelético/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Membrana Nuclear/metabolismo , Proteínas Nucleares/metabolismo , Timopoyetinas/metabolismo , Citoesqueleto de Actina/química , Empalme Alternativo , Sitios de Unión , Fraccionamiento Celular , Humanos , Inmunoprecipitación , Proteínas de Microfilamentos , Músculo Esquelético/química , Músculo Esquelético/ultraestructura , Proteínas del Tejido Nervioso/química , Proteínas del Tejido Nervioso/genética , Proteínas Nucleares/química , Proteínas Nucleares/genética , Isoformas de Proteínas/análisis , Isoformas de Proteínas/química , Isoformas de Proteínas/metabolismo , Estructura Terciaria de ProteínaRESUMEN
Lipid accumulation by vascular smooth muscle cells (VSMC) is a feature of atherosclerotic plaques. In this study we describe two mechanisms whereby human VSMC foam cell formation is driven by de novo synthesis of fatty acids leading to triacylglycerol accumulation in intracellular vacuoles, a process distinct from serum lipoprotein uptake. VSMC cultured in adipogenic differentiation medium accumulated lipids and were induced to express the adipocyte marker genes adipsin, adipocyte fatty acid-binding protein, C/EBPalpha, PPARgamma, and leptin. However, complete adipocyte differentiation was not observed as numerous genes present in mature adipocytes were not detected, and the phenotype was reversible. The rate of lipid accumulation was not affected by PPARgamma agonists, but screening for the effects of other nuclear receptor agonists showed that activation of the liver X receptors (LXR) dramatically promoted lipid accumulation in VSMC. Both LXRalpha and LXRbeta were present in VSMC, and their activation with TO901317 resulted in induction of the lipogenic genes fatty acid synthetase, sterol regulatory element binding protein (SREBP1c), and stearoyl-CoA desaturase. 27-Hydroxycholesterol, an abundant oxysterol synthesized by VSMC acted as an LXR antagonist and, therefore, may have a protective role in preventing foam cell formation. Immunohistochemistry showed that VSMC within atherosclerotic plaques express adipogenic and lipogenic markers, suggesting these pathways are present in vivo. Moreover, the development of an adipogenic phenotype in VSMC is consistent with their known phenotypic plasticity and may contribute to their dysfunction in atherosclerotic plaques and, thus, impinge on plaque growth and stability.
Asunto(s)
Adipocitos/metabolismo , Colesterol/análogos & derivados , Músculo Liso Vascular/metabolismo , Receptores Citoplasmáticos y Nucleares/metabolismo , Triglicéridos/metabolismo , Transportadoras de Casetes de Unión a ATP/metabolismo , Adipocitos/citología , Arteriosclerosis/metabolismo , Biomarcadores , Proteínas Potenciadoras de Unión a CCAAT/metabolismo , Diferenciación Celular/fisiología , Células Cultivadas , Colesterol/farmacología , Factor D del Complemento , Medios de Cultivo/farmacología , Proteínas de Unión al ADN/metabolismo , Ácido Graso Sintasas/metabolismo , Expresión Génica , Humanos , Hidroxicolesteroles/farmacología , Receptores X del Hígado , Músculo Liso Vascular/citología , Ácido Oléico/metabolismo , Receptores Nucleares Huérfanos , Regiones Promotoras Genéticas/fisiología , Receptores Citoplasmáticos y Nucleares/genética , Serina Endopeptidasas/metabolismo , Proteína 1 de Unión a los Elementos Reguladores de Esteroles , Factores de Transcripción/metabolismo , Regulación hacia ArribaRESUMEN
Implants of collagen-fibronectin gels containing Bcl-2-transduced human umbilical vein endothelial cells (Bcl-2-HUVECs) induce the formation of human endothelial cell (EC)/murine vascular smooth muscle cell (VSMC) chimeric vessels in immunodeficient mice. Microfil casting of the vasculature 60 d after implantation reveals highly branched microvascular networks within the implants that connect with and induce remodeling of conduit vessels arising from the abdominal wall circulation. Approximately 85% of vessels within the implants are lined by Bcl-2-positive human ECs expressing VEGFR1, VEGFR2, and Tie-2, but not integrin alpha(v)beta(3). The human ECs are seated on a well formed human laminin/collagen IV-positive basement membrane, and are surrounded by mouse VSMCs expressing SM-alpha actin, SM myosin, SM22alpha, and calponin, all markers of contractile function. Transmission electron microscopy identified well formed EC-EC junctions, chimeric arterioles with concentric layers of contractile VSMC, chimeric capillaries surrounded by pericytes, and chimeric venules. Bcl-2-HUVEC-lined vessels retain 70-kDa FITC-dextran, but not 3-kDa dextran; local histamine rapidly induces leak of 70-kDa FITC-dextran or India ink. As in skin, TNF induces E-selectin and vascular cell adhesion molecule 1 only on venular ECs, whereas intercellular adhesion molecule-1 is up-regulated on all human ECs. Bcl-2-HUVEC implants are able to engraft within and increase perfusion of ischemic mouse gastrocnemius muscle after femoral artery ligation. These studies show that cultured Bcl-2-HUVECs can differentiate into arterial, venular, and capillary-like ECs when implanted in vivo, and induce arteriogenic remodeling of the local mouse vessels. Our results support the utility of differentiated EC transplantation to treat tissue ischemia.