Originally thought to be physiologically inert, artificial sweeteners are more and more recognized to alter various biological functions through their interaction with the sweet taste receptor in extraoral sites. Alarmingly, recent epidemiological data have shown that frequent consumption of artificial sweeteners (AS) is associated with an increased risk of vascular events. However, to date, no studies have tested the hypothesis that AS might directly impact the vasculature. The aim is to characterize the effect of the highly consumed AS, Sucralose and Acesulfame K (AceK), on the vascular wall. The specific objective of the present study is to focus on the vasomotor function. Biomolecular and functional investigations were performed on isolated rodent aortas, human dermal micro-arteries and omental arteries. Ex-vivo vasomotor function was assessed using isometric tension measurements in an organ bath system. Our preliminary data show that mRNA of both T1R2 and T1R3, the two subunits of the sweet taste receptor, are expressed in the vascular wall. Cumulative addition of AceK or sucralose revealed that high concentration (10 mM) of these molecules exert respectively vasoconstrictive and vasorelaxant properties on both rodent and human arteries. Lower concentrations (1 mM) of AceK were associated with an exacerbated vasoreactivity to the α1 adrenergic agonist phenylephrine. All these effects were independent of the presence of the endothelium. Surprisingly, T1R inhibition with gurmarin, as well as T1R3 invalidation (KO mice), had no consequence on sucralose and AceK vasoactive effects. Our work first show that AS can modulate smooth muscle vascular tone. The in-vivo significance and molecular mechanisms involved remain to be determined. Future investigations will also address other vascular functions to better understand the possible consequences of AS consumption on the cardiovascular system.

Atherosclerosis is a leading cause of mortality associated with endothelial dysfunction, oxidative stress and inflammation. One of the main risk factors is a Western diet rich in n-6 polyunsaturated fatty acids (n-6PUFA) which are sensitive to oxidation by heme iron of red meat in the gastrointestinal tract. This oxidation may increase 4-hydroxy-2-nonenal (4-HNE) formation, a cytotoxic aldehyde generated from n-6PUFA. Moreover, coupling of 4-HNE to LDL can lead to endothelial dysfunction and atherosclerosis development. By contrast, a diet rich in proanthocyanidins (PCs) (polyphenols, flavonoid class) is known to reduce oxidative stress as well as coronary artery disease.

Non-nutritive sweeteners (NNS) are increasingly used in food and beverages to replace high-energy, added sugars. By providing consumers with products that have a sweet taste and low-energy content, NNS appear to be the magic bullet to enhance weight loss and reduce cardiometabolic diseases. However, several recent studies have reported associations between NNS consumption and weight gain, increased incidence of type 2 diabetes, and cardiovascular events. We aimed to evaluate the effects of chronic NNS sucralose consumption on glucose metabolism and vascular function, well recognized as an early marker of cardiovascular disorders, in healthy or diet-induced obese mice. Sixty male C57BL/6JR mice were divided in four groups to follow a 12 weeks diet. Control group had access to normal chow diet (NC) and water, whereas three other consumed high fat diet (HF) with either access to water, or 10% sucrose solution, or 0.017% sucralose solution (Acceptable Daily Intake). Fasting glucose, insulin and glucose tolerance test as well as body composition has been measured. Ex vivo aortic vasomotor function of the aorta has been investigated with a pharmacological approach. Mice consuming HF diet and sucralose had a lower weight gain compared to other HF groups despite no difference in their caloric intake. Adiposity index as well as sub cutaneous fat was also decreased in this group. Moreover, sucralose consumption lead to an increased glucose tolerance and increased insulin sensitivity compared to other HF groups and comparable with NC group. Finally, sucralose chronic consumption also improved vascular endothelial function compared to the three other groups. Chronic sucralose consumption could restrain the deleterious effect of HF diet on body composition and blood glucose regulation, but also seems to moderately increase vascular function. Nevertheless, more study are needed to understand the underlying mechanisms.

Atherosclerosis is a leading cause of mortality in industrialized countries and is associated with endothelial dysfunction, oxidative stress and inflammation. One of the main risk factors is a pro-oxidant Western diet rich in ω-6 polyunsaturated fatty acids (ω-6 PUFA) which are sensitive to oxidation by heme iron of red meat in the gastrointestinal tract. This oxidation may increase 4-hydroxy-2-nonenal (4-HNE) formation, a cytotoxic aldehyde generated from ω-6 PUFA. Moreover, coupling of 4-HNE to LDL is a key step in atherosclerosis development. By contrast, a diet rich in proanthocyanidins (PCs) (polyphenols, flavonoid class) is known to reduce oxidative stress as well as coronary artery disease. Evaluate chronic pro-oxidant Western diet effects and the potential protective capacity of PCs on vascular function and atherosclerosis development in an ApoE-/- mouse model. ApoE-/- mice were fed with: high-fat/red meat (HF-RM); HF-RM + ω-6 PUFA; HF-RM + ω-6 PUFA supplemented with apple puree or a phenolic extract (0.06% w/w) for 12 weeks. We reported an increase in fecal 4-HNE formation associated with a rise in plasmatic 4-HNE and LDLox concentrations in ω-6 PUFA group. This increase was prevented by apple polyphenols supplementation. Moreover, adding oxidizable ω-6 PUFA to high fat diet worsens endothelial dysfunction, blood pressure and atheromatous plaque formation (136 vs. 166mm2 in HF-RM). However, necrotic core size, fibrosis and lipid accumulation in atheromatous plaque were not affected. Interestingly, both polyphenol supplementations prevented the exacerbation of endothelial dysfunction and atherosclerosis impairments which was associated with an increase in eNOS activity. Apple polyphenols limit the formation of absorbable lipid oxidation products during digestion (4-HNE) and consequently protect vascular integrity. Consumption of PC-rich fruits should thus be encouraged within the Western diet.

Recent prospective epidemiological studies highlighted the link between non-nutritive sweeteners (NNS) consumption and increase in cardiometabolic diseases risk. However, underlying mechanisms remain unknown. The aim of this study was to characterize, in a healthy rat population, the effect of chronic NNS consumption on body composition, metabolic parameters and vascular function, as an early marker for cardiovascular disease. Healthy Wistar rats (n = 15) followed a 10 weeks standard diet including water consumption sweetened or not with a sucralose/acesulfame potassium solution at different concentrations: 1 and 2 mg/kg/d, respectively (regular consumption) or 15 mg/kg/d, for both molecules (Acceptable Daily Intake ADI). Fasting glucose and lipid profile, insulin and glucose tolerance test as well as body composition has been measured. Ex vivo aortic vasomotor function has been investigated with a pharmacological approach. NNS consumption did not change total caloric or liquid intake. Both groups of NNS-treated rats showed an increased adiposity index, without total body mass modifications. Plasma HDL cholesterol and HDL/LDL ratio were reduced. No change was observed regarding glucose and insulin metabolism, in a fasting state or in response to an oral hyperglycemic challenge. Rats that consumed ADI intake of NNS revealed a significative vascular endothelial dysfunction compared to the other groups. These data seem exhibit changes in body composition and lipid metabolism, potentially linked to aortic endothelial dysfunction observed after 10 weeks of NNS treatment in healthy rats. These results need to be completed providing a better understanding in the physiological impact of chronic consumption of NNS in healthy individuals but also in patients with cardiovascular or metabolic disease. These findings will help to revisit safety and regulatory status of these NNS as requested by the European Food Safety Authority.

Overconsumption of sugar has recently been implicated in the pathogenesis of cardiovascular pathologies. Previously, we managed to confirm that an acute hyperglycemia may decrease vascular function even in healthy young adults and that oxidative stress seems to be the main factor leading to vascular dysfunction. According to recent literature on other tissues, this oxidative stress would be dependent of sodium-glucose cotransporters (SGLT/SMIT) activation by hyperglycemia. Consequently, this study investigated the potential expression of these cotransporters in vascular tissues and their involvement in oxidative stress impairments of vascular function during acute hyperglycemia. First SGLT1, SGLT2 and SMIT1 expressions were evaluated, in aortas of Wistar rats by Western blot. Then vascular function was evaluated in aortic rings from Wistar rats (n = 20) mounted in an organ chamber to evaluate endothelium dependent vasodilatation (ACh 10−10 to 10−5M). This evaluation was performed in normoglycemic (11 mM) and hyperglycemic (100 mM) conditions in presence or not of an antioxidant (NAC 10 μM) or an NADPH inhibitor (Apocynin 10 μM). Implication of SGLT/SMITs and glucose transporter (GLUT) activities were assessed through their inhibition by respectively phlorizin (1 mM) and phloretin (1 mM). Our first results managed to confirm the deleterious effects of hyperglycemia on vascular function and the role of oxidative stress was pointed out through the protective effects of antioxidants. Secondly, we managed to demonstrate that SGLT1/2 and SMIT1 are expressed in aortic tissues. Moreover, SGLT/SMIT inhibition by phlorizin managed to protect endothelial function in hyperglycemic condition. Such protective effect was not observed when GLUT transporters were inhibited. Those results points out the involvement of sodium glucose cotransporters in the oxidative damaged induced by hyperglycemia while excluding GLUT implication.

The Obstructive Sleep Apnea Syndrome (OSAS) features intermittent upper airway occlusions during sleep, leading to intermittent hypoxia (IH) and blood oxygen desaturation. OSAS affects up to 38% of the population (up to 49% in the elderly), and mainly concerns males. OSAS has severe detrimental effects on the cardiovascular system, such as hypertension and increased risk of cardiac infarct. In this study, we assessed the impact of ageing on the IH-induced deleterious effects in the aorta of aged and adult (24 and 6 months old) mice, male and female, exposed to IH (8 hours/day, 1 minute cycles, alternating 30 s at 21% O2 and 30 s at 5% O2 in 6 months old and 10% O2 in 24 months old mice) or normoxia (21% O2) for 14 days. Using the techniques of pressure-arteriography and two-photon microscopy, we have shown that both IH and age affect the mechanical and structural properties of the aorta, with gender-dependent characteristics. IH and ageing induce disruptions in and disorganization of the aortic elastic fibres, although differently in males and females. While IH and age increase the aorta diameter in both gender, they generally decrease aortic thickness and increase rigidity in females only, while, in males, the impacts of hypoxia are different as a function of age. The aortic reactivity is also differentially impacted by IH as a function of gender and age, with a higher acetylcholine-induced vasodilation in IH aged females and a higher phenylephrine(PE)-induced constriction in IH adult males. The latter fits with the higher PE-induced increase in intracellular calcium level that we measured in cultured vascular smooth muscle cells from IH adult males. These results emphasize on the fact that OSAS has different impacts on the mouse cardiovascular system, depending on both age and gender. These new findings should be verified in patients, in order to optimize the therapeutic strategy for each age and gender groups.