RESUMEN
The aim of the study was to assess the protective effect of (-)-epigallocatechin gallate (EGCG), a flavonoid abundant in green tea, against ammonium metavanadate (AMV)-induced oxidative stress in male Wistar rats. Four groups of animals have been used, a control group and three test groups. In the first test group, AMV was intra-peritoneally (i.p) injected daily (5 mg/kg body weight for five consecutive days). The second test group of animals was also injected daily with EGCG (5 mg/kg body weight) during the same period. However, the third test group was i.p. injected with both AMV and EGCG (5 mg/kg body weight for five consecutive days). When given alone, AMV induced an oxidative stress evidenced by an increase of lipid peroxidation levels (expressed as TBARS concentration) in kidney. In these animals, activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) were significantly decreased, suggesting significant reduction of the antioxidant defense system at the cell level. Kidney histological sections, showed glomerular hypertrophy and tubular dilatation. In AMV-treated animals receiving EGCG, the oxidative stress was much less pronounced and activities of antioxidant enzymes were kept close to control values. Histopathological changes were less prominent. Our results confirm that green tea and other sources of flavonoids might confer a strong protection against ammonium metavanadate-induced oxidative stress.
Asunto(s)
Lesión Renal Aguda/prevención & control , Catequina/análogos & derivados , Intoxicación por Metales Pesados/fisiopatología , Riñón/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Sustancias Protectoras/uso terapéutico , Vanadio/envenenamiento , Lesión Renal Aguda/etiología , Lesión Renal Aguda/metabolismo , Lesión Renal Aguda/patología , Animales , Antioxidantes/administración & dosificación , Antioxidantes/efectos adversos , Antioxidantes/uso terapéutico , Catequina/administración & dosificación , Catequina/efectos adversos , Catequina/uso terapéutico , Intoxicación por Metales Pesados/etiología , Hipertrofia , Inyecciones Intraperitoneales , Riñón/metabolismo , Riñón/patología , Glomérulos Renales/efectos de los fármacos , Glomérulos Renales/metabolismo , Glomérulos Renales/patología , Túbulos Renales/efectos de los fármacos , Túbulos Renales/metabolismo , Túbulos Renales/patología , Peroxidación de Lípido/efectos de los fármacos , Masculino , Oxidorreductasas/antagonistas & inhibidores , Oxidorreductasas/metabolismo , Sustancias Protectoras/administración & dosificación , Sustancias Protectoras/efectos adversos , Ratas Wistar , Vanadatos/administración & dosificación , Vanadio/administración & dosificación , Vitamina A/agonistas , Vitamina A/antagonistas & inhibidores , Vitamina A/sangre , Vitamina E/agonistas , Vitamina E/antagonistas & inhibidores , Vitamina E/sangreRESUMEN
In vertebrates, the retinol (vitamin A) signaling pathway (RSP) controls the biosynthesis and catabolism of all-trans retinoic acid (atRA), which regulates transcription of genes essential for embryonic development. Chemicals that interfere with the RSP to cause abnormal intracellular levels of atRA are potential developmental toxicants. To assess chemicals for the ability to interfere with retinol signaling, we have developed a cell-based RARE (Retinoic Acid Response Element) reporter gene assay to identify RSP disruptors. To validate this assay in a quantitative high-throughput screening (qHTS) platform, we screened the Library of Pharmacologically Active Compounds (LOPAC) in both agonist and antagonist modes. The screens detected known RSP agonists, demonstrating assay reliability, and also identified novel RSP agonists including kenpaullone, niclosamide, PD98059 and SU4312, and RSP antagonists including Bay 11-7085, LY294002, 3,4-Methylenedioxy-ß-nitrostyrene, and topoisomerase inhibitors (camptothecin, topotecan, amsacrine hydrochloride, and idarubicin). When evaluated in the P19 pluripotent cell, these compounds were found to affect the expression of the Hoxa1 gene that is essential for embryo body patterning. These results show that the RARE assay is an effective qHTS approach for screening large compound libraries to identify chemicals that have the potential to adversely affect embryonic development through interference with retinol signaling.
Asunto(s)
Ensayos Analíticos de Alto Rendimiento , Vitamina A/metabolismo , Animales , Línea Celular , Genes Reporteros , Luciferasas/genética , Ratones , Elementos de Respuesta , Transducción de Señal , Vitamina A/agonistas , Vitamina A/antagonistas & inhibidoresRESUMEN
Foreign CpG-DNA from viruses and bacteria can activate memory B cells through binding to toll-like receptor 9, and this pathway has been hypothesized to be involved in the continuous activation of memory B cells ensuring life-long humoral immunity. In this study, we demonstrate that retinoic acid (RA) is a potent coactivator of this pathway in human B cells. RA enhanced the CpG-mediated proliferation of CD27(+) memory B cells, and the proliferative response was accompanied by increased immunoglobulin (Ig) secretion indicative of plasma-cell formation. The RA-induced proliferation was preceded by enhanced expression of cyclin D3, and both the expression of cyclin D3 and the induced Ig secretion were found to be dependent on IL-10. Of importance, RA increased the CpG-induced phosphorylation of ERK1/2, p38MAPK, and IkappaB as early as 30 minutes after stimulation. By using specific inhibitors, all the RA-mediated events, including proliferation, cyclin D3 expression, IL-10 secretion, and Ig secretion, were shown to be dependent on p38MAPK. Hence, we propose that RA can strengthen humoral immunity by promoting CpG-mediated stimulation of CD27(+) B cells via activation of p38MAPK resulting in increased proliferation and differentiation to Ig-secreting plasma cells.
Asunto(s)
Adyuvantes Inmunológicos/farmacología , Diferenciación Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Memoria Inmunológica/efectos de los fármacos , Oligodesoxirribonucleótidos/farmacología , Células Plasmáticas/inmunología , Vitamina A/farmacología , Vitaminas/farmacología , Adyuvantes Inmunológicos/agonistas , Formación de Anticuerpos/efectos de los fármacos , Formación de Anticuerpos/inmunología , Diferenciación Celular/inmunología , Células Cultivadas , Ciclina D3 , Ciclinas/inmunología , Sinergismo Farmacológico , Activación Enzimática/efectos de los fármacos , Activación Enzimática/inmunología , Humanos , Proteínas I-kappa B/inmunología , Memoria Inmunológica/inmunología , Interleucina-10/inmunología , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Sistema de Señalización de MAP Quinasas/inmunología , Proteína Quinasa 1 Activada por Mitógenos/inmunología , Proteína Quinasa 3 Activada por Mitógenos/inmunología , Oligodesoxirribonucleótidos/agonistas , Células Plasmáticas/citología , Factores de Tiempo , Vitamina A/agonistas , Vitaminas/agonistas , Proteínas Quinasas p38 Activadas por Mitógenos/inmunologíaAsunto(s)
Queratolíticos/uso terapéutico , Alveolos Pulmonares/efectos de los fármacos , Enfisema Pulmonar/tratamiento farmacológico , Tretinoina/uso terapéutico , Animales , Modelos Animales de Enfermedad , Humanos , Estructura Molecular , Elastasa Pancreática/metabolismo , Alveolos Pulmonares/metabolismo , Alveolos Pulmonares/patología , Enfisema Pulmonar/metabolismo , Enfisema Pulmonar/patología , Pruebas de Función Respiratoria , Vitamina A/agonistas , Vitamina A/metabolismo , Vitamina A/uso terapéuticoRESUMEN
Numerous epidemiological studies support a strong inverse relationship between consumption of carotenoid-rich fruits and vegetables and the incidence of some degenerative diseases. One proposed mechanism of protection by carotenoids centers on their putative antioxidant activity, although direct evidence in support of this contention is limited at the cellular level. The antioxidant potential of beta-carotene (BC) and lutein (LUT), carotenoids with or without provitamin A activity, respectively, was evaluated using the human liver cell line HepG2. Pilot studies showed that a 90-min exposure of confluent cultures to 500 mumol/L tert-butylhydroperoxide (TBHP) at 37 degrees C significantly (P < 0.05) increased lipid peroxidation and cellular leakage of lactate dehydrogenase (LDH), and decreased the uptake of 3H-alpha-aminoisobutyric acid and 3H-2-deoxyglucose. Protein synthesis, mitochondrial activity and glucose oxidation were not affected by TBHP treatment, suggesting that the plasma membrane was the primary site of TBHP-induced damage. Overnight incubation of cultures with > or = 1 mumol/L dl-alpha-tocopherol protected cells against oxidant-induced changes. In parallel studies, overnight incubation of HepG2 in medium containing micelles with either BC or LUT (final concentrations of 1.1 and 10.9 mumol/L, respectively), the cell content of the carotenoids increased from < 0.04 to 0.32 and 3.39 nmol/mg protein, respectively. Carotenoid-loaded cells were partially or completely protected against oxidant-induced changes in lipid peroxidation, LDH release and amino acid and deoxyglucose transport. These data demonstrate that BC and LUT or their metabolites protect HepG2 cells against oxidant-induced damage and that the protective effect is independent of provitamin A activity.