Vicent Ribas

Moderate beer consumption does not change early or mature atherosclerosis in mice

BackgroundAlthough the consumption of wine in particular has been associated with a lower risk of atherothrombotic cardiovascular disease, systematic reviews differ as to the relative protective effect of beer, wine and spirits. Two previous studies showed that red wine reduces fatty streak formation (early atherosclerosis) but not mature atherosclerosis in apolipoprotein (apo) E-deficient (apoE-/-) mice.Aim of the studyTo determine whether a moderate beer intake would affect early and mature atherosclerotic lesion formation using control C57BL/6 and apoE-/- mice, respectively, as models.MethodsControl C57BL/6 and apoE-/- mice were randomized to receive either water, ethanol, mild beer, dark beer or ethanol-free beer. The level of beer was designed to approximate the alcohol intake currently believed to be beneficial in reducing human vascular risk. Control C57BL/6 mice were fed a Western diet for 24 weeks, and apoE-/- mice a chow diet for 12 weeks. At the end of the trial period, mice were euthanized and atherosclerotic lesions quantified. Plasma lipid concentrations were also measured.ResultsThe amount of atherosclerosis and average number of lesions in the proximal aortic region did not differ among groups in control C57BL/6 mice (p = 0.32 and p = 0.29, respectively) and apoE-/- mice (p = 0.19 and p = 0.59, respectively). No consistent differences were observed in plasma lipid and lipoprotein concentrations among water, ethanol and beer groups.ConclusionsModerate beer consumption does not change the development of early or mature atherosclerosis in mice. Our findings do not support the hypothesis of an anti-atherogenic effect of beer. Other potential protective actions of moderate beer consumption such as plaque stabilization, a reduction in plaque intrinsic thrombogenicity, or a reduction in the systemic propensity to thrombosis, remain to be studied.

Human Apolipoprotein A-II Enrichment Displaces Paraoxonase From HDL and Impairs Its Antioxidant Properties: A New Mechanism Linking HDL Protein Composition and Antiatherogenic Potential

Apolipoprotein A-II (apoA-II), the second major high-density lipoprotein (HDL) apolipoprotein, has been linked to familial combined hyperlipidemia. Human apoA-II transgenic mice constitute an animal model for this proatherogenic disease. We studied the ability of human apoA-II transgenic mice HDL to protect against oxidative modification of apoB-containing lipoproteins. When challenged with an atherogenic diet, antigens related to low-density lipoprotein (LDL) oxidation were markedly increased in the aorta of 11.1 transgenic mice (high human apoA-II expressor). HDL from control mice and 11.1 transgenic mice were coincubated with autologous very LDL (VLDL) or LDL, or with human LDL under oxidative conditions. The degree of oxidative modification of apoB lipoproteins was then evaluated by measuring relative electrophoretic mobility, dichlorofluorescein fluorescence, 9- and 13-hydroxyoctadecadienoic acid content, and conjugated diene kinetics. In all these different approaches, and in contrast to control mice, HDL from 11.1 transgenic mice failed to protect LDL from oxidative modification. A decreased content of apoA-I, paraoxonase (PON1), and platelet-activated factor acetyl-hydrolase activities was found in HDL of 11.1 transgenic mice. Liver gene expression of these HDL-associated proteins did not differ from that of control mice. In contrast, incubation of isolated human apoA-II with control mouse plasma at 37°C decreased PON1 activity and displaced the enzyme from HDL. Thus, overexpression of human apoA-II in mice impairs the ability of HDL to protect apoB-containing lipoproteins from oxidation. Further, the displacement of PON1 by apoA-II could explain in part why PON1 is mostly found in HDL particles with apoA-I and without apoA-II, as well as the poor antiatherogenic properties of apoA-II–rich HDL.

Platelet-Activating Factor Acetylhydrolase Is Mainly Associated With Electronegative Low-Density Lipoprotein Subfraction

Background Electronegative LDL [LDL(−)], a modified subfraction of LDL present in plasma, induces the release of interleukin‐8 and monocyte chemotactic protein‐1 from cultured endothelial cells. Methods and Results We demonstrate that platelet‐activating factor acetylhydrolase (PAF‐AH) is mainly associated with LDL(−). LDL(−) had 5‐fold higher PAF‐AH activity than the nonelectronegative LDL subfraction [LDL(+)] in both normolipemic and familial hypercholesterolemic subjects. Western blot analysis after SDS‐PAGE confirmed these results, because a single band of 44 kDa corresponding to PAF‐AH appeared in LDL(−) but not in LDL(+). Nondenaturing polyacrylamide gradient gel electrophoresis demonstrated that PAF‐AH was bound to LDL(−) regardless of LDL size. In accordance with the above findings, nonesterified fatty acids, a cleavage product of PAF‐AH, were increased in LDL(−) compared with LDL(+). Conclusions The high PAF‐AH activity observed in LDL(−) could be related to the proinflammatory activity of these lipoproteins toward cultured endothelial cells. (Circulation. 2003;108:92‐96.)

Overexpression of Human Apolipoprotein A-II in Transgenic Mice Does Not Impair Macrophage-Specific Reverse Cholesterol Transport In Vivo

BACKGROUND Overexpression of human apolipoprotein (apo) A-II in transgenic mice induces high-density lipoprotein (HDL) deficiency, and increased atherosclerosis susceptibility only when fed an atherogenic diet. This may, in part, be caused by impairment in reverse cholesterol transport (RCT). METHODS AND RESULTS [3H]cholesterol-labeled macrophages were injected intraperitoneally into mice maintained on a chow diet or an atherogenic diet. Plasma [3H]cholesterol did not differ from human apoA-II transgenic and control mice at 24 or 48 hours after the label injection. On the chow diet, human apoA-II transgenic mice presented increased [3H]cholesterol in liver (1.3-fold) and feces (6-fold) compared with control mice (P<0.05). The magnitude of macrophage-specific RCT did not differ between transgenic and control mice fed the atherogenic diet. CONCLUSIONS Human apoA-II maintains effective RCT from macrophages to feces in vivo despite an HDL deficiency. These findings suggest that the increased atherosclerotic lesions observed in apoA-II transgenic mice fed an atherogenic diet are not caused by impairment in macrophage-specific RCT.

Human Apolipoprotein A-II Enrichment Displaces Paraoxonase From High-Density Lipoprotein (HDL) and Impairs Its Antioxidant Properties. A New Mechanism Linking HDL Protein Composition and Antiatherogenic Potential

Apolipoprotein A-II (apoA-II), the second major high-density lipoprotein (HDL) apolipoprotein, has been linked to familial combined hyperlipidemia. Human apoA-II transgenic mice constitute an animal model for this proatherogenic disease. We studied the ability of human apoA-II transgenic mice HDL to protect against oxidative modification of apoB-containing lipoproteins. When challenged with an atherogenic diet, antigens related to low-density lipoprotein (LDL) oxidation were markedly increased in the aorta of 11.1 transgenic mice (high human apoA-II expressor). HDL from control mice and 11.1 transgenic mice were coincubated with autologous very LDL (VLDL) or LDL, or with human LDL under oxidative conditions. The degree of oxidative modification of apoB lipoproteins was then evaluated by measuring relative electrophoretic mobility, dichlorofluorescein fluorescence, 9- and 13-hydroxyoctadecadienoic acid content, and conjugated diene kinetics. In all these different approaches, and in contrast to control mice, HDL from 11.1 transgenic mice failed to protect LDL from oxidative modification. A decreased content of apoA-I, paraoxonase (PON1), and platelet-activated factor acetyl-hydrolase activities was found in HDL of 11.1 transgenic mice. Liver gene expression of these HDL-associated proteins did not differ from that of control mice. In contrast, incubation of isolated human apoA-II with control mouse plasma at 37°C decreased PON1 activity and displaced the enzyme from HDL. Thus, overexpression of human apoA-II in mice impairs the ability of HDL to protect apoB-containing lipoproteins from oxidation. Further, the displacement of PON1 by apoA-II could explain in part why PON1 is mostly found in HDL particles with apoA-I and without apoA-II, as well as the poor antiatherogenic properties of apoA-II–rich HDL.

Human Apolipoprotein A-II Determines Plasma Triglycerides by Regulating Lipoprotein Lipase Activity and High-Density Lipoprotein Proteome

Introduction—Apolipoprotein (apo) A-II is the second most abundant high-density lipoprotein (HDL) apolipoprotein. We assessed the mechanism involved in the altered postprandial triglyceride-rich lipoprotein metabolism of female human apoA-II-transgenic mice (hapoA-II-Tg mice), which results in up to an 11-fold increase in plasma triglyceride concentration. The relationships between apoA-II, HDL composition, and lipoprotein lipase (LPL) activity were also analyzed in a group of normolipidemic women. Methods and Results—Triglyceride-rich lipoprotein catabolism was decreased in hapoA-II-Tg mice compared to control mice. This suggests that hapoA-II, which was mainly associated with HDL during fasting and postprandially, impairs triglyceride-rich lipoprotein lipolysis. HDL isolated from hapoA-II-Tg mice impaired bovine LPL activity. Two-dimensional gel electrophoresis, mass spectrometry, and immunonephelometry identified a marked deficiency in the HDL content of apoA-I, apoC-III, and apoE in these mice. In normolipidemic women, apoA-II concentration was directly correlated with plasma triglyceride and inversely correlated with the HDL-apoC-II+apoE/apoC-III ratio. HDL-mediated induction of LPL activity was inversely correlated with apoA-II and directly correlated with the HDL-apoC-II+apoE/apoC-III ratio. Purified hapoA-II displaced apoC-II, apoC-III, and apoE from human HDL2. Human HDL3 was, compared to HDL2, enriched in apoA-II but poorer in apoC-II, apoC-III, and apoE. Conclusion—ApoA-II plays a crucial role in triglyceride catabolism by regulating LPL activity, at least in part, through HDL proteome modulation.

Caracterización de un modelo murino en el que la deficiencia parcial de folato no induce hiperhomocisteinemia

Introduccion y objetivos El posible papel de los folatos en la prevencion de enfermedades cardiovasculares o neurodegenerativas es un tema de actualidad. Diversos estudios epidemiologicos han demostrado una asociacion inversa entre los valores de esta vitamina en sangre y la morbimortalidad cardiovascular o la enfermedad de Alzheimer. Multiples estudios han constatado los efectos hipohomocisteinemiantes del folato. Recientemente se han descrito efectos beneficiosos del folato en el endotelio que son homocisteinaindependientes. Para evaluar su potencial relevancia fisiopatologica se requiere que haya modelos en que los que se pueda disociar hiperhomocisteinemia y deficiencia de folato. Material y metodos Estudio histologico y morfometrico de las lesiones arterioscleroticas en ratones C57BL/6 alimentados con dieta Western (una dieta con un alto contenido en grasas saturadas) deficiente o no en folatos. Resultados Los animales con deficit vitaminico de folato no presentaron hiperhomocisteinemia. Tampoco presentaron diferencias en la glucosa ni en los parametros lipidicos, hematologicos o la funcion renal. La deficiencia en folatos no aumento el area (5.310 ± 1.346 frente a 4522 ± 1276 mm2 en el grupo control) ni el numero de lesiones arterioscleroticas (1,4 ± 0,3 frente a 2,0 ± 0,5 en el grupo control). Conclusiones El raton es un buen modelo para diferenciar los efectos debidos a deficit de folato de los ocasionados por hiperhomocisteinemia, un binomio que suele ser inseparable en humanos. La deficiencia de folato, en ausencia de hiperhomocisteinemia, no incrementa la magnitud ni el numero de lesiones arterioscleroticas en el raton.

Análisis del proteoma hepático de ratones transgénicos de apo A-II humana: identificación de proteínas potencialmente implicadas en la regulación del metabolismo de triglicéridos y la respuesta a la insulina

Introduccion La funcion de la apolipoproteina A-II (apo A-II) en el metabolismo lipoproteico y su relacion con la arteriosclerosis es poco conocida. Los estudios realizados en humanos y ratones modificados geneticamente han demostrado un efecto directo de la apo A-II en el metabolismo de los trigliceridos y los acidos grasos libres (AGL) y la sensibilidad a la insulina. El objetivo principal de este estudio es la identificacion de proteinas diferencialmente expresadas en el higado de ratones transgenicos de apo A-II humana (h) y su potencial relacion con el metabolismo de los trigliceridos y la glucosa. Material y metodos Se realizaron estudios metabolicos de las lipoproteinas ricas en trigliceridos, la betaoxidacion hepatica y la prueba de tolerancia a la glucosa en ratones transgenicos de apo A-IIh y en controles en situacion de ayunas y tras una carga oral de aceite de oliva. Los cambios en el perfil de expresion proteica se analizaron mediante el analisis comparativo de geles bidimensionales y la identificacion de proteinas mediante espectrometria de masas MALDI-TOF. Resultados Los ratones transgenicos de apo A-IIh presentaban un incremento del colesterol y los trigliceridos de las lipoproteinas que contienen apo B, hipertrigliceridemia aumentada tras la carga oral de acido oleico, asi como un aclaramiento acelerado de la glucosa tras la prueba de sobrecarga de glucosa. Estos cambios estaban asociados a una reduccion en el catabolismo de las lipoproteinas ricas en trigliceridos y la tasa de betaoxidacion hepatica, pero sin cambios significativos en la actividad de la lipoproteina lipasa. De las mas de 1.000 manchas resueltas en el rango pH 3 a 10, se identificaron 55 alteraciones significativas en los ratones transgenicos en comparacion con los ratones controles, 16 de las cuales estaban relacionadas directamente con el metabolismo de los AGL y los carbohidratos. Conclusiones La sobreexpresion apo A-IIh en ratones transgenicos induce hipertrigliceridemia posprandial debido, al menos en parte, a un defecto en el catabolismo de las lipoproteinas ricas en trigliceridos. La aproximacion proteomica nos ha permitido detectar y caracterizar diferencias en el proteoma hepatico de los ratones transgenicos de apo A-IIh y establecer proteinas potencialmente involucradas en el metabolismo de los AGL. Se requieren mas estudios bioquimicos y moleculares para investigar el significado funcional de los cambios encontrados.