Search

International audience; Despite long traditional utilization and some reports on the antihyperglycemic and antihyperlipidemic action of Cassia siamea, the mechanisms involved have not been investigated yet. Thus, the objective of the present study was to investigate whether and how oral administration of the ethanolic extract of Cassia siamea Lam leaves (LECS) improves glucose and insulin homoeostasis, liver damage, and endothelial dysfunction in an experimental model of type 2 diabetes, the leptin-deficient ob/ob mice. Oxidative stress and protein expression of insulin-dependent and insulin -independent signaling pathways were studied. Obese ( ob/ob) vs. control (ob/+) mice were treated daily with intragastric administration of either vehicle or LECS (200 mg/kg, per day) for 4 weeks. Fasting blood glucose, body weight, food intake, glucose and insulin tolerance, oxidative stress, and liver damage as well as vascular complications with respect to endothelial dysfunction were examined. Administration of LECS in obese mice significantly reduced blood glucose and insulin levels, improved glucose tolerance and insulin sensitivity, and restored the increase of circulating AST and ALT without modification of body weight and food intake. These effects were associated with increased activity of both insulin and AMPK pathways in the liver and skeletal muscles. Of particular interest, administration of LECS in obese mice completely prevented the endothelial dysfunction resulting from an increased NO· and decreased reactive oxygen species (ROS) production in the aorta. Altogether, oral administration of LECS remarkably attenuates features of type 2 diabetes on glucose, hepatic inflammation, insulin resistance, endothelial function, and vascular oxidative stress, being as most of these effects are related to insulin-dependent and insulin-independent mechanisms. Therefore, this study points for the therapeutic potential of Cassia siamea in correcting both metabolic and vascular alterations linked to type 2 diabetes.

Carrots’ genotype and growing conditions influence their potential properties to fight against cardiovascular and metabolic diseases. The present study evaluated the influence of carrot genotypes contrasted by root color (Bolero, Presto, Karotan, Deep Purple, Kintoki and Blanche des Vosges) growing under standard, water-restricted, biotic stress (Alternaria dauci inoculation), and combined stress conditions (water restriction and A. dauci inoculation). The effect of carrots’ polyphenol and carotenoid content was assessed on endothelial and smooth muscle cells, hepatocytes, adipocytes and macrophages functions (oxidative stress, apoptosis, proliferation, lipid accumulation and inflammation). Independently of varieties or growing conditions, all carrot extracts affected vascular cells’ oxidative stress and apoptosis, and metabolic cells’ oxidative stress and lipid accumulation. Three clusters were revealed and displayed beneficial properties mostly for adipocytes function, smooth muscle cells and hepatocytes, and endothelial cells and hepatocytes, respectively. Karotan and Presto varieties exhibited endothelial tropism while Blanche des Vosges targeted adipocytes. Carrots under biotic stress are more efficient in inducing beneficial effects, with the Bolero variety being the most effective. However, extracts from carrots which grew under combined stress conditions had limited beneficial effects. This report underscores the use of certain carrot extracts as potential effective nutraceutical supplements for metabolic diseases.

Metabolic pathologies such as diabetes and obesity are associated with decreased level of circulating and bone marrow (BM)‐derived endothelial progenitor cells (EPCs). It is known that activation of peroxisome proliferator‐activated receptor alpha (PPARα) may stimulate cell differentiation. In addition, microparticles (MPs), small membrane vesicles produced by activated and apoptotic cells, are able to reprogram EPCs. Here, we evaluated the role of MPs carrying PPARα on both phenotype and function of progenitor cells from mice fed with a high‐fat diet (HFD). HFD reduced circulating EPCs and, after 7 days of culture, BM‐derived EPCs and monocytic progenitor cells from HFD‐fed mice displayed impaired differentiation. At the same time, we show that MPs bearing PPARα, MPsPPARα+/+, increased the differentiation of EPCs and monocytic progenitors from HFD‐fed mice, whereas MPs taken from PPARα knockout mice (MPsPPARα–/–) had no effect on the differentiation of all types of progenitor cells. Furthermore, MPsPPARα+/+ increased the ability of progenitor cells to promote in vivo angiogenesis in mice fed with HFD. The in vitro and in vivo effects of MPsPPARα+/+ were abolished in presence of MK886, a specific inhibitor of PPARα. Collectively, these data highlight the ability of MPs carrying PPARα to restore the failed differentiation and functionality of BM‐derived cells induced by HFD. stem cells translational medicine 2018;7:135–145

International audience; Delphinidin, an anthocyanin present in red wine, has been reported to preserve the integrity of endothelium via an estrogen receptor alpha (ERα)-dependent mechanism. However, the effect of delphinidin on the immune response in obesity-related inflammation remains unknown. Given the important role of T lymphocytes in obesity-related inflammation, we investigated the effect of delphinidin on proliferation and differentiation of T lymphocytes from healthy subjects and metabolic syndrome patients. Delphinidin decreased the proliferation stimulated by different agents acting through different mechanisms. This effect of delphinidin was associated with its ability to inhibit Ca2+ signaling via reduced store-operated Ca2+ entry and release, and subsequent decrease of HDAC and NFAT activations. Delphinidin also inhibited ERK1/2 activation. Pharmacological inhibition of ER with fulvestrant, or deletion of ERα, prevented the effect of delphinidin. Further, delphinidin suppressed the differentiation of T cells toward Th1, Th17 and Treg without affecting Th2 subsets. Interestingly, delphinidin inhibited both proliferation and differentiation of T cells taken from patients with cardiovascular risks associated with metabolic syndrome. Together, we propose that delphinidin, by acting on ERα via multiple cellular targets, may represent a new approach against chronic inflammation associated with T lymphocyte activation, proliferation and differentiation, in patients with cardiovascular risk factors.

Traditional remedies prepared from Lannea microcarpa leaves, barks, roots, and fruits are used to treat many diseases including hypertension. This study investigated whether oral administration of the ethyl acetate fraction of Lannea microcarpa trunk barks (LMAE) corrects angiotensin (Ang) II-induced hypertension in mice. Its effects on vascular function were specifically investigated. Experiments explored hemodynamic and echocardiographic parameters in vivo and vascular reactivity to acetylcholine (ACh) and CaCl2 ex vivo on isolated aortas. Mice received LMAE for 3 weeks (50 mg/kg/day) by oral gavage. In the last two weeks of treatment, mice were implanted with osmotic minipumps delivering NaCl (0.9%) or Ang II (0.5 mg/kg/day). LMAE completely prevented the increase in systolic and diastolic blood pressure induced by Ang II. Echocardiographic and kidney parameters were not affected by the different conditions. LMAE abrogated Ang II-induced impairment of ACh-induced relaxation without affecting that of sodium nitroprusside. LMAE also completely prevented CaCl2-induced contraction in KCl-exposed aorta ex vivo. The extract alone did not modify superoxide (O2 −) and nitric oxide (NO·) production in femoral arteries from control mice but significantly limited Ang II-induced O2 − production. These effects were associated with reduced expression of inducible isoform of cyclooxygenase- (COX-) 2 and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase isoform NOX-2 in aortas. Finally, phytochemical analysis showed that LMAE contains sterols, triterpenes, coumarins, and anthraquinone. These results showed that LMAE prevents Ang II-induced hypertension and vascular dysfunction through a reduction of oxidative stress linked to COX-2 and NOX-2 pathway and inhibition of calcium entry. This study provides pharmacological basis of the empirical use of Lannea microcarpa trunk bark extract against hypertension.

International audience; Red wine polyphenol extracts improve cardiovascular and metabolic disorders linked to obesity. Their vascular protection is mediated by the activation of the alpha isoform of the estrogen receptor (ERα). In the present study, we explored the effects of a grape seed extract (GSE) enriched in the flavan-3-ols procyanidin dimers on obesity-related cardiovascular and metabolic disorders; with a particular interest in the role/contribution of ERα. Ovariectomized wild type or ERα knockout (KO) mice were fed with standard or western diet, supplemented or not with GSE, for 12 weeks. Their body weight was monitored throughout the study, and an echocardiography was performed at the end of the treatment. Blood and tissues were collected for biochemical and functional analysis, including nitric oxide and oxidative stress measurement. Vascular reactivity and liver mitochondrial complexes activity were also analyzed. In western diet-fed mice, GSE reduced adiposity, plasma triglycerides, and oxidative stress in the heart, liver, adipose and skeletal tissues; but did not improve the vascular dysfunction. In western diet-fed mice, ERα deletion prevented or reduced the beneficial effects of GSE on plasma triglycerides and visceral adiposity. ERα deletion also prevented/reduced the anti-oxidant effect of GSE in the liver, but did not affect its capacity to reduce oxidative stress in the heart and adipose tissue. In conclusion, dietary supplementation of GSE attenuated features of metabolic syndrome partially through ERα-dependent mechanisms. This report highlights the therapeutic potential of polyphenols, and especially extract enriched in procyanidin dimers, against the metabolic disorders associated with excessive energy intake.

National audience

International audience; Microvesicles (MVs) are small membrane-derived fragments shed from various cell types during activation and/or apoptosis and represent a new class of biological information mediators. MVs generated from T lymphocytes undergoing activation and apoptosis exert a beneficial potential effect on the cardiovascular system through their dual capacity to increase nitric oxide and reduce reactive oxygen species production. This study investigated the effect of MVs on the apoptosis of human umbilical vein endothelial cells triggered by actinomycin D (Act D). The effect of Act D treatment on reactive oxygen species (ROS) production was biphasic. Indeed, ROS levels significantly increased during the early phase of apoptosis (2 h) and after 10 h of treatment, but not at 4, 8 and 24 h. MVs significantly attenuated the increase in ROS production induced by Act D at 2 h, but not at 10 h, indicating that they normalize ROS production during the early phase of apoptosis by acting directly as ROS scavengers, owing to their ability to carry active antioxidant enzymes such as catalase and the three isoforms of the superoxide dismutase. Furthermore, the effects of MVs on the late phases of apoptosis were associated with the ability of these vesicles to increase the expression of manganese-superoxide dismutase, probably by the transfer of its mRNA, in endothelial cells, through internalization process. These findings illustrate new mechanisms by which MVs from T lymphocytes exert their vasculo-protective effects by improving endothelial function under pathological conditions in which apoptosis and oxidative stress are enhanced.

International audience; Microparticles (MPs), small membrane-derived fragments shed from various cell types during activation and/or apoptosis, represent a new class of biological information mediators. MPs generated from T lymphocytes undergoing activation and apoptosis exert a beneficial potential effect on the cardiovascular system through their dual capacity to increase nitric oxide and reduce reactive oxygen species production. This study investigated the effect of MPs on both the angiogenesis and apoptosis of human umbilical vein endothelial cells. MPs induced the formation of capillary-like structures in an in vitro model, by regulating cell proliferation. Both cell adhesion and expression of proteins involved in this process, such as Rho A, and phosphorylation of focal-activated kinase were increased by MPs, via a ROCK inhibitor-sensitive pathway. MPs increased mRNA and protein levels of pro-angiogenic factors as measured by qRT-PCR and western blot. MPs significantly attenuated the increase in reactive oxygen species (ROS) associated with Act D-induced apoptosis at early phase of apoptosis (2 h), by acting directly as ROS scavengers, owing to their ability to carry active antioxidant enzymes such as catalase and the 3 isoforms of the superoxide dismutase. Furthermore, the effects of MPs on the late phases of apoptosis were associated with the ability of these vesicles to increase the expression of manganese-superoxide dismutase through internalisation process. Interestingly, the effects induced by MPs on the formation of capillary-like structures, expression of adhesion molecules and pro-angiogenic factors and on apoptosis were reversed when Sonic Hedgehog signalling was pharmacologically inhibited with cyclopamine. These findings illustrate new mechanisms by which MPs from T lymphocytes exert their vasculo-protective effects by improving endothelial function under pathological conditions in which cell integrity is impaired.

National audience

National audience

International audience; Neovascularization represents a pivotal process consisting in the development of vascular network during embryogenesis and adult life. Postnatally, it arises mainly through angiogenesis, which has physiological and pathological roles in health and disease. Blood vessel formation results as tightly regulated multistep process which needs coordination and precise regulation of the balance of proangiogenic and antiangiogenic factors.Sonic Hedgehog (SHH), a morphogen belonging to Hedgehog (HH) family proteins, is implicated in a remarkably wide variety of process, including vessel development. Recent evidence demonstrate that, in addition to the classic factors, microvesicles (MVs), both microparticles (MPs) and exosomes, small vesicles released distinct cellular compartments, are involved in modulation of neovascularization. MPs generated from T lymphocytes undergoing both activation and apoptosis harbor at their surface SHH and play a crucial role in modulation of neovascularization. They are able to modulate the different steps implicated in angiogenesis process in vitro and to enhance postischemic neovascularization in vivo. As the consequence, we suggest that the MPs carrying SHH contribute to generation of a vascular network and may represent a new therapeutic approach to treat pathologies associated with failed angiogenesis.

National audience; Red wine polyphenol (RWPC) extracts has been reported to possess vasoprotective properties that involve nitric oxide (NO) release from endothelial cells via a redox- sensitive pathway. Besides, the molecular target of RWPC to release NO has been recently revealed and it involves the activation of the estrogen receptor alpha (ERα). Paradoxical effects of RWPC have been shown with regard to angiogenesis. Indeed in a rat model of postischemic neovascularization, low- dose is pro- whereas high dose is anti- angiogenic. NO and ERαare key regulators of mitochondrial function. Furthermore, angiogenesis is a highly energetic process associated with mitochondrial biogenesis. However, whether RWPC induces changes in mitochondrial function has never been addressed and it is the aim of this study.The effects of RWPC at low concentration (10- 4 g/l, LCP) and high concentration (10- 2 g/l, HCP) after 48 hours time exposure were investigated on human endothelial cells. Mitochondrial respiration, expression of biogenesis factors and DNA content was assessed using oxygraphy and qRT- PCR, respectively. In vitro capillary formation using Matrigel® was performed. The mechanism involved with respect to ER using the ER- antagonist fulvestrant was studied. The involvement of both NADPH oxidase and NO synthase was addressed using apocynin and L- NA respectively.LCP, but not HCP, increased mitochondrial respiration. The effect of LCP was associated with an increase of both expression of several mitochondrial biogenesis factors (NRF- 1, NRF- 2, ERRα, Tfam, PolG) and mitochondrial DNA content whereas HCP had no effect on these parameters. All the effects of LCP on mitochondrial respiration are prevented by fulvestrant, apocynin and L- NA. LCP also promoted in vitro capillary elongation that was prevented by fulvestrant, apocynin and L- NA. Finally, the inhibition of mitochondrial protein synthesis using chloramphenicol suppressed the pro- angiogenic property of LCP.The present study highlights the implication of the axis ER, NADPH oxidase and NOS pathways on both increase mitochondrial function and capillary elongation in response to RWPC at low concentration. They explain the paradoxical effect of RWPC depending on the concentration with respect to angiogenesis, mitochondria being key targets for its pro- angiogenic properties.