RESUMEN
OBJECTIVE: We hypothesized that aspirin may exhibit its anti-atherosclerotic effects via mechanisms other than cyclooxygenase inhibition in platelets. METHODS AND RESULTS: Using enhanced subtraction hybridization analysis, we found in human umbilical vein endothelial cells (HUVECs) that aspirin up-regulates the expression of aminopeptidase N (APN/CD13) mRNA and its surface protein levels in a dose-dependent manner. Enzymatic activity of APN/CD13 on HUVECs was increased approximately 1.5-fold by 1 mmol L(-1) of aspirin, and treatment with bestatin, an inhibitor for APN/CD13 metalloprotease activity, attenuated the enhanced activities of APN/CD13. Since activated thrombin receptor is reported to be inactivated by APN/CD13 in vitro, protective actions of aspirin on HUVECs by thrombin stimulation were examined, resulting in the suppression of endothelin-1 and reactive oxygen species productions in HUVECs. These inhibitory actions of aspirin were partially abrogated by bestatin. CONCLUSIONS: Aspirin may exert its anti-atherothrombotic effects in part via the inhibition of thrombin action by up-regulating APN/CD13 on endothelial cells.
Asunto(s)
Aspirina/farmacología , Antígenos CD13/biosíntesis , Endotelio Vascular/efectos de los fármacos , Fibrinolíticos/farmacología , Antígenos CD13/antagonistas & inhibidores , Antígenos CD13/genética , Antígenos CD13/fisiología , Células Cultivadas/efectos de los fármacos , Células Cultivadas/enzimología , Células Endoteliales/efectos de los fármacos , Células Endoteliales/enzimología , Endotelina-1/biosíntesis , Endotelina-1/genética , Endotelio Vascular/enzimología , Inducción Enzimática/efectos de los fármacos , Genes Reporteros , Humanos , Leucina/análogos & derivados , Leucina/farmacología , Inhibidores de Proteasas/farmacología , ARN Mensajero/biosíntesis , Especies Reactivas de Oxígeno/metabolismo , Técnica de Sustracción , Trombina/antagonistas & inhibidores , Trombina/farmacología , Transcripción Genética/efectos de los fármacos , Transfección , Venas UmbilicalesRESUMEN
Glucocorticoid (GC) excess often elicits serious adverse effects on the vascular system, such as hypertension and atherosclerosis, and effective prophylaxis for these complications is limited. We sought to reveal the mechanism underlying GC-induced vascular complications. Responses in forearm blood flow to reactive hyperemia in 20 GC-treated patients were significantly decreased to 43+/-8.9% (mean+/-SEM) from the values obtained before GC therapy (130+/-14%). An administration of vitamin C almost normalized blood flow responses. In human umbilical vein endothelial cells (HUVECs), production of hydrogen peroxide was increased up to 166.5+/-3.3% of control values by 10(-7) mol/L dexamethasone (DEX) treatment (P<0.01). Concomitant with DEX-induced hydrogen peroxide production, intracellular amounts of peroxynitrite significantly increased and those of nitric oxide (NO) decreased, respectively (P<0.01). Immunoblotting analysis using anti-nitrotyrosine antibody showed that peroxynitrite formation was increased in DEX-treated HUVECs. Using inhibitors against metabolic pathways for generation of reactive oxygen species (ROS), we identified that the major production sources of ROS by DEX treatment were mitochondrial electron transport chain, NAD(P)H oxidase, and xanthine oxidase. These findings suggest that GC excess causes overproduction of ROS and thereby perturbs NO availability in the vascular endothelium, leading to vascular complications in patients with GC excess.
Asunto(s)
Enfermedades Autoinmunes/fisiopatología , Endotelio Vascular/efectos de los fármacos , Endotelio Vascular/fisiopatología , Glucocorticoides/farmacología , Superóxidos/metabolismo , Tirosina/análogos & derivados , Adolescente , Adulto , Anciano , Antioxidantes/farmacología , Enfermedades Autoinmunes/tratamiento farmacológico , Células Cultivadas , Dexametasona/efectos adversos , Dexametasona/farmacología , Dexametasona/uso terapéutico , Transporte de Electrón/efectos de los fármacos , Endotelio Vascular/patología , Inhibidores Enzimáticos/farmacología , Femenino , Antebrazo/irrigación sanguínea , Glucocorticoides/efectos adversos , Glucocorticoides/uso terapéutico , Humanos , Peróxido de Hidrógeno/metabolismo , Masculino , Persona de Mediana Edad , Músculo Esquelético/irrigación sanguínea , Músculo Esquelético/química , Músculo Esquelético/patología , NADH NADPH Oxidorreductasas/metabolismo , NADPH Oxidasas , Óxido Nítrico/metabolismo , Donantes de Óxido Nítrico/farmacología , Ácido Peroxinitroso/metabolismo , Especies Reactivas de Oxígeno/antagonistas & inhibidores , Especies Reactivas de Oxígeno/metabolismo , Flujo Sanguíneo Regional/efectos de los fármacos , Tirosina/análisis , Vasodilatación/efectos de los fármacos , Xantina Oxidasa/metabolismoRESUMEN
BACKGROUND: Increased serum lipoprotein(a) [Lp(a)] is an independent risk factor for atherosclerosis. We previously reported that aspirin reduced Lp(a) production by cultured hepatocytes via the reduction of apolipoprotein(a) [apo(a)] gene transcription. METHODS: We evaluated both the effect of aspirin treatment (81 mg/day) on serum Lp(a) concentrations and the correlation between the degree of reduction in serum Lp(a) and the type of apo(a) isoform in 70 patients with coronary artery disease or cerebral infarction. RESULTS: Aspirin lowered serum Lp(a) concentrations to approximately 80% of the baseline values in patients with high Lp(a) concentrations (>300 mg/L). The percentage of decrease in serum Lp(a) was larger in patients with high Lp(a) than in patients with low Lp(a) (<300 mg/L), irrespective of apo(a) isoform size. The decreases in serum Lp(a) in high Lp(a) patients with both the high-molecular-weight and the low-molecular-weight isoforms were positively correlated with the baseline Lp(a) concentrations. CONCLUSIONS: Because the secretory efficiencies of apo(a) in the same isoform are likely to be similar, the difference in serum Lp(a) concentrations in patients having the same apo(a) isoform depends on the transcriptional activity of the apo(a) gene. These findings suggest that aspirin decreases serum Lp(a) concentrations via a decrease in apo(a) gene transcription more effectively in patients with high transcriptional activity of this gene.
Asunto(s)
Arteriosclerosis/metabolismo , Arteriosclerosis/prevención & control , Aspirina/uso terapéutico , Hipolipemiantes/uso terapéutico , Lipoproteína(a)/sangre , Arteriosclerosis/sangre , Infarto Cerebral/sangre , Infarto Cerebral/metabolismo , Infarto Cerebral/prevención & control , Enfermedad Coronaria/sangre , Enfermedad Coronaria/metabolismo , Enfermedad Coronaria/prevención & control , Femenino , Humanos , Masculino , Persona de Mediana Edad , Isoformas de ProteínasRESUMEN
Corticosteroid myopathy is a major clinical problem in patients undergoing chronic corticosteroid treatment and shows insidious and progressive muscle atrophy in proximal limbs. Although several mechanisms underlying the pathophysiology of muscle injury have been postulated, precise pathogenesis is still not clear. We evaluated the mitochondrial functions in patients receiving corticosteroids compared with those in healthy controls or patients not receiving corticosteroids. The serum levels and total production of lactate were investigated by an aerobic exercise test using a bicycle ergometer. Mitochondrial respiratory activities and oxidative damage in biopsied skeletal muscles were also studied. The results of aerobic exercise tests revealed a significant overproduction of lactate in patients treated with corticosteroids ( p < 0.005), which was positively correlated with total corticosteroid doses administered ( p < 0.0001). In these patients, mitochondrial enzyme activity in complex I was significantly decreased ( p < 0.05) and oxidative damage of biopsied skeletal muscle was remarkable both in mitochondrial and nuclear DNAs ( p < 0.001). The results suggest that chronic corticosteroid administration induces mitochondrial dysfunction and oxidative damage in skeletal muscles, which may be the pathogenesis, at least in part, of corticosteroid-induced myopathy.