Consequences of PPARα Invalidation on Glutathione Synthesis: Interactions with Dietary Fatty Acids

Glutathione (GSH) derives from cysteine and plays a key role in redox status. GSH synthesis is determined mainly by cysteine availability and γ-glutamate cysteine ligase (γGCL) activity. Because PPARα activation is known to control the metabolism of certain amino acids, GSH synthesis from cysteine and related metabolisms were explored in wild-type (WT) and PPARα-null (KO) mice, fed diets containing either saturated (COCO diet) or 18 : 3 n-3, LIN diet. In mice fed the COCO diet, but not in those fed the LIN diet, PPARα deficiency enhanced hepatic GSH content and γGCL activity, superoxide dismutase 2 mRNA levels, and plasma uric acid concentration, suggesting an oxidative stress. In addition, in WT mice, the LIN diet increased the hepatic GSH pool, without effect on γGCL activity, or change in target gene expression, which rules out a direct effect of PPARα. This suggests that dietary 18 : 3 n-3 may regulate GSH metabolism and thus mitigate the deleterious effects of PPARα deficiency on redox status, without direct PPARα activation

Consequences of PPARα Invalidation on Glutathione Synthesis: Interactions with Dietary Fatty Acids

Glutathione (GSH) derives from cysteine and plays a key role in redox status. GSH synthesis is determined mainly by cysteine availability and γ-glutamate cysteine ligase (γGCL) activity. Because PPARα activation is known to control the metabolism of certain amino acids, GSH synthesis from cysteine and related metabolisms were explored in wild-type (WT) and PPARα-null (KO) mice, fed diets containing either saturated (COCO diet) or 18 : 3 n-3, LIN diet. In mice fed the COCO diet, but not in those fed the LIN diet, PPARα deficiency enhanced hepatic GSH content and γGCL activity, superoxide dismutase 2 mRNA levels, and plasma uric acid concentration, suggesting an oxidative stress. In addition, in WT mice, the LIN diet increased the hepatic GSH pool, without effect on γGCL activity, or change in target gene expression, which rules out a direct effect of PPARα. This suggests that dietary 18 : 3 n-3 may regulate GSH metabolism and thus mitigate the deleterious effects of PPARα deficiency on redox status, without direct PPARα activation

L'embouchure du fleuve antique dans les étangs narbonnais

International audienceThe archaeological site of Castelou/Mandirac, located approximately 6 km south of Narbonne, is one of three archaeological research projects focused on the ancient ports of Narbonne. The excavations confirmed the canalization of one of the branches of the River Aude, which was undertaken during the 2nd century BC over a distance of 1,7 km. The river mouth located between the « La Clape » range and the Bages lagoons, plays a key role in the Narbonne harbour complex by maintaining the river’s course and enabling the construction of a large transhipment area.Les fouilles du Castélou/Mandirac, à 6 km au sud de Narbonne, correspondent à l’un des trois chantiers programmés réalisés dans le cadre du Programme Collectif de Recherche sur Les Ports antiques de Narbonne. Ces fouilles ont confirmé la présence d’une chenalisation d’un bras du fleuve Aude dans la lagune, sur 1,7 km. Cette zone d’embouchure, entre le massif de la Clape et les étangs de Bages, joue un rôle déterminant dans le complexe portuaire narbonnais, en permettant de maintenir le fleuve dans son cours et d’aménager un vaste espace de transbordement des marchandises

Early postprandial low-grade inflammation after high-fat meal in healthy rats : possible involvement of visceral adipose tissue

International audienceIn the postprandial period, low-grade inflammation may contribute to vascular endothelial dysfunction, a hallmark of atherogenesis. Little is known about the involvement of the adipose tissue in the initiation of the postprandial inflammatory response such as obtained after a high-saturated fat meal (HFM). In the present study, we first studied the time course of appearance of systemic inflammation after a HFM in healthy rats, and then we investigated whether a HFM activates the inflammatory signaling in the visceral adipose tissue, with a focus on the key component, nuclear factor-kappaB (NF-kappaB). Two hours after the HFM, plasma IL-6 and PAI-1, but not plasma C-reactive protein and soluble intracellular adhesion molecule-1, showed a marked, transient increase. These changes were specific to the postprandial state as not observed after a control water load. Neutrophils count and activation markers CD11B and CD62L, assessed by flow cytometry, also rose significantly 2 h after the HFM, while remaining steady after the control. At the same time, the HFM decreased significantly B-cell count and expression of the activation marker CD62L. Interestingly, at the same early time after the HFM, in the visceral adipose tissue, there was a 2.2-fold increase in the activation of NF-kappaB (p65) in nuclear extract and an increase in IL-6 mRNA. As far as we know, this is the first study evidencing an acute, postprandial activation of inflammation in visceral adipose tissue. This early activation of NF-kappaB pathway after a HFM may play a triggering role in the initiation of the complex postprandial proatherogenic phenotype

L'inflammation postprandiale à bas bruit n'implique pas la voie TLR4 chez le rat

International audiencedu syndrome métabolique, en particulier par l'installation d'une inflammation à bas bruit. Au plan expérimental, un repasriche en AGS et en sucre induit transitoirement un ensemble de réactions inflammatoires postprandiales vasculaires etsystémiques (ERIPP). L’ERIPP est associé à une activation de la voie inflammatoire NF-kB dans le tissu adipeux (TA)viscéral. Le récepteur TLR4, connu pour être activé par les AGS, pourrait jouer un rôle important dans cette activation,mais il n’existe pas à ce jour de preuve directe en période postprandiale (PP). Cette étude vise à déterminer l'implicationde l’activation de TLR4 dans la survenue de l’ERIPP.Matériel et méthodes: Etude 1. Cinétique PP plasmatique. Selon un dispositif croisé, 12 rats mâles à jeun ont reçu pari.v. soit un inhibiteur spécifique de TLR4 (INH) soit le véhicule de l'inhibiteur comme témoin (VEH), puis un repas decharge gras et sucré par gavage 5 min après. Du sang a été prélevé à jeun, puis 1, 2, 3, 4 et 6 h après gavage. Unesemaine a séparé les deux explorations sur chaque rat. Les marqueurs plasmatiques métaboliques (glucose,triglycérides), inflammatoires systémiques (IL-6, IL-1β, MCP-1, PAI-1) et vasculaires (ICAM-1, E-sélectine) ont étémesurés à chaque temps. Statistiques : modèle mixte pour données répétées.Etude 2. Inflammation PP tissulaire. Selon un dispositif en parallèle, 20 rats mâles à jeun ont reçu l'INH ou le VEH par i.v.(10 rats par groupe), puis le même repas de charge. Du sang a été prélevé avant et 3h après le repas, puis le foie et leTA épididymaire ont été prélevés. L'activation de NF-kB a été mesurée dans le TA, et l'expression génique (IL-6, IL-1β,TNFα, PAI-1, MCP-1, TLR4 et TLR2) a été mesurée dans le TA et le foie. Statistiques : test t de Student aprèsnormalisation.Résultats et Analyse statistique: Etude 1. Cinétique PP plasmatique. Le pic de glycémie est atteint 1h après gavage, etles triglycérides atteignent un plateau au bout de 3h. Les marqueurs inflammatoires augmentent significativement pour IL-6 (x5) et PAI-1 (x4), avec des maximums 3-4h après gavage, mais pas pour les autres marqueurs. Comparé au VEH,l'INH ne modifie aucune des cinétiques PP. Les prélèvements de l'Etude 2, ont donc été faits 3 heures après gavage.Etude 2. Inflammation PP tissulaire. Trois heures après gavage, le taux d'ARNm dans le TA est beaucoup plus élevédans le groupe INH vs VEH pour IL-1β (x130), IL-6 (x55), TNFα (x45), MCP-1 (x25) et PAI-1 (x2). L’INH n’a pas eu d’effetsur TLR4, mais a accru l’expression de TLR2 (x9) avec une tendance à l’augmentation de la translocation de NF-kB (x3,NS). Dans le foie, l'INH a accru l'expression de IL-1β (x3), TNFα (x3), et MCP-1 (x3) et TLR2 (x2), mais pas d’IL-6 ou dePAI-1, et sans effet significatif sur les TLR. Cette augmentation paradoxale de la transcription de gènes-ciblesinflammatoires pourrait donc s’expliquer par une activation compensatoire de TLR2.Conclusion: Dans nos conditions, en réponse à un inhibiteur spécifique de TLR4, l'inflammation postprandiale à basbruit, mesurée au niveau circulant, se maintient au niveau de celui du groupe témoin. Elle reposerait donc sur desmécanismes autres que l’activation de TLR4

The nano-bio interface mapped by oxidative footprinting of the adsorption sites of myoglobin

International audienceOxidative footprinting has been used to study the structure of macromolecular assemblies such as protein-protein and protein-ligand complexes. We propose a novel development of this technique to probe the protein corona that forms at the surface of nanoparticles in any biological medium. Indeed, very few techniques allow studying this interface at the molecular and residue level. Based on hydroxyl radical-mediated oxidation of proteins and analysis by nanoscale liquid chromatography coupled to tandem mass spectrometry (nanoLC-MS/MS), two sites of adsorption of myoglobin on silica nanoparticles are identified. This method gives new insights in the understanding of protein adsorption on nanomaterials

Postprandial low-grade inflammation does not specifically require TLR4 activation in the rat

Background: Toll-like receptor 4 (TLR4), an innate immune receptor, is suspected to play a key role in the postprandial inflammation that is induced by a high-fat meal rich in saturated fatty acids (SFA). Our objective was to test this hypothesis by using a specific competitive inhibitor of TLR4 (INH) vs vehicle (VEH) administered immediately before a high-SFA meal in rats. Methods: First, in a cross-over kinetic study of 12 rats receiving INH and VEH i.v. 10 min before the test meal, we measured plasma inflammatory and vascular markers for 6 h. Then, in 20 rats, 3 h after INH or VEH followed by the test meal (parallel study), we measured the mRNA level of a set of cytokines (Il1-beta, Il-6, Tnfa, Mcp-1, Pai-1), and of Tlr4 and Tlr2 in the adipose tissue and the liver, and that of adhesion molecules (Icam-1 and Vcam-1) in the aorta. Results: Plasma IL-6 and PAI-1 increased > 4-fold at 3-4 h after test-meals, very similarly after INH as compared to VEH. The expression of TLR2 and of all measured cytokine genes in the adipose tissue was dramatically higher after INH (vs VEH). In the liver, gene expression of Il1-beta, Tnfa, Mcp-1 and Tlr2, was also higher after INH, though more moderately, whereas that of Il-6 and Pai-1 was similar between groups. INH did not affect mRNA level of Icam-1 and Vcam-1 in the aorta. Conclusion: TLR4 activation is not specifically required to mediate systemic postprandial inflammation and we propose that TLR2 and TLR4 exert a dual and interdependent mediation of the postprandial inflammatory response, at least in the adipose tissue

Natural Isotope Abundances of Carbon and Nitrogen in Tissue Proteins and Amino Acids as Biomarkers of the Decreased Carbohydrate Oxidation and Increased Amino Acid Oxidation Induced by Caloric Restriction under a Maintained Protein Intake in Obese Rats

A growing body of evidence supports a role for tissue-to-diet 15N and 13C discrimination factors (Δ15N and Δ13C), as biomarkers of metabolic adaptations to nutritional stress, but the underlying mechanisms remain poorly understood. In obese rats fed ad libitum or subjected to gradual caloric restriction (CR), under a maintained protein intake, we measured Δ15N and Δ13C levels in tissue proteins and their constitutive amino acids (AA) and the expression of enzymes involved in the AA metabolism. CR was found to lower protein mass in the intestine, liver, heart and, to a lesser extent, some skeletal muscles. This was accompanied by Δ15N increases in urine and the protein of the liver and plasma, but Δ15N decreases in the proteins of the heart and the skeletal muscles, alongside Δ13C decreases in all tissue proteins. In Lys, Δ15N levels rose in the plasma, intestine, and some muscles, but fell in the heart, while in Ala, and to a lesser extent Glx and Asx, Δ13C levels fell in all these tissues. In the liver, CR was associated with an increase in the expression of genes involved in AA oxidation. During CR, the parallel rises of Δ15N in urine, liver, and plasma proteins reflected an increased AA catabolism occurring at the level of the liver metabolic branch point, while Δ15N decreases in cardiac and skeletal muscle proteins indicated increased protein and AA catabolism in these tissues. Thus, an increased protein and AA catabolism results in opposite Δ15N effects in splanchnic and muscular tissues. In addition, the Δ13C decrease in all tissue proteins, reflects a reduction in carbohydrate (CHO) oxidation and routing towards non-indispensable AA, to achieve fuel economy