Association of endothelial and vascular smooth muscle dysfunction with cardiovascular risk factors, vascular complications, and subclinical carotid atherosclerosis in type 2 diabetic patients

Serum Fibroblast Growth Factor 23 Levels are Associated with Vascular Smooth Muscle Dysfunction in Type 2 Diabetes

AIM

Increased level of serum fibroblast growth factor 23 (FGF23) is a hallmark of abnormal phosphate metabolism in patients with chronic kidney disease (CKD) and is recently shown to be associated with the risk of cardiovascular disease even in those without CKD. This study investigated the association between serum FGF23 levels and vascular function in patients with type 2 diabetes.

METHODS

This was a cross-sectional study involving 283 Japanese patients with type 2 diabetes. Flow-mediated dilatation (FMD) and nitroglycerin-mediated dilatation (NMD) of the brachial artery were measured via ultrasonography to evaluate vascular endothelial and smooth muscle functions, respectively. Serum intact FGF23 levels were determined via a sandwich enzyme-linked immunosorbent assay.

RESULTS

The median values of FMD, NMD, and serum FGF23 were 6.0%, 14.0%, and 27.3 pg/mL, respectively. The serum FGF23 levels were inversely associated with NMD but not with FMD, and the association was independent of atherosclerotic risk factors, estimated glomerular filtration rate (eGFR), and serum phosphate levels. Furthermore, the relationship between serum FGF23 levels and NMD was modified by kidney function, which was pronounced in subjects with normal kidney function (eGFR ≥ 60 mL/min/1.73 m2).

CONCLUSION

Serum FGF23 levels are independently and inversely associated with NMD in patients with type 2 diabetes, particularly in those with normal kidney function. Our results indicate that FGF23 is involved in vascular smooth muscle dysfunction and that increased serum levels of FGF23 may serve as a novel biomarker for vascular smooth muscle dysfunction in patients with type 2 diabetes.

Association of plasma xanthine oxidoreductase activity with vascular endothelial function independent of serum uric acid level: MedCity21 health examination registry

Background

Xanthine oxidoreductase (XOR) inhibitor administration, known to reduce uric acid and reactive oxygen species (ROS) production, also improves vascular endothelial function (VEF). This cross-sectional study examined our hypothesis that XOR contributes to impaired VEF through ROS but not uric acid production.

Methods

In 395 subjects (196 males, 199 females) without urate-lowering agent administration who underwent a health examination, plasma XOR activity was determined using our highly sensitive assay based on [13C2,15N2] xanthine and liquid chromatography/triple quadrupole mass spectrometry. For VEF evaluation, flow-mediated dilatation (FMD) in the brachial artery was determined by ultrasound, with physical and laboratory measurements also obtained.

Results

The median values for plasma XOR activity, serum uric acid, and FMD were 26.6 pmol/h/mL, 5.4 mg/dL, and 6.2%, respectively. Simple regression analysis showed weak correlations of both log plasma XOR activity and serum uric acid level with FMD (r = -0.213, p < 0.001 and r = -0.139, p = 0.006, respectively). However, multivariable linear regression analyses revealed that log plasma XOR activity but not serum uric acid level remained associated with FMD (β = -0.116, p = 0.037 and β = 0.041, p = 0.549, respectively) after adjustments for various clinical parameters, with no remarkable inconsistencies for the association observed in subgroups divided based on sex or uric acid level. Finally, a series of mediation analyses showed that serum uric acid level did not meet the criteria for mediator of the association of plasma XOR activity with FMD (p = 0.538).

Conclusions

These findings suggest the possibility that XOR contributes to the pathophysiology of impaired VEF through ROS but not uric acid production.

Metabolic Factors Predict Changes in Endothelial Function During the Early Course of Type 1 and Type 2 Diabetes

CONTEXT

Endothelial dysfunction may occur early in the development of cardiovascular and metabolic diseases; however, it remains often underestimated and studies rarely discriminate between diabetes types. We have examined endothelial function and its determinants during the early course of type 1 and type 2 diabetes.

METHODS

Caucasian participants of the prospective German Diabetes Study (GDS) with known diabetes duration <1 year (n = 398) or without diabetes, but of similar age, body mass index (BMI) and sex distribution (n = 109), underwent measurements of flow-mediated dilation (FMD) and nitroglycerin-mediated dilatation (NMD). Whole-body insulin sensitivity (M-value) was assessed by hyperinsulinemic-euglycemic clamps and physical fitness (VO2max) by spiroergometry. A subset of individuals with type 1 or type 2 diabetes (n = 108) was re-evaluated after 5 years.

RESULTS

At baseline, neither FMD nor NMD differed between people with diabetes and the matched glucose-tolerant groups. At the 5-year follow-up, decline in FMD (-13.9%, P = .013) of persons with type 2 diabetes was independent of age, sex, and BMI, but associated with baseline adipose tissue insulin resistance and indices of liver fibrosis. The M-value decreased in both type 1 and type 2 diabetes groups by 24% and 15% (both P < .001, respectively) over 5 years. Higher HbA1c, lower M-value, and lower VO2max at baseline was associated with lower FMD in both type 1 and type 2 diabetes.

CONCLUSION

Endothelial function decreases during the early course of type 2 diabetes. In addition to age and BMI, insulin sensitivity at diagnosis was the best predictor of progressive impairment in endothelial function in type 2 diabetes.

Endothelial Function Assessment by Flow-Mediated Dilation Method: A Valuable Tool in the Evaluation of the Cardiovascular System

Cardiovascular diseases (CVDs) in the course of atherosclerosis are one of the most critical public health problems in the world. Endothelial cells synthesize numerous biologically active substances involved in regulating the functions of the cardiovascular system. Endothelial dysfunction is an essential element in the pathogenesis of atherosclerosis. Thus, the assessment of endothelial function in people without overt CVD allows for a more accurate estimate of the risk of developing CVD and cardiovascular events. The assessment of endothelial function is primarily used in scientific research, and to a lesser extent in clinical practice. Among the tools for assessing endothelial function, we can distinguish biochemical and physical methods, while physical methods can be divided into invasive and non-invasive methods. Flow-mediated dilation (FMD) is based on the ultrasound assessment of changes in the diameter of the brachial artery as a result of increased blood flow. FMD is a non-invasive, safe, and repeatable test, but it must be performed by qualified and experienced medical staff. The purpose of this paper is to present the literature review results on the assessment of endothelial function using the FMD method, including its methodology, applications in clinical practice and research, limitations, and future perspectives.

Exercise training and vascular function in postmenopausal individuals: a systematic review and meta-analysis

IMPORTANCE

Cardiovascular disease (CVD) is a leading cause of morbidity and mortality for menopausal individuals. Flow-mediated dilation (FMD), a surrogate marker of CVD, improves with aerobic exercise training in healthy and nonhealthy cohorts. However, systematic evaluation and precise estimate of this effect for menopausal individuals are unknown.

OBJECTIVE

We conducted a systematic review with meta-analysis to evaluate the influence of exercise training on FMD in postmenopausal individuals.

EVIDENCE REVIEW

Studies were identified from systematic search of major electronic databases (PubMed, ScienceDirect, and Cochrane Library) from inception to February 2021. Healthy, postmenopausal individuals were included, following an aerobic exercise intervention assessing FMD. A random-effects meta-analysis was used to calculate a pooled effect size (mean difference [MD]) with 95% confidence interval. Heterogeneity was assessed using I2 statistics. Metaregression was used to assess the association between changes in FMD and physical characteristics (eg, blood pressure, age, baseline FMD) and intervention details (metabolic equivalents and change in maximal oxygen uptake [∆V˙ o2max ]). For variables that significantly correlated, a multiple metaregression model was used to assess the accounted variance in between-study ∆FMD%. Study quality was assessed using the National Heart, Lung, and Blood Institute assessment tool.

FINDINGS

Nine studies, including 11 interventions (6 controlled interventions and 5 pre-post interventions; N = 182), with age range of 52 ± 4 to 64 ± 7 years underwent quantitative pooling of data. Exercise training significantly improved ∆FMD% (MD, 0.99; 95% confidence interval, 0.46-1.52; P < 0.001). Between-study heterogeneity was large and statistically significant ( I2 = 93.8%, P < 0.001). Post hoc analysis based on study design identified significant heterogeneity in the MD in ∆FMD% between controlled and pre-post study interventions ( P < 0.05). According to multiple metaregression, diastolic and systolic blood pressure and ∆V˙ o2max significantly predicted ∆FMD% ( Q = 15.74, df = 3, P < 0.01, R2 = 0.72).

CONCLUSIONS AND RELEVANCE

Aerobic exercise training improves FMD for postmenopausal individuals, and this observation was greater among controlled versus pre-post interventions. A higher resting blood pressure and the greatest ∆V˙ o2max yielded the largest improvements in FMD.

Topical Reappraisal of Molecular Pharmacological Approaches to Endothelial Dysfunction in Diabetes Mellitus Angiopathy

Diabetes mellitus (DM) is a frequent medical problem, affecting more than 4% of the population in most countries. In the context of diabetes, the vascular endothelium can play a crucial pathophysiological role. If a healthy endothelium—which is a dynamic endocrine organ with autocrine and paracrine activity—regulates vascular tone and permeability and assures a proper balance between coagulation and fibrinolysis, and vasodilation and vasoconstriction, then, in contrast, a dysfunctional endothelium has received increasing attention as a potential contributor to the pathogenesis of vascular disease in diabetes. Hyperglycemia is indicated to be the major causative factor in the development of endothelial dysfunction. Furthermore, many shreds of evidence suggest that the progression of insulin resistance in type 2 diabetes is parallel to the advancement of endothelial dysfunction in atherosclerosis. To present the state-of-the-art data regarding endothelial dysfunction in diabetic micro- and macroangiopathy, we constructed this literature review based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We interrogated five medical databases: Elsevier, PubMed, PMC, PEDro, and ISI Web of Science.

Astragaloside IV prevents endothelial dysfunction by improving oxidative stress in streptozotocin-induced diabetic mouse aortas

Oxidative stress serves a role in endothelial dysfunction exhibited by patients with diabetes mellitus. Astragaloside IV (AS-IV) is a major active ingredient of Radix Astragali, which is considered to exhibit vasoprotective effects through unknown mechanisms. Thus, the current study was performed to investigate the protective effects of AS-IV in streptozotocin (STZ)-induced endothelial dysfunction and to explore whether antioxidant mechanisms were involved. The protective effects of AS-IV on the endothelium-dependent relaxation and contraction of aortic rings were determined by isometric tension recordings. NADPH subunits and endothelial nitric oxide synthase (eNOS) expression was identified via western blotting. Superoxide dismutase and malondialdehyde levels were assayed using ELISA. Furthermore, the generation of reactive oxygen species (ROS) and nitric oxide (NO) was detected via dihydroethidium and 4,5-diaminofluorescein diacetate staining, respectively. The results revealed that STZ-injected mice exhibited increased aortic endothelium-dependent vasoconstriction and decreased vasorelaxation to acetylcholine. However, AS-IV treatment reversed these effects. N^G-nitro-L-arginine was subsequently used to completely inhibit impaired relaxation. Accordingly, impaired NO generation was restored following AS-IV treatment by increasing eNOS phosphorylation levels. Furthermore, ROS formation was also depressed following AS-IV treatment compared with that in STZ-injected mice. AS-IV also decreased the expression of various NADPH subunits, including human neutrophil cytochrome b light chain, neutrophil cytosolic factor 1, NADPH oxidase (NOX)2, NOX4 and Rac-1. The results of the current study may provide novel evidence that diabetes-induced vascular injury arises from either the inhibition of eNOS or the activation of NOX-derived ROS generation. In addition, the results warrant further investigation into the application of AS-IV treatment, leading to the improvement of oxidative stress, in patients with diabetes exhibiting endothelial dysfunction.

Albuminuria rather than glomerular filtration rate is associated with vascular endothelial function in patients with type 2 diabetes

AIMS

Albuminuria and reduced glomerular filtration rate (GFR) are manifestations of diabetic kidney disease and are both shown to be associated with cardiovascular outcomes. However, the differential association of albuminuria and reduced GFR with endothelial dysfunction, an early feature of atherosclerotic vascular damage, remains unclear. In this study, we investigated the association between albuminuria or estimated GFR (eGFR) and flow-mediated dilatation (FMD), a marker of endothelial function, in patients with type 2 diabetes.

METHODS

This study included 633 patients with type 2 diabetes. The FMD of the brachial artery was measured by ultrasonography. Albuminuria was evaluated by urinary albumin-to-creatinine ratio (ACR).

RESULTS

The mean FMD and eGFR, and the median value of ACR were 6.7%, 66.5 mL/min/1.73m² and 12.5 mg/g creatinine, respectively. Impaired FMD was found in patients with advanced stages of chronic kidney disease based on both GFR and albuminuria categories. Multivariate analysis after adjusting for potential confounders revealed that ACR, but not eGFR, was significantly and inversely associated with FMD.

CONCLUSIONS

Albuminuria is associated with FMD, independently of traditional cardiovascular risk factors in patients with type 2 diabetes. This study suggests a close relationship between albuminuria, rather than reduced GFR, and endothelial dysfunction in type 2 diabetes.

Effects of Unilateral Arm Warming or Cooling on the Modulation of Brachial Artery Shear Stress and Endothelial Function during Leg Exercise in Humans

Aim: We examined the effect of modulating the shear stress (SS) profile using forearm warming and cooling on subsequent endothelial function in the brachial artery (BA) during exercise.

Methods: Twelve healthy young subjects immersed their right forearm in water (15°C or 42°C) during a leg cycling exercise at 120–130 bpm for 60 min. The same exercise without water immersion served as a control. The BA diameter and blood velocity were simultaneously recorded using Doppler ultrasonography to evaluate the antegrade, retrograde, and mean shear rates (SRs, an estimate of SS) before, during, and after exercise. The endothelial function in the right BA was evaluated using flow-mediated dilation (FMD) (%) using two-dimensional high-resolution ultrasonography before (baseline) and 15 and 60 min after exercise.

Results: During exercise, compared with the control trial, higher antegrade and mean SRs and lower retrograde SRs were observed in the warm trial; conversely, lower antegrade and mean SRs and higher retrograde SRs were observed in the cool trial. At 15 min postexercise, no significant change was observed in the FMD from baseline in the warm (Δ%FMD: +1.6%, tendency to increase; p = 0.08) and control trials (Δ %FMD: +1.1%). However, in the cool trial, the postexercise FMD at 60 min decreased from baseline (Δ%FMD: −2.7%) and was lower than that of the warm (Δ%FMD: +1.5%) and control (Δ%FMD: +1.2%) trials. Accumulated changes in each SR during and after exercise were significantly correlated with postexercise FMD changes.

Conclusion: Modulation of shear profiles in the BA during exercise appears to be associated with subsequent endothelial function.

The role of age in determining the effects of lipo-PGE1 infusion on immediate arterial maximal flow velocity in patients with diabetes undergoing free flap surgery for lower extremity reconstruction: A prospective observational study

BACKGROUND

Diabetes mellitus may have a negative effect on free flap perfusion in patients undergoing reconstructive surgery. Little is known of the effects of lipo-prostaglandin E1 (lipo-PGE1) on flap blood flow in diabetes. This study investigated the effects of lipo-PGE1 on maximal blood flow velocity of the free flap arterial pedicle in patients with diabetes.

METHODS

This prospective observational study assessed maximal blood flow velocity in the arterial pedicle before and 30 min after infusion of 0.4 μg/h lipo-PGE1 in 40 patients with diabetes who received a free flap for lower extremity reconstruction. Multivariate logistic regression analysis was performed to determine whether age, hemoglobin A1c concentration, duration of diabetes, and flap type were significantly associated with increased maximal blood flow velocity after lipo-PGE1 infusion or not.

RESULTS

The maximal blood flow velocity of the free flap did not differ significantly before and 30 min after lipo-PGE1 infusion. Multivariate logistic regression analysis showed that age <65 years was the only independent factor associated with increased maximal blood flow velocity after lipo-PGE1 infusion (odds ratio = 5.344; p = 0.022).

CONCLUSION

Assessments of all patients with diabetes undergoing free flap surgery, when age was not taken into consideration, found that lipo-PGE1 did not significantly increase the maximal blood flow velocity of the free flap arterial pedicle. However, when age was taken into consideration, lipo-PGE1 increased blood flow velocity in patients <65 years old, suggesting that age influences the effect of lipo-PGE1 on the blood flow velocity.

Effects of Dapagliflozin on Endothelial Dysfunction in Type 2 Diabetes With Established Ischemic Heart Disease (EDIFIED)

Objectives

To evaluate the effect of the sodium-glucose cotransporter 2 inhibitor (SGLT2-I) dapagliflozin on endothelial function in patients with high-risk type 2 diabetes mellitus (T2DM).

Methods

This was a prospective, double-blind, randomized, placebo-controlled, clinical trial of patients with T2DM with underlying ischemic heart disease who were receiving metformin and insulin therapy (n = 81). After 12-weeks of additional therapy with either dapagliflozin (n = 40) or placebo (n = 41), systemic endothelial function was evaluated by change in flow-mediated dilation (ΔFMD), change in nitroglycerin-mediated dilation (ΔNMD) and surrogate markers including intercellular adhesion molecule 1 (ICAM-1), endothelial nitric oxide synthase (eNOS), high-sensitivity C-reactive protein (hs-CRP), and lipoprotein(a) (Lp[a]). Glycemic and lipid profiles were also measured.

Results

The dapagliflozin group demonstrated significant reductions of hemoglobin A1c (HbA1c) and fasting blood glucose (FBG) compared to the placebo group (ΔHbA1c –0.83 ± 1.47% vs –0.16 ± 1.25%, P = 0.042 and ΔFBG vs –0.73 ± 4.55 mmol/L vs –1.90 ± 4.40 mmol/L, P = 0.015, respectively). The placebo group showed worsening of ΔFMD while the dapagliflozin group maintained similar measurements pre- and posttherapy (P = not significant). There was a reduction in ICAM-1 levels in the dapagliflozin group (–83.9 ± 205.9 ng/mL, P < 0.02), which remained unchanged in the placebo group (–11.0 ± 169.1 ng/mL, P = 0.699). Univariate correlation analysis revealed a significant negative correlation between HbA1c and ΔFMD within the active group.

Conclusion

A 12-week therapy with dapagliflozin, in addition to insulin and metformin therapies, in high-risk patients resulted in significant reductions in HbA1c, FBG, and surrogate markers of the endothelial function. Although the dapagliflozin group demonstrated a significant association between reduction in HbA1c and improvement in FMD, there was no significant difference in FMD between the 2 groups.

Heterogeneity in the vasodilatory function of individual extremities

Objectives

Heterogeneity and homogeneity in the flow-mediated dilation of the human body's individual extremities are not fully understood, and the relationship between flow-mediated dilation and local muscle activity is unclear. We assessed the flow-mediated dilation of four individual extremities and sought to determine the contribution of local muscle activity (evaluated as muscle strength) to the flow-mediated dilation in each extremity.

Methods

Thirteen healthy young right-handed nonactive males participated. The flow-mediated dilation in the brachial and popliteal arteries at both arms and legs was assessed by ultrasound Doppler. Muscle strength was evaluated as the grip strength and knee extension.

Results

There was a significant difference in the brachial artery (BA)-FMD values between the subjects' dominant and non-dominant sides (8.0 ± 2.8 vs. 5.5 ± 2.2%, p < 0.05), whereas the two sides showed similar popliteal artery (PA)-FMD values. There was no significant correlation in flow-mediated dilation between the dominant brachial artery and popliteal artery. The BA-FMD was significantly correlated with the grip strength in both upper extremities (dominant: r = 0.562, non-dominant: r = 0.548; p < 0.05, respectively).

Conclusion

These results demonstrated heterogeneity in the flow-mediated dilation of individual extremities. We observed that local muscle activity can affect the local vascular function. Measurements of vasodilatory function in individual extremities should thus be carefully considered.

Hemodynamic and autonomic effects of low-dose glyceryl trinitrate used to test endothelium-independent vasodilation of the brachial artery

Smooth muscle function is explored by sublingual glyceryl trinitrate (GTN) administration to compare with endothelium-dependent vasodilation of the brachial artery by flow-mediated-dilation (FMD). This study compared the hemodynamic and autonomic effects of the two most often used GTN dosages. In 80 essential hypertensive patients (HT) and 60 normotensive subjects (NT), FMD of the brachial artery and endothelium-independent response to sublingual GTN (25 μg and 400 μg) were evaluated by high-resolution ultrasound and automated image analysis. In 10 HT, muscle sympathetic nerve activity (MSNA) was also assessed by microneurography. HT showed significantly (p < .01) lower FMD (5.5 ± 3.3%) compared to NT (6.9 ± 2.2%). The response to GTN 25 μg tended to be lower (HT:7.2 ± 3.3%; NT:7.9 ± 2.9%; p = .06), whereas response to GTN 400 μg was similar (HT:14.3 ± 4.8%, NT:14.5 ± 4.7%, p = ns). Blood pressure (BP) reduction induced by GTN 400 μg (systolic-BP:-3.2 ± 7.7 mm Hg, diastolic-BP:-4.7 ± 5.0 mm Hg) was greater (p < .001) compared to GTN 25 μg (systolic-BP:-0.7 ± 5.8 mm Hg, diastolic-BP:-0.7 ± 4.4 mm Hg). Changes in heart rate were also greater (+5.6 ± 6.4 bpm versus -0.2 ± 5.4 bpm, p < .001). This behaviour was similar in either NT or HT. MSNA was significantly increased by GTN 400 μg (31 ± 7bursts/min to 41 ± 6bursts/min, p < .001) but not by 25 μg (33 ± 9bursts/min to 37 ± 11bursts/min, p = .19). In conclusion, the administration of low-dose GTN allows exploring endothelium-independent vasodilation in FMD protocols, inducing only modest hemodynamic and sympathetic responses.

Assessment of endothelium-independent vasodilation: from methodology to clinical perspectives

: Vascular response to exogenously administered nitroglycerine, an index of endothelium-independent vasodilation, has been used as a control test for the assessment of endothelium-dependent vasodilation (endothelial function) in humans. However, evidence has been accumulating that not only endothelium-dependent vasodilation but also endothelium-independent vasodilation per se is impaired in individuals with cardiovascular risk factors and cardiovascular disease. Impaired endothelium-independent vasodilation is associated with structural vascular alterations and alterations in vascular smooth muscle cells. Several methods, including assessment of vascular responses to vasoactive agents using angiography in a coronary artery and vascular responses to vasoactive agents using venous occlusion plethysmography and ultrasonography in a peripheral artery, are used to assess endothelium-independent vasodilation in humans. Measurement of endothelium-independent vasodilation is also useful for assessment of atherosclerosis and may be a predictor of future cardiovascular events. In this review, we focus on assessment of endothelium-independent vasodilation from methodology aspects to clinical perspectives.

Skin microvascular dysfunction as an early cardiovascular marker in primary hyperoxaluria type I

BACKGROUND

Primary hyperoxaluria type 1 (PH1) is an orphan inborn error of oxalate metabolism leading to hyperoxaluria, progressive renal failure, oxalate deposition, and increased cardiovascular complications. As endothelial dysfunction and arterial stiffness are early markers of cardiovascular risk, we investigated early endothelial and vascular dysfunction in young PH1 patients either under conservative treatment (PH1-Cons) or after combined kidney liver transplantation (PH1-T) in comparison to healthy controls (Cont-H) and patients with a past of renal transplantation (Cont-T).

METHODS

Skin microvascular function was non-invasively assessed by laser Doppler flowmetry before and after stimulation by current, thermal, or pharmacological (nitroprussiate (SNP) or acetylcholine (Ach)) stimuli in young PH1 patients and controls.

RESULTS

Seven PH1-Cons (6 F, median age 18.2) and 6 PH1-T (2 F, median age 13.3) were compared to 96 Cont-H (51 F, median age 14.2) and 6 Cont-T (4 F, median age 14.5). The endothelium-independent vasodilatation (SNP) was severely decreased in PH1-T compared to Cont-H. Ach, current-induced vasodilatation (CIV), and thermal response was increased in PH1-Cons and Cont-T compared to controls.

CONCLUSIONS

PH1-T patients displayed severely decreased smooth muscle capacity to vasodilate. An exacerbated endothelial-dependent vasodilation suggests a role for silent inflammation in the early dysfunction of microcirculation observed in PH1-Cons and Cont-T.

Plasma omentin levels are associated with vascular endothelial function in patients with type 2 diabetes at elevated cardiovascular risk

AIMS

Omentin is an adipokine that has protective effects against cardiovascular damage. Previous studies showed an inverse relationship between omentin and obesity, diabetes, and cardiovascular disease. This study aimed to investigate the association between omentin and vascular endothelial function in patients with type 2 diabetes (T2D).

METHODS

The subjects were 425 patients with T2D and 223 non-diabetic controls. Fasting plasma omentin levels were measured by enzyme-linked immunosorbent assay, and the endothelium-dependent, flow-mediated dilatation (FMD) was measured by ultrasonography.

RESULTS

Plasma omentin levels were higher, while FMD was lower in participants with T2D than in non-diabetic controls. No significant correlation was found between plasma omentin levels and FMD in either non-diabetic controls or participants with T2D on multivariate analysis. However, stratified analysis in T2D patients revealed that plasma omentin levels were independently and positively associated with FMD in high cardiovascular risk subgroups according to age (≥65 years), estimated glomerular filtration rate (<60 mL/min/1.73 m²), or preexisting cardiovascular diseases but not in low-risk subgroups.

CONCLUSIONS

Plasma omentin levels are independently associated with endothelial function in subgroups of patients with T2D at elevated cardiovascular risk. This study suggests a protective role of omentin against endothelial dysfunction, particularly in high-risk patients.

Increased nitroglycerin-mediated vasodilation in migraineurs without aura in the interictal period

PURPOSE

Migraine is associated with vascular disorders, but the underlying mechanism is unknown. Nitric oxide (NO) sensitivity is believed to play a major role in migraine pathophysiology. We investigated flow-mediated vasodilatation (FMD) and nitroglycerin-mediated vasodilatation (NMD) of the brachial artery by means of a key molecular mediator, NO, in patients with migraine without aura in the interictal period whether the abnormality is found.

METHODS

A total of 12 patients with migraine without aura and 12 matched healthy controls were enrolled in this study. FMD and NMD were measured in all patients and controls using brachial artery ultrasonography.

RESULTS

There was no significant difference in brachial artery diameter between migraineurs and nonmigraineurs (3.39 ± 0.68 vs 3.89 ± 0.67 mm, respectively; p = 0.083). A significant difference in FMD was not found between migraineurs and nonmigraineurs (6.94 ± 5.72 vs 6.08 ± 2.98%, respectively; p = 0.651). However, NMD in migraineurs was significant higher than that in nonmigraineurs (21.56 ± 7.36 vs 14.23 ± 7.41%, respectively; p = 0.024).

CONCLUSION

We think that patients with migraine without aura in the interictal period have selective sensitivity in dilator response to nitroglycerin and may have systemic NO sensitivity.

Chronic kidney disease is associated with vascular smooth muscle dysfunction but not with endothelial dysfunction

BACKGROUNDS

Nitroglycerine-induced vasodilation (NID) is usually assessed as a control test for flow-mediated vasodilation (FMD). However, NID per se is impaired in patients with high cardiovascular risk. The purpose of this study was to investigate the associations of chronic kidney disease (CKD) with NID and FMD.

METHODS

We measured NID and FMD in a total of 1567 adult subjects without end-stage renal disease (ESRD), 28% of whom had CKD as judged by measurements of estimated glomerular filtration rate (995 men and 572 women; mean age, 59.0±16.9years; age range, 18 to 92years).

RESULTS

NID was significantly smaller in patients with CKD than in those without CKD (10.8±6.0% vs. 12.7±5.7%, P<0.001). The prevalence of vascular smooth muscle dysfunction, defined as NID of less than the division point for the lowest quartile, was significantly higher in patients with CKD than in those without CKD (37.5% vs. 21.5%, P<0.001). Multivariate analysis revealed that CKD was independently associated with vascular smooth muscle dysfunction (OR: 1.36, 95% CI: 1.02 to 1.81, P=0.04). FMD was significantly smaller in patients with CKD than in those without CKD (3.1±2.8% vs. 4.0±3.0%, P<0.001). The prevalence of endothelial dysfunction, defined as FMD of less than the division point for the lowest quartile, was significantly higher in patients with CKD than in those without CKD (31.7% vs. 23.1%, P=0.002). However, CKD was not independently associated with endothelial dysfunction in an age- and sex-adjusted model (OR: 0.95, 95% CI: 0.71 to 1.26, P=0.72).

CONCLUSIONS

Non-ESRD CKD is independently associated with vascular smooth muscle dysfunction but not with endothelial dysfunction.

Effect of Metformin on Vascular Function in Children With Type 1 Diabetes: A 12-Month Randomized Controlled Trial

CONTEXT

Children with type 1 diabetes have vascular dysfunction preceding atherosclerosis. Early interventions are needed to reduce cardiovascular disease.

OBJECTIVE

To evaluate the effect of metformin on vascular function in children with type 1 diabetes.

DESIGN

Twelve-month double-blind, randomized, placebo-controlled trial.

SETTING

Tertiary pediatric diabetes clinic.

PARTICIPANTS

Ninety children (8 to 18 years of age), >50th percentile body mass index (BMI), with type 1 diabetes.

INTERVENTION

Metformin (up to 1 g twice a day) or placebo.

MAIN OUTCOME MEASURE

Vascular function measured by brachial artery ultrasound [flow-mediated dilatation/glyceryl trinitrate-mediated dilatation (GTN)].

RESULTS

Ninety participants were enrolled [41 boys, 13.6 (2.5) years of age, 45 per group], 10 discontinued intervention, and 1 was lost to follow-up. On metformin, GTN improved, independent of glycosylated hemoglobin (HbA1c), by 3.3 percentage units [95% confidence interval (CI) 0.3, 6.3, P = 0.03] and insulin dose reduced by 0.2 U/kg/d (95% CI 0.1, 0.3, P = 0.001) during 12 months, with effects from 3 months. Metformin had a beneficial effect on HbA1c at 3 months (P = 0.001) and difference in adjusted HbA1c between groups during 12 months was 1.0%; 95% CI 0.4, 1.5 (10.9 mmol/mol; 95% CI 4.4, 16.4), P = 0.001. There were no effects on carotid/aortic intima media thickness, BMI, lipids, blood pressure, or other cardiovascular risk factors. Median (95% CI) adherence, evaluated by electronic monitoring, was 75.5% (65.7, 81.5), without group differences. More gastrointestinal side effects were reported on metformin (incidence rate ratio 1.65, 95% CI 1.08, 2.52, P = 0.02), with no difference in hypoglycemia or diabetic ketoacidosis.

CONCLUSIONS

Metformin improved vascular smooth muscle function and HbA1c, and lowered insulin dose in type 1 diabetes children. These benefits and good safety profile warrant further consideration of its use.

Regulation of Coronary Arterial Large Conductance Ca2+-Activated K+ Channel Protein Expression and Function by n-3 Polyunsaturated Fatty Acids in Diabetic Rats

AIM

The objective of this study was to examine the effects of n-3 polyunsaturated fatty acids (n-3 PUFAs) on coronary arterial large conductance Ca2+-activated K+ (BK) channel function in coronary smooth muscle cells (SMCs) of streptozotocin-induced diabetic rats.

METHODS

The effects of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on coronary BK channel open probabilities were determined using the patch clamp technique. The mRNA and protein expressions of BK channel subunits were measured using qRT-PCR and Western blots. The coronary artery tension and coronary SMC Ca2+ concentrations were measured using a myograph system and fluorescence Ca2+ indicator.

RESULTS

Compared to nondiabetic control rats, the BK channel function was impaired with a reduced response to EPA and DHA in freshly isolated SMCs of diabetic rats. Oral administration of n-3 PUFAs had no effects on protein expressions of BK channel subunits in nondiabetic rats, but significantly enhanced those of BK-β1 in diabetic rats without altering BK-α protein levels. Moreover, coronary ring tension induced by iberiotoxin (a specific BK channel blocker) was increased and cytosolic Ca2+ concentrations in coronary SMCs were decreased in diabetic rats, but no changes were found in nondiabetic rats.

CONCLUSIONS

n-3 PUFAs protect the coronary BK channel function and coronary vasoreactivity in diabetic rats as a result of not only increasing BK-β1 protein expressions, but also decreasing coronary artery tension and coronary smooth muscle cytosolic Ca2+ concentrations.

Endothelium-Dependent and -Independent Vascular Function in Advanced Chronic Kidney Disease

BACKGROUND AND OBJECTIVES

CKD is associated with increased cardiovascular risk not fully attributable to traditional risk factors. We compared endothelium-dependent and -independent vascular function among individuals with advanced CKD with function in those with vascular disease but preserved kidney function.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Matched cohort analysis randomly selected from 1259 participants at a single center with measurements of brachial artery flow-mediated dilation, an endothelium-dependent process, and nitroglycerin-mediated dilation, an endothelium-independent process. Patients with advanced CKD (n=70) were matched 1:1 to controls with preserved kidney function and (1) no overt vascular disease, (2) hypertension, and (3) coronary artery disease.

RESULTS

The trend toward lower flow-mediated dilation (mean±SEM) in advanced CKD (5.4%±0.5%) compared with no overt vascular disease (7.3%±0.6%), hypertension (6.2%±0.5%), and coronary artery disease (5.8%±0.5%) did not reach statistical significance in adjusted analyses (P=0.05). Nitroglycerin-mediated dilation was lower in advanced CKD compared with in the other groups (adjusted nitroglycerin-mediated dilation: 6.9%±0.8%, 11.8%±0.9%, 11.0%±0.7%, and 10.5%±0.7% in advanced CKD, no overt vascular disease, hypertension, and coronary artery disease groups, respectively; P<0.001). Using tertiles generated from the full cohort and no overt vascular disease as the reference, the adjusted odds of flow-mediated dilation falling within the lowest tertile was higher in both the advanced CKD (odds ratio, 4.84; 95% confidence interval, 2.09 to 11.25) and coronary artery disease (odds ratio, 4.17; 95% confidence interval, 1.76 to 9.87) groups. In contrast, the adjusted odds of lowest tertile nitroglycerin-mediated dilation was higher in advanced CKD (odds ratio, 24.25; 95% confidence interval, 7.16 to 82.13) but not in the hypertension (odds ratio, 0.79; 95% confidence interval, 0.23 to 2.77) or coronary artery disease (odds ratio, 2.34; 95% confidence interval, 0.74 to 7.40) group.

CONCLUSIONS

Impairment in endothelium-dependent vascular function is present in patients with CKD and those with clinically evident vascular disease but preserved kidney function. In contrast, substantial reduction in endothelium-independent function was observed only in the CKD group, suggesting differences in severity and pathophysiology of vascular dysfunction between CKD and other disease states.

Association between potassium channel SNPs and essential hypertension in Xinjiang Kazak Chinese patients

The aim of the present study was to examine whether single-nucleotide polymorphisms (SNPs) of β1 subunit of large-conductance Ca²⁺-activated K⁺ channel (KCNMB1) and inwardly rectifying K⁺ channel, subfamily J, member-11 (KCNJ11) are associated with essential hypertension (EH) in Xinjiang Kazak Chinese patients. A polymerase chain reaction-restriction fragment length polymorphism technique was applied to detect the distribution of selected alleles and genotype frequencies in a cohort of Xinjiang Kazak Chinese patients. Samples from 267 patients with EH and 259 normotensive (NT) controls were analyzed. An unconditional logistic regression analysis was used to estimate the odds ratio and 95% confidence interval of the risk factors that are associated with the development of EH. Genotype and allele frequency analyses revealed that the frequency of genotypes KCNJ11-rs2285676 and KCNMB1-rs11739136 was not significantly different between the EH and NT groups. Individuals carrying the GG genotype of KCNJ11-rs5219 had a 2.08 times higher risk of having EH than individuals carrying the GA+AA genotype of KCNJ11-rs5219. Furthermore, the G allele frequency of KCNJ11-rs5219 in the EH group was significantly higher than that of the NT group (P=0.048). Additionally, logistic regression analysis revealed that the body weight and GG genotype of KCNJ11-rs5219 were positively associated with EH in Xinjiang Kazak Chinese patients (P<0.01).

Impaired endothelial function and arterial stiffness in patients with type 2 diabetes - The effect of a very low-dose combination of fluvastatin and valsartan

AIM

Patients with type 2 diabetes are at increased cardiovascular risk. The aim was to explore whether the impaired arterial wall characteristics typical of these patients could be improved by the unique beneficial effects of a very low-dose combination of fluvastatin and valsartan (low-flu/val).

METHODS

Forty middle-aged males (50.4±6.1years) with type 2 diabetes were recruited to a double-blind, randomized study. Patients (N=20) received low-flu/val (10/20mg) or placebo (N=20) over 30days in addition to their regular therapy. Brachial artery flow mediated dilation (FMD), common carotid artery pulse wave velocity (PWV) and β-stiffness were assessed before and after treatment, and 3 and 6months after treatment discontinuation. The treatment was then repeated.

RESULTS

Arterial wall characteristics significantly improved. After 30days of intervention, FMD increased from 2.4±0.3 to 4.2±0.3 (p<0.001), PWV decreased from 6.4±0.1 to 5.8±0.2 (p<0.001) and β stiffness decreased from 7.8±0.4 to 6.7±0.4 (p<0.001). Lipids and arterial pressure did not change. After treatment discontinuation, the beneficial effects decreased over the following months. The repetition of treatment completely regained the initial benefits. No changes were observed in the placebo group.

CONCLUSIONS

Low-flu/val added on-top of optimal therapy substantially improves arterial wall characteristics in patients with type 2 diabetes.

Effect of trelagliptin on vascular endothelial functions and serum adiponectin level in patients with type 2 diabetes: a preliminary single-arm prospective pilot study

Background

Trelagliptin, an oral DPP-4 inhibitor, which is administered once per week and characterized by a long half-life in blood. The effects of trelagliptin on vascular endothelial functions have not been clarified to date. The objective of the present study was to examine the effects of trelagliptin on vascular endothelial functions in patients with type 2 diabetes mellitus (DM) using flow-mediated dilatation (FMD), adiponectin, and asymmetric dimethylarginine (ADMA) as evaluation indicators.

Methods

This study was a preliminary single-arm prospective pilot study. The subjects of this study were type 2 DM patients aged 20–74 years, who visited our outpatient department. The patients were treated with trelagliptin, and their FMD, adiponectin, and ADMA levels were measured at baseline and at 12 weeks after initial treatment to determine the changes during the study period.

Results

A total of 27 patients, excluding three dropouts, were included in the population for analysis. Trelagliptin treatment showed no significant changes in FMD (2.42 ± 2.7% at baseline vs. 2.66 ± 3.8% post-treatment, P = 0.785) and ADMA (0.41 ± 0.0 µg/mL at baseline vs. 0.40 ± 0.0 µg/mL post-treatment, P = 0.402). Trelagliptin treatment resulted in a significant increase of serum adiponectin level (7.72 ± 6.9 µg/mL at baseline vs. 8.82 ± 8.3 µg/mL post-treatment, P < 0.002).

Conclusions

In this pilot study, trelagliptin treatment showed no significant changes in FMD. On the other hand, it was believed that trelagliptin treatment may increase serum adiponectin level.

Trial Registrationhttp://www.umin.ac.jp (Trial ID UMIN000018311)

The relevance of epigenetics to occlusive cerebral and peripheral arterial disease

Athero-thrombosis of the arteries supplying the brain and lower limb are the main causes of stroke and limb loss. New therapies are needed to improve the outcomes of athero-thrombosis. Recent evidence suggests a role for epigenetic changes in the development and progression of ischaemic injury due to atherosclerotic occlusion of peripheral arteries. DNA hypermethylation have been associated with cardiovascular diseases. Histone post-translational modifications have also been implicated in atherosclerosis. Oxidized low-density lipoprotein regulated pro-inflammatory gene expression within endothelial cells is controlled by phosphorylation/acetylation of histone H3 and acetylation of histone H4 for example. There are a number of challenges in translating the growing evidence implicating epigenetics in atherosclerosis to improved therapies for patients. These include the small therapeutic window in conditions such as acute stroke and critical limb ischaemia, since interventions introduced in such patients need to act rapidly and be safe in elderly patients with many co-morbidities. Pre-clinical animal experiments have also reported conflicting effects of some novel epigenetic drugs, which suggest that further in-depth studies are required to better understand their efficacy in resolving ischaemic injury. Effective ways of dealing with these challenges are needed before epigenetic approaches to therapy can be introduced into practice.

Reduction of NO-mediated Relaxing Effects in the Thoracic Aorta in an Experimental Chronic Kidney Disease Mouse Model

AIM

Chronic kidney disease (CKD) is known to frequently cause cardiovascular events. However, it is unclear how renal dysfunction affects the vascular response. We herein studied the effects of renal dysfunction on the aortic behavior in adenine-fed mice, investigating mechanisms underlying the occurrence of cardiovascular events in CKD patients.

METHODS

Biochemical analyses of the plasma creatinine, blood urea nitrogen (BUN) and glucose levels and measurements of the blood pressure were performed using C57BL/6 mice fed with and without an adenine-containing diet. The relaxing effects of acetylcholine (ACh) or sodium nitropurusside (SNP) and effects of NO synthase (NOS) inhibitors on the contractions induced by phenylephrine (PE) were measured in endothelium-intact aortas obtained from both mice.

RESULTS

The mice fed 0.25% adenine for four weeks showed greater plasma creatinine and BUN concentrations than the control mice, suggesting that adenine-fed mice are a useful CKD model. Furthermore, ACh relaxed the PE-stimulated, endothelium-intact aortas, the effect of which was less potent in the adenine-fed mice than in the control mice. In contrast, the degree of SNP-induced relaxation of the aortas was the same in the adenine-fed mice and control mice. The α1-adrenergic agonist, PE, induced more potent absolute tension of the endothelium-intact aortas in the CKD model mice than in the control mice, while the NOS inhibitors, N-nitro-L-arginine (LNA) and asymmetric dimethylarginine (ADMA) enhanced the contraction effects of PE in both mice.

CONCLUSIONS

The findings of this study indicate that spontaneous and stimulated NO release from the endothelium is decreased in the CKD model mouse aorta. The NO-mediated correlation between renal and elastic arterial endothelial dysfunction is suggested to be a cause of cardiovascular events in patients with CKD.

Flow Mediated Dilatation Is Reduced with the Progressive Stages of Glomerular Filtration Rate and Albuminuria in Type 2 Diabetic Patients without Coronary Heart Disease

We aimed to clarify the usefulness of measuring the flow mediated dilatation (FMD) in patients with type 2 diabetes mellitus without and with coronary heart disease (CHD). The FMD was measured in 480 patients with type 2 diabetes and in 240 nondiabetic subjects. The FMD was significantly lower in the subjects with CHD (n = 145, 5.4 ± 3.2%) than in those without CHD (n = 95, 6.9 ± 3.5%) among the nondiabetic subjects. The FMD was also lower in the subjects both with CHD (n = 161, 5.6 ± 2.8%) and without CHD (n = 319, 6.1 ± 3.3%) among the patients with diabetes compared to those without both diabetes and CHD. The FMD showed a significant positive correlation with the estimated glomerular filtration rate (eGFR) in the diabetic patients without CHD, while there was no significant association in those with CHD. The FMD was significantly lower with the progressive stages of the GFR or albuminuria in the patients without CHD among those with diabetes, although the FMD was not different in those with CHD. In conclusion, the FMD is considered to be useful for the detection of atherosclerosis in patients with type 2 diabetes, even if overt macroangiopathy is not diagnosed.

Correlations between brachial endothelial function and cardiovascular risk factors: a survey of 2,511 Chinese subjects

OBJECTIVE

We examined the relationship of several cardiovascular risk factors (CVRF) to brachial artery flow-mediated dilatation (FMD) in Chinese subjects.

METHODS

This was a cross-sectional study. In 2,511 Chinese adults (age 46.86±9.52 years, 1,891 men and 620 women) recruited from people who underwent health screening at The Third Xiangya Hospital, patients' CVRF [age, body mass index (BMI), waist circumference (WC), blood pressure (BP), cholesterol parameters, creatinine (Cr), uric acid (UA), glucose level and smoking] and prevalence of present disease (hypertension, diabetes mellitus, coronary heart disease and hyperlipidemia) were investigated.

RESULTS

Multivariate analysis revealed that FMD negative correlated with age (β=-0.29, P<0.001), gender (β=-0.12, P<0.001), BMI (β=-0.12, P=0.001), WC (β=-0.10, P=0.011), systolic BP (SBP) (β=-0.12, P<0.001), fasting glucose (β=-0.04, P=0.009), total cholesterol (TC) (β=-0.04, P=0.014), smoking (β=-0.05, P=0.003), and baseline brachial artery diameter (β=-0.35, P<0.001). FMD decreased with increasing age in both genders. In women, FMD was higher than men and age-related decline in FMD was steepest after age 40; FMD was similar in men above 55 years old.

CONCLUSIONS

In Chinese subjects, FMD may be a usefully marker of CVRF. Age, gender, BMI, WC, SBP, fasting glucose, TC, smoking, and baseline brachial artery diameter were independent variables related to the impairment of FMD. The influence of CVRF on endothelial function is more in women than men.

Effects of exercise training on arterial function in type 2 diabetes mellitus: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Controversy exists among trials assessing whether exercise can improve arterial function in type 2 diabetes mellitus (T2DM) subjects. Therefore the aim of this study was to systematically review and quantify the effects of exercise on arterial function in T2DM subjects.

METHODS

MEDLINE, Cochrane, Scopus and Web of Science were searched up until January 2013 for randomized controlled trials evaluating the effects of exercise interventions lasting 4 weeks or more on arterial function in T2DM subjects. Flow-mediated dilation (FMD) and nitrate-mediated dilation (NMD) of the brachial conduit artery were considered for assessment of arterial endothelial function and smooth muscle function, respectively.

RESULTS

Five randomized trials comparing exercise and control groups (overall n = 217) met the inclusion criteria. The mean exercise characteristics were as follows: 3.6 sessions per week, 67.5 min per session, intensity at 74.4 % of the maximum heart rate (HR(max)), for 14 weeks. The post-intervention mean difference in FMD favoured the exercise groups over the control groups (2.23 %; P < 0.0001). No significant post-intervention mean difference in NMD (1.22 %; P = 0.29) was found between the groups. Neither heterogeneity nor publication bias was detected among the trials.

CONCLUSION

Exercise training alone improved FMD, showing its capacity to restore arterial endothelial function in T2DM subjects. However, further research is needed to determine whether longer and/or more intense exercise interventions could enhance arterial smooth muscle function in this population.

Regulation of large conductance Ca2+-activated K+ (BK) channel β1 subunit expression by muscle RING finger protein 1 in diabetic vessels

The large conductance Ca(2+)-activated K(+) (BK) channel, expressed abundantly in vascular smooth muscle cells (SMCs), is a key determinant of vascular tone. BK channel activity is tightly regulated by its accessory β1 subunit (BK-β1). However, BK channel function is impaired in diabetic vessels by increased ubiquitin/proteasome-dependent BK-β1 protein degradation. Muscle RING finger protein 1 (MuRF1), a muscle-specific ubiquitin ligase, is implicated in many cardiac and skeletal muscle diseases. However, the role of MuRF1 in the regulation of vascular BK channel and coronary function has not been examined. In this study, we hypothesized that MuRF1 participated in BK-β1 proteolysis, leading to the down-regulation of BK channel activation and impaired coronary function in diabetes. Combining patch clamp and molecular biological approaches, we found that MuRF1 expression was enhanced, accompanied by reduced BK-β1 expression, in high glucose-cultured human coronary SMCs and in diabetic vessels. Knockdown of MuRF1 by siRNA in cultured human SMCs attenuated BK-β1 ubiquitination and increased BK-β1 expression, whereas adenoviral expression of MuRF1 in mouse coronary arteries reduced BK-β1 expression and diminished BK channel-mediated vasodilation. Physical interaction between the N terminus of BK-β1 and the coiled-coil domain of MuRF1 was demonstrated by pulldown assay. Moreover, MuRF1 expression was regulated by NF-κB. Most importantly, pharmacological inhibition of proteasome and NF-κB activities preserved BK-β1 expression and BK-channel-mediated coronary vasodilation in diabetic mice. Hence, our results provide the first evidence that the up-regulation of NF-κB-dependent MuRF1 expression is a novel mechanism that leads to BK channelopathy and vasculopathy in diabetes.

Leptin is associated with vascular endothelial function in overweight patients with type 2 diabetes

BACKGROUND

The adipocyte-derived hormone leptin plays a key role in the regulation of appetite and body weight. Recent studies have suggested that leptin is also involved in the pathogenesis of obesity-related atherosclerosis and cardiovascular disease. In this study, we investigated the association of plasma leptin levels with vascular endothelial function in lean and overweight patients with type 2 diabetes.

METHODS

One hundred seventy-one type 2 diabetic patients, of which 85 were overweight (body mass index (BMI) ≥ 25 kg/m2), were enrolled in this cross-sectional study. Plasma leptin concentrations were measured by enzyme-linked immunosorbent assay. Flow-mediated dilatation (FMD) of the brachial artery was measured to evaluate vascular endothelial function using ultrasound.

RESULTS

No significant difference in FMD was found between the lean and overweight groups (7.0 ± 3.8% and 6.5 ± 3.6%, respectively; p = 0.354). FMD was negatively correlated with age (r = -0.371, p < 0.001) and serum creatinine levels (r = -0.236, p = 0.030), but positively correlated with BMI (r = 0.330, p = 0.002) and plasma leptin levels (r = 0.290, p = 0.007) in the overweight group. FMD was not associated with any parameters in the lean group. Multiple regression analysis including possible atherosclerotic risk factors revealed that the plasma leptin level (β = 0.427, p = 0.013) was independently associated with FMD in the overweight group (R2 = 0.310, p = 0.025), but not the lean group.

CONCLUSION

Plasma leptin levels are associated with vascular endothelial function in overweight patients with type 2 diabetes.

The peroxisome proliferator activated receptor-γ pioglitazone improves vascular function and decreases disease activity in patients with rheumatoid arthritis

Background

Rheumatoid arthritis (RA) is associated with heightened mortality due to atherosclerotic cardiovascular disease (CVD). Inflammatory pathways in RA negatively affect vascular physiology and promote metabolic disturbances that contribute to CVD. We hypothesized that the peroxisome proliferator activated receptor‐γ (PPAR‐γ) pioglitazone could promote potent vasculoprotective and anti‐inflammatory effects in RA.

Methods and Results

One hundred forty‐three non‐diabetic adult RA patients (76.2% female, age 55.2±12.1 [mean±SD]) on stable RA standard of care treatment were enrolled in a randomized, double‐blind placebo controlled crossover trial of 45 mg daily pioglitazone versus placebo, with a 3‐month duration/arm and a 2‐month washout period. Pulse wave velocity of the aorta (PWV), brachial artery flow mediated dilatation (FMD), nitroglycerin mediated dilatation (NMD), microvascular endothelial function (reactive hyperemia index [RHI]), and circulating biomarkers of inflammation, insulin resistance, and atherosclerosis risk all were quantified. RA disease activity was assessed with the 28‐Joint Count Disease Activity Score (DAS‐28) C‐reactive protein (CRP) and the Short Form (36) Health Survey quality of life questionnaire. When added to standard of care RA treatment, pioglitazone significantly decreased pulse wave velocity (ie, aortic stiffness) (P=0.01), while FMD and RHI remained unchanged when compared to treatment with placebo. Further, pioglitazone significantly reduced RA disease activity (P=0.02) and CRP levels (P=0.001), while improving lipid profiles. The drug was well tolerated.

Conclusions

Addition of pioglitazone to RA standard of care significantly improves aortic elasticity and decreases inflammation and disease activity with minimal safety issues. The clinical implications of these findings remain to be established.

Clinical Trial Registration

URL: ClinicalTrials.gov Unique Identifier: NCT00554853.

SirT1 regulation of antioxidant genes is dependent on the formation of a FoxO3a/PGC-1α complex

SirT1 is a class III histone deacetylase that has been implicated in metabolic and reactive oxygen species control. In the vasculature it has been shown to decrease endothelial superoxide production, prevent endothelial dysfunction and atherosclerosis. However, the mechanisms that mediate SirT1 antioxidant functions remain to be characterized. The transcription factor FoxO3a and the transcriptional coactivator peroxisome proliferator activated receptor γ-coactivator 1α (PGC-1α) have been shown to induce the expression of antioxidant genes and to be deacetylated by SirT1.

AIMS

Here we investigated SirT1 regulation of antioxidant genes and the roles played by FoxO3a and PGC-1α in this regulation.

RESULTS

We found that SirT1 regulates the expression of several antioxidant genes in bovine aortic endothelial cells, including Mn superoxide dismutase (MnSOD), catalase, peroxiredoxins 3 and 5 (Prx3, Prx5), thioredoxin 2 (Trx2), thioredoxin reductase 2 (TR2), and uncoupling protein 2 (UCP-2) and can be localized in the regulatory regions of these genes. We also found that knockdown of either FoxO3a or PGC-1α prevented the induction of antioxidant genes by SirT1 over-expression. Furthermore, SirT1 increased the formation of a FoxO3a/PGC-1α complex as determined by co-immunoprecipitation (IP) assays, concomitantly reducing H2O2-dependent FoxO3a and PGC-1α acetylation. Data showing that FoxO3a knockdown increases PGC-1α acetylation levels and vice versa, suggest that SirT1 activity on FoxO3a and PGC-1α may be dependent of the formation of a FoxO3a/PGC-1α complex.

INNOVATION

A unifying mechanism for SirT1 activities is suggested.

CONCLUSION

We show that SirT1 regulation of antioxidant genes in vascular endothelial cells depends on the formation of a FoxO3a/PGC-1α complex.

Vascular smooth muscle function in type 2 diabetes mellitus: a systematic review and meta-analysis

AIMS/HYPOTHESIS

In type 2 diabetes, in contrast to the well-documented endothelial dysfunction, studies assessing vascular smooth muscle (VSM) function have yielded discrepant results over the last two decades. We therefore sought to determine whether or not VSM function is impaired in individuals with type 2 diabetes.

METHODS

We conducted a systematic search of MEDLINE, Cochrane, Scopus and Web of Science databases, from their respective inceptions until December 2012, for articles evaluating VSM function in individuals with type 2 diabetes. A meta-analysis was performed to compare the standardised mean difference (SMD) in VSM function between individuals with type 2 diabetes and age-matched controls. Subgroup analyses and meta-regression were used to identify sources of heterogeneity.

RESULTS

Twenty-seven articles (1,042 individuals with type 2 diabetes and 601 control subjects) were included in this analysis. VSM function was significantly impaired in diabetic compared with control subjects (SMD -0.68, 95% CI -0.84, -0.52; p < 0.001). Although moderate heterogeneity among studies was found (I (2) = 52%), no significant publication bias was detected. Subgroup analyses showed a further decline in VSM function assessed in the microcirculation compared with the macrocirculation of individuals with type 2 diabetes (p = 0.009). In meta-regression, VSM function in the microcirculation was inversely associated with BMI and triacylglycerols and was positively associated with HDL-cholesterol.

CONCLUSIONS/INTERPRETATION

In addition to the endothelium, the VSM is a source of vascular dysfunction in type 2 diabetes. An exacerbation of VSM function in the microcirculation may be a distinctive feature in type 2 diabetes.

Evaluation of digital thermal monitoring as a tool to assess perioperative vascular reactivity

AIM

The inflammatory response following tissue injury after major surgery is known to affect endothelial function and vascular reactivity. In this study we evaluated the utility of bedside Digital Thermal Monitoring (DTM) as a surrogate for evaluating vascular function in the postoperative period.

METHODS

Ischemia-induced reactive hyperemia variables were measured in sixty patients scheduled for major thoracic surgery using DTM (VENDYS 5000BC; Endothelix, Inc., Houston, TX, USA) at baseline and at 24, 48, 72 hours, and day 5 postoperatively. Furthermore, baseline DTM variables (TR, aTR and AUCTR) and postoperative kinetics of these variables were compared among patients with and without preoperative chemo-radiation and cardiovascular risk factors.

RESULTS

There were no significant differences in the DTM parameters measured at baseline and on each of the studied postoperative days. Compared to the baseline, the lowest measures of all variables were observed 24 hrs postoperatively and the highest measures of all variables were observed at 72 hrs. Patients with abdominal obesity and smoking had lower DTM values than the rest of the study group.

CONCLUSIONS

In our study, DTM as measured by the VENDYS 5000BC DTM system (Endothelix, Inc.) did not reveal significant changes in ischemia-induced reactive hyperemia (vascular reactivity) between the baseline and after surgery in the postoperative period. Patients with certain cardiovascular risk factors (abdominal obesity, smoking) had a significant lower DTM signal. Whether this novel non-invasive technique is able to serve as a perioperative diagnostic tool for patients in a clinical setting warrants further study.