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

Seasonal variations in endothelium-dependent flow-mediated vasodilation and endothelium-independent nitroglycerine-induced vasodilation

Cardiovascular mortality has been shown to vary seasonally. However, it has not been determined whether vascular function is affected by the season. The purpose of this study was to investigate the associations of vascular function with season and outdoor temperature. Between April 2007 and March 2022, measurements of flow-mediated vasodilation (FMD) of the brachial artery as an index of endothelial function and nitroglycerine-induced vasodilation (NID) as an index of endothelium-independent vasodilation were performed in 2190 subjects. There was no significant seasonal difference in FMD (spring, 3.9 ± 3.1%; summer, 3.5 ± 3.0%; fall, 3.7 ± 3.0%; winter, 3.6 ± 3.2%; P = 0.14). There was no significant correlation between FMD and daily mean outdoor temperature (r = -0.02, P = 0.25). Multivariate analyses revealed that neither season (β = -0.020, P = 0.31) nor outdoor temperature (β = 0.005, P = 0.81) was significantly associated with FMD after adjustment for other confounding factors. There were significant seasonal differences in NID (spring, 12.8 ± 6.3%; summer, 12.0 ± 6.1%; fall, 11.7 ± 6.1%; winter, 12.3 ± 5.9%; P = 0.02). However, multivariate analysis revealed that there was no significant association between season and NID after adjustment for other confounding factors (β = -0.012, P = 0.56). There was no significant correlation between NID and daily outdoor mean temperature (r = -0.03, P = 0.17). Multivariate analysis revealed that outdoor temperature was not significantly associated with NID (β = -0.006, P = 0.78). There was no significant association of FMD or NID with season or outdoor temperature, suggesting that it is not necessary to take into account the effects of season and outdoor temperature on vascular function when interpreting the results of FMD and NID measurements. Public trials registry number: UMIN000039512.

Role of thrombospondin-1 in high-salt-induced mesenteric artery endothelial impairment in rats

The matrix glycoprotein thrombospondin-1 (THBS1) modulates nitric oxide (NO) signaling in endothelial cells. A high-salt diet induces deficiencies of NO production and bioavailability, thereby leading to endothelial dysfunction. In this study we investigated the changes of THBS1 expression and its pathological role in the dysfunction of mesenteric artery endothelial cells (MAECs) induced by a high-salt diet. Wild-type rats, and wild-type and Thbs1-/- mice were fed chow containing 8% w/w NaCl for 4 weeks. We showed that a high salt diet significantly increased THBS1 expression and secretion in plasma and MAECs, and damaged endothelium-dependent vasodilation of mesenteric resistance arteries in wild-type animals, but not in Thbs1-/- mice. In rat MAECs, we demonstrated that a high salt environment (10-40 mM) dose-dependently increased THBS1 expression accompanied by suppressed endothelial nitric oxide synthase (eNOS) and phospho-eNOS S1177 production as well as NO release. Blockade of transforming growth factor-β1 (TGF-β1) activity by a TGF-β1 inhibitor SB 431542 reversed THBS1 up-regulation, rescued the eNOS decrease, enhanced phospho-eNOS S1177 expression, and inhibited Smad4 translocation to the nucleus. By conducting dual-luciferase reporter experiments in HEK293T cells, we demonstrated that Smad4, a transcription promoter, upregulated Thbs1 transcription. We conclude that THBS1 contributes to endothelial dysfunction in a high-salt environment and may be a potential target for treatment of high-salt-induced endothelium dysfunction.

Recent progress in understanding mitokines as diagnostic and therapeutic targets in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most prevalent tumors worldwide and the leading contributor to cancer-related deaths. The progression and metastasis of HCC are closely associated with altered mitochondrial metabolism, including mitochondrial stress response. Mitokines, soluble proteins produced and secreted in response to mitochondrial stress, play an essential immunomodulatory role. Immunotherapy has emerged as a crucial treatment option for HCC. However, a positive response to therapy is typically dependent on the interaction of tumor cells with immune regulation within the tumor microenvironment. Therefore, exploring the specific immunomodulatory mechanisms of mitokines in HCC is essential for improving the efficacy of immunotherapy. This study provides a comprehensive overview of the association between HCC and the immune microenvironment and highlights recent progress in understanding the involvement of mitochondrial function in preserving liver function. In addition, a systematic review of mitokines-mediated immunomodulation in HCC is presented. Finally, the potential diagnostic and therapeutic roles of mitokines in HCC are prospected and summarized. Recent progress in mitokine research represents a new prospect for mitochondrial therapy. Considering the potential of mitokines to regulate immune function, investigating them as a relevant molecular target holds great promise for the diagnosis and treatment of HCC.

An acute bout of prolonged sitting blunts popliteal endothelium-independent dilation in young, healthy adults

A single bout of prolonged uninterrupted sitting increases oxidative stress, reduces popliteal blood flow-induced shear stress, and diminishes endothelium-dependent, flow-mediated dilation (FMD). The FMD response is also influenced by the sensitivity of vascular smooth muscle cells to nitric oxide (i.e., endothelium-independent dilation), which is also attenuated by elevated oxidative stress. However, it is currently unknown whether prolonged sitting impacts popliteal endothelium-independent dilation responses, which may uncover a novel mechanism associated with sitting-induced vascular dysfunction. This study tested the hypothesis that prolonged sitting attenuates both popliteal FMD and endothelium-independent, nitroglycerin-mediated dilation responses (NMD, 0.4 mg sublingual dose). Popliteal blood flow (mL/min), relative FMD (%), and NMD (%) were assessed via duplex ultrasonography before and after a ∼3-h bout of sitting in 14 young, healthy adults (8♀; 22 ± 2 yr). Prolonged sitting attenuated resting blood flow (57 ± 23 to 32 ± 16 mL/min, P < 0.001), relative FMD (4.6 ± 2.8% to 2.2 ± 2.5%; P = 0.001), and NMD (7.3 ± 4.0% to 4.6 ± 3.0%; P = 0.002). These novel findings demonstrate that both endothelium-dependent and independent mechanisms contribute to the adverse vascular consequences associated with prolonged bouts of sitting.NEW & NOTEWORTHY We demonstrate that lower-limb vascular smooth muscle function is attenuated in young, healthy adults after an acute bout of prolonged sitting. These data indicate that prolonged sitting-induced vascular dysfunction involves both endothelium-dependent and -independent mechanisms.

Mitochondrial oxidative stress in brain microvascular endothelial cells: Triggering blood-brain barrier disruption

Blood-brain barrier disruption plays an important role in central nervous system diseases. This review provides information on the role of mitochondrial oxidative stress in brain microvascular endothelial cells in cellular dysfunction, the disruption of intercellular junctions, transporter dysfunction, abnormal angiogenesis, neurovascular decoupling, and the involvement and aggravation of vascular inflammation and illustrates related molecular mechanisms. In addition, recent drug and nondrug therapies targeting cerebral vascular endothelial cell mitochondria to repair the blood-brain barrier are discussed. This review shows that mitochondrial oxidative stress disorder in brain microvascular endothelial cells plays a key role in the occurrence and development of blood-brain barrier damage and may be critical in various pathological mechanisms of blood-brain barrier damage. These new findings suggest a potential new strategy for the treatment of central nervous system diseases through mitochondrial modulation of cerebral vascular endothelial cells.

Coronary Microvascular Dysfunction in Patients with Congenital Heart Disease

Congenital heart diseases represent a wide range of cardiac malformations. Medical and surgical advances have dramatically increased the survival of patients with congenital heart disease, leading to a continuously growing number of children, adolescents, and adults with congenital heart disease. Nevertheless, congenital heart disease patients have a worse prognosis compared to healthy individuals of similar age. There is substantial overlap in the pathophysiology of congenital heart disease and heart failure induced by other etiologies. Among the pathophysiological changes in heart failure, coronary microvascular dysfunction has recently emerged as a crucial modulator of disease initiation and progression. Similarly, coronary microvascular dysfunction could be important in the pathophysiology of congenital heart diseases as well. For this systematic review, studies on maximal vasodilatory capacity in the coronary microvascular bed in patients with congenital heart disease were searched using the PubMed database. To date, coronary microvascular dysfunction in congenital heart disease patients is incompletely understood because studies on this topic are rare and heterogeneous. The prevalence, extent, and pathophysiological relevance of coronary microvascular dysfunction in congenital heart diseases remain to be elucidated. Herein, we discuss what is currently known about coronary microvascular dysfunction in congenital heart disease and future directions.

Vasorelaxant Effect of Trachelospermi caulis Extract on Rat Mesenteric Resistance Arteries

Background: Trachelospermi caulis (T. caulis) has been used as a traditional herbal medicine in Asian countries. Although it is well known that T. caulis has beneficial effects, no sufficient research data are available on the cardiovascular effect of T. caulis. We investigated whether T. caulis extract has vascular effects in rat resistance arteries in this study. Methods: To examine whether T. caulis extract affects vascular reactivity, we measured isometric tension of rat mesenteric resistance arteries using a multi-wire myograph system. T. caulis extract was administered after arteries were pre-contracted with high K⁺ (70 mM) or phenylephrine (5 µM). Vanillin, a single active component of T. caulis, was used to treat mesenteric arteries. Results: T. caulis extract caused vascular relaxation in a concentration-dependent manner, which was endothelium-independent. To further identify the mechanism, we incubated the arteries in Ca²⁺-free solution containing high K⁺, followed by a cumulative administration of CaCl₂ (0.01–2.0 mM) with or without T. caulis extract (250 µg/mL). The treatment of T. caulis extract decreased contractile responses induced by the addition of Ca²⁺, which suggested that the extracellular Ca²⁺ influx was inhibited by the T. caulis extract. Moreover, an active compound of T. caulis extract, vanillin, also induced vasodilation in mesenteric resistance arteries. Conclusion: T. caulis extract and its active compound, vanillin, concentration-dependently induced vascular relaxation in mesenteric resistance arteries. These results suggest that the administration of T. caulis extract could help decrease blood pressure.

Update on Hypertension Research in 2021

In 2021, 217 excellent manuscripts were published in Hypertension Research. Editorial teams greatly appreciate the authors' contribution to hypertension research progress. Here, our editorial members have summarized twelve topics from published work and discussed current topics in depth. We hope you enjoy our special feature, "Update on Hypertension Research in 2021".

High fructose induces dysfunctional vasodilatation via PP2A-mediated eNOS Ser1177 dephosphorylation

Background

Processed foods are popular and contain large amounts of industrial fructose, which changes people’s diet and exacerbates the negative health effects of high fructose. Several studies have shown that excessive intake of fructose has a major impact on vascular disease. However, the mechanism of the effect of high fructose on blood vessels is currently unclear.

Methods

The effect of fructose on the vasodilatation of isolated thoracic aortic rings was observed by using wire myography in wild-type (WT) mice. Cell viability and nitric oxide (NO) production were assessed by the corresponding kits in mouse vascular endothelial cells. The effect of fructose on endothelial nitric oxide synthase (eNOS) and protein phosphatase 2A (PP2A) and their changes in phosphorylation were detected by using Western blots. Moreover, a PP2A inhibitor (okadaic acid, OA) was used to evaluate the relationship between fructose and PP2A. Furthermore, PP2ACα endothelial-specific knockout (PP2A cKO) mice were used to detect the vasodilatation of in vitro fructose-incubated thoracic aortic rings by using wire myography.

Results

High fructose induced endothelium-dependent dysfunctional vasodilatation. High fructose reduced acetylcholine (Ach)-induced vasodilation but did not affect sodium nitroprusside (SNP)-induced vasodilation. Accordingly, NO production and the phosphorylation level of eNOS at serine (Ser) 1177 (P-eNOS) in vascular endothelial cells were remarkably reduced without changes in cell viability. The expression of protein phosphatase 2A catalytic subunit (PP2AC) was increased and the expression of phosphorylated PP2AC (P-PP2A, tyrosine [Tyr] 307) was significantly decreased. Nevertheless, these effects were reversed by OA. Moreover, knockout of the PP2A gene could recover the response of vessels to Ach under high fructose stimulation.

Conclusions

Our observations demonstrate an underlying mechanism of fructose-induced dysfunctional vasodilatation. Fructose could activate PP2A, which leads to decrease in the phosphorylation of eNOS at Ser1177 and the reduction of NO release, thus leading to the occurrence of endothelium-dependent dysfunctional vasodilatation.

The Role of Endothelial Progenitor Cells in Atherosclerosis and Impact of Anti-Lipemic Treatments on Endothelial Repair

Cardiovascular complications are associated with advanced atherosclerosis. Although atherosclerosis is still regarded as an incurable disease, at least in its more advanced stages, the discovery of endothelial progenitor cells (EPCs), with their ability to replace old and injured cells and differentiate into healthy and functional mature endothelial cells, has shifted our view of atherosclerosis as an incurable disease, and merged traditional theories of atherosclerosis pathogenesis with evolving concepts of vascular biology. EPC alterations are involved in the pathogenesis of vascular abnormalities in atherosclerosis, but many questions remain unanswered. Many currently available drugs that impact cardiovascular morbidity and mortality have shown a positive effect on EPC biology. This review examines the role of endothelial progenitor cells in atherosclerosis development, and the impact standard antilipemic drugs, including statins, fibrates, and ezetimibe, as well as more novel treatments such as proprotein convertase subtilisin/kexin type 9 (PCSK9) modulating agents and angiopoietin-like proteins (Angtpl3) inhibitors have on EPC biology.

Serum Potassium Levels of 4.5 to Less Than 5.0 mmol/L Are Associated with Better Vascular Function

Aim: An experimental study showed that potassium inhibits the formation of reactive oxygen species by vascular cells. The purpose of this study was to investigate the association between serum potassium levels and vascular function.

Methods: We measured flow-mediated vasodilation (FMD) as an index of endothelial function in 3045 subjects (1964 men; mean age, 62.3±13.8 years) and nitroglycerine-induced vasodilation (NID) as an index of vascular smooth muscle function in 1578 subjects (1001 men; mean age, 61.8±16.3 years).

Results: In the 3045 subjects, there was a significant positive correlation between FMD and serum potassium levels (r=0.09,P＜0.001). Multivariate analysis revealed that serum potassium levels were significantly associated with FMD (β=0.109,P＜0.001). When subjects were divided into two groups based on treatment with drugs that could alter serum potassium levels, the association between serum potassium levels and FMD was significant both in subjects with (β=0.096,P＜0.001) and subjects without (β=0.123,P＜0.001) treatment with drugs that could alter serum potassium levels. In the 1578 subjects, there was a significant positive correlation between NID and serum potassium levels (r=0.11,P＜0.001). Multivariate analysis revealed that serum potassium levels were significantly associated with NID (β=0.098,P＜0.001). The association between serum potassium levels and NID was significant both in subjects with (β=0.121,P=0.001) and subjects without (β=0.083,P=0.03) treatment with drugs that could alter serum potassium levels.

Conclusions: Serum potassium levels of 4.5-＜5.0 mmol/L are associated with better vascular function regardless of the presence or absence of treatment with drugs that could alter serum potassium levels.

Diagnostic and prognostic role of nitroglycerin-induced dilation in patients with suspected vasospastic angina, combined with ergonovine provocation test

The diagnostic and prognostic role of nitroglycerin-induced dilation (NID) combined with ergonovine provocation test in patients with suspected VSA patients is not clear. A total of 438 consecutive patients who underwent the ergonovine provocation test for the diagnosis of vasospastic angina (VSA) were enrolled. Patients with VSA (n = 52) had a significantly greater coronary response to ergonovine (− 84.3 ± 10.5% vs. − 38.4 ± 17.9%, p < 0.001) and NID (26.3 ± 31.0% vs. 12.5 ± 19.0%, p < 0.001) than non-VSA patients. However, positive NID (more than 13.8% dilation, n = 170) showed a poor accuracy (AUC 0.64 [95% CI: 0.56–0.73], p = 0.001, sensitivity 60.4%, specificity 61.3%) for the diagnosis of VSA by ergonovine provocation test. Major adverse cardiovascular events (MACE) occurred more frequently in the VSA group than in the non-VSA group (9.6% vs. 2.2%, p = 0.006). In addition, the positive NID group showed a lower rate of MACE than the negative NID group (1.2% vs. 4.3%, p = 0.021). Interestingly, the group of VSA with negative NID had poor prognosis than any other combinations (Log-rank, p < 0.0001). Although NID had a limited role in the detection of VSA defined by ergonovine provocation test, NID combined with the ergonovine provocation test has an additive prognostic role in the clinical outcomes in patients with suspected VSA.

Bioenzyme-responsive L-arginine-based carbon dots: the replenishment of nitric oxide for nonpharmaceutical therapy

Nitric oxide (NO) is a short-lived, bioactive gas that has been found to have affinitive effects on cardiovascular diseases as well as cancer biology, while NO deficiency may cause serious pathological responses. The existing chemically-synthesized NO donors have inevitable systemic toxicity and cannot be released adaptively. Hence, L-arginine, an endogenous NO precursor, merits investigation as a natural efficient NO donor. Herein, we designed amino acid-doped L-arginine CDs-based bioenzyme-responsive NO donors, which could adaptively replenish NO/ONOO^- in response to different microenvironments. Our results indicated the mechanism of the NO/ONOO^- supplementation of L-arginine-based CDs and their potential for nonpharmaceutical gas-involving theranostics for the first time.

Volume Elastic Modulus, Vascular Function, and Vascular Structure in Patients with Cardiovascular Risk Factors

Aims: Volume elastic modulus (V _E ), an index of arterial elasticity, and arterial diameter of the brachial artery can be automatically measured by a newly developed oscillometric device. We investigated the associations of V _E with flow-mediated vasodilation (FMD), an index of endothelium-dependent vasodilation, nitroglycerine-induced vasodilation (NID), an index of endothelium-independent vasodilation, and intima-media thickness (IMT) of the brachial artery and association of oscillometrically measured brachial artery diameter with ultrasonographically measured brachial artery diameter in patients with cardiovascular risk factors.

Methods: Oscillometric measurements of V _E and brachial artery diameter and ultrasound measurements of brachial artery diameter, FMD, NID, and IMT of the brachial artery were performed in 50 patients with cardiovascular risk factors.

Results: The mean values were 2.1±0.4 mmHg/% for V _E , 0.31±0.05 mm for brachial IMT, 4.48±0.70 mm for oscillometric brachial artery diameter, and 4.30±0.55 mm for ultrasound brachial artery diameter. V _E significantly correlated with brachial IMT (r=0.51, P ＜0.001), whereas there was no significant correlation of V _E with FMD (r=-0.08, P =0.58) or NID (r=0.07, P =0.61). Multivariate analysis revealed that V _E was significantly associated with brachial IMT (β=0.33, P =0.04). Oscillometric brachial artery diameter significantly correlated with ultrasound brachial artery diameter (r=0.79, P ＜0.001). The Bland-Altman plot showed good agreement between oscillometric brachial artery diameter and ultrasound brachial artery diameter (mean difference, -0.17 mm; limits of agreement, -1.03 mm to 0.69 mm).

Conclusions: In patients with cardiovascular risk factors, V _E may represent atherosclerotic structural alterations of the vascular wall but not vascular function. The accuracy of oscillometric measurement of brachial artery diameter is acceptable.

Εndothelial and microvascular function in CKD: Evaluation methods and associations with outcomes

BACKGROUND

Cardiovascular disease is the major cause of morbidity and mortality in patients with chronic kidney disease (CKD). Endothelial dysfunction, the hallmark of atherosclerosis, is suggested to be involved pathogenetically in cardiovascular and renal disease progression in these patients.

METHODS

This is a narrative review presenting the techniques and markers used for assessment of microvascular and endothelial function in patients with CKD and discussing findings of the relevant studies on the associations of endothelial dysfunction with co-morbid conditions and outcomes in this population.

RESULTS

Venous Occlusion Plethysmography was the first method to evaluate microvascular function; subsequently, several relevant techniques have been developed and used in patients with CKD, including brachial Flow-Mediated Dilatation, and more recently, Near-Infrared Spectroscopy and Laser Speckle Contrast Analysis. Furthermore, several circulating biomarkers are commonly used in clinical research. Studies assessing endothelial function using the above techniques and biomarkers suggest that endothelial dysfunction occurs early in CKD and contributes to the target organ damage, cardiovascular events, death and progression towards end-stage kidney disease.

CONCLUSIONS

Older and newer functional methods and several biomarkers have assessed endothelial dysfunction in CKD; accumulated evidence supports an association of endothelial dysfunction with outcomes. Future research with new, non-invasive and easily applicable methods could further delineate the role of endothelial dysfunction on cardiovascular and renal disease progression in patients with CKD.

Human microvascular reactivity: a review of vasomodulating stimuli and non-invasive imaging assessment

The microvasculature serves an imperative function in regulating perfusion and nutrient exchange throughout the body, adaptively altering blood flow to preserve hemodynamic and metabolic homeostasis. Its normal functioning is vital to tissue health, whereas its dysfunction is present in many chronic conditions, including diabetes, heart disease, and cognitive decline. As microvascular dysfunction often appears early in disease progression, its detection can offer early diagnostic information. To detect microvascular dysfunction, one uses imaging to probe the microvasculature's ability to react to a stimulus, also known as microvascular reactivity (MVR). An assessment of MVR requires an integrated understanding of vascular physiology, techniques for stimulating reactivity, and available imaging methods to capture the dynamic response. Practical considerations, including compatibility between the selected stimulus and imaging approach, likewise require attention. In this review, we provide a comprehensive foundation necessary for informed imaging of MVR, with a particular focus on the challenging endeavor of assessing microvascular function in deep tissues.

Vascular endothelial damage in COPD: current functional assessment methods and future perspectives

Introduction: Cardiovascular disease is a major cause of death in chronic obstructive pulmonary disease (COPD), but the relationship between these two entities is not fully understood; smoking, inflammation, arterial stiffness and endothelial dysfunction are significant determinants. Endothelial dysfunction is not only associated with cardiovascular disease, but also with COPD severity.Areas covered: Several functional methods have been developed to evaluate endothelial function in healthy and diseased individuals; from the invasive angiography of epicardial coronary arteries and Venous-Occlusion-Plethysmography, to more modern, noninvasive approaches such as Flow-Mediated-Dilatation, Peripheral-Arterial-Tonometry and Near-Infrared-Spectroscopy, all these methods have boosted clinical research in this field. In this context, this narrative review, which included articles published in PubMed and Scopus up to 25-November-2020, summarizes available functional methods for endothelial damage assessment in COPD and discusses existing evidence on their associations with comorbidities and outcomes in this population.Expert opinion: Accumulated evidence suggests that endothelial dysfunction occurs in early stages of CΟPD and worsens with pulmonary obstruction severity and during acute exacerbations. Novel methods evaluating endothelial function offer a detailed, real-time assessment of different parameters related to vascular function and should be increasingly used to shed more light on the role of endothelial damage on cardiovascular and COPD progression.

Endothelial Dysfunction during Acute Exacerbations of Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-Analysis

Chronic obstructive pulmonary disease (COPD) is characterized by high cardiovascular risk, which is further amplified during acute COPD exacerbations (AECOPD). Endothelial dysfunction has been previously suggested as one of the potential pathogenetic mechanisms. In order to study the effects of AECOPD on endothelial function assessed by available functional methods, we performed a literature search involving Pubmed and Scopus databases. Eligible studies were those that included adult patients with COPD and evaluated endothelial damage via semi-invasive or noninvasive functional methods, during AECOPD and after recovery or in stable condition. Newcastle-Ottawa Scale was applied to evaluate the quality of retrieved studies. Endothelial function was significantly impaired during AECOPD compared to recovery/stable condition (SMD: -0.87, 95%CI [-1.19, -0.55]). Patients during AECOPD presented a significantly worse response in endothelium-dependent (flow-mediated dilatation WMD: -2.59, 95%CI [-3.75, -1.42]) and independent vasodilation (nitroglycerine-mediated dilatation WMD: -3.13, 95%CI [-5.18, -1.09]) compared to recovery. Sensitivity analyses confirmed the above results. In conclusion, endothelium-dependent and independent vasodilation is worse during AECOPD compared to the stable condition. Endothelial dysfunction could play a role in the high cardiovascular risk during AECOPD.

Assessment of Endothelial and Microvascular Function in CKD: Older and Newer Techniques, Associated Risk Factors, and Relations with Outcomes

BACKGROUND

Endothelium is the inner cellular lining of the vessels that modulates multiple biological processes including vasomotor tone, permeability, inflammatory responses, hemostasis, and angiogenesis. Endothelial dysfunction, the basis of atherosclerosis, is characterized by an imbalance between endothelium-derived relaxing factors and endothelium-derived contracting factors.

SUMMARY

Starting from the semi-invasive venous occlusion plethysmography, several functional techniques have been developed to evaluate microvascular function and subsequently used in patients with CKD. Flow-mediated dilatation of the forearm is considered to be the "gold standard," while in the last years, novel, noninvasive methods such as laser speckle contrast imaging and near-infrared spectroscopy are scarcely used. Moreover, several circulating biomarkers of endothelial function have been used in studies in CKD patients. This review summarizes available functional methods and biochemical markers for the assessment of endothelial and microvascular function in CKD and discusses existing evidence on their associations with comorbid conditions and outcomes in this population. Key Messages: Accumulated evidence suggests that endothelial dysfunction occurs early in CKD and is associated with target organ damage, progression of renal injury, cardiovascular events, and mortality. Novel methods evaluating microvascular function can offer a detailed, real-time assessment of underlying phenomena and should be increasingly used to shed more light on the role of endothelial dysfunction on cardiovascular and renal disease progression in CKD.

Circulating senescent angiogenic T cells are linked with endothelial dysfunction and systemic inflammation in hypertension

Objective:

Angiogenic T cells (T_ang cells), a recently discovered T-cell subset, have been reported involved in the repair of endothelial injury. The purpose of this study was to explore the correlation of immunologic senescence and pro-inflammatory capacity of T_ang cells with endothelial dysfunction in hypertensive patients.

Methods:

Immunological characteristics of T_ang cells (CD3⁺CD31⁺CXCR4⁺) from hypertensive patients with or without endothelial dysfunction were elucidated by surface immunophenotyping and intracellular cytokine staining. Endothelial function was measured by flow-mediated dilation (FMD).

Results:

The frequency of CD28^null subset in CD4⁺ T_ang cells was notably elevated in hypertensive patients with endothelial dysfunction, which was negatively associated with FMD. The high frequency of CD28^nullCD4⁺ T_ang cells was an independent risk factor of endothelial dysfunction with good diagnostic performance in ROC curve analysis. Immunophenotyping revealed that this specific subset of T_ang cells exhibited senescent profile and has low hTERT expression. CD28^nullCD4⁺ T_ang cells produced high levels of inflammatory cytokines, IL-6, IFN-γ and TNF-α, and significantly correlated with the systemic inflammation in hypertensive patients with endothelial dysfunction.

Conclusion:

Collectively, our findings demonstrate for the first time that CD28^null subset in CD4⁺ T_ang cells with senescent and pro-inflammatory phenotype is dependently correlated with impaired FMD and systemic inflammation, which might contribute to the immunopathologic mechanism of endothelial dysfunction. Identification of a pathogenic CD4⁺ T_ang-cell subset lacking CD28 may offer opportunities for the evaluation and management of endothelial dysfunction in hypertension.

Effects of combined exercise training and Chlorella intake on vasorelaxation mediated by nitric oxide in aged mice

Chronic Chlorella intake and aerobic exercise training reduce arterial stiffness and increase circulating nitric oxide (NO) levels, which has beneficial effects. This study aimed to clarify the combined aortic NO-mediated effects of chronic Chlorella intake and aerobic exercise training on endothelial vasorelaxation in aged mice. In this study, 38-week-old male senescence-accelerated mouse prone 1 (SAMP1) mice were divided into aged sedentary control (Con), aerobic exercise training (AT; voluntary wheel running for 12 weeks), Chlorella intake (CH; 0.5% Chlorella powder in normal diet), and AT and CH combined (AT+CH) groups. Endothelium-dependent vasorelaxation by addition of acetylcholine to the isolated mouse aortic rings was significantly higher in the AT, CH, and AT+CH groups than in the Con group; a significantly greater effect was seen in the AT+CH group than in the AT and CH groups. Similarly, plasma and arterial nitrite/nitrate levels and arterial endothelial NO synthase phosphorylation were significantly higher in the AT, CH, and AT+CH groups than in the Con group; the AT+CH group had higher values than the AT and CH groups. Thus, chronic Chlorella intake combined with aerobic exercise training had pronounced effects on endothelial vasorelaxation in aged mice via an additive increase in arterial NO production. Novelty: Endothelium-dependent vasorelaxation was improved by Chlorella intake and exercise. Chlorella intake and exercise increased arterial Akt/eNOS/NO signaling. This combination approach further improved vasorelaxation via arterial NO production.

Echinacoside‑induced nitric oxide production in endothelial cells: Roles of androgen receptor and the PI3K‑Akt pathway

Echinacoside (ECH) is a natural compound with an endothelium‑dependent vasodilatory effect. Nitric oxide (NO) is an important vasorelaxant released from endothelial cells. In order to examine the molecular mechanism of ECH‑induced NO production in endothelial cells, the present study investigated the involvement of androgen receptor (AR) and the phosphatidylinositol 3‑kinase (PI3K)/protein kinase B (Akt) pathway in the phosphorylation of endothelial nitric oxide synthase (eNOS) in human umbilical vein endothelial cells (HUVECs). Using the fluorescent probe DAF‑FM, the production of NO was found to be significantly increased, and eNOS was phosphorylated at Ser1177 in a concentration‑​dependent manner under 0.01‑10 µM ECH treatment in HUVECs. In addition, NO production and eNOS phosphorylation induced by ECH were diminished when pretreated with the AR antagonist nilutamide, or when transfected with AR small interfering RNAs. Furthermore, the ECH‑induced phosphorylation of the Akt at Ser473 was abrogated by 5 µM wortmannin (a PI3K inhibitor). These data indicated that ECH stimulated NO production via the AR‑dependent activation of eNOS in HUVECs, and that the PI3K/Akt pathway may be involved in eNOS phosphorylation induced by ECH.

Diagnostic Criteria of Flow-Mediated Vasodilation for Normal Endothelial Function and Nitroglycerin-Induced Vasodilation for Normal Vascular Smooth Muscle Function of the Brachial Artery

Background

Diagnostic criteria of flow‐mediated vasodilation (FMD), an index of endothelial function, and nitroglycerin‐induced vasodilation (NID), an index of vascular smooth muscle function, of the brachial artery have not been established. The purpose of this study was to propose diagnostic criteria of FMD and NID for normal endothelial function and normal vascular smooth muscle function.

Methods and Results

We investigated the cutoff values of FMD and NID in subjects with (risk group) and those without cardiovascular risk factors or cardiovascular diseases (no‐risk group) in 7277 Japanese subjects (mean age 51.4±10.8 years) from the Flow‐Mediated Dilation Japan study and the Flow‐Mediated Dilatation Japan Registry study for analysis of the cutoff value of FMD and in 1764 Japanese subjects (62.2±16.1 years) from the registry of Hiroshima University Hospital for analysis of the cutoff value of NID. Receiver‐operator characteristic curve analysis of FMD to discriminate subjects in the no‐risk group from patients in the risk group showed that the optimal cutoff value of FMD to diagnose subjects in the no‐risk group was 7.1%. Receiver‐operator characteristic curve analysis of NID to discriminate subjects in the no‐risk group from patients in the risk group showed that the optimal cutoff value of NID to diagnose subjects in the no‐risk group was 15.6%.

Conclusions

We propose that the cutoff value for normal endothelial function assessed by FMD of the brachial artery is 7.1% and that the cutoff value for normal vascular smooth muscle function assessed by NID of the brachial artery is 15.6% in Japanese subjects.

Clinical Trial Registration

http://www.umin.ac.jp Unique identifiers: UMIN000012950, UMIN000012951, UMIN000012952, and UMIN000003409

gp91phox, a Novel Biomarker Evaluating Oxidative Stress, Is Elevated in Subclinical Hypothyroidism

BACKGROUND

gp91^phox, the catalytic core of NADPH oxidase (NOX) and biomarker of NOX activation, has been recently recognized as a parameter of systemic oxidative stress in several studies. Subclinical hypothyroidism (SH) is characteristic of elevated level of serum thyroid stimulating hormone (TSH) and is frequently accompanied with cholesterolemia. In this study, the levels of serum soluble gp91^phox were measured to assess the oxidative stress in patients with SH. And the relationship among gp91^phox, low-density lipoprotein-C (LDL-C), and TSH was also investigated.

METHODS

A total of 51 subjects were enrolled and categorized into four groups: the healthy controls subjects (n = 13), controls with high level of LDL-C alone (n = 12), SH with normal level of LDL-C (n = 11), and SH with high level of LDL-C (n = 15). The related clinical and laboratory data were collected for statistical analysis. All the patients were newly diagnosed and did not take any medication. The information of lipid profile and thyroid function was extracted, and the concentrations of gp91phox were obtained with ELISA.

RESULTS

The levels of serum soluble gp91phox evidently increased in the patients with SH with a high level of LDL-C (81.52 ± 37.00 ug/mL) as compared to the healthy controls (54.98 ± 1.83ug/mL, p < 0.001), controls with high level of LDL-C (61.21 ± 4.48 ug/mL, p=0.038) and SH with a normal level of LDL-C (62.82 ± 11.67ug/mL, p=0.027). Additionally, the levels of gp91^phox showed a significant positive correlation with both the levels of LDL-C (r = 0.595, p < 0.001) and TSH (r = 0.346, p=0.013) by the Spearman correlation analyses. The correlation remained significant even when the effect of another factor was controlled (TSH: when the effect of LDL-C was controlled, r = 0.453, p=0.001; LDL-C: when the effect of TSH was controlled, r = 0.291, p=0.040). The main effect analysis showed an independent main effect of either LDL-C (p = 0.041) or TSH (p=0.022) on gp91^phox without interaction (p=0.299).

CONCLUSIONS

Our work demonstrated that the levels of gp91^phox, a novel biomarker for measuring the oxidative stress, were significantly elevated in the patients with SH. And LDL-C and TSH were both independent predictors of gp91^phox. Abbreviations. BMI : Body mass index; TC : Total cholesterol; LDL-C : Low-density lipoprotein cholesterol; HDL-C : High-density lipoprotein cholesterol; TG : Triglyceride; FBG : Fasting blood glucose; FT3 : Free triiodothyronine; FT4 : Free thyroxine; TSH: Thyroid stimulating hormone; SBP : Systolic blood pressure; DBP : Diastolic blood pressure; SD : Standard deviation; LSD: Least significant difference.

Metabolic remodeling induced by mitokines in heart failure

The prevalence rates of heart failure (HF) are greater than 10% in individuals aged >75 years, indicating an intrinsic link between aging and HF. It has been recognized that mitochondrial dysfunction contributes to the pathology of HF. Mitokines are a type of cytokines, peptides, or signaling pathways produced or activated by the nucleus or the mitochondria through cell non-autonomous responses during cellular stress. In addition to promoting the communication between the mitochondria and the nucleus, mitokines also exert a systemic regulatory effect by circulating to distant tissues. It is noteworthy that increasing evidence has demonstrated that mitokines are capable of reducing the metabolic-related HF risk factors and are associated with HF severity. Consequently, mitokines might represent a potential therapy target for HF.

Integrated Transcriptomic and Proteomic Analysis of Primary Human Umbilical Vein Endothelial Cells

Understanding the molecular profile of every human cell type is essential for understanding its role in normal physiology and disease. Technological advancements in DNA sequencing, mass spectrometry, and computational methods allow us to carry out multiomics analyses although such approaches are not routine yet. Human umbilical vein endothelial cells (HUVECs) are a widely used model system to study pathological and physiological processes associated with the cardiovascular system. In this study, next-generation sequencing and high-resolution mass spectrometry to profile the transcriptome and proteome of primary HUVECs is employed. Analysis of 145 million paired-end reads from next-generation sequencing confirmed expression of 12 186 protein-coding genes (FPKM ≥0.1), 439 novel long non-coding RNAs, and revealed 6089 novel isoforms that were not annotated in GENCODE. Proteomics analysis identifies 6477 proteins including confirmation of N-termini for 1091 proteins, isoforms for 149 proteins, and 1034 phosphosites. A database search to specifically identify other post-translational modifications provide evidence for a number of modification sites on 117 proteins which include ubiquitylation, lysine acetylation, and mono-, di- and tri-methylation events. Evidence for 11 "missing proteins," which are proteins for which there was insufficient or no protein level evidence, is provided. Peptides supporting missing protein and novel events are validated by comparison of MS/MS fragmentation patterns with synthetic peptides. Finally, 245 variant peptides derived from 207 expressed proteins in addition to alternate translational start sites for seven proteins and evidence for novel proteoforms for five proteins resulting from alternative splicing are identified. Overall, it is believed that the integrated approach employed in this study is widely applicable to study any primary cell type for deeper molecular characterization.

Cardiometabolic risks in PCOS: a review of the current state of knowledge

INTRODUCTION

Polycystic ovary syndrome (PCOS) is a common endocrine disorder affecting up to 18% women of reproductive age. It is associated with a range of metabolic, reproductive, and psychological features. Current evidence indicates a role of PCOS in the development of metabolic and increased cardiovascular risk factors (CVRF) with implications for compromised cardiovascular endpoint disease, which may have a considerable impact on health and health care costs.

AREAS COVERED

Existing studies examining long-term cardiometabolic health in PCOS are heterogeneous with inconsistent findings. In the current review, we aim to explore and critically review retrospective, prospective, meta-analysis and review articles relating to PCOS on cardiometabolic risk factors and clinical consequences to summarize the evidence, note evidence gaps, and suggest implications for future research.

EXPERT COMMENTARY

Although there is an established association between PCOS and metabolic health, implications on cardiac health are more uncertain with associations observed for CVRF and subclinical disease, yet limited and conflicting data on actual cardiovascular endpoints. There is a lack of population-based long-term studies examining cardiometabolic morbidity and mortality in PCOS with a need for further research to progress toward a better understanding of the long-term cardiometabolic impacts in women with PCOS.