RESUMEN
BACKGROUND: Insufficient information is available on the relationship between obesity and outcome of paediatric patients with acute pancreatitis. OBJECTIVES: This study aimed to investigate the effect of obesity on outcomes of paediatric patients with acute pancreatitis based on a national administrative database. METHODS: A total of 500 cases in 416 paediatric patients with acute pancreatitis (aged 5-17 years) were referred from 260 hospitals between 2010 and 2012 in Japan. Patients were divided into two groups according to the presence of obesity: with obesity (n = 65) and without obesity (n = 435). Patient data were collected from the administrative database to compare the prevalence of severe acute pancreatitis, in-hospital mortality, length of stay (LOS) and medical costs between the groups. RESULTS: Both prevalence of severe acute pancreatitis and in-hospital mortality were significantly higher in paediatric patients with obesity than those without (36.9% vs. 16.3% and 3.1% vs. 0.0%; P < 0.001, respectively). Longer LOS and higher medical costs were also observed in paediatric patients with obesity (25.7 vs. 15.2 days, P < 0.001 and 14 169.5 vs. 7457.7 US dollars, P < 0.001, respectively). CONCLUSION: This study demonstrated that obesity significantly influenced the outcomes of paediatric acute pancreatitis.
Asunto(s)
Obesidad/complicaciones , Pancreatitis/epidemiología , Enfermedad Aguda , Adolescente , Niño , Preescolar , Bases de Datos Factuales , Femenino , Mortalidad Hospitalaria , Humanos , Japón/epidemiología , Tiempo de Internación , Masculino , Pancreatitis/mortalidad , PronósticoRESUMEN
Oxidized LDL can induce an increase in intracellular calcium concentration and the activation of protein kinase C in mouse peritoneal macrophages. The activation of protein kinase C leads to the release into the culture medium of granulocyte-macrophage colony-stimulating factor, which plays a priming role in oxidized LDL-induced macrophage proliferation. The expression of granulocyte-macrophage colony-stimulating factor in macrophages by oxidized LDL is positively regulated in the 5'-flanking region of granulocyte-macrophage colony-stimulating factor gene from sequence -169 to -160, but negatively regulated from -91 to -82. Granulocyte-macrophage colony-stimulating factor released by oxidized LDL from macrophages induces proliferation in autocrine or paracrine fashion via the activation of phosphatidylinositol 3-kinase. The capacity of oxidized LDL to induce macrophage proliferation in vitro may be involved in the enhanced progression of atherosclerosis in vivo.
Asunto(s)
Arteriosclerosis/patología , Macrófagos/patología , Animales , Arteriosclerosis/etiología , Arteriosclerosis/metabolismo , Calcio/metabolismo , División Celular/efectos de los fármacos , Factor Estimulante de Colonias de Granulocitos y Macrófagos/genética , Factor Estimulante de Colonias de Granulocitos y Macrófagos/metabolismo , Humanos , Técnicas In Vitro , Lipoproteínas LDL/metabolismo , Lipoproteínas LDL/farmacología , Macrófagos/efectos de los fármacos , Macrófagos/metabolismo , Ratones , Fosfolipasas A/metabolismo , Proteína Quinasa C/metabolismo , Receptores Inmunológicos/metabolismo , Receptores Depuradores , Transducción de SeñalRESUMEN
Oxidized low density lipoprotein (Ox-LDL) can induce macrophage proliferation in vitro. To explore the mechanisms involved in this process, we reported that activation of protein kinase C (PKC) is involved in its signaling pathway (Matsumura, T., Sakai, M., Kobori, S., Biwa, T., Takemura, T., Matsuda, H., Hakamata, H., Horiuchi, S., and Shichiri, M. (1997) Arterioscler. Thromb. Vasc. Biol. 17, 3013-3020) and that expression of granulocyte/macrophage colony-stimulating factor (GM-CSF) and its subsequent release in the culture medium are important (Biwa, T., Hakamata, H., Sakai, M., Miyazaki, A., Suzuki, H., Kodama, T., Shichiri, M., and Horiuchi, S. (1998) J. Biol. Chem. 273, 28305-28313). However, a recent study also demonstrated the involvement of phosphatidylinositol 3-kinase (PI3K) in this process. In the present study, we investigated the role of PKC and PI3K in Ox-LDL-induced macrophage proliferation. Ox-LDL-induced macrophage proliferation was inhibited by 90% by a PKC inhibitor, calphostin C, and 50% by a PI3K inhibitor, wortmannin. Ox-LDL-induced expression of GM-CSF and its subsequent release were inhibited by calphostin C but not by wortmannin, whereas recombinant GM-CSF-induced macrophage proliferation was inhibited by wortmannin by 50% but not by calphostin C. Ox-LDL activated PI3K at two time points (10 min and 4 h), and the activation at the second but not first point was significantly inhibited by calphostin C and anti-GM-CSF antibody. Our results suggest that PKC plays a role upstream in the signaling pathway to GM-CSF induction, whereas PI3K is involved, at least in part, downstream in the signaling pathway after GM-CSF induction.
Asunto(s)
Lipoproteínas LDL/metabolismo , Macrófagos/enzimología , Fosfatidilinositol 3-Quinasas/química , Proteína Quinasa C/química , Androstadienos/farmacología , Animales , Sitios de Unión , División Celular , Células Cultivadas , Relación Dosis-Respuesta a Droga , Inhibidores Enzimáticos/farmacología , Ensayo de Inmunoadsorción Enzimática , Factor Estimulante de Colonias de Granulocitos y Macrófagos/metabolismo , Humanos , Masculino , Ratones , Ratones Endogámicos C3H , Modelos Biológicos , Naftalenos/farmacología , Pruebas de Precipitina , ARN Mensajero/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Timidina/metabolismo , Factores de Tiempo , WortmaninaRESUMEN
Cerivastatin sodium a synthetic and pure enantiomeric 3-hydroxy-3-methylglutaril-coenzyme A (HMG-CoA) reductase inhibitor, is considered effective in the treatment of mild-to-moderate primary hypercholesterolemia (total cholesterol < or = 220-259 mg/dL) at a daily dose of 0.15 mg. We compared the efficacy and tolerability of a dosage of 0.3 mg/d with those of a dosage of 0.15 mg/d in patients with severe primary hypercholesterolemia (serum total cholesterol > or = 260 mg/dL). After a minimum of 4 week's lead-in with placebo, 73 patients with severe primary hypercholesterolemia were randomly assigned to receive either 0.15 or 0.3 mg of cerivastatin sodium once daily after the evening meal for 12 weeks. In 58 patients, the same drug was continued at a flexible dosage for an additional 36 weeks or longer to assess the long-term efficacy and tolerability of cerivastatin sodium. During the 12-week treatment period, serum total cholesterol levels decreased significantly from baseline in both dosage groups, but the percentage reduction was significantly greater in the 0.3-mg group (range, 24.4% to 25.6%) than in the 0.15-mg group (range, 19.4% to 21.6%). The percentage reduction in levels of low-density lipoprotein cholesterol, triglycerides, and apolipoprotein B and the percentage increase in levels of high-density lipoprotein cholesterol were significantly greater in the 0.3-mg group than in the 0.15-mg group. When the results for the 0.3- and 0.15-mg groups were combined, the percentage of change in serum lipid levels at 48 weeks remained as stable as at 12 weeks. No serious adverse reactions were observed. We concluded that the higher dose of cerivastatin sodium was more effective than the lower dose, with comparable tolerability, in the treatment of patients with severe primary hypercholesterolemia.
Asunto(s)
Anticolesterolemiantes/uso terapéutico , Inhibidores de Hidroximetilglutaril-CoA Reductasas/uso terapéutico , Hipercolesterolemia/tratamiento farmacológico , Piridinas/uso terapéutico , Adulto , Anticolesterolemiantes/administración & dosificación , Anticolesterolemiantes/efectos adversos , Apolipoproteínas B/sangre , Colesterol/sangre , HDL-Colesterol/sangre , LDL-Colesterol/sangre , Femenino , Humanos , Inhibidores de Hidroximetilglutaril-CoA Reductasas/administración & dosificación , Inhibidores de Hidroximetilglutaril-CoA Reductasas/efectos adversos , Hipercolesterolemia/sangre , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Placebos , Piridinas/administración & dosificación , Piridinas/efectos adversos , Estereoisomerismo , Triglicéridos/sangreRESUMEN
Glucocorticoid, an anti-inflammatory agent, inhibits the development of atherosclerosis in various experimental animal models. This is partially explained by its ability to inhibit smooth muscle cell migration and proliferation in the intima and to reduce chemotaxis of circulating monocytes and leukocytes into the subendothelial spaces. We have recently demonstrated that oxidized LDL (Ox-LDL) has a mitogenic activity for macrophages in vitro in which Ox-LDL-induced granulocyte/macrophage colony-stimulating factor (GM-CSF) production plays an important role. Proliferation of cellular components is one of the characteristic events in the development and progression of atherosclerotic lesions. In the present study, we investigated the effects of glucocorticoids on Ox-LDL-induced macrophage growth. Dexamethasone, prednisolone, and cortisol inhibited Ox-LDL-induced thymidine incorporation into macrophages by 85%, 70%, and 50%, respectively. Ox-LDL induced a significant production of GM-CSF by macrophages, which was effectively inhibited by dexamethasone, prednisolone, and cortisol by 80%, 65%, and 50%, respectively. Dexamethasone-mediated inhibition of Ox-LDL-induced GM-CSF mRNA expression and macrophage growth was significantly abrogated by RU-486, a glucocorticoid receptor antagonist. Our results suggest that the inhibitory effects of glucocorticoids on macrophage growth may be due to the inhibition of Ox-LDL-induced GM-CSF production through transactivation of the glucocorticoid receptor.
Asunto(s)
Dexametasona/farmacología , Factor Estimulante de Colonias de Granulocitos y Macrófagos/antagonistas & inhibidores , Lipoproteínas LDL/antagonistas & inhibidores , Macrófagos/efectos de los fármacos , Animales , División Celular/efectos de los fármacos , Factor Estimulante de Colonias de Granulocitos y Macrófagos/biosíntesis , Factor Estimulante de Colonias de Granulocitos y Macrófagos/genética , Lipoproteínas LDL/metabolismo , Lisofosfatidilcolinas/metabolismo , Macrófagos/fisiología , Masculino , Ratones , Ratones Endogámicos C3H , Mifepristona/farmacología , ARN Mensajero/análisisRESUMEN
BACKGROUND: The plasma concentration of 5-hydroxytryptamine (5-HT) in diabetic patients is higher than that in normal subjects. Since recent reports have demonstrated the presence of 5-HT2A receptor in glomerular mesangial cells, it is possible that 5-HT may be involved in the development of diabetic nephropathy through the 5-HT2A receptor in mesangial cells. Because expansion of the glomerular mesangial lesion is a characteristic feature of diabetic nephropathy, we examined the effect of 5-HT on the production of type IV collagen by human mesangial cells. METHODS: Human mesangial cells were incubated with 5-HT with or without 5-HT receptor antagonists, protein kinase C (PKC) inhibitor or transforming growth factor-beta (TGF-beta) antibody. Type IV collagen mRNA and protein concentration in medium were measured by Northern blot analysis and enzyme-linked immunosorbent assay (ELISA), respectively. TGF-beta mRNA and bioactivity in the medium were measured by Northern blot analysis and bioassay using mink lung epithelial cells, respectively. RESULTS: 5-HT stimulated the production of type IV collagen by human mesangial cells, which was inhibited by ketanserin and sarpogrelate hydrochloride, 5-HT2A receptor antagonists, but not by ondansetron, a 5-HT3 receptor antagonist. 5-HT increased the bioactivities of both active and total TGF-beta. However, the 5-HT-enhanced production of type IV collagen was completely inhibited by an anti-TGF-beta antibody. Furthermore, a PKC inhibitor, calphostin C, inhibited the 5-HT-induced increase in type IV collagen secretion, and the activity of membrane PKC was increased by 5-HT. Phorbol ester activated type IV collagen production as well as active and total TGF-beta. Calphostin C completely inhibited the 5-HT-enhanced activity of active TGF-beta, but did not inhibit exogenous TGF-beta-induced increase in type IV collagen secretion. CONCLUSIONS: Our results suggest that 5-HT-enhanced production of type IV collagen by human mesangial cells is mediated by activation of PKC and subsequent increase in active TGF-beta activity.
Asunto(s)
Colágeno/biosíntesis , Mesangio Glomerular/efectos de los fármacos , Mesangio Glomerular/metabolismo , Serotonina/farmacología , Células Cultivadas , Nefropatías Diabéticas/etiología , Nefropatías Diabéticas/metabolismo , Humanos , Ketanserina/farmacología , Cinética , Proteína Quinasa C/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Receptor de Serotonina 5-HT2A , Receptores de Serotonina/efectos de los fármacos , Receptores de Serotonina/metabolismo , Antagonistas de la Serotonina/farmacología , Succinatos/farmacología , Factor de Crecimiento Transformador beta/genética , Factor de Crecimiento Transformador beta/metabolismoRESUMEN
Cerivastatin sodium, a synthetic and pure enantiomeric 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor, is considered effective in the treatment of mild-to-moderate primary hyper-cholesterolemia (total cholesterol < or = 220-259 mg/dL) at a daily dose of 0.15 mg. We compared the efficacy and tolerability of a dosage of 0.3 mg/d with those of a dosage of 0.15 mg/d in patients with severe primary hypercholesterolemia (serum total cholesterol > or = 260 mg/dL). After a minimum of 4 weeks' lead-in with placebo, 73 patients with severe primary hypercholesterolemia were randomly assigned to receive either 0.15 or 0.3 mg of cerivastatin sodium once daily after the evening meal for 12 weeks. In 58 patients, the same drug was continued at a flexible dosage for an additional 36 weeks or longer to assess the long-term efficacy and tolerability of cerivastatin sodium. During the 12-week treatment period, serum total cholesterol levels decreased significantly from baseline in both dosage groups, but the percentage reduction was significantly greater in the 0.3-mg group (range, 24.4% to 25.6%) than in the 0.15-mg group (range, 19.4% to 21.6%). The percentage reduction in levels of low-density lipoprotein cholesterol, triglycerides, and apolipoprotein B and the percentage increase in levels of high-density lipoprotein cholesterol were significantly greater in the 0.3-mg group than in the 0.15-mg group. When the results for the 0.3- and 0.15-mg groups were combined, the percentage of change in serum lipid levels at 48 weeks remained as stable as at 12 weeks. No serious adverse reactions were observed. We concluded that the higher dose of cerivastatin sodium was more effective than the lower dose, with comparable tolerability, in the treatment of patients with severe primary hypercholesterolemia.
Asunto(s)
Anticolesterolemiantes/uso terapéutico , Inhibidores de Hidroximetilglutaril-CoA Reductasas/uso terapéutico , Hipercolesterolemia/tratamiento farmacológico , Piridinas/uso terapéutico , Adulto , Anticolesterolemiantes/administración & dosificación , Anticolesterolemiantes/efectos adversos , Apolipoproteínas/sangre , Colesterol/sangre , Relación Dosis-Respuesta a Droga , Método Doble Ciego , Femenino , Humanos , Inhibidores de Hidroximetilglutaril-CoA Reductasas/administración & dosificación , Inhibidores de Hidroximetilglutaril-CoA Reductasas/efectos adversos , Hipercolesterolemia/sangre , Lípidos/sangre , Lipoproteínas/sangre , Masculino , Persona de Mediana Edad , Piridinas/administración & dosificación , Piridinas/efectos adversosRESUMEN
A pregnant woman was found to have severe hypertriglyceridemia, fasting chylomicronemia, and low platelet count. The activities of serum lipoprotein lipase (LPL) and hepatic triglyceride lipase (HTGL) proved to be extremely low. The activities of the enzymes in normal plasma were completely inhibited by addition of the patient's plasma. We concluded that autoantibodies to lipases were responsible for this patient's hypertriglyceridemia.
Asunto(s)
Enfermedades Autoinmunes , Quilomicrones/sangre , Complicaciones del Embarazo , Adulto , Autoanticuerpos/sangre , Femenino , Humanos , Hipertrigliceridemia/inmunología , Lipasa/deficiencia , Lipasa/inmunología , Lipoproteína Lipasa/deficiencia , Lipoproteína Lipasa/inmunología , Hígado/enzimología , Embarazo , Resultado del Embarazo , Trombocitopenia/inmunologíaRESUMEN
Recent studies demonstrated that oxidized LDL (Ox-LDL) induces macrophage growth in vitro. The present study was undertaken to elucidate the intracellular signaling pathways for macrophage growth. Ox-LDL initiated a rapid and transient rise in intracellular free calcium ion and induced activation of membrane protein kinase C (PKC). Pertussis toxin completely inhibited the Ox-LDL-induced rise in free calcium ion and significantly inhibited macrophage growth by 50%. Moreover, PKC inhibitors calphostin C and H-7 significantly inhibited Ox-LDL-induced macrophage growth by 80%. On the other hand, phospholipase A2-treated acetylated LDL did not induce a rise in calcium but significantly activated PKC and led to significant macrophage growth that was significantly inhibited by calphostin C by 90%. These results suggest the presence of two intracellular signaling pathways for activation of PKC, a rise in calcium that was mediated by pertussis toxin-sensitive G protein and the internalization of lysophosphatidylcholine through the scavenger receptors. These two pathways may play an important role in Ox-LDL-induced macrophage growth.
Asunto(s)
Lipoproteínas LDL/farmacología , Macrófagos Peritoneales/efectos de los fármacos , Proteína Quinasa C/metabolismo , Transducción de Señal/fisiología , 1-(5-Isoquinolinesulfonil)-2-Metilpiperazina/farmacología , Animales , Calcio/fisiología , División Celular/efectos de los fármacos , Replicación del ADN/efectos de los fármacos , Activación Enzimática/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Proteínas de Unión al GTP/antagonistas & inhibidores , Proteínas de Unión al GTP/fisiología , Lípidos/análisis , Lipoproteínas LDL/química , Lipoproteínas LDL/efectos de los fármacos , Macrófagos Peritoneales/enzimología , Masculino , Ratones , Ratones Endogámicos C3H , Naftalenos/farmacología , Toxina del Pertussis , Fosfolipasas A/farmacología , Fosfolipasas A2 , Factores de Virulencia de Bordetella/farmacologíaRESUMEN
To elucidate the mechanism of triglyceride (TG) accumulation in adipocytes induced by TG-rich lipoproteins, we examined the effect of beta-very low density lipoprotein (beta-VLDL) on TG accumulation in 3T3-L1 adipocytes. Beta-VLDL did not induce TG accumulation in 3T3-L1 preadipocytes but in 3T3-L1 adipocytes. TG accumulation was significantly inhibited by cytochalasin B, an inhibitor of receptor mediated endocytosis. In contrast, cytochalasin B did not inhibit free fatty acid induced TG accumulation in adipocytes. The binding of [125I]beta-VLDL to preadipocytes was inhibited completely by both beta-VLDL and LDL. In sharp contrast, the binding of [125I]beta-VLDL to adipocytes was inhibited completely by beta-VLDL, but partially by LDL. The VLDL receptor mRNA was only expressed in adipocytes. These results suggest that beta-VLDL induced TG accumulation in adipocytes may be mediated through the VLDL receptor pathway.
Asunto(s)
Adipocitos/metabolismo , Adipocitos/fisiología , Endocitosis , Lipoproteínas VLDL/fisiología , Receptores de LDL/fisiología , Transducción de Señal , Triglicéridos/metabolismo , Células 3T3 , Adipocitos/citología , Animales , Northern Blotting , Diferenciación Celular/efectos de los fármacos , Endocitosis/efectos de los fármacos , Ratones , Unión Proteica/efectos de los fármacos , Conejos , Transducción de Señal/efectos de los fármacos , Células Madre/citologíaRESUMEN
3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors ameliorate atherosclerotic diseases in several models of vascular disease. This is largely due to their ability to reduce plasma cholesterol levels in vivo. Proliferation of cellular components is one of the major events in the development and progression of atherosclerotic lesions. We recently demonstrated that oxidized low density lipoprotein (Ox-LDL), a likely atherogenic lipoprotein present in vivo, is capable of inducing macrophage growth in vitro. In the present study, we investigated the effect of HMG-CoA reductase inhibitors, simvastatin and pravastatin, on Ox-LDL-induced macrophage growth. Our results demonstrated that these inhibitors effectively suppressed Ox-LDL-induced macrophage growth with concentrations required for 50% inhibition by simvastatin and pravastatin being 0.1 and 80 microM, respectively, and that this inhibitory effect was reversed by mevalonate but not by squalene. Under these conditions, simvastatin did not affect the endocytic degradation of Ox-LDL, nor subsequent accumulation of intracellular cholesteryl esters. Our results suggest that a non-cholesterol metabolites(s) of mevalonate pathway may play an important role in Ox-LDL-induced macrophage growth. Since it is well known that macrophage-derived foam cells are the key cellular element in the early stage of atherosclerosis, a significant inhibition of Ox-LDL-induced macrophage growth by HMG-CoA reductase inhibitors in vitro, particularly simvastatin, may also explain, at least in part, their anti-atherogenic action in vivo.
Asunto(s)
Inhibidores de Hidroximetilglutaril-CoA Reductasas , Lipoproteínas LDL/farmacología , Macrófagos/efectos de los fármacos , Animales , Arteriosclerosis/patología , División Celular , Colesterol/biosíntesis , Interacciones Farmacológicas , Inhibidores Enzimáticos/farmacología , Humanos , Lovastatina/análogos & derivados , Lovastatina/farmacología , Macrófagos/citología , Masculino , Ácido Mevalónico/metabolismo , Ratones , Ratones Endogámicos C3H , Oxidación-Reducción , Pravastatina/farmacología , SimvastatinaRESUMEN
To elucidate the mechanism of foam cell formation in the mesangial region of a kidney observed in a familial type III hyperlipoproteinemic patient presenting with diabetes mellitus and nephrotic syndrome, we have examined, in the present study, the effect of human beta-VLDL (apo E2/E2) on foam cell formation in human mesangial cells, since an increase in beta-VLDL is a characteristic feature of this patient. Human beta-VLDL (apo E2/E2) induced foam cell formation in human mesangial cells. The binding of [125I]LDL to human mesangial cells was inhibited completely by both LDL and beta-VLDL. On the other hand, the binding of [125I]beta-VLDL was completely inhibited by beta-VLDL, but partially by LDL. The LDL receptor, but not the VLDL receptor was down-regulated by accumulation of cholesteryl esters. These results suggest that human beta-VLDL (apo E2/E2)-induced foam cell formation in mesangial cells is mediated through both the LDL receptor pathway and the beta-VLDL specific pathway, in which the VLDL receptor is one of the candidates.
Asunto(s)
Células Espumosas/patología , Mesangio Glomerular/patología , Lipoproteínas VLDL/fisiología , Northern Blotting , Células Cultivadas , Ésteres del Colesterol/metabolismo , Células Espumosas/efectos de los fármacos , Células Espumosas/metabolismo , Mesangio Glomerular/metabolismo , Humanos , Ligandos , Lipoproteínas VLDL/metabolismo , Unión Proteica/efectos de los fármacosRESUMEN
We have recently demonstrated that the growth of murine macrophages is induced by oxidized low density lipoprotein (Ox-LDL) and that lysophosphatidylcholine (lyso-PC), a major phospholipid component of Ox-LDL, plays an essential role in its mitogenic effect. The present study was undertaken to further characterize the role of the macrophage scavenger receptor (MSR) in Ox-LDL-induced macrophage growth. The growth-stimulating effect of Ox-LDL on murine resident peritoneal macrophages was inhibited by maleylated bovine serum albumin (maleyl-BSA), a non-lipoprotein ligand for MSR but a poor carrier of lyso-PC, while maleyl-BSA itself failed to induce macrophage growth even in the presence of lyso-PC. Moreover, it competitively inhibited the endocytic uptake of 125I-Ox-LDL and the specific uptake of lyso-PC by MSR, whereas nonspecific lyso-PC transfer to cells was not affected. Furthermore, the Ox-LDL-induced cell growth of peritoneal macrophages obtained from MSR knockout mice was significantly weaker than that of macrophages obtained from their wild-type littermates. Our results suggest that the MSR is an important and efficient internalization pathway for lyso-PC in Ox-LDL-induced macrophage growth.
Asunto(s)
Lipoproteínas LDL/farmacología , Lisofosfatidilcolinas/metabolismo , Macrófagos Peritoneales/metabolismo , Proteínas de la Membrana , Receptores Inmunológicos/metabolismo , Receptores de Lipoproteína , Albúmina Sérica Bovina , Albúminas/farmacología , Animales , Bovinos , División Celular/efectos de los fármacos , Células Cultivadas , Cruzamientos Genéticos , Endocitosis , Heterocigoto , Humanos , Cinética , Lipoproteínas LDL/metabolismo , Macrófagos Peritoneales/citología , Macrófagos Peritoneales/efectos de los fármacos , Masculino , Ratones , Ratones Endogámicos C3H , Ratones Endogámicos C57BL , Ratones Noqueados , Receptores Inmunológicos/genética , Receptores Depuradores , Receptores Depuradores de Clase BRESUMEN
To elucidate the atherogenicity of lipoprotein(a) (Lp(a)), we examined its growth-stimulating activity in rat resident peritoneal macrophages. When macrophages were incubated with Lp(a), cell numbers were increased 1.5-fold as compared with control macrophages. Furthermore, apolipoprotein(a) (apo(a)), a plasminogen-like glycoprotein which is covalently attached to a low density lipoprotein-like particle (Lp(a)), also induced macrophage growth, while the growth-stimulating effect of Lp(a-) was negligible. These results suggest that apo(a) plays an active role in the mitogenic activity of Lp(a). Lp(a)-induced macrophage growth was inhibited by exogenously added active transforming growth factor-beta (TGF-beta) dose-dependently, and also by the addition of plasmin, which converts latent TGF-beta to an active form. Moreover, the amounts of endogenous active TGF-beta in the medium were significantly reduced by the incubation with Lp(a). It is evident from these results that Lp(a) induces macrophage growth by inhibiting TGF-beta activation. The capacity of Lp(a) to stimulate macrophage growth shown here could be novel atherogenic function of Lp(a).
Asunto(s)
Arteriosclerosis/etiología , Lipoproteína(a)/farmacología , Macrófagos Peritoneales/efectos de los fármacos , Factor de Crecimiento Transformador beta/antagonistas & inhibidores , Animales , Apolipoproteínas A/farmacología , División Celular/efectos de los fármacos , Células Cultivadas , Endocitosis/efectos de los fármacos , Fibrinolisina/farmacología , Lipoproteínas HDL/farmacología , Lipoproteínas LDL/farmacología , Masculino , Oxidación-Reducción , Ratas , Ratas Wistar , Factor de Crecimiento Transformador beta/sangre , Factor de Crecimiento Transformador beta/farmacologíaRESUMEN
Many studies have shown that sterols can stimulate acyl-coenzyme A:cholesterol acyltransferase (ACAT) activity in cells. To elucidate this mechanism, effects of sterol-mediated induction on both the enzyme activity of ACAT and its mRNA levels were studied in human hepatoblastoma cell line, HepG2 cells. When HepG2 cells were loaded with cholesterol and 25-hydroxycholesterol, both the whole-cell ACAT activity and the microsomal ACAT activity were increased by 85.1% and 41.3%. In contrast, cholesterol depletion of HepG2 cells with compactin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, resulted in a decrease in both the whole-cell and the microsomal ACAT activity by 46.4% and 58.3%. Under identical conditions, RT-PCR and Northern blotting analyses revealed that neither cholesterol loading nor cholesterol depletion of HepG2 cells altered the amounts of ACAT mRNA. Moreover, these treatments had no effect on the enzymatic ACAT activity determined by the reconstituted assay in which HepG2 cell homogenate had been supplemented in vitro with a saturating level of exogenous cholesterol. These results indicate that cholesterol-induced up-regulation of ACAT activity in HepG2 cells does not occur at the level of transcription, but rather at a posttranscriptional level.
Asunto(s)
Colesterol/farmacología , ARN Mensajero/análisis , Esterol O-Aciltransferasa/efectos de los fármacos , Secuencia de Bases , Northern Blotting , Hepatoblastoma/enzimología , Humanos , Lipoproteínas LDL/metabolismo , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , Esterol O-Aciltransferasa/genética , Esterol O-Aciltransferasa/metabolismo , Células Tumorales CultivadasRESUMEN
The growth of murine peritoneal macrophages is induced by oxidized LDL (Ox-LDL), and lysophosphatidylcholine (lysoPC) plays an important role in its mitogenic activity. In the present++ study, Ox-LDL-induced macrophage growth was examined with human monocyte-derived macrophages. The cell growth of human macrophages was significantly induced by Ox-LDL but not by acetylated LDL (acetyl-LDL). The treatment of acetyl-LDL with phospholipase A2, however, led to a marked increase in its mitogenic activity, with a concomitant conversion of 75% of its phospholipids to lysoPC. The growth-stimulating activity became positive only when both acetyl-LDL and lysoPC were coincubated, although neither of them exhibited cell growth-promoting activity. These results suggest that Ox-LDL could stimulate the growth of human monocyte-derived macrophages, and lysoPC may play an essential role in the mitogenic activity of Ox-LDL.
Asunto(s)
Lipoproteínas LDL/farmacología , Lisofosfatidilcolinas/farmacología , Macrófagos/efectos de los fármacos , Mitógenos/farmacología , Monocitos/citología , División Celular/efectos de los fármacos , Línea Celular/efectos de los fármacos , Sinergismo Farmacológico , Humanos , Macrófagos/citología , Oxidación-Reducción , Fosfolipasas A/farmacología , Fosfolipasas A2 , Esterol O-Aciltransferasa/antagonistas & inhibidoresRESUMEN
We investigated whether low density lipoprotein (LDL) under oxidative stress might induce the release of fructose, glucose-6-phosphate and fructose-6-phosphate from perivascular cells, and also whether these substances might accelerate the formation of advanced glycation end products (AGE) from proteins in vitro. When vascular smooth muscle cells were incubated with LDL in Ham's F10 at 37 degrees C for 48 h. release of all these substances was increased dose-dependently by oxidized LDL. Fructose release was increased in a dose-dependent manner by glucose. Indomethacin (20 microM) significantly (P < 0.01) suppressed the release of fructose (25.4 +/- 15.7% of control) and hexose phosphates (29.4 +/- 4.0) with the inhibition of release of lactate dehydrogenase (35.5 +/- 4.9) as well as probucol, whereas an aldose reductase inhibitor, epalrestat, significantly (P < 0.001) inhibited only the fructose release (0.9 +/- 0.8). Release of fructose and hexose phosphates from vascular endothelial cells was also induced by oxidized LDL. AGE immunoreactivities and AGE-related fluorescence formed from proteins and glucose were significantly increased (P < 0.001) in the presence of small amounts of the cellular glucose metabolites (6.6%) with glucose (93.4%). These data suggest that release of potent AGE initiators, fructose and hexose phosphates, from perivascular cells induced by oxidized LDL may be an important phenomenon for vascular complications.
Asunto(s)
Endotelio Vascular/metabolismo , Fructosa/metabolismo , Glicoproteínas/metabolismo , Hexosafosfatos/metabolismo , Lipoproteínas LDL/farmacología , Músculo Liso Vascular/metabolismo , Factor de Activación Plaquetaria/análisis , Aldehído Reductasa/antagonistas & inhibidores , Animales , Aorta Torácica , Células Cultivadas , Endotelio Vascular/citología , Endotelio Vascular/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Glicosilación , Humanos , Cinética , L-Lactato Deshidrogenasa , Músculo Liso Vascular/citología , Músculo Liso Vascular/efectos de los fármacos , Oxidación-Reducción , Estrés Oxidativo , Probucol/farmacología , Conejos , Rodanina/análogos & derivados , Rodanina/farmacología , Tiazolidinas , Sustancias Reactivas al Ácido Tiobarbitúrico , Venas UmbilicalesAsunto(s)
Lipoproteínas LDL/metabolismo , Lisofosfatidilcolinas/metabolismo , Macrófagos/metabolismo , Proteínas de la Membrana , Receptores Inmunológicos/metabolismo , Receptores de Lipoproteína , Animales , Arteriosclerosis/fisiopatología , Células Espumosas/fisiología , Humanos , Técnicas In Vitro , Ratones , Oxidación-Reducción , Ratas , Receptores Depuradores , Receptores Depuradores de Clase BRESUMEN
Oxidized low density lipoprotein (ox-LDL) was incubated with discoidal complexes of apolipoprotein A-I (apo A-I) and dimyristoylphosphatidylcholine (DMPC) (DMPC/apo A-I) in a cell-free system and re-isolated on Sephacryl S-400 gel filtration chromatography. Analyses of re-isolated ox-LDL showed that apo A-I was transferred from DMPC/apo A-I to ox-LDL, which accounted for 10% of the total protein of ox-LDL. Re-isolated ox-LDL also showed a 2.2-fold increase in phospholipid and a 14% decrease in cholesterol content on an apo B basis. The electrophoretic mobility of re-isolated ox-LDL was markedly reduced almost to that of native LDL. Moreover, the amounts of re-isolated ox-LDL to be degraded by mouse peritoneal macrophages as well as the capacity of re-isolated ox-LDL to accumulate cholesteryl esters (CE) in these cells were markedly reduced (60% and 80% reduction, respectively), suggesting that the ligand activity of ox-LDL for the scavenger receptor was significantly reduced upon treatment with DMPC/apo A-I. Parallel incubation of ox-LDL with free apo A-I led to a similar incorporation of apo A-I into ox-LDL. However, it had no effects on the ligand activity of ox-LDL. Thus, it is likely that the reduction in the ligand activity of ox-LDL by DMPC/apo A-I is explained by the change in the lipid moiety (mainly phospholipid) of ox-LDL. Since discoidal high density lipoprotein (HDL) is known to occur in vivo, this phenomenon might explain one of the anti-atherogenic functions of HDL.