Catherine Riva

Hydroxytyrosol in the Prevention of the Metabolic Syndrome and Related Disorders

Virgin olive oil (VOO) constitutes the main source of fat in the Mediterranean diet. VOO is rich in oleic acid, displaying health-promoting properties, but also contains minor bioactive components, especially phenolic compounds. Hydroxytyrosol (HT), the main polyphenol of olive oil, has been reported to be the most bioactive component. This review aims to compile the results of clinical, animal and cell culture studies evaluating the effects of HT on the features of Metabolic Syndrome (MetS) (body weight/adiposity, dyslipidemia, hypertension, and hyperglycemia/insulin resistance) and associated complications (oxidative stress and inflammation). HT was able to improve the lipid profile, glycaemia, and insulin sensitivity, and counteract oxidative and inflammatory processes. Experimental studies identified multiple molecular targets for HT conferring its beneficial effect on health in spite of its low bioavailability. However, rodent experiments and clinical trials with pure HT at biologically relevant concentrations are still lacking. Moreover, the roles of intestine and its gut microbiota have not been elucidated.

Antioxidant properties of tea blunt ROS-dependent lipogenesis: beneficial effect on hepatic steatosis in a high fat-high sucrose diet NAFLD obese rat model.

Oxidative stress could trigger lipid accumulation in liver and thus hepatic steatosis. Tea is able to prevent liver disorders, but a direct link between antioxidant capacities and prevention of steatosis has not been reported yet. We aimed to investigate such relationship in a rat model of high fat-high sucrose diet (HFS)-induced obesity and to explore more deeply the mechanisms in isolated hepatocytes. Wistar rats were divided into a control group (standard diet), an HFS group (high fat-sucrose diet) and an HFS+tea group (HFS diet with ad-libitum access to tea drink). Body weight, fat mass, glycemic parameters in blood, lipid and oxidative stress parameters in blood and liver were measured in each group after 14 weeks. Isolated hepatocytes were treated with the reactive oxygen species (ROS) inducer t-BHP in the presence or not of antioxidants (tempol or tea), and superoxide anion production and lipid accumulation were measured using specific fluorescent probes. We reported that the HFS diet highly increased hepatic lipids content, while tea consumption attenuated steatosis and improved the oxidative status (decrease in hepatic oxidative stress, increase in plasma total antioxidant capacity). The role of antioxidant properties of tea in such phenomenon was confirmed in primary cultured rat hepatocytes. Indeed, the increase of mitochondrial ROS production with t-BHP resulted in lipid accumulation in hepatocytes (positive linear regression), and antioxidants (tempol or tea) normalized both. We reported that the antioxidant properties of tea protect rats from an obesogenic HFS diet-induced hepatic steatosis by counteracting the ROS-dependent lipogenesis.

Role of eNOS- and NOX-containing microparticles in endothelial dysfunction in patients with obesity

To explore the pathophysiological profile of patients who have obesity and to investigate the potential role of circulating microparticles (MPs) in endothelial dysfunction in patients who have obesity.

Microparticle miRNAs as Biomarkers of Vascular Function and Inflammation Response to Aerobic Exercise in Obesity?: Exercise and Microparticles/microRNAs in Obesity

This study aimed to explore the role of nine microRNAs (miRNAs) in microparticles (MPs) on the efficacy of aerobic exercise in the regulation of inflammation and vascular function in obesity.

Involvement of bilitranslocase and beta-glucuronidase in the vascular protection by hydroxytyrosol and its glucuronide metabolites in oxidative stress conditions

Olive oil vascular benefits have been attributed to hydroxytyrosol (HT). However, HT biological actions are still debated because it is extensively metabolized into glucuronides (GCs). The aim of this study was to test HT and GC vasculoprotective effects and the underlying mechanisms using aorta rings from 8-week-old male Wistar rats. In the absence of oxidative stress, incubation with 100 μM HT or GC for 5 min did not exert any vasorelaxing effect and did not influence the vascular function. Conversely, in condition of oxidative stress [upon incubation with 500 μM tert-butylhydroperoxide (t-BHP) for 30 min], preincubation with HT or GC improved acetylcholine-induced vasorelaxation compared with untreated samples (no t-BHP). This protective effect was lost for GC, but not for HT, when a washing step (15 min) was introduced between preincubation with HT or GC and t-BHP addition, suggesting that only HT enters the cells. In agreement, bilitranslocase inhibition with 100 μM phenylmethanesulfonyl fluoride for 20 min reduced significantly HT, but not GC, effect on the vascular function upon stress induction. Moreover, GC protective effect (improvement of endothelium-dependent relaxation in response to acetylcholine) in oxidative stress conditions was reduced by preincubation of aorta rings with 300 μM D-saccharolactone to inhibit β-glucuronidase, which can deconjugate polyphenols. Finally, only HT was detected by high-pressure liquid chromatography in aorta rings incubated with GC and t-BHP. These results suggest that, in conditions of oxidative stress, GC can be deconjugated into HT that is transported through the cell membrane by bilitranslocase to protect vascular function.

0311 : Physical exercise regulates angiogenesis in adipose tissue of dietinduced obese mice thru ECSCR/Akt pathways

Reduced capillary density in adipose tissue is associated with obesity and results in decrease perfusion, decreased oxygen consumption and insulin resistance. Pro- (VEGF-A) and anti-angiogenic (TSP-1) factors expression is central determinant of angiogenesis, with greater VEGF-A/TSP-1 ratio promoting angiogenesis. Since endothelial cells are involved in the pathogenesis of insulin resistance through their role in insulin delivery and adipose tissue angiogenesis, we investigated the role of ECSCR (endothelial cell surface expressed chemotaxis and apoptosis regulator) – Akt axis. In this context, we studied effects of voluntary exercise in mice fed with a high fat diet (HFD) on the AT vascularization. We have demonstrated that 7 weeks-exercise training reduced epididymal and subcutaneous white adipose tissue (eWAT) and (sWAT) mass by 33% and 45% respectively compared to sedentary HFD mice and stimulated capillary growth in AT with a significant increased of capillaries/ adipocyte ratio on eWAT and sWAT (+16% and 28% respectively), associated with a significant VEGF-A/TSP-1 expression ratio increase. Furthermore, while ECSCR protein expression was decreased and associated to a lower ratio of PhosphoAkt/Akt in eWAT and sWAT of HFD mice in comparison to control mice, 7 weeks-exercise training led to a significant increase of ECSCR protein expression associated to the raise of PhosphoAkt/Akt ratio in both eWAT and sWAT. In addition, eWAT and sWAT thermogenic and metabolic activities were stimulated by 7 weeks-exercise training, with increased PGC-1α, Sirt-3 and PPARα in comparison to eWAT and sWAT from sedentary HFD mice. In conclusion, our results indicate that physical exercise acts as a pro-angiogenic stimulus in AT in favor of capillary growth, and that ECSCR – Akt axis as well as VEGF-A/TSP-1 play central role in angioadaptation of AT. The author hereby declares no conflict of interest

0149 : Antioxidant molecules of tea (Camellia sinensis) decrease hepatic lipogenesis and steatosis in a high fat-sucrose diet NAFLD rat model

Recent studies suggested that oxidative stress could trigger lipid accumulation in liver and thus subsequent development of hepatic steatosis which contributes to alter blood lipid level leading to increase cardiovascular risk factors. Tea has been described to prevent liver disorders and decrease cardiovascular risk. However, whether tea decreases oxidative stress and thus prevents hepatic steatosis has never been investigated. Therefore we aimed to investigate the effects of tea on oxidative stress and lipid accumulation in a rat model of high fatsucrose diet (HFS) induced metabolic syndrome (fed during 14 weeks) and in isolated rat hepatocytes.Wistar rats were randomly divided into three groups: Ctrl, HFS and HFS+Tea rats which had free access to tea infusion drink instead of water (n=15). Lipid profile of the liver, lipogenesis gene expression and oxidative stress were measured in each group of rat. Isolated hepatocytes were treated with the ROS inducer t-BHP in the presence or not of antioxidant tempol or tea. Then, superoxide anion production and lipid accumulation were measured using specific fluorescent probes. We reported that HFS diet-induced elevated hepatic lipid content by enhancing lipogenic gene expression in HFS rats compared to Ctrl ones. HFS diet-induced hepatic steatosis was attenuated by tea which was mainly associated with decrease hepatic oxidative stress and increased plasma total antioxidant capacity. The key role of antioxidant properties of tea in such phenomenon was confirmed in primary culture of rat hepatocytes. Indeed, we reported that increased ROS production with t-BHP resulted in lipid accumulation in hepatocytes, which was normalized by both tempol and tea. To conclude, we clearly reported that the antioxidant properties of tea protect rats from HFS diet-induced hepatic steatosis via its anti-lipogenesis effects. The consequence of such nutritional strategy on cardiovascular risk factor would constitute the next step of this work. The author declares a conflict of interest : Les travaux ont ete realises dans le cadre d’une bourse CIFRE Thes de la Pagode-Universite de Toulon

0229 : Aerobic exercise training modulates microparticles miRNAs: link to improved endothelial function and regulation of inflammation?

Exercise training is known to stimulate vascular function and remodeling in a shear stress and inflammation dependent manner. Microparticles (MPs) released from vascular cells in response to shear stress, play a role in cell-cell crosstalk through carrying bioactive molecules such as miRNAs. Thus, the aim of our study was to explore whether exercise training impacts vascular wall cells and contributes to vascular function improvement through the modulation of inflammation molecules release. Therefore, we investigated the presence in MPs of 9 inflammation-regulatory miRNAs. A group of sedentary women (n=6, BMI The author hereby declares no conflict of interest

0230 : Physical exercise angio-adaptation ameliorates metabolic dysfunction and inflammation in visceral adipose tissue of diet-induced obese mice

Adipose tissue (AT) homeostasis and growth are dependent on microvasculature. Adipose capillary bed displays a remarkable plasticity, a process called tissue angio-adaptation. In response to metabolic alterations linked to obesity, signaling pathways involved in vascular and microenvironment homeostasis maintenance of AT appear to be affected. We demonstrated that Mdm-2/FoxO1 axis had a key role in muscle angio-adaptive response to exercise affecting pro- (VEGF-A) and anti-angiogenic (TSP-1) factors expression. However, regulation of this process in AT occurring during obesity and/or physical exercise remains unknown. In this context, we studied effects of voluntary exercise in mice fed with a high fat diet (HFD) on the AT vascularization and microenvironment. Trained HFD mice after 7 week-exercise showed a 30% lower body fat mass and 33% reduced epididymal white adipose tissue (eWAT) mass compared to sedentary HFD mice. Histological analysis of eWAT revealed a decreased adipocyte size (-26%) combined with reduced fibrotic area per adipocyte (-45%) in trained HFD vs. sedentary HFD mice. Furthermore, 7 weeks of exercise training of HFD mice stimulated the angiogenesis process in AT with significant increased of capillaries/adipocyte ratio on eWAT (+16%) associated to VEGF-A/TSP-1 expression ratio and Mdm 2 protein expression while FoxO1 protein was decreased. In addition, eWAT inflammatory status evaluated by mRNA analysis indicated that CD11c (M1 macrophage marker), TNFα, IL-6 and leptin (pro-inflammatory cytokines) levels were decreased by 65%, 45% and 55% respectively in comparison to eWAT from sedentary HFD mice. A concomitant increase in Chil3 (M2 macrophage marker) (+84%) and IL-10 (anti-inflammatory cytokine) (+29%) were also observed. In conclusion, our results show that physical exercise acts as a pro-angiogenic stimulus in AT in favor of capillary growth, thru activation of Mdm 2 – FoxO1 and rise of VEGF-A/TSP-1 ratio ultimately promoting an improvement of AT microenvironment by reducing fibrosis, adipocyte hypertrophy and inflammation. The author hereby declares no conflict of interest

0117 : Microparticles-containing microRNAs: new players in the vascular endothelial dysfunction in obese patients

Microparticles (MPs) play essential roles in cell-cell crosstalk throw carrying bioactive molecules such as proteins and microRNAs (miRNAs). For this study, the MPs profile was explored in order to understand their implication in endothelial dysfunction in a group of obese (n=69, BMIe30Kg/m2) and normal weight subjects (n=46, BMI