Altered vascular function in chronic kidney disease: evidence from passive leg movement

Sympathetic transduction to blood pressure in patients with chronic kidney disease

PURPOSE

Patients with chronic kidney disease (CKD) are more than twice as likely to die from a cardiovascular event than those with normal kidney function. Although CKD may increase resting sympathetic activity, quantification of resting sympathetic outflow alone does not account for the ensuing vasoconstriction, and blood pressure (BP) change (i.e., sympathetic transduction). Patients with CKD have been reported to exhibit elevated α-adrenergic receptor sensitivity, which may predispose this population to greater sympathetic transduction. We tested the hypothesis that patients with CKD have augmented sympathetic transduction to BP.

METHODS

In 16 patients with CKD, 17 bodyweight-matched (BWM) controls, and 11 lean controls of a similar age muscle sympathetic nerve activity (MSNA) and beat-to-beat BP were continuously recorded during quiet supine rest. Signal averaging was used to quantify changes in mean arterial pressure (MAP) and total vascular conductance (TVC) following spontaneous bursts of MSNA.

RESULTS

Peak increases in MAP following MSNA bursts were not different among patients with CKD and the control groups (CKD: 2.3 ± 1.1 mmHg; BWM controls: 2.1 ± 1.0 mmHg; lean controls: 1.7 ± 0.9 mmHg; P = 0.28). Likewise, nadir reductions in TVC following all bursts of MSNA were not different among patients with CKD and either control group (P = 0.69). Both patients with CKD and controls had graded increases in MAP and decreases in TVC with increasing burst size, which were not different among groups (all P > 0.05).

CONCLUSION

In summary, these data indicate that patients with CKD do not have augmented sympathetic transduction to BP.

Differential risk of autoimmune disorders in non-traumatic osteonecrosis: clue to pathogenesis

INTRODUCTION

Non-traumatic osteonecrosis is a frequent complication in patients with autoimmune disorders, though its prevalence varies markedly depending upon the type of disorder. Understanding the causes of this difference can help uncover the underlying pathophysiology of osteonecrosis and guide the development of effective preventive and therapeutic strategies.

AREAS COVERED

In this perspective study, we reviewed available databases, including PubMed, Cochrane Library, Scopus, and Web of Science, to explore why the risk of osteonecrosis varies among different autoimmune disorders. Is this variation primarily due to the disease's pathophysiology, the use of medications such as corticosteroids, or a combination of both? If both factors are involved, what is the extent of each contribution in this context?

EXPERT OPINION

Non-traumatic osteonecrosis is often induced by an interaction between disease pathophysiology and corticosteroid use. In patients with different autoimmune disorders but an identical history of corticosteroid use, the risk of osteonecrosis is influenced by how the underlying pathophysiology compromises bone health. In autoimmune disorders with multiple adverse effects on bone, such as SLE (systemic lupus erythematosus), there is a much higher risk of osteonecrosis compared to disorders with minimal impact on bone health, such as celiac disease and MS (multiple sclerosis).

Physiologically Based Pharmacokinetic Modelling in Critically Ill Children Receiving Anakinra While on Extracorporeal Life Support

BACKGROUND AND OBJECTIVE

Because of the pathophysiological changes associated with critical illness and the use of extracorporeal life support (ECLS) such as continuous renal replacement therapy (CRRT) and extracorporeal membrane oxygenation (ECMO), the pharmacokinetics of drugs are often altered. The objective of this study was to develop a physiologically based pharmacokinetic (PBPK) model for anakinra in children that accounts for the physiological changes associated with critical illness and ECLS technology to guide appropriate pharmacotherapy.

METHODS

A PBPK model for anakinra was first developed in healthy individuals prior to extrapolating to critically ill children receiving ECLS. To account for the impact of anakinra clearance by the dialysis circuit, a CRRT compartment was added to the pediatric PBPK model and parameterized using data from a previously published ex-vivo study. Additionally, an ECMO compartment was added to the whole-body structure to create the final anakinra ECLS-PBPK model. The final model structure was validated by comparing predicted concentrations with observed patient data. Due to limited information in guiding anakinra dosing in this population, in-silico dose simulations were conducted to provide baseline recommendations.

RESULTS

By accounting for changes in physiology and the addition of ECLS compartments, the final ECLS-PBPK model predicted the observed plasma concentrations in an adolescent receiving subcutaneous anakinra. Furthermore, dosing simulations suggest that anakinra exposure in adolescents receiving ECLS is similar to that in healthy counterparts.

CONCLUSION

The anakinra ECLS-PBPK model developed in this study is the first to predict plasma concentrations in a population receiving simultaneous CRRT and ECMO. Dosing simulations provided may be used to inform anakinra use in critically ill children and guide future clinical trial planning.

Effect of Resveratrol on Endothelial Function in Patients with CKD and Diabetes: A Randomized Controlled Trial

BACKGROUND

Patients with CKD and diabetes are at higher risk of developing cardiovascular disease, in part, because of impaired endothelial function. Cardioprotective compounds such as resveratrol could improve endothelial function and attenuate the cardiovascular burden in patients with CKD and diabetes. We hypothesized that resveratrol supplementation would improve endothelial function in patients with CKD and diabetes.

METHODS

Twenty-eight adults aged 68±7 years (84% men) with stage 3 CKD and diabetes were enrolled in a randomized, double-blind, placebo-controlled, crossover study to investigate the effects of 6-week resveratrol supplementation (400 mg/d) on endothelial function. Endothelial function was determined through brachial artery flow-mediated dilation.

RESULTS

The mean values for eGFR and hemoglobin A 1c were 40±9 ml/min per 1.73 m 2 and 7.36%±0.72%, respectively. Compared with placebo, resveratrol supplementation increased flow-mediated dilation (ratio of geometric mean changes and 95% confidence interval for between-group comparisons, 1.43 (1.15 to 1.77); P value = 0.001). eGFR, hemoglobin A 1c , BP, and nitroglycerin-mediated dilation were unchanged with resveratrol or placebo ( P = 0.15), suggesting the observed change in flow-mediated dilation was likely independent of changes in traditional cardiovascular risk factors.

CONCLUSIONS

Resveratrol supplementation improved endothelial function in patients with CKD and diabetes.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Resveratrol and Vascular Function in CKD, NCT03597568 .

PODCAST

This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/CJASN/2023_11_20_CJN0000000000000337.mp3.

Acute high-dose MitoQ does not increase urinary kidney injury markers in healthy adults: a randomized crossover trial

Several human studies have used the mitochondrial antioxidant MitoQ. Recent in vitro data indicating that MitoQ may induce nephrotoxicity caused concern regarding the safety of MitoQ on the kidneys, but the doses were supraphysiological. Therefore, we sought to determine whether acute MitoQ elicits changes in urinary biomarkers associated with tubular injury in healthy adults with our hypothesis being there would be no changes. Using a randomized crossover design, 32 healthy adults (16 females and 16 males, 29 ± 11 yr old) consumed MitoQ (100-160 mg based on body mass) or placebo capsules. We obtained serum samples and a 4- to 6-h postcapsule consumption urine sample. We assessed creatinine clearance and urine kidney injury biomarkers including the chitinase 3-like-1 gene product YKL-40, kidney-injury marker-1, monocyte chemoattractant protein-1, epidermal growth factor, neutrophil gelatinase-associated lipocalin, interleukin-18, and uromodulin using multiplex assays. We used t tests, Wilcoxon tests, and Hotelling's T2 to assess global differences in urinary kidney injury markers between conditions. Acute MitoQ supplementation did not influence urine flow rate (P = 0.086, rrb = 0.39), creatinine clearance (P = 0.085, rrb = 0.42), or urinary kidney injury markers (T22,8 = 30.6, P = 0.121, univariate ps > 0.064). Using exploratory univariate analysis, MitoQ did not alter individual injury markers compared with placebo (e.g., placebo vs. MitoQ: YKL-40, 507 ± 241 vs. 442 ± 236 pg/min, P = 0.241; kidney injury molecule-1, 84.1 ± 43.2 vs. 76.2 ± 51.2 pg/min, P = 0.890; and neutrophil gelatinase-associated lipocalin, 10.8 ± 10.1 vs. 9.83 ± 8.06 ng/min, P = 0.609). In conclusion, although longer-term surveillance and data are needed in clinical populations, our findings suggest that acute high-dose MitoQ had no effect on urinary kidney injury markers in healthy adults.NEW & NOTEWORTHY We found acute high-dose mitochondria-targeted antioxidant (MitoQ) supplementation was not nephrotoxic and had no effect on markers of acute kidney injury in healthy adults. These findings can help bolster further confidence in the safety of MitoQ, particularly for future investigations seeking to examine the role of mitochondrial oxidative stress, via acute MitoQ supplementation, on various physiological outcomes.

Augmented resting beat-to-beat blood pressure variability in patients with chronic kidney disease

PURPOSE

Our aim was to test the hypothesis that patients with chronic kidney disease (CKD) would exhibit augmented resting beat-to-beat blood pressure variability (BPV) that is associated with poor clinical outcomes independent of mean blood pressure (BP). In addition, since the arterial baroreflex plays a critical role in beat-to-beat BP regulation, we further hypothesized that an impaired baroreflex control would be associated with an augmented resting beat-to-beat BPV.

METHODS

In 25 sedentary patients with CKD stages III-IV (62 ± 9 years) and 20 controls (57 ± 10 years), resting beat-to-beat BP (finger photoplethysmography) and heart rate (electrocardiography) were continuously measured for 10 min. We calculated the standard deviation (SD), average real variability (ARV) and other indices of BPV. The sequence technique was used to estimate spontaneous cardiac baroreflex sensitivity.

RESULTS

Compared with controls (CON), the CKD group had significantly increased resting BPV. The ARV (2.2 ± 0.6 versus 1.6 ± 0.5 mmHg, P < 0.001; 1.6 ± 0.7 versus 1.3 ± 0.3 mmHg, P = 0.039; 1.4 ± 0.5 versus 1.0 ± 0.2 mmHg, P < 0.001) of systolic, diastolic and mean BP, respectively, was increased in CKD versus controls. Other traditional measures of variability showed similar results. The cardiac baroreflex sensitivity was lower in CKD compared with controls (CKD: 8.4 ± 4.5 ms/mmHg versus CON: 14.0 ± 8.2 ms/mmHg, P = 0.008). In addition, cardiac baroreflex sensitivity was negatively associated with BPV [systolic blood pressure (SBP) ARV; r = -0.44, P = 0.003].

CONCLUSION

In summary, our data demonstrate that patients with CKD have augmented beat-to-beat BPV and lower cardiac baroreflex sensitivity. BPV and cardiac baroreflex sensitivity were negatively correlated in this cohort. These findings may further our understanding about cardiovascular dysregulation observed in patients with CKD.

The effect of exercise on vascular health in chronic kidney disease: a systematic review and meta-analysis of randomized controlled trials

Patients with chronic kidney disease (CKD) are at increased risk of cardiovascular disease. This increased risk cannot be fully explained by traditional risk factors such as hypertension. Endothelial dysfunction and arterial stiffness have been suggested as factors that explain some of the increased risk and are independently associated with important cardiovascular outcomes in patients with CKD. Studies in other disease populations have shown the positive effects of exercise on vascular dysfunction. The aim of this review was to determine whether exercise training interventions improve measures of vascular function and morphology in patients across the spectrum of CKD and which exercise training interventions are most efficacious. A systematic search of Medline, Embase, and the Cochrane Central Register identified 25 randomized controlled trials. Only randomized control trials using an exercise intervention with a nonexercising control group and at least one measure of vascular function or morphology were included. Participants were patients with nondialysis CKD or transplant patients or those requiring dialysis therapy. A systematic review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A meta-analysis was completed for pulse wave velocity, augmentation index, and measures of endothelium-dependent vasodilation. Data from 25 studies with 872 participants showed that exercise training reduced pulse wave velocity and augmentation index but had no effect on endothelium-dependent vasodilation. Subgroup analyses suggested that exercise interventions of at least moderate intensity were more likely to be effective. Limitations included the absence of observational studies or other interventions aimed at increasing habitual physical activity. Further studies are warranted to investigate which are the most effective exercise interventions.NEW & NOTEWORTHY A thorough systematic review and meta-analysis of the effects of exercise training on measures of vascular function in patients with chronic kidney disease, including arterial stiffness and endothelial function, were conducted. Subgroup analyses investigated how differences in exercise training, according to frequency, intensity, type, and timing, have an impact on the efficacy of the intervention.

Effects of a mitochondrial-targeted ubiquinol on vascular function and exercise capacity in chronic kidney disease: a randomized controlled pilot study

Mitochondria-derived oxidative stress has been implicated in vascular and skeletal muscle abnormalities in chronic kidney disease (CKD). The purpose of this study was to investigate the effects of a mitochondria-targeted ubiquinol (MitoQ) on vascular function and exercise capacity in CKD. In this randomized controlled trial, 18 patients with CKD (means ± SE, age: 62 ± 3 yr and estimated glomerular filtration rate: 45 ± 3 mL/min/1.73 m2) received 4 wk of 20 mg/day MitoQ (MTQ group) or placebo (PLB). Outcomes assessed at baseline and follow-up included macrovascular function measured by flow-mediated dilation, microvascular function assessed by laser-Doppler flowmetry combined with intradermal microdialysis, aortic hemodynamics assessed by oscillometry, and exercise capacity assessed by cardiopulmonary exercise testing. Compared with PLB, MitoQ improved flow-mediated dilation (baseline vs. follow-up: MTQ, 2.4 ± 0.3% vs. 4.0 ± 0.9%, and PLB, 4.2 ± 1.0% vs. 2.5 ± 1.0%, P = 0.04). MitoQ improved microvascular function (change in cutaneous vascular conductance: MTQ 4.50 ± 2.57% vs. PLB -2.22 ± 2.67%, P = 0.053). Central aortic systolic and pulse pressures were unchanged; however, MitoQ prevented increases in augmentation pressures that were observed in the PLB group (P = 0.026). MitoQ did not affect exercise capacity. In conclusion, this study demonstrates the potential for a MitoQ to improve vascular function in CKD. The findings hold promise for future investigations of mitochondria-targeted therapies in CKD.NEW & NOTEWORTHY In this randomized controlled pilot study, we investigated the effects of a mitochondria-targeted ubiquinol (MitoQ) on vascular function and exercise capacity in chronic kidney disease. Our novel findings showed that 4-wk supplementation of MitoQ was well tolerated and improved macrovascular endothelial function, arterial hemodynamics, and microvascular function in patients with stage 3-4 chronic kidney disease. Our mechanistic findings also suggest that MitoQ improved microvascular function in part by reducing the NADPH oxidase contribution to vascular dysfunction.

Identification of peripheral vascular function measures and circulating biomarkers of mitochondrial function in patients with mitochondrial disease

The development of pharmacological therapies for mitochondrial diseases is hampered by the lack of tissue-level and circulating biomarkers reflecting effects of compounds on endothelial and mitochondrial function. This phase 0 study aimed to identify biomarkers differentiating between patients with mitochondrial disease and healthy volunteers (HVs). In this cross-sectional case-control study, eight participants with mitochondrial disease and eight HVs matched on age, sex, and body mass index underwent study assessments consisting of blood collection for evaluation of plasma and serum biomarkers, mitochondrial function in peripheral blood mononuclear cells (PBMCs), and an array of imaging methods for assessment of (micro)circulation. Plasma biomarkers GDF-15, IL-6, NT-proBNP, and cTNI were significantly elevated in patients compared to HVs, as were several clinical chemistry and hematology markers. No differences between groups were found for mitochondrial membrane potential, mitochondrial reactive oxygen production, oxygen consumption rate, or extracellular acidification rate in PBMCs. Imaging revealed significantly higher nicotinamide-adenine-dinucleotide-hydrogen (NADH) content in skin as well as reduced passive leg movement-induced hyperemia in patients. This study confirmed results of earlier studies regarding plasma biomarkers in mitochondrial disease and identified several imaging techniques that could detect functional differences at the tissue level between participants with mitochondrial disease and HVs. However, assays of mitochondrial function in PBMCs did not show differences between participants with mitochondrial disease and HVs, possibly reflecting compensatory mechanisms and heterogeneity in mutational load. In future clinical trials, using a mix of imaging and blood-based biomarkers may be advisable, as well as combining these with an in vivo challenge to disturb homeostasis.

We like to move it, move it: A perspective on performing passive leg movement as a non-invasive assessment of vascular function in pediatric populations

The passive leg movement (PLM) technique is a non-invasive assessment of lower-limb vascular function. PLM is methodologically simple to perform and utilizes Doppler ultrasound to determine leg blood flow (LBF) through the common femoral artery at rest and in response to passive movement of the lower leg. LBF responses to PLM have been reported to be mostly nitric oxide (NO)-mediated when performed in young adults. Moreover, PLM-induced LBF responses, as well as the NO contribution to PLM-induced LBF responses, are reduced with age and in various diseased populations, demonstrating the clinical utility of this non-invasive test. However, no PLM studies to date have included children or adolescents. Since its conception in 2015, our laboratory has performed PLM on hundreds of individuals including a large cohort of children and adolescents. Thus, the purpose of this perspective article is threefold: 1) to uniquely discuss the feasibility of performing PLM in children and adolescents, 2) to report PLM-induced LBF values from our laboratory in 7-17-year-olds, and 3) to discuss considerations for making comparisons among pediatric populations. Based on our experiences performing PLM in children and adolescents (among various other age groups), it is our perspective that PLM can feasibly be performed in this population. Further, data from our laboratory may be used to provide context for typical PLM-induced LBF values that could be observed in children and adolescents, as well as across the lifespan.

TNF-α and IL-1β Promote Renal Podocyte Injury in T2DM Rats by Decreasing Glomerular VEGF/eNOS Expression Levels and Altering Hemodynamic Parameters

PURPOSE

Diabetic nephropathy (DN) is a serious microvascular complication in those with type 2 diabetes mellitus (T2DM). Evidence confirms that serum tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in the T2DM stage are proposed as prognostic markers for DN development, but it is unclear how they affect renal podocyte-associated nephrin and WT-1 expression. In the presence of podocyte injury, glomerular vascular endothelial growth factor (VEGF), endothelial nitric oxide synthase (eNOS) and hemodynamic parameters are dysregulated. The current research aimed to clarify the relationship of TNF-α and IL-1β with podocyte injury by altering VEGF/eNOS expression and hemodynamic parameters.

METHODS

A high-fat diet/streptozotocin-induced DN rat model was established. Serum TNF-α and IL-1β levels were tracked in the pre-T2DM, T2DM and DN stages. In the DN stage, the mRNA and protein expression levels of renal TNF-α, IL-1β, VEGF, eNOS, nephrin and WT-1 were studied. Renal hemodynamic parameters, including peak systolic velocity, end-diastolic flow velocity and mean velocity were measured with a color Doppler ultrasound technique.

RESULTS

Compared to those in the normal control (CTL) group, serum TNF-α and IL-1β levels increased significantly in the pre-T2DM stage (obesity, insulin resistance and hyperlipidemia), T2DM stage (hyperglycemia) and DN stage (abnormal renal functions) (all: P < 0.05) in the DN group. Serum TNF-α and IL-1β levels in the T2DM stage were significantly higher than those in the pre-T2DM stage (two: P < 0.05). Compared to the CTL group, renal nephrin, WT-1, TNF-α, IL-1β, eNOS and VEGF expression and hemodynamic parameters in the DN stage all showed significant differences separately (all: P < 0.05).

CONCLUSION

Increased serum and renal TNF-α and IL-1β levels played important roles in reducing renal nephrin and WT-1 expression levels, which may be related to the fact that the former affected renal VEGF/eNOS expression and blood flow parameters in the DN rats.

Associations between noninvasive upper- and lower-limb vascular function assessments: extending the evidence to young women

Brachial artery (BA) flow-mediated dilation (FMD) is a well-established measure of peripheral vascular function prognostic of future cardiovascular events. The vasodilatory response to FMD (FMD%) reflects upper-limb conduit artery function, whereas reactive hyperemia (RH) following cuff-occlusion release reflects upper-limb resistance artery function. Comparatively, passive leg movement (PLM) is a newer, increasingly utilized assessment of lower-limb resistance artery function. To increase its clinical utility, PLM-induced leg blood flow (LBF) responses have been compared with hemodynamic responses to FMD, but only in men. Therefore, the purpose of this study was to retrospectively compare LBF responses to FMD% and RH responses in women. We hypothesized that LBF responses would be positively associated with both FMD% and RH, but to a greater extent with RH. FMD and PLM were performed on 72 women (23 ± 4 yr). Arterial diameter and blood velocity were assessed using Doppler ultrasound. Pearson correlation coefficients were used to evaluate associations. Measures of resistance artery function were weakly positively associated: change in BA blood flow ΔBABF and ΔLBF (r = 0.33, P < 0.01), BABF area under the curve (BABF AUC) and LBF AUC (r = 0.33, P < 0.01), and BABFpeak and LBFpeak (r = 0.37, P < 0.01). However, FMD% was not associated with any index of PLM (all P > 0.30). In women, indices of resistance artery function in the upper- and lower limbs were positively associated. However, contrary to the previous work in men, upper-limb conduit artery function was not associated with lower-limb resistance artery function suggesting these assessments capture different aspects of vascular function and should not be used interchangeably in women.NEW & NOTEWORTHY Upper- and lower-limb indices of resistance artery function are positively associated in young women when assessed by reactive hyperemia following brachial artery flow-mediated dilation (FMD) cuff-occlusion release and leg blood flow responses to passive leg movement (PLM), respectively. However, despite previous data demonstrating a positive association between upper-limb conduit artery function assessed by FMD and lower-limb resistance artery function assessed by PLM in young men, these measures do not appear to be related in young women.

Association of Exercise With Vascular Function in Patients With CKD: A Meta-Analysis of Randomized Controlled Trials

Background and Aim

Vascular function is associated with an increased risk of cardiovascular events in patients with chronic kidney disease (CKD). Whether exercise improves vascular function in such patients remains controversial. This study aimed to conduct a meta-analysis on the effect of exercise training on the vascular function of patients with CKD.

Methods

Embase, the Cochrane Central Register of Controlled Trials, and Medline were searched from inception until November 15, 2021. The terms exercise, CKD, dialysis, kidney transplant, and randomized controlled trial (RCT) were searched alone or in combination. RCTs were included when studies compared exercise with active control, usual care, or no intervention, and the studies reported vascular function on patients with CKD.

Results

This meta-analysis included 18 RCTs with 817 patients. Exercise training was significantly associated with decreased pulse wave velocity weighted mean difference (WMD), −0.56; 95% confidence interval (CI), −1.02 to −0.09, P = 0.02 and augmentation index (WMD, −3.26; 95% CI, −5.46 to −1.05, P = 0.004). It was also significantly associated with improved peak VO2 (WMD, 2.64; 95% CI, 1.94–3.35, P < 0.00001), general health (WMD, 7.03; 95% CI, 0.65–13.42, P = 0.03), and vitality (WMD, 9.1; 95% CI, 2.50–15.69, P = 0.007).

Conclusions

The meta-analysis suggested that exercise training improved vascular function in patients with CKD. An exercise program should be considered as one of the management strategies for vascular dysfunction in patients with CKD. Further studies are needed to demonstrate that exercise training improves cardiovascular diseases in patients with CKD.

Vascular Health Triad in Humans With Hypertension-Not the Usual Suspects

Hypertension (HTN) affects more than one-third of the US population and remains the top risk factor for the development of cardiovascular disease (CVD). Identifying the underlying mechanisms for developing HTN are of critical importance because the risk of developing CVD doubles with ∼20 mmHg increase in systolic blood pressure (BP). Endothelial dysfunction, especially in the resistance arteries, is the primary site for initiation of sub-clinical HTN. Furthermore, inflammation and reactive oxygen and nitrogen species (ROS/RNS) not only influence the endothelium independently, but also have a synergistic influence on each other. Together, the interplay between inflammation, ROS and vascular dysfunction is referred to as the vascular health triad, and affects BP regulation in humans. While the interplay of the vascular health triad is well established, new underlying mechanistic targets are under investigation, including: Inducible nitric oxide synthase, hydrogen peroxide, hydrogen sulfide, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and nuclear factor activated T cells. This review outlines the role of these unusual suspects in vascular health and function in humans. This review connects the dots using these unusual suspects underlying inflammation, ROS and vascular dysfunction especially in individuals at risk of or with diagnosed HTN based on novel studies performed in humans.

Sleep duration regularity, but not sleep duration, is associated with microvascular function in college students

STUDY OBJECTIVES

Vascular dysfunction is a hypothesized mechanism linking poor sleep habits to an increased incidence of cardiovascular diseases (CVDs). However, the vascular profile associated with free-living sleep duration and sleep regularity has not been well elucidated, particularly in young adults. Thus, this study aimed to evaluate the associations between mean sleep duration, regularity in sleep duration, and peripheral vascular function in young adult college students.

METHODS

Fifty-one healthy undergraduate students (20 ± 1 years) completed 14 days of 24-hour wrist actigraphy and subsequent vascular assessments. Macrovascular function was measured using brachial artery flow-mediated dilation (FMD) while microvascular function was measured via passive leg movement (PLM).

RESULTS

Mean sleep duration was unrelated to FMD and PLM. Conversely, more irregular sleep duration (14-day sleep duration standard deviation [SD]) was unfavorably associated with all three measures of PLM-induced hyperemia (peak leg blood flow [LBF], p = 0.01; change in LBF from baseline to peak, p < 0.01; LBF area under the curve, p < 0.01), and remained significant in regression models which adjusted for sex, body mass index, blood pressure, physical activity, alcohol and caffeine consumption, and sleep duration (all p < 0.05). When using a median split to dichotomize "low" and "high" sleep duration SD groups, those demonstrating high variability in sleep duration exhibited ~45% lower PLM responses compared with those demonstrating low variability.

CONCLUSIONS

Irregular sleep duration is associated with poorer microvascular function as early as young adulthood. These findings support the growing body of evidence that irregular sleep patterns may be an independent and modifiable risk factor for CVD.

Inhibitory Effects of Green Asparagus Extract, Especially Phospholipids, on Allergic Responses in Vitro and in Vivo

Asparagus (Asparagus officinalis L.) is one of the widely consumed vegetables. To investigate the mechanism underlying the anti-allergic responses of asparagus, we extracted different fractions from asparagus and measured their inhibitory effects on β-hexosaminidase release in RBL-2H3 cells in vitro and an atopic dermatitis NC/Nga mouse model in vivo. The lipid fractions from asparagus were extracted with 50% ethanol, separated using chloroform by liquid-liquid phase separation, and fractionated by solid-phase extraction. Among them, acetone fraction (rich in glycolipid) and MeOH fraction (rich in phospholipid) markedly inhibited β-hexosaminidase release from RBL-2H3 cells. In NC/Nga mice treated with picryl chloride, atopic dermatitis was alleviated following exposure to the 50% EtOH extract, acetone fraction, and methanol fraction. The inhibitory effects of asparagus fractions in vivo were supported by the significant decrease in serum immunoglobulin E (IgE) levels. The phospholipid fractions showed significantly better inhibitory effects, and phosphatidic acid from this fraction showed the best inhibitory effect on β-hexosaminidase release. In mice challenged with ovalbumin (OVA), oral administration of asparagus extract and its fractions decreased the OVA-specific IgE level and total IgE, indicating that these effects may be partly mediated through the downregulation of antigen-specific IgE production. Taken together, the present study shows for the first time that asparagus extract and its lipid fractions could potentially mitigate allergic reactions by decreasing degranulation in granulocytes. Our study provides useful information to develop nutraceuticals and functional foods fortified with asparagus.

Nutraceuticals as a potential adjunct therapy toward improving vascular health in CKD

Chronic kidney disease (CKD) is a major public health epidemic and increases risk for developing cardiovascular disease (CVD). Vascular dysfunction is a major independent risk factor toward increased risk for CVD in CKD. Several mechanisms have been postulated to result in vascular dysfunction in CKD, including oxidative stress-mediated inflammation by redox imbalance and reduced nitric oxide (NO) bioavailability and synthesis. Therefore, strategies that decrease oxidative stress and/or increase NO bioactivity may have major clinical implications toward improving vascular health and reducing the burden of CVD in CKD. Nutraceutical therapy in the form of polyphenols, dietary nitrates, or selective mitochondria-targeting therapies has recently been shown to improve vascular function by reducing oxidative stress and/or increasing NO bioavailability and synthesis. This review, therefore, highlights these three emerging nutraceuticals recently implicated in pathophysiological improvement of vascular function in CKD. This review also describes those pathophysiological mechanisms thought to be responsible for the beneficial effects on the vasculature and possible experimental considerations that may exist within human CKD populations. It is clear throughout this review that human-based mechanistic preclinical and health-related clinical studies are lacking regarding whether nutraceuticals do indeed improve vascular function in patients with CKD. As such, a comprehensive, detailed, and fully integrated understanding of nutraceuticals and vasculature function is necessary in patients with CKD. Many opportunities exist for original mechanistic and therapeutic discoveries and investigations on select nutraceuticals and their impact on vascular outcomes in patients with CKD, and these will remain exciting avenues of research in the future.