Endothelial mechanotransduction proteins and vascular function are altered by dietary sucrose supplementation in healthy young male subjects

Short-term dietary intervention improves endothelial dysfunction induced by high-fat feeding in mice through upregulation of the AMPK-CREB signaling pathway

AIM

In addition to functioning as an energy sensor switch, AMPK plays a key role in the maintenance of cardiovascular homeostasis. However, obesity disrupts AMPK signaling, contributing to endothelial dysfunction and cardiovascular disease. This study aimed to elucidate if a short-term dietary intervention consisting in replacing the high-fat diet with a standard diet for 2 weeks could reverse obesity-induced endothelial dysfunction via AMPK-CREB activation.

METHODS

For this, 5-week-old male C57BL6J mice were fed a standard (Chow) or a high-fat (HF) diet for 8 weeks. The HF diet was replaced by the chow diet for the last 2 weeks in half of HF mice, generating 3 groups: Chow, HF and HF-Chow. Vascular reactivity and western-blot assays were performed in the thoracic aorta.

RESULTS

Returning to a chow diet significantly reduced body weight and glucose intolerance. Relaxant responses to acetylcholine and the AMPK activator (AICAR) were significantly impaired in HF mice but improved in HF-Chow mice. The protein levels of AMPKα, p-CREB and antioxidant systems (heme oxygenase-1 (HO-1) and catalase) were significantly reduced in HF but normalized in HF-Chow mice.

CONCLUSION

Improving dietary intake by replacing a HF diet with a standard diet improves AMPK-mediated responses due to the upregulation of the AMPK/CREB/HO-1 signaling pathway.

Biomechanical and Mechanobiological Drivers of the Transition From PostCapillary Pulmonary Hypertension to Combined Pre-/PostCapillary Pulmonary Hypertension

Combined pre-/postcapillary pulmonary hypertension (Cpc-PH), a complication of left heart failure, is associated with higher mortality rates than isolated postcapillary pulmonary hypertension alone. Currently, knowledge gaps persist on the mechanisms responsible for the progression of isolated postcapillary pulmonary hypertension (Ipc-PH) to Cpc-PH. Here, we review the biomechanical and mechanobiological impact of left heart failure on pulmonary circulation, including mechanotransduction of these pathological forces, which lead to altered biological signaling and detrimental remodeling, driving the progression to Cpc-PH. We focus on pathologically increased cyclic stretch and decreased wall shear stress; mechanotransduction by endothelial cells, smooth muscle cells, and pulmonary arterial fibroblasts; and signaling-stimulated remodeling of the pulmonary veins, capillaries, and arteries that propel the transition from Ipc-PH to Cpc-PH. Identifying biomechanical and mechanobiological mechanisms of Cpc-PH progression may highlight potential pharmacologic avenues to prevent right heart failure and subsequent mortality.

Elevated shear rate-induced by exercise increases eNOS ser1177 but not PECAM-1 Tyr713 phosphorylation in human conduit artery endothelial cells

Although evidence demonstrates the fundamental role of shear stress in vascular health, predominantly through the release of nitric oxide (NO), the mechanisms by which endothelial cells (EC)s sense and transduce shear are poorly understood. In cultured ECs tyrosine phosphorylation of PECAM-1 has been shown to activate eNOS in response to shear stress. However, in the human skeletal muscle microcirculation PECAM-1 was not activated in response to exercise or passive leg movement. Given this contradiction, this study aimed to assess the effect of exercise on conduit artery PECAM-1 and eNOS activation in humans. Eleven males were randomised to two groups; 30 minutes of handgrip exercise (n = 6), or a time-control group (n = 5). Protein content of eNOS and PECAM-1, alongside eNOS Ser¹¹⁷⁷ and PECAM-1 Tyr⁷¹³ phosphorylation were assessed in ECs obtained from the radial artery pre- and post-intervention. Handgrip exercise resulted in a 5-fold increase in mean shear rate in the exercise group, with no change in the control group (group*time, P < 0.001). There was a 54% increase in eNOS Ser¹¹⁷⁷ phosphorylation in the exercise group, when compared to control group (group*time, P = 0.016), but no change was reported in PECAM-1 Tyr⁷¹³ phosphorylation in either group (group*time, P > 0.05). eNOS and PECAM-1 protein content were unchanged (group*time, P > 0.05). Our data show that exercise-induced elevations in conduit artery shear rate increase eNOS Ser¹¹⁷⁷ phosphorylation but not PECAM-1 Tyr⁷¹³ phosphorylation. This suggests PECAM-1 phosphorylation may not be involved in the vascular response to acute but prolonged elevations in exercise-induced shear rate in conduit arteries of healthy, active men.

Redox balance in human skeletal muscle-derived endothelial cells - Effect of exercise training

Aerobic training can improve vascular endothelial function in-vivo. The aim of this study was to elucidate the mechanisms underlying this improvement in isolated human microvascular endothelial cells. Sedentary males, aged 57 ± 6 years completed 8 weeks of intense aerobic training. Resting muscle biopsies were obtained from the thigh muscle and used for isolation of endothelial cells (pre n = 23, post n = 16). The cells were analyzed for mitochondrial respiration, H₂O₂ emission, glycolysis, protein levels of antioxidants, NADPH oxidase, endothelial nitric oxide (NO) synthase and prostacyclin synthase (PGI₂S). In-vivo microvascular function, assessed by acetylcholine infusion and arterial blood pressure were also determined. Endothelial mitochondrial respiration and H₂O₂ formation were similar before and after training whereas the expression of superoxide dismutase and the expression of glutathione peroxidase were 2.4-fold (p = 0.012) and 2.3-fold (p = 0.006) higher, respectively, after training. In-vivo microvascular function was increased by 1.4-fold (p = 0.036) in parallel with a 2.1-fold increase in endothelial PGI₂S expression (p = 0.041). Endothelial cell glycolysis was reduced after training, as indicated by a 65% lower basal production of lactate (p = 0.003) and a 30% lower expression of phosphofructokinase (p = 0.011). Subdivision of the participants according to blood pressure at base-line (n = 23), revealed a 2-fold higher (p = 0.049) rate of H₂O₂ production in endothelial cells from hypertensive participants. Our data show that exercise training increases skeletal muscle microvascular endothelial cell metabolism, antioxidant capacity and the capacity to form prostacyclin. Moreover, elevated blood pressure is associated with increased endothelial mitochondrial ROS formation.

Dietary sugars and subclinical vascular damage in moderate-to-high cardiovascular risk adults

BACKGROUND AND AIMS

The association between dietary sugars and vascular damage has been scarcely examined out of the context of established cardiovascular disease. We aimed to investigate the association between different types of sugars with subclinical atheromatosis and arteriosclerosis, in individuals free of cardiovascular disease being, however, at moderate-to-high cardiovascular risk.

METHODS AND RESULTS

Two 24-h dietary recalls were conducted to estimate sugars intake. Subclinical atheromatosis was assessed by B-mode ultrasonography and arteriosclerosis (arterial stiffness) via tonometry (carotid-to-femoral pulse wave velocity). Multiple logistic regression analysis was performed to determine the relationship of quartiles of total sugars, monosaccharides and disaccharides with atheromatosis and arteriosclerosis, adjusting for potential confounders [Odds Ratio (95%Confidence Interval)]. In 901 participants (52.4 ± 13.8 years, 45.2% males), total sugars intake was not associated with any type of subclinical vascular damage. Subjects at 4th quartile of lactose intake (15.3 ± 5.5 g/day) had lower probability to present atheromatosis compared to those at 1st quartile (0.00 ± 0.01 g/day) even in the fully adjusted model [0.586 (0.353-0.974)]. Subjects at 3rd quartile of total disaccharides intake and particularly sucrose (15.1 ± 2.2 g/day) had higher probability to present arteriosclerosis compared to those at 1st quartile (3.0 ± 1.9 g/day) even after adjustment for all potential confounders [2.213 (1.110-4.409)].

CONCLUSIONS

Overall, the present data suggest a distinct role of each type of sugars on vascular damage. These observations highlight the need for further studies investigating not only foods rich in sugars, but sugars as separate components of food as they probably contribute via different ways on the development of arterial pathologies.

Cytoskeletal Remodeling Mimics Endothelial Response to Microgravity

Mechanical cues contribute to the maintenance of a healthy endothelium, which is essential for vascular integrity. Indeed endothelial cells are mechanosensors that integrate the forces in the form of biochemical signals. The cytoskeleton is fundamental in sensing mechanical stimuli and activating specific signaling pathways. Because the cytoskeleton is very rapidly remodeled in endothelial cells exposed to microgravity, we investigated whether the disruption of actin polymerization by cytochalasin D in 1g condition triggers and orchestrates responses similar to those occurring in micro- and macro-vascular endothelial cells upon gravitational unloading. We focused our attention on the effect of simulated microgravity on stress proteins and transient receptor potential melastatin 7 (TRPM7), a cation channel that acts as a mechanosensor and modulates endothelial cell proliferation and stress response. Simulated microgravity downregulates TRPM7 in both cell types. However, 24 h of treatment with cytochalasin D decreases the amounts of TRPM7 only in macrovascular endothelial cells, suggesting that the regulation and the role of TRPM7 in microvascular cells are more complex than expected. The 24 h culture in the presence of cytochalasin D mimics the effect of simulated microgravity in modulating stress response in micro- and macro-vascular endothelial cells. We conclude that cytoskeletal disruption might mediate some effects of microgravity in endothelial cells.

Structural analysis and prediction of potent bioactive molecule for eNOS protein through molecular docking

Reactive oxygen species by uncoupled eNOS is linked to endothelial dysfunction. Ellagic acid (EA), a polyphenol possesses numerous biological activities including radical scavenging. whether EA exerts a vasculo-protective effect via antioxidant mechanisms in blood vessels remains unknown. Molecular docking provides an initial model of protein and molecular interactions in various physiological and/or pathological functions. To identify a eNOS modulatory biomolecule through molecular docking as possible vascular protective agent. On the basis of binding affinities and other physicochemical features, a molecular docking-based approach was used to classify and evaluate eNOS binding micronutrients found in natural sources, Lipinski's rule was used taking into account their adsorption, delivery, metabolism, and excretion (ADME). An insilico approach focused on the ligand-protein interaction technique to determine the therapeutic potential of certain phytochemical-based drugs for the vascular remodelling.20 bioactive molecules were screened, docking analysis on human eNOS proteins was performed. The best poses for target protein was established based on binding energy and inhibition constant. EA and caffeine acid are the strongest candidates for eNOS protein functional norms. This provides a novel insight into the interaction properties of known human eNOS protein with EA and used as a therapeutic agent in various pathologies. Predicting interaction of ellagic acid with eNOS protein by molecular docking in endothelial dysfunction.

High metabolic substrate load induces mitochondrial dysfunction in rat skeletal muscle microvascular endothelial cells

The influence of glucose and palmitic acid (PA) on mitochondrial respiration and emission of hydrogen peroxide (H2 O2 ) was determined in skeletal muscle-derived microvascular endothelial cells. Measurements were assessed in intact and permeabilized (cells treated with 0.025% saponin) low passage endothelial cells with acute-or prolonged (3 days) incubation with regular (1.7 mM) or elevated (2.2 mM) PA concentrations and regular (5 mM) or elevated (11 mM) glucose concentrations. In intact cells, acute incubation with 1.7 mM PA alone or with 1.7 mM PA + 5 mM glucose (p < .001) led to a lower mitochondrial respiration (p < 0.01) and markedly higher H2 O2 /O2 emission (p < 0.05) than with 5 mM glucose alone. Prolonged incubation of intact cells with 1.7 mM PA +5 mM glucose led to 34% (p < 0.05) lower respiration and 2.5-fold higher H2 O2 /O2 emission (p < 0.01) than incubation with 5 mM glucose alone. Prolonged incubation of intact cells with elevated glucose led to 60% lower (p < 0.05) mitochondrial respiration and 4.6-fold higher H2 O2 /O2 production than incubation with 5 mM glucose in intact cells (p < 0.001). All effects observed in intact cells were present also in permeabilized cells (State 2). In conclusion, our results show that acute and prolonged lipid availability, as well as prolonged hyperglycemia, induces mitochondrial dysfunction as evidenced by lower mitochondrial respiration and enhanced H2 O2/ O2 emission. Elevated plasma substrate availability may lead to microvascular dysfunction in skeletal muscle by impairing endothelial mitochondrial function.

Impact of Nutritional Epigenetics in Essential Hypertension: Targeting microRNAs in the Gut-Liver Axis

PURPOSE OF REVIEW

To review the current knowledge on interactions between dietary factors and microRNAs (miRNAs) in essential hypertension (EH) pathogenesis.

RECENT FINDINGS

There exists an integration of maintenance signals generated by genetic, epigenetic, immune, and environmental (e.g., dietary) factors that work to sustain balance in the gut-liver axis. It is well established that an imbalance in this complex, intertwined system substantially increases the risk for EH. As such, pertinent research has been taken to decipher how each signal operates in isolation and together in EH progression. Recent literature indicates that both macro- and micronutrients interrupt regulatory miRNA expressions and thus, alter multiple cellular processes that contribute to EH and its comorbidities. We highlight how carbohydrates, lipids, proteins, salt, and potassium modify miRNA signatures during EH. The disruption in miRNA expression can negatively impact communication systems such as over activating the renin-angiotensin-aldosterone system, modulating the vascular smooth muscle cell phenotype, and promoting angiogenesis to favor EH. We also delineate the prognostic value of miRNAs in EH and discuss the pros and cons of surgical vs dietary prophylactic approaches in EH prevention. We propose that dietary-dependent perturbation of the miRNA profile is one mechanism within the gut-liver axis that dictates EH development.

Sucrose-Sweetened Drinks Reduce the Physical Performance and Increase the Cardiovascular Risk in Physically Active Males

INTRODUCTION

The intake of sugar-sweetened beverages (SSBs) has increased rapidly, but the effects of this habit on health and physical performance are unknown. This study assessed the effect of excessive SSB intake on biochemical, physical performance, and biochemical and cardiovascular parameters of physically active males.

METHODS

Seventeen volunteers consumed a placebo drink (Pd; carbohydrate free) and an excessive SSB drink (eSSBd = Pd plus 300 g sucrose). In a blind randomized crossover study, the subjects were assigned to Pd or eSSBd groups for 15 days. After an interval of 7 days, subjects were reassigned to the other condition.

RESULTS

After eSSBd intake, there was an increase in weight (69.34 ± 13.71 vs. 70.62 ± 14.06), body mass index (24.49 ± 4.01 vs. 24.97 ± 4.13), waist circumference (75.33 ± 11.22 vs. 76.79 ± 11.51), VLDL (19.54 ± 9.50 vs. 25.52 ± 11.18), triglycerides (78.94 ± 23.79 vs. 114.77 ± 43.65), and peak systolic blood pressure (178.57 ± 26.56 vs. 200.71 ± 24.64). The cardiorespiratory response to exercise (VO2max) (48.15 ± 10.42 vs. 40.98 ± 11.20), peak heart rate (186.64 ± 8.00 vs. 179.64 ± 6.28), total exercise time (15.02 ± 1.57 vs. 14.00 ± 2.18), and mechanical work (15.83 ± 4.53 vs. 13.68 ± 5.67) decreased after eSSBd intake (all values expressed in initial mean ± DP vs. final). The rates of perceived exertion were higher (1.300 vs.1.661 slope and -0.7186 vs. -1.118 y-intercept) after eSSBd intake.

CONCLUSION

The present study shows that 15 days of eSSBd intake may negatively modulate biochemical parameters associated with cardiovascular risk. In addition, this overintake can impair the physical performance and cardiovascular responses to physical exercise.

Hormetic modulation of angiogenic factors by exercise-induced mechanical and metabolic stress in human skeletal muscle

This study used an integrative experimental model in humans to investigate whether muscle angiogenic factors are differentially modulated by exercise stimuli eliciting different degrees of mechanical and metabolic stress. In a randomized crossover design, 12 men performed two low-volume high-intensity exercise regimens, including short sprint intervals (SSI) or long sprint intervals (LSI) inducing pronounced mechanical/metabolic stress, and a high-volume moderate-intensity continuous exercise protocol (MIC) inducing mild but prolonged mechanical/metabolic stress. Gene and protein expression of angiogenic factors was determined in vastus lateralis muscle samples obtained before and after exercise. Exercise upregulated muscle VEGF mRNA to a greater extent in LSI and MIC compared with SSI. Analysis of angiogenic factors sensitive to shear stress revealed more marked exercise-induced VEGF receptor 2 (VEGF-R2) mRNA responses in MIC than SSI, as well as greater platelet endothelial cell adhesion molecule (PECAM-1) and endothelial nitric oxide synthase (eNOS) mRNA responses in LSI than SSI. No apparent exercise-induced phosphorylation of shear stress-sensory proteins VEGF-R2^Tyr1175, PECAM-1^Tyr713, and eNOS^Ser1177 was observed despite robust elevations in femoral artery shear stress. Exercise evoked greater mRNA responses of the mechanical stretch sensor matrix metalloproteinase-9 (MMP9) in SSI than MIC. Exercise-induced mRNA responses of the metabolic stress sensor hypoxia-inducible factor-1α (HIF-1α) were more profound in LSI than SSI. These results suggest that low-volume high-intensity exercise transcriptionally activates angiogenic factors in a mechanical/metabolic stress-dependent manner. Furthermore, the angiogenic potency of low-volume high-intensity exercise appears similar to that of high-volume moderate-intensity exercise, but only on condition of eliciting severe mechanical/metabolic stress. We conclude that the angiogenic stimulus produced by exercise depends on both magnitude and protraction of myocellular homeostatic perturbations.NEW & NOTEWORTHY Skeletal muscle capillary growth is orchestrated by angiogenic factors sensitive to mechanical and metabolic signals. In this study, we employed an integrative exercise model to synergistically target, yet to different extents and for different durations, the mechanical and metabolic components of muscle activity that promote angiogenesis. Our results suggest that the magnitude of the myocellular perturbations incurred during exercise determines the amplitude of the angiogenic molecular signals, implying hormetic modulation of skeletal muscle angiogenesis by exercise-induced mechanical and metabolic stress.

Aerobic exercise offsets endothelial dysfunction induced by repetitive consumption of sugar-sweetened beverages in young healthy men

Consumption of a single, sugar-sweetened beverage (SSB) impairs vascular endothelial function. Regular aerobic exercise improves endothelium-dependent vasodilation; however, it is unknown whether these beneficial effects persist with frequent SSB consumption. Therefore, the purpose of this study was twofold; we studied the effects of repetitive SSB consumption (75 g d-glucose, 3 times/day) for 1 wk (Glu, n = 13, 23 ± 4 yr, 23.5 ± 3.4 kg/m²) on endothelium-dependent vasodilation (FMD). Then, in a separate cohort, we investigated whether 45 min of moderate-intensity aerobic exercise on five separate days offset the hypothesized decrease in FMD during the Glu protocol (Glu+Ex, n = 11, 21 ± 3 yr, 23.8 ± 2.4 kg/m²). Baseline, fasting [glucose] (P = 0.15), [insulin] (P = 0.25), %FMD (P = 0.48), absolute FMD (P = 0.66), and shear rate area under the curve (SR_AUC; P = 0.82) were similar between groups. Following the interventions, fasting [glucose] (Glu: 94 ± 6 to 92 ± 6 mg/dL, Glu+Ex: 89 ± 8 to 87 ± 6 mg/dL, P = 0.74) and [insulin] (Glu: 11.3 ± 6.2 to 11.8 ± 8.9 μU/mL, Glu+Ex: 8.7 ± 2.9 to 9.4 ± 3.2 μU/mL, P = 0.89) were unchanged. %FMD was reduced in Glu (6.1 ± 2.2 to 5.1 ± 1.3%) and increased in Glu+Ex (6.6 ± 2.2 to 7.8 ± 2.4%, P < 0.05 for both). SR_AUC increased similarly in both Glu [17,715 ± 8,275 to 22,922 ± 4,808 arbitrary units (A.U.)] and Glu+Ex (18,216 ± 4,516 to 21,666 ± 5,392 A.U., main effect of time P < 0.05). When %FMD was adjusted for SR_AUC, attenuation was observed in Glu (0.41 ± 0.18 to 0.23 ± 0.08%/s × 103, P < 0.05) but not Glu+Ex (0.38 ± 0.14 to 0.38 ± 0.13%/s × 103, P = 0.88). Despite unchanged fasting [glucose] and [insulin], repeated consumption of SSBs impaired conduit artery vascular endothelial function. Additionally, subjects who engaged in regular moderate-intensity aerobic exercise did not demonstrate the same SSB-induced endothelial dysfunction. Collectively, these data suggest aerobic exercise may offset the deleterious effects of repetitive SSB consumption.

Relevance of control diet choice in metabolic studies: impact in glucose homeostasis and vascular function

The experimental approach for the study of cardiometabolic disorders requires the use of animal models fed with commercial diets whose composition differs notably, even between diets used for control groups. While chow diets are usually made of agricultural by-products, purified low-fat diets (LF) contain a higher percentage of easy metabolizable carbohydrates, together with a reduced amount of polyunsaturated fatty acids, micronutrients and fiber, all associated with metabolic and vascular dysfunction. We hypothesize that the LF diet, commonly used in control animals, could promote adverse vascular and metabolic outcomes. To address this issue, 5-week-old male C57BL6J mice were fed with a standard (Chow) or a LF diet for 6 weeks. Changes in body weight, adiposity, biochemical parameters, systemic and aortic insulin sensitivity and endothelial function were recorded. LF diet did not modify body weight but significantly impaired systemic glucose tolerance and increased triglycerides and cholesterol levels. Endothelial function and aortic insulin sensitivity were significantly impaired in the LF group, due to a reduction of NO availability. These findings highlight the importance of selecting the proper control diet in metabolic studies. It may also suggest that some cardiometabolic alterations obtained in experimental studies using LF as a control diet may be underestimated.

The Endothelial Mechanotransduction Protein Platelet Endothelial Cell Adhesion Molecule-1 Is Influenced by Aging and Exercise Training in Human Skeletal Muscle

Aim: The aim was to determine the role of aging and exercise training on endothelial mechanosensor proteins and the hyperemic response to shear stress by passive leg movement.

Methods: We examined the expression of mechanosensor proteins and vascular function in young (n = 14, 25 ± 3 years) and old (n = 14, 72 ± 5 years) healthy male subjects with eight weeks of aerobic exercise training. Before and after training, the hyperaemic response to passive leg movement was determined and a thigh muscle biopsy was obtained before and after passive leg movement to assess the acute effect of increased shear stress. Biopsies were analyzed for protein amount and phosphorylation of mechanosensor proteins; Platelet endothelial cell adhesion molecule-1 (PECAM-1), Vascular endothelial cadherin, Vascular endothelial growth factor receptor-2 and endothelial nitric oxide synthase (eNOS).

Results: Before training, the old group presented a lower hyperaemic response to passive leg movement and a 35% lower (P < 0.05) relative basal phosphorylation level of PECAM-1 whereas there was no difference for the other mechanosensor proteins. After training, the eNOS protein amount, the amount of PECAM-1 protein and the passive leg movement-induced phosphorylation of PECAM-1 were higher in both groups. The hyperaemic response to passive leg movement was higher after training in the young group only.

Conclusion: Aged individuals have a lower hyperaemic response to passive leg movement and a lower relative basal phosphorylation of PECAM-1 than young. The higher PECAM-1 phosphorylation despite a similar hyperemic level in the aged observed after training, suggests that training improved shear stress responsiveness of this mechanotransduction protein.