Caracterización del proceso de secado con aire caliente de piensos experimentales

Los piensos experimentales empleados en investigaciones biomédicas difieren considerablemente respecto a los comerciales; en este caso, se elaboran con ingredientes purificados (almidón, caseína, grasas, celulosa, etc.) y pueden estar suplementados con un determinado compuesto, droga o medicamento. Otra diferencia sustancial es su proceso de elaboración, en este caso, al ser “casero” debe añadirse agua a la harina para conseguir una masa homogénea, que pueda compactarse en pellets o gránulos y posteriormente secarse para eliminar el agua. En este estudio, se han elaborado dos tipos de piensos con ingredientes purificados, uno de control denominado Chow y otro, denominado West, basado en el anterior, pero con un 20% de grasa de palma añadida. Ambos piensos se suplementaron con escualeno (1% en masa). Los objetivos del trabajo han sido: (i) deducir el tiempo mínimo de secado necesario para alcanzar la humedad del sólido correspondiente a un valor de actividad de agua (aw) de 0,6, y (ii) evaluar la posible degradación del escualeno debido al tratamiento de secado de los piensos. Para ello, los piensos se sometieron a un tratamiento de secado con aire caliente en un túnel de bandejas en las que se variaron las condiciones de temperatura (50; 65 y 80 ºC) y velocidad de aire (0,60; 1,10 y 1,65 m/s). Para conocer la humedad de equilibrio que debían alcanzar los piensos durante el secado para conseguir la estabilidad microbiológica (aw =0,6), se determinó la isoterma de sorción sometiendo los piensos a unas condiciones de ambiente saturado (a 20 ºC) en presencia de soluciones de MgCl2, K2CO3, NaCl, Mg(NO3)2 y CuCl2, de humedad relativa conocida. El contenido de escualeno se determinó por cromatografía de gases y espectrometría de masas en muestras tomadas a la salida del túnel de secado. Las diferencias en la cantidad de agua y grasa entre ambos piensos originaron diferencias significativas en las curvas de secado entre piensos Chow y West, mientras que de las condiciones impuestas para el secado, solo la temperatura afectó significativamente al tiempo de secado necesario para alcanzar la humedad crítica, obteniéndose valores de 4,85a ± 0,45, 2,32b ± 0,21 y 1,69ab ± 0,25 horas para piensos Chow para temperaturas de 50, 65 y 80 ºC, respectivamente; para piensos West los tiempos de secado fueron de 21,0a ±1,90, 23,1a ±0,37 y 11,6b ±0,83 horas a 50, 65 y 80 ºC, respectivamente. No se ha observado ningún efecto significativo de la velocidad del aire. Las conclusiones más importantes deducidas del presente trabajo son las siguientes: (1) únicamente la temperatura de secado influyó de forma significativa en el tiempo necesario para alcanzar la humedad crítica y en el tiempo total de secado; (2) la diferencia en la composición entre ambos piensos provoca diferencias en las pautas de secado; y (3) la mayor concentración de grasa saturada del pienso West compensa parcialmente la pérdida de escualeno por efecto del secado en comparación con el pienso Chow.<br /

Hepatic galectin-3 is associated with lipid droplet area in non-alcoholic steatohepatitis in a new swine model

Non-alcoholic fatty liver disease (NAFLD) is currently a growing epidemic disease that can lead to cirrhosis and hepatic cancer when it evolves into non-alcoholic steatohepatitis (NASH), a gap not well understood. To characterize this disease, pigs, considered to be one of the most similar to human experimental animal models, were used. To date, all swine-based settings have been carried out using rare predisposed breeds or long-term experiments. Herein, we fully describe a new experimental swine model for initial and reversible NASH using cross-bred animals fed on a high saturated fat, fructose, cholesterol, cholate, choline and methionine-deficient diet. To gain insight into the hepatic transcriptome that undergoes steatosis and steatohepatitis, we used RNA sequencing. This process significantly up-regulated 976 and down-regulated 209 genes mainly involved in cellular processes. Gene expression changes of 22 selected transcripts were verified by RT-qPCR. Lipid droplet area was positively associated with CD68, GPNMB, LGALS3, SLC51B and SPP1, and negatively with SQLE expressions. When these genes were tested in a second experiment of NASH reversion, LGALS3, SLC51B and SPP1 significantly decreased their expression. However, only LGALS3 was associated with lipid droplet areas. Our results suggest a role for LGALS3 in the transition of NAFLD to NASH

Microarray analysis of hepatic genes differentially expressed in the presence of the unsaponifiable fraction of olive oil in apolipoprotein E-deficient mice

The hypothesis that the unsaponifiable fraction of olive oil dramatically influences hepatic gene expression was tested in mice. Two olive oils, obtained from the same olive cultivar but by different technological procedures, were characterized to show that they differed mainly in terms of the composition/quantity of this unsaponifiable fraction. Using DNA microarrays, hepatic gene expression was analysed in apoE-deficient mice fed one of two isoenergetic, isonitrogenous diets containing either 10% (w/w) olive oil or unsaponifiable fraction-enriched olive oil. To provide an initial screening of potential candidate genes involved in a differential response, only genes with remarkably modified expression (signal log2 ratio ≥3 or < -3) were further considered. The eleven genes fulfilling these prerequisites were confirmed by quantitative RT-PCR, and then analysed in apoE-deficient mice with a C57BL/6J genetic background. Orosomucoid and serum amyloid A2 were upregulated (to variable extents depending on the genetic background) in the absence of hepatic steatosis and inflammation. Fabp5 and Mt2 were also strongly upregulated. Several proteases were highly suppressed by the unsaponifiable-enriched olive diet, independent of the genetic background. The findings indicate that change in the expression of these genes is a good marker of the intake of the unsaponifiable fraction of olive oil. The results highlight the important biological effects of the unsaponifiable fraction of olive oil. The term 'monounsaturated fatty acid-enriched oil' no longer appears appropriate for describing all the oils to which it is currently applied since it does not adequately reflect that they have different biological effects. © The Authors 2007.This research was supported by grants FEGA-FEOGA (CAO99-014), Ministerio de Educación y Ciencia, CICYT (SAF2004-08 173-C03-02 and AGL2005-00 572), Junta de Andalucía (CAO01-002), FISS 01/0202, Redes FISS de investigación cooperativa C03-01 and G03-140 and by the Fundación Española del Corazón.Peer Reviewe

Dietary oleanolic acid mediates circadian clock gene expression in liver independently of diet and animal model but requires apolipoprotein A1

Oleanolic acid is a triterpene widely distributed throughout the plant kingdom and present in virgin olive oil at a concentration of 57 mg/kg. To test the hypotheses that its long-term administration could modify hepatic gene expression in several animal models and that this could be influenced by the presence of APOA1-containing high-density lipoproteins (HDLs), diets including 0.01% oleanolic acid were provided to Apoe- and Apoa1-deficient mice and F344 rats. Hepatic transcriptome was analyzed in Apoe-deficient mice fed long-term semipurified Western diets differing in the oleanolic acid content. Gene expression changes, confirmed by reverse transcriptase quantitative polymerase chain reaction, were sought for their implication in hepatic steatosis. To establish the effect of oleanolic acid independently of diet and animal model, male rats were fed chow diet with or without oleanolic acid, and to test the influence of HDL, Apoa1-deficient mice consuming the latter diet were used. In Apoe-deficient mice, oleanolic acid intake increased hepatic area occupied by lipid droplets with no change in oxidative stress. Bmal1 and the other core component of the circadian clock, Clock, together with Elovl3, Tubb2a and Cldn1 expressions, were significantly increased, while Amy2a5, Usp2, Per3 and Thrsp were significantly decreased in mice receiving the compound. Bmal1 and Cldn1 expressions were positively associated with lipid droplets. Increased Clock and Bmal1 expressions were also observed in rats, but not in Apoa1-deficient mice. The core liver clock components Clock-Bmal1 are a target of oleanolic acid in two animal models independently of the diets provided, and this compound requires APOA1-HDL for its hepatic action

Olive oil preparation determines the atherosclerotic protection in apolipoprotein E knockout mice

Oils enriched in monounsaturated fatty acids do not seem to behave similarly in protecting against the development of atherosclerosis in animal models, which has been attributed to the presence of soluble phenolic compounds. To test the relevance of other components of oils in the prevention of atherosclerosis, two olive oils from the same cultivar devoid of soluble phenolic compounds were prepared using different procedures (pressure or centrifugation), characterized and fed to apolipoprotein E-deficient mice as 10% (w/w) of their diet. The 2 olive oils had similar levels of monounsaturated fatty acids and squalene, but they differed in their content of linoleic, phytosterols, tocopherols, triterpenes and waxes, which were particularly enriched in the test olive oil obtained by centrifugation. In mice that received a diet enriched in the olive oil derived through centrifugation, the progression of atherosclerosis was delayed compared to the mice that received standard olive oil. That effect was associated with decreases in plasma triglycerides, total and non-high-density lipoprotein cholesterol and isoprostane 8-iso-prostaglandin F2α. Our results clearly indicate that the preparation of olive oil is crucial in determining its antiatherosclerotic effect, which extends beyond the presence of phenolic compounds. The test olive oil exerted its antiatherosclerotic effects by modifying plasma lipids and oxidative stress, and it might be a good candidate to replace other fats in functional foods.This research was supported by grants FEGA-FEOGA (CAO99-014), CICYT (SAF2004-08173-C03-02 and AGL2002-00495), Junta de Andalucía (CAO01-002), FISS 01/0202, Redes DGA (A-26) and FISS de investigación cooperativa C03-01 and G03-140 and by Fundación Española del Corazón.Peer reviewe

Squalene in a sex-dependent manner modulates atherosclerotic lesion which correlates with hepatic fat content in apoE-knockout male mice

BACKGROUND: Squalene is an intermediate of cholesterol biosynthesis which can be obtained from the diet where it is abundant, for example, in olive oil. The effect of this isoprenoid on the development of atherosclerosis was investigated on apoE-knockout mice. METHODS AND RESULTS: Two groups of animals, separated according to sex, were fed on standard chow diet: the control group receiving only vehicle and the second group an aqueous solution of squalene to provide a dose of 1g/kg/day in male and female mice. This treatment was maintained for 10 weeks. At the end of this period, plasma lipid parameters, oxidative stress markers and hepatic fat were measured as well as cross-sectional lesion area of aortic root in both groups. Data showed that in males squalene feeding reduced atherosclerotic lesion area independently of plasma lipids and activation of circulating monocytes. In contrast, squalene intake did not decrease lesion area in females, despite reducing plasma cholesterol and triglycerides, isoprostane and percentage of Mac-1 expressing white cells. In males, atherosclerotic lesion area was positively and significantly associated with hepatic fat content and the plasma triglycerides were also strongly associated with liver weight. CONCLUSIONS: These results indicate that administration of squalene modulates lesion development in a gender specific manner, and that accumulation of hepatic fat by liver is highly correlated with lesion progression in males. Hence, squalene administration could be used as a safe alternative to correct hepatic steatosis and atherosclerosis particularly in males.Peer reviewe

Thioredoxin domain containing 5 is involved in the hepatic storage of squalene into lipid droplets in a sex-specific way

Hepatic thioredoxin domain-containing 5 (TXNDC5) is a member of the protein disulfide isomerase family found associated with anti-steatotic properties of squalene and located in the endoplasmic reticulum and in lipid droplets. Considering that the latter are involved in hepatic squalene accumulation, the present research was aimed to investigate the role of TXNDC5 on hepatic squalene management in mice and in the AML12 hepatic cell line. Wild-type and TXNDC5-deficient (KO) mice were fed Western diets with or without 1% squalene supplementation for 6 weeks. In males, but not in females, absence of TXNDC5 blocked hepatic, but not duodenal, squalene accumulation. Hepatic lipid droplets were isolated and characterized using label-free LC-MS/MS analysis. TXNDC5 accumulated in this subcellular compartment of mice receiving squalene and was absent in TXNDC5-KO male mice. The latter mice were unable to store squalene in lipid droplets. CALR and APMAP were some of the proteins that responded to the squalene administration in all studied conditions. CALR and APMAP were positively associated with lipid droplets in the presence of squalene and they were decreased by the absence of TXNDC5. The increased squalene content was reproduced in vitro using AML12 cells incubated with squalene-loaded nanoparticles and this effect was not observed in an engineered cell line lacking TXNDC5. The phenomenon was also present when incubated in the presence of a squalene epoxidase inhibitor, suggesting a mechanism of squalene exocytosis involving CALR and APMAP. In conclusion, squalene accumulation in hepatic lipid droplets is sex-dependent on TXNDC5 that blocks its secretion

Hydroxytyrosol administration enhances atherosclerotic lesion development in apo E deficient mice

Hydroxytyrosol is a phenol found in olive oil. To verify the effect of hydroxytyrosol on the development of atherosclerosis, two groups of apo E deficient male mice on a standard chow diet were used: the control group receiving only water, and the second group an aqueous solution of hydroxytyrosol in order to provide a dose of 10 mg/kg/day to each mouse. This treatment was maintained for 10 weeks. At the moment of sacrifice, blood was drawn and heart removed. Plasma lipids, apolipoproteins and monocyte Mac-1 expression were assayed as well as aortic atherosclerotic areas in both groups. Data showed no significant changes in HDL cholesterol, paraoxonase, apolipoprotein B or triglyceride levels. However, hydroxytyrosol administration decreased apolipoprotein A-I and increased total cholesterol, atherosclerotic lesion areas and circulating monocytes expressing Mac-1. The latter was highly correlated with lesion areas (r = 0.65, P < 0.01). These results indicate that administration of hydroxytyrosol in low cholesterol diets increases atherosclerotic lesion associated with the degree of monocyte activation and remodelling of plasma lipoproteins. Our data supports the concept that phenolic-enriched products, out of the original matrix, could be not only non useful but also harmful. Our results suggest that the formulation of possible functional foods should approximate as much as possible the natural environment in which active molecules are found.This research was supported by grants FEGA-FEOGA (CAO99-0014), CICYT (SAF2004-08173-C03-02 and AGL2002-00495), Junta de Andalucía (CAO01-002), FISS 01/0202, Redes DGA (A-26) and FISS de investigación cooperativa C03-01 and G03-140 and by Fundación Española del Corazón.This research was supported by grants FEGA-FEOGA (CAO99-0014), CICYT (SAF2004-08173-C03-02 and AGL2002-00495), Junta de Andalucía (CAO01-002), FISS 01/0202, Redes DGA (A-26) and FISS de investigación cooperativa C03-01 and G03-140 and by Fundación Española del Corazón. R.C., S.A., M.A.N. and N.G. were recipient of DGA, FEGA-FEOGA and Fundación Cuenca Villoro fellowships.Peer reviewe

Dietary squalene supplementation decreases triglyceride species and modifies phospholipid lipidomic profile in the liver of a porcine model of non-alcoholic steatohepatitis.

Squalene is a key minor component of virgin olive oil, the main source of fat in the Mediterranean diet, and had shown to improve the liver metabolism in rabbits and mice. The present research was carried out to find out whether this effect was conserved in a porcine model of hepatic steatohepatitis and to search for the lipidomic changes involved. The current study revealed that a 0.5% squalene supplementation to a steatotic diet for a month led to hepatic accumulation of squalene and decreased triglyceride content as well as area of hepatic lipid droplets without influencing cholesterol content or fiber areas. However, ballooning score was increased and associated with the hepatic squalene content. Of forty hepatic transcripts related to lipid metabolism and hepatic steatosis, only citrate synthase and a non-coding RNA showed decreased expressions. The hepatic lipidome, assessed by liquid chromatography-mass spectrometry in a platform able to analyze 467 lipids, revealed that squalene supplementation increased ceramide, Cer(36:2), and phosphatidylcholine (PC[32:0], PC[33:0] and PC[34:0]) species and decreased cardiolipin, CL(69:5), and triglyceride (TG[54:2], TG[55:0] and TG[55:2]) species. Plasma levels of interleukin 12p40 increased in pigs receiving the squalene diet. The latter also modified plasma lipidome by increasing TG(58:12) and decreasing non-esterified fatty acid (FA 14:0, FA 16:1 and FA 18:0) species without changes in total NEFA levels. Together this shows that squalene-induced changes in hepatic and plasma lipidomic profiles, non-coding RNA and anti-inflammatory interleukin are suggestive of an alleviation of the disease despite the increase in the ballooning score