RESUMEN
AIMS: Aldosterone plays a crucial role in cardiovascular disease. 'Systemic' inhibition of its mineralocorticoid receptor (MR) decreases atherosclerosis by reducing inflammation and oxidative stress. Obesity, an important cardiovascular risk factor, is an inflammatory disease associated with increased plasma aldosterone levels. We have investigated the role of the 'endothelial' MR in obesity-induced endothelial dysfunction, the earliest stage in atherogenesis. METHODS AND RESULTS: C57BL/6 mice were exposed to a normal chow diet (ND) or a high-fat diet (HFD) alone or in combination with the MR antagonist eplerenone (200 mg/kg/day) for 14 weeks. Diet-induced obesity impaired endothelium-dependent relaxation in response to acetylcholine, whereas eplerenone treatment of obese mice prevented this. Expression analyses in aortic endothelial cells isolated from these mice revealed that eplerenone attenuated expression of pro-oxidative NADPH oxidase (subunits p22phox, p40phox) and increased expression of antioxidative genes (glutathione peroxidase-1, superoxide dismutase-1 and -3) in obesity. Eplerenone did not affect obesity-induced upregulation of cyclooxygenase (COX)-1 or prostacyclin synthase. Endothelial-specific MR deletion prevented endothelial dysfunction in obese (exhibiting high 'endogenous' aldosterone) and in 'exogenous' aldosterone-infused lean mice. Pre-incubation of aortic rings from aldosterone-treated animals with the COX-inhibitor indomethacin restored endothelial function. Exogenous aldosterone administration induced endothelial expression of p22phox in the presence, but not in the absence of the endothelial MR. CONCLUSION: Obesity-induced endothelial dysfunction depends on the 'endothelial' MR and is mediated by an imbalance of oxidative stress-modulating mechanisms. Therefore, MR antagonists may represent an attractive therapeutic strategy in the increasing population of obese patients to decrease vascular dysfunction and subsequent atherosclerotic complications.
Asunto(s)
Dieta Alta en Grasa/efectos adversos , Endotelio Vascular/efectos de los fármacos , Antagonistas de Receptores de Mineralocorticoides/farmacología , Obesidad/etiología , Receptores de Mineralocorticoides/fisiología , Espironolactona/análogos & derivados , Tejido Adiposo/efectos de los fármacos , Aldosterona/metabolismo , Animales , Antioxidantes/metabolismo , Aorta/efectos de los fármacos , Ciclooxigenasa 1/metabolismo , Inhibidores de la Ciclooxigenasa/farmacología , Sistema Enzimático del Citocromo P-450/metabolismo , Eplerenona , Glutatión Peroxidasa/metabolismo , Hiperglucemia/tratamiento farmacológico , Inflamación/tratamiento farmacológico , Oxidorreductasas Intramoleculares/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Obesidad/fisiopatología , Estrés Oxidativo/efectos de los fármacos , Espironolactona/farmacología , Superóxido Dismutasa/metabolismo , Superóxido Dismutasa-1 , Regulación hacia Arriba , Glutatión Peroxidasa GPX1RESUMEN
AIMS: Epidemiological studies report an inverse association between plant-derived dietary α-linolenic acid (ALA) and cardiovascular events. However, little is known about the mechanism of this protection. We assessed the cellular and molecular mechanisms of dietary ALA (flaxseed) on atherosclerosis in a mouse model. METHODS AND RESULTS: Eight-week-old male apolipoprotein E knockout (ApoE(-/-)) mice were fed a 0.21 % (w/w) cholesterol diet for 16 weeks containing either a high ALA [7.3 % (w/w); n = 10] or low ALA content [0.03 % (w/w); n = 10]. Bioavailability, chain elongation, and fatty acid metabolism were measured by gas chromatography of tissue lysates and urine. Plaques were assessed using immunohistochemistry. T cell proliferation was investigated in primary murine CD3-positive lymphocytes. T cell differentiation and activation was assessed by expression analyses of interferon-γ, interleukin-4, and tumour necrosis factor α (TNFα) using quantitative PCR and ELISA. Dietary ALA increased aortic tissue levels of ALA as well as of the n-3 long chain fatty acids (LC n-3 FA) eicosapentaenoic acid, docosapentaenoic acid, and docosahexaenoic acid. The high ALA diet reduced plaque area by 50% and decreased plaque T cell content as well as expression of vascular cell adhesion molecule-1 and TNFα. Both dietary ALA and direct ALA exposure restricted T cell proliferation, differentiation, and inflammatory activity. Dietary ALA shifted prostaglandin and isoprostane formation towards 3-series compounds, potentially contributing to the atheroprotective effects of ALA. CONCLUSION: Dietary ALA diminishes experimental atherogenesis and restricts T cell-driven inflammation, thus providing the proof-of-principle that plant-derived ALA may provide a valuable alternative to marine LC n-3 FA.
Asunto(s)
Aterosclerosis/dietoterapia , Linfocitos T/inmunología , Ácido alfa-Linolénico/administración & dosificación , Animales , Aterosclerosis/inmunología , Aterosclerosis/prevención & control , Diferenciación Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Activación de Linfocitos/efectos de los fármacos , Masculino , Ratones , Ratones Noqueados , Placa Aterosclerótica/dietoterapia , Placa Aterosclerótica/inmunología , Placa Aterosclerótica/prevención & control , Linfocitos T/patología , Ácido alfa-Linolénico/farmacologíaRESUMEN
Excessive production of reactive oxygen species (ROS) contributes to progression of atherosclerosis, at least in part by causing endothelial dysfunction and inflammatory activation. The class III histone deacetylase SIRT1 has been implicated in extension of lifespan. In the vasculature,SIRT1 gain-of-function using SIRT1 overexpression or activation has been shown to improve endothelial function in mice and rats via stimulation of endothelial nitric oxide (NO) synthase (eNOS). However, the effects of SIRT1 loss-of-function on the endothelium in atherosclerosis remain to be characterized. Thus, we have investigated the endothelial effects of decreased endogenous SIRT1 in hypercholesterolemic ApoE-/- mice. We observed no difference in endothelial relaxation and eNOS (Ser1177) phosphorylation between 20-week old male atherosclerotic ApoE-/- SIRT1+/- and ApoE-/- SIRT1+/+ mice. However, SIRT1 prevented endothelial superoxide production, inhibited NF-kappaB signaling, and diminished expression of adhesion molecules. Treatment of young hypercholesterolemic ApoE-/- SIRT1+/- mice with lipopolysaccharide to boost NF-kappaB signaling led to a more pronounced endothelial expression of ICAM-1 and VCAM-1 as compared to ApoE-/- SIRT1+/+ mice. In conclusion, endogenous SIRT1 diminishes endothelial activation in ApoE-/- mice, but does not affect endothelium-dependent vasodilatation.
Asunto(s)
Aterosclerosis/metabolismo , Células Endoteliales/metabolismo , Sirtuina 1/metabolismo , Animales , Apolipoproteínas E/deficiencia , Apolipoproteínas E/genética , Aterosclerosis/etiología , Espectroscopía de Resonancia por Spin del Electrón , Activación Enzimática/fisiología , Técnica del Anticuerpo Fluorescente , Expresión Génica , Humanos , Hipercolesterolemia/complicaciones , Hipercolesterolemia/metabolismo , Inmunohistoquímica , Inmunoprecipitación , Inflamación/metabolismo , Molécula 1 de Adhesión Intercelular/metabolismo , Masculino , Ratones , Ratones Noqueados , Óxido Nítrico Sintasa de Tipo III/metabolismo , ARN Interferente Pequeño , Transfección , Molécula 1 de Adhesión Celular Vascular/metabolismo , Vasodilatación/fisiologíaRESUMEN
AIMS: Endothelial activation, macrophage infiltration, and foam cell formation are pivotal steps in atherogenesis. Our aim in this study was to analyse the role of SIRT1, a class III deacetylase with important metabolic functions, in plaque macrophages and atherogenesis. METHODS AND RESULTS: Using partial SIRT1 deletion in atherosclerotic mice, we demonstrate that SIRT1 protects against atherosclerosis by reducing macrophage foam cell formation. Peritoneal macrophages from heterozygous SIRT1 mice accumulate more oxidized low-density lipoprotein (oxLDL), thereby promoting foam cell formation. Bone marrow-restricted SIRT1 deletion confirmed that SIRT1 function in macrophages is sufficient to decrease atherogenesis. Moreover, we show that SIRT1 reduces the uptake of oxLDL by diminishing the expression of lectin-like oxLDL receptor-1 (Lox-1) via suppression of the NF-κB signalling pathway. CONCLUSION: Our findings demonstrate protective effects of SIRT1 in atherogenesis and suggest pharmacological SIRT1 activation as a novel anti-atherosclerotic strategy by reducing macrophage foam cell formation.
Asunto(s)
Aterosclerosis/etiología , Células Espumosas/patología , Receptores Depuradores de Clase E/fisiología , Sirtuina 1/fisiología , Animales , Aterosclerosis/prevención & control , Trasplante de Médula Ósea , Diferenciación Celular/fisiología , Células Cultivadas , Colesterol/metabolismo , Eliminación de Gen , Hipercolesterolemia/metabolismo , Hipercolesterolemia/patología , Lipoproteínas/metabolismo , Lipoproteínas LDL/metabolismo , Macrófagos Peritoneales/fisiología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Sirtuina 1/genéticaRESUMEN
OBJECTIVE: Atherosclerosis is a chronic inflammatory disease of major conduit arteries. Similarly, obesity and type 2 diabetes mellitus are associated with accumulation of macrophages in visceral white adipose tissue and pancreatic islets. Our goal was to characterize systemic inflammation in atherosclerosis with hypercholesterolemia, but without obesity. METHODS AND RESULTS: We compared 22-week-old apolipoprotein E knockout (ApoE(-/-)) with wild-type mice kept for 14 weeks on a high cholesterol (1.25%) diet (CD, n=8) and 8-week-old ApoE(-/-) with wild-type mice kept on a normal diet (ND, n=8). Hypercholesterolemic, atherosclerotic ApoE(-/-) mice on CD exhibited increased macrophages and T-cells in plaques and periadventitial adipose tissue that revealed elevated expression of MIP-1alpha, IL-1beta, IL-1 receptor, and IL-6. Mesenteric adipose tissue and pancreatic islets in ApoE(-/-) mice showed increased macrophages. Expression of IL-1beta was enhanced in mesenteric adipose tissue of ApoE(-/-) mice on CD. Furthermore, these mice exhibited steatohepatitis with macrophage and T-cell infiltrations as well as increased MIP-1alpha and IL-1 receptor expression. Blood glucose, insulin and total body weight did not differ between the groups. CONCLUSIONS: In hypercholesterolemic lean ApoE(-/-) mice, inflammation extends beyond atherosclerotic plaques to the periadventitial and visceral adipose tissue, liver, and pancreatic islets without affecting glucose homeostasis.
Asunto(s)
Aterosclerosis/inmunología , Tejido Conectivo/inmunología , Hipercolesterolemia/complicaciones , Inflamación/inmunología , Grasa Intraabdominal/inmunología , Islotes Pancreáticos/inmunología , Hígado/inmunología , Animales , Apolipoproteínas E/deficiencia , Apolipoproteínas E/genética , Aterosclerosis/genética , Aterosclerosis/patología , Glucemia/metabolismo , Peso Corporal , Tejido Conectivo/patología , Citocinas/sangre , Modelos Animales de Enfermedad , Hígado Graso/inmunología , Hígado Graso/patología , Hipercolesterolemia/genética , Hipercolesterolemia/inmunología , Hipercolesterolemia/patología , Inflamación/genética , Inflamación/patología , Mediadores de Inflamación/sangre , Insulina/sangre , Grasa Intraabdominal/patología , Islotes Pancreáticos/patología , Hígado/patología , Macrófagos/inmunología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Linfocitos T/inmunologíaRESUMEN
BACKGROUND: Subacute stent thrombosis is a major clinical concern, and the search for new molecules to cover stents remains important. Dimethyl sulfoxide (DMSO) is used for preservation of hematopoietic progenitor cells and is infused into patients undergoing bone marrow transplantation. Despite its intravenous application, the impact of DMSO on vascular cells has not been assessed. METHODS AND RESULTS: In human endothelial cells, monocytes, and vascular smooth muscle cells (VSMC), DMSO inhibited tissue factor (TF) expression and activity in response to tumor necrosis factor-alpha or thrombin in a concentration-dependent manner. DMSO did not exert any toxic effects as assessed by phase-contrast microscopy, trypan blue exclusion, and lactate dehydrogenase release. Real-time polymerase chain reaction revealed that inhibition of TF expression occurred at the mRNA level. This effect was mediated by reduced activation of the mitogen-activated protein kinases c-Jun terminal NH2 kinase (51+/-6%; P=0.0005) and p38 (50+/-3%; P<0.0001) but not p44/42 (P=NS). In contrast to TF, DMSO did not affect expression of TF pathway inhibitor or plasminogen activator inhibitor-1. In vivo, DMSO treatment suppressed TF activity (41%; P<0.002) and prevented thrombotic occlusion in a mouse carotid artery photochemical injury model. DMSO also inhibited VSMC proliferation (70%; P=0.005) and migration (77%; P=0.0001) in a concentration-dependent manner; moreover, it prevented rapamycin and paclitaxel-induced upregulation of TF expression. CONCLUSIONS: DMSO suppresses TF expression and activity, as well as thrombus formation; in addition, it inhibits VSMC proliferation and migration. Given its routine use in modern clinical practice, we propose DMSO as a novel strategy for coating drug-eluting stents and treating acute coronary syndromes.