RESUMEN
BACKGROUND: Adipocytes behave like a rich source of pro-inflammatory cytokines including monocyte chemoattractant protein-1 (MCP-1). Oxidized low-density lipoprotein (oxLDL) participates in the local chronic inflammatory response, and high-density lipoprotein could counterbalance the proinflammatory function of oxLDL, but the underlying mechanism is not completely understood. This study aimed to evaluate the effect of apolipoprotein A-I mimetic peptide L-4F on the secretion and expression of MCP-1 in fully differentiated 3T3-L1 adipocytes induced by oxLDL and to elucidate the possible mechanisms. METHODS: Fully differentiated 3T3-L1 adipocytes were incubated in the medium containing various concentration of L-4F (0-50 µg/ml) with oxLDL (50 µg/ml) stimulated, with/without protein kinase A (PKA) inhibitor H-89 (10 µmol/L) preincubated. The concentrations of MCP-1 in the supernatant, the mRNA expression of MCP-1, the levels of CCAAT/enhancer binding protein α (C/EBPα), and CCAAT/enhancer binding protein ß (C/EBPß) were evaluated. The monocyte chemotaxis assay was performed by micropore filter method using a modified Boyden chamber. RESULTS: OxLDL stimulation induced a significant increase of MCP-1 expression and secretion in 3T3-L1 adipocytes, which were inhibited by L-4F preincubation in a dose-dependent manner. PKA inhibitor H-89 markedly reduced the oxLDL-induced MCP-1 expression, but no further decrease was observed when H-89 was used in combination with L-4F (50 µg/ml) (P > 0.05). OxLDL stimulation showed no significant effect on C/EBPα protein level but increased C/EBPß protein level in a time-dependent manner. H-89 and L-4F both attenuated C/EBPß protein level in oxLDL-induced 3T3-L1 adipocytes. CONCLUSIONS: OxLDL induces C/EBPß protein synthesis in a time-dependent manner and enhances MCP-1 secretion and expression in 3T3-L1 adipocytes. L-4F dose-dependently counterbalances the pro-inflammatory effect of oxLDL, and cyclic AMP/PKA-C/EBPß signaling pathway may participate in it.
Asunto(s)
Proteína beta Potenciadora de Unión a CCAAT/fisiología , Quimiocina CCL2/metabolismo , Proteínas Quinasas Dependientes de AMP Cíclico/fisiología , AMP Cíclico/fisiología , Lipoproteínas LDL/antagonistas & inhibidores , Péptidos/farmacología , Transducción de Señal/fisiología , Células 3T3-L1 , Animales , Proteína beta Potenciadora de Unión a CCAAT/análisis , Quimiocina CCL2/genética , Humanos , Lipoproteínas LDL/farmacología , RatonesRESUMEN
BACKGROUND: Growing epidemiologic evidence has indicated that genetics can predispose individuals to the occurrence of lone atrial fibrillation (AF). The angiotensin-converting enzyme 2 (ACE2) gene has been established to be associated with hypertension and left ventricular hypertrophy. The objective of our study was to investigate the association of ACE2 gene polymorphisms with lone AF. METHODS: A total of 265 consecutive lone AF patients and 289 healthy controls were successfully investigated. The polymorphisms rs2106809 and rs2285666 were genotyped by polymerase chain reaction (PCR) and direct sequencing. A Logistic regression model was used to determine the odds ratio (OR) and 95% confidence intervals (CI) of variations of ACE2 for lone AF. RESULTS: The T allele of rs2106809 conferred an increased risk for lone AF (OR 1.24, 95% CI 1.01-1.52, P = 0.03) in males after adjustment for conventional risk factors. SNP at rs2285666 in males was not significantly different between AF patients and controls. No association was found between the two polymorphisms in the female population with lone AF. After (36.3 ± 4.5) months of follow-up, the end point data were obtained: death (cardiac and noncardiac), ischemic stroke, and heart failure. In the male subgroup, the associations between rs2106809 T male carriers and combined end points including ischemic stroke, heart failure, and death in our study were of significance (OR 3.6, 95% CI 1.0-13.1, P = 0.04). CONCLUSIONS: The results indicate that polymorphism at ACE2 gene is associated with male lone AF in a Chinese Han population. Lone AF males who carry the rs2106809 T allele are associated with adverse cardiac events.
Asunto(s)
Fibrilación Atrial/genética , Peptidil-Dipeptidasa A/genética , Polimorfismo Genético/genética , Anciano , Enzima Convertidora de Angiotensina 2 , Pueblo Asiatico/genética , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Masculino , Persona de Mediana EdadRESUMEN
Curcumin affects the functions of adipocytes. But it is not known whether curcumin has some effect on the cholesterol efflux process of adipocytes. Rabbit subcutaneous adipocytes were incubated with 5, 10 and 20 µg/ml curcumin for 24 h. The cholesterol efflux onto apoAI was assessed, and the peroxisome proliferators-activated receptor (PPAR) γ, liver X receptor (LXR) α and ATP-binding cassette transporter A1 (ABCA1) mRNA expression in adipocytes were quantified by reverse-transcription polymerase chain reaction (RT-PCR). Curcumin increased the cholesterol efflux from adipocytes in dose-dependent manner. The increased expression of PPARγ, LXRα and ABCA1 caused by curcumin were parallel. When the adipocytes were pre-treated by GW9662, the increased expression of PPARγ induced by curcumin was partially prevented, subsequent to the down-regulation of LXRα and ABCA1. Curcumin can affect the cholesterol efflux from adipocytes by regulating the PPARγ-LXR-ABCA1 passway.
Asunto(s)
Transportadoras de Casetes de Unión a ATP/metabolismo , Adipocitos/efectos de los fármacos , Colesterol/metabolismo , Curcumina/farmacología , Receptores Nucleares Huérfanos/metabolismo , PPAR gamma/metabolismo , Transducción de Señal/efectos de los fármacos , Transportador 1 de Casete de Unión a ATP , Transportadoras de Casetes de Unión a ATP/genética , Adipocitos/metabolismo , Animales , Regulación de la Expresión Génica/efectos de los fármacos , Receptores X del Hígado , Receptores Nucleares Huérfanos/genética , PPAR gamma/genética , Conejos , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Tejido Subcutáneo/metabolismoRESUMEN
BACKGROUND: The adipocyte has been proven to recognize and degrade oxidized low-density lipoprotein (oxLDL), while cholesterol efflux from adipocytes to clear excess cholesterol loaded by oxLDL is essential to maintain its normal function. Thus, it is intriguing to explore the effects of oxLDL on cholesterol efflux in adipocytes. METHODS: Fully differentiated 3T3-L1 cells were incubated in the medium containing various concentrations of oxLDL (0 to 50 microg/mL) for 8 or 24 h. 10 micromol/L 22(R)-hydroxycholesterol was exposed to preconditioned adipocytes with 25 microg/mL oxLDL for 24 h. Reverse transcription polymerase chain reaction (RT-PCR) was used to evaluate adipocytes mRNA expression. Cholesterol efflux rate was determined through measuring release of radioactivity from (3)H-cholesterol prelabeled cells into medium containing apolipoprotein A-I (apoA-I). RESULTS: Low concentrations of oxLDL caused a significant increase in apoA-I-mediated cholesterol efflux via enhancement of ATP binding cassette transporter A1 (ABCA1) pathway, whereas higher concentrations were incapable. In adipocytes preincubated with 25 microg/mL oxLDL for 24 h, 22(R)-hydroxycholesterol could increase ABCA1 and LXR* mRNA levels and apoA-I-mediated cholesterol efflux. CONCLUSION: OxLDL has dual effects on ABCA1 pathway in adipocytes. It depends on the concentration and exposure time. The new action of low levels of oxLDL may provide further understanding to its atheroprotective effects.
Asunto(s)
Adipocitos/metabolismo , Colesterol/metabolismo , Lipoproteínas LDL/farmacología , Células 3T3-L1 , Adipocitos/efectos de los fármacos , Animales , Apolipoproteína A-I/metabolismo , Hidroxicolesteroles/farmacología , Metabolismo de los Lípidos , Ratones , Oxidación-Reducción , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Regulación hacia ArribaRESUMEN
OBJECTIVE: To explore whether oxidized low-density lipoprotein (ox-LDL) can stimulate the cholesterol efflux in fully differentiated 3T3-L1 cells and the possible mechanism. METHODS: Fully differentiated 3T3-L1 cells were incubated in the medium containing various concentrations of ox-LDL ( 0 to 50 microg/mL) for 8 or 24 hours. 22(R)-Hydroxycholesterol (10 micromol/L) was exposed to preconditioned adipocytes with 25 microg/mL ox-LDL for 24 hours. Reverse transcription polymerase chain reaction (RT-PCR) was used to evaluate ATP binding cassette transporter A1 (ABCA1), scavenger receptor class B type I (SR-BI), and liver X receptor alpha (LXRalpha) mRNA expression. Cholesterol efflux mediated by apolipoprotein A-I (apoA-I) was determined using liquid scintillator. RESULTS: Low levels (12.5-25 microg/mL) of ox-LDL could increase cholesterol efflux via the enhancement of ABCA1 pathway and SR-BI expression, whereas the higher concentration (50 microg/mL) could not. In adipocytes preincubated with 25 microg/mL ox-LDL for 24 hours, 22(R)-hydroxycholesterol could increase ABCA1 and LXRalpha mRNA and apoA-I-mediated cholesterol efflux, but had no effect on the SR-BI mRNA expression. CONCLUSION: Low levels of ox-LDL may enhance the LXRalpha-ABCA1-apoA-I pathway in adipocytes, up-regulate SR-BI mRNA expression, and then increase the cholesterol efflux. This new effect of ox-LDL will not only make contribution to cholesterol homeostasis in adipocytes, but also be potentially atheroprotective.
Asunto(s)
Adipocitos/metabolismo , Colesterol/metabolismo , Lipoproteínas LDL/farmacología , Células 3T3-L1 , Transportador 1 de Casete de Unión a ATP/metabolismo , Adipocitos/efectos de los fármacos , Animales , Metabolismo de los Lípidos , Receptores X del Hígado , Ratones , Receptores Nucleares Huérfanos/metabolismo , Receptores Depuradores de Clase B/metabolismoRESUMEN
BACKGROUND: Human hepatic lipase (HL) is a glycoprotein that catalyzes the hydrolysis of triglycerides and phospholipids in all major classes of lipoproteins. We studied whether the hepatic lipase gene -250G(guanine)-->A(adenine) polymorphism affect blood lipids level and the coronary heart disease. METHODS: Two hundred and thirty subjects were included. Among them there were 122 patients with coronary heart disease and 108 subjects without coronary heart disease. Polymerase chain reaction-restricted fragments length polymorphism was used to determine HL genotype. RESULTS: The serum HDL-C level of HL-250A heterozygote (carriers of GA genotype) and homozygote (carriers of AA genotype) [(1.32+/-0.35) mmol/l] was significantly higher than wild type [carriers of GG genotype, (1.19+/-0.30) mmol/l, P<0.005]. This effect to blood lipids appears more evident in women (P<0.005). But the distribution of the 3 genotypes of HL-250 among the patients with coronary heart disease (GG54.1%, GA37.7%, AA8.2%) were similar with those of the control (GG54.6%, GA37.0%, AA8.4%, P>0.05). Both the male and the female had similar ratio for 3 HL genotypes. CONCLUSIONS: HL-250G-->A variation affects blood lipids profile and results in the increasing of the serum HDL-C level. This beneficial effect to blood lipids profile is more obviously seen in the female.