Mechanism Of Vascular Endothelial Dysfunction Research Articles

Abstract 10789: Disruption of Stromal Interaction Molecule 1 in Immune Regulatory T Cells Protects Vascular Endothelial Function in Renovascular Hypertension

Introduction & Hypothesis: Microvascular dysfunction in renovascular hypertension is a major risk factor for cardiovascular diseases. However, the underlying mechanism of vascular endothelial dysfunction in renovascular hypertension is not fully understood. Here, we sought to determine the role and impact of the stromal interaction molecule 1 (STIM1) knockout in immune regulatory T cells (Stim1 Treg-/- ) in renovascular hypertension-induced vascular endothelial dysfunction. Methods: Mice were divided into four groups. Group 1 and 2: Stim1 flx/flx male and female mice with and without 2-kidney-1-clip (2K1C) surgery for four weeks. Group 3 and 4: Stim1 Treg-/- male and female mice with and without 2K1C for four weeks. We measured body weight, arterial blood pressure, cardiac hypertrophy, lung edema, inflammation, fibrosis, and assessed microvascular endothelial function. Results: Stim1 flx/flx both male and female mice subjected to 2K1C for four weeks develop hypertension, cardiac hypertrophy, lung edema, low running performance, and vascular dysfunction. Interestingly, the disruption of STIM1 in Treg cells in both male and female mice protected from 2K1C-induced hypertension, cardiac hypertrophy, and lung edema. Moreover, microvascular endothelial function was also protected in both groups. Conclusion: Our data illustrate that STIM1 in immune Treg cells has s significant impact in renovascular hypertension-induced cardiovascular complications. Thus, targeting STIM1 in Treg cells could be a potential therapeutic approach to protect from renovascular hypertension-induced cardiovascular diseases.

Association of enhanced circulating trimethylamine N-oxide with vascular endothelial dysfunction in periodontitis patients.

Accumulating evidences indicate that periodontitis is closely associated with endothelial dysfunction. Trimethylamine-N-oxide (TMAO), a harmful microbiota generated metabolite, has been implicated as a nontraditional risk factor for impaired endothelial function. However, whether increased circulating levels of TMAO in periodontitis patients induces endothelial dysfunction remains unknown. Patients with periodontitis and periodontally healthy controls were enrolled. Periodontal inflamed surface area (PISA) was calculated to assess the inflammatory burden posed by periodontitis. The circulating TMAO was measured by high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). Vascular endothelial function including peripheral endothelial progenitor cells (EPCs), brachial arterial flow-mediated vasodilation (FMD), and brachial-ankle pulse wave velocity (baPWV) were assessed. We also isolated and cultured EPCs from participants' peripheral blood to investigate the effect of TMAO on EPC functions in vitro. One hundred and twenty two patients with Stage III-IV periodontitis and 81 healthy controls were included. Patients with periodontitis presented elevated TMAO (P=0.002), lower EPCs (P=0.025), and declined FMD levels (P=0.005). The TMAO concentrations were correlated with reduced circulating EPCs and FMD levels. Moreover, TMAO can injury EPCs function in vitro, and may induce cell pyroptosis via Bax/caspase-3/GSDME pathway. The present study demonstrates for the first time that circulating TMAO levels are increased in patients with Stage III-IV periodontitis, and correlated with vascular endothelial dysfunction. These findings may provide a novel insight into the mechanism of vascular endothelial dysfunction in patient with periodontitis via TMAO-downregulated EPC functions.

Thioredoxin deficiency exacerbates vascular dysfunction during diet-induced obesity in small mesenteric artery in mice.

Thioredoxin (Trx) is a small cellular redox protein with established antioxidant and disulfide reductase properties. We hypothesized that Trx deficiency in mice would cause increased oxidative stress with consequent redox imbalance that would exacerbate obesity-induced vascular dysfunction. Non-transgenic (NT, C57BL/6) and dominant-negative Trx (dnTrx-Tg, low levels of redox-active protein) mice were either fed a normal diet (NC) or high fat diet plus sucrose (HFS) diet for 4months (3-month HFD+ 1-month HFS). Weight gain, glucose tolerance test (GTT), insulin tolerance test (ITT), and other metabolic parameters were performed following NC or HFS diet. Arterial structural remodeling and functional parameters were assessed by myography. Our study found that dnTrx mice with lower levels of active Trx exacerbated myogenic tone, inward arterial remodeling, arterial stiffening, phenylephrine-induced contraction, and endothelial dysfunction of MA. Additionally, FeTMPyP, a peroxynitrite decomposition catalyst, acutely decreased myogenic tone and contraction and normalized endothelial function in MA from dnTrx-Tg mice on HFS via increasing nitric oxide (NO)-mediated relaxation. Our results indicate that deficiency of active Trx exacerbates MA contractile and relaxing properties during diet-induced obesity demonstrating that loss of redox balance in obesity is a key mechanism of vascular endothelial dysfunction.

Vascular Endothelial Glycocalyx as a Mechanism of Vascular Endothelial Dysfunction and Atherosclerosis

Atherosclerosis occurs as a result of organized processes that include vascular endothelial dysfunction, lipid accumulation, abnormal inflammatory reaction, excessive reactive oxygen species production, and vascular cell proliferation and migration. In patients with atherosclerosis, vascular endothelial dysfunction is commonly observed with the damage of vascular endothelial glycocalyx, which is an extracellular matrix bound to and encapsulating the endothelial cells that line the blood vessel wall. Unhealthy lifestyle choices such as smoking and physical inactivity also induce glycocalyx degradation. Additionally, vascular endothelial glycocalyx can be damaged by various pathological conditions including dehydration, acute infectious disease, trauma, sepsis, acute respiratory distress syndrome, Kawasaki disease, preeclampsia, gestational diabetes mellitus, hypertension, diabetes mellitus, chronic kidney disease, atherosclerosis, stroke, dementia, microvascular angina, acute coronary syndrome, and heart failure. Vascular endothelial glycocalyx has been shown to be important as a physical cytoprotective barrier for vascular endothelial cells and as a regulatory mechanism for intracellular cell signaling. Therefore, vascular endothelial glycocalyx has immense potential in the exploration of novel strategies for the evaluation of beneficial conditions of healthy vasculature.

Insulin sensitivity and vascular responses to flow mediated dilation in Metabolic Syndrome women.

PurposeSedentary populations with obesity and metabolic syndrome (MetSyn) have presented with impaired vascular dysfunction, including vasodilation reduced 40–50%. The mechanisms of vascular endothelial dysfunction have also been associated to the bioavailability of nitric oxide levels and in metabolic compromised individuals the diminished content of endothelial NO are a prime mechanistic target for study. The present study was designed to examine the association between insulin sensitivity and endothelial dysfunction with respect to the nitric oxide eNOS pathway in MetSyn women using flow mediated dilation (FMD). We hypothesize that lower production of nitric oxide and lower Insulin Sensitivity Index (ISI) will be observed in MetSyn compared to age matched‐control patients, primarily due to mechanistic dysfunction of the eNOS pathway.MethodsIn this study, 30 participants (10 MetSyn and 20 Controls) were recruited for FMD testing and vascular changes were recorded using Doppler ultrasound with a linear vascular probe. A blood pressure cuff was placed on the upper forearm and upper calf for analysis of brachial and popliteal arteries sheer rate and reactive hyperemia. Images were continuously analyzed with Brachial Analyzer software and sheer rate calculated by digital recordings of blood velocity through with a digital auditory transducer recordings with a BIOPAC 150 system and AcqKnowlege software. Insulin sensitivity index was assessed by an oral glucose tolerance test with fasting and post‐prandal glucose measured with a glucometer and insulin measured by a Human Insulin ELISA kit (Cayman Chemical). The resting bioavailability of Nitric Oxide assessed by Nitrate/Nitrite ELISA assay and NO EPR spectroscopy measurementsResultsIn the brachial arteries there is significant differences (P<0.05) in the time and rate to peak diameter from reperfusion but not within the % Dilation or sheer rate between the MetSyn and Control sedentary groups. In the popliteal arteries there is a significant difference between the % dilation, time and rate to peak from reperfusion. We observed correlations among changes in arterial measurements, Insulin Sensitivity Index (ISI) and resting Nitric oxide concentration (NO). ISI is observed to be correlated to Peak Diameter (p=0.0943, r= 0.59) and Rate to Peak (p=0.07, r=.0628) measurements in the MetSyn group in the brachial arteries with no calculated relationship identified in the popliteal artery.ConclusionWe predict that significant deficiencies will be observed between the control and MetSyn group. These comparisons may explain the vascular mechanisms of developing deficits associated with the metabolic deficiencies and provide a target for the decline in vascular function within this sedentary population. A postulated mechanism of this endothelial dysfunction during insulin resistance begins with the decreased sensitivity of the insulin receptor preventing the effect of insulin and the AKT/PKB eNOS pathway.Support or Funding InformationResearch reported in this publication was supported by an Institutional Development Award (IDeA) from the National Institute of General Medical Sciences of the National Institutes of Health under grant number P20GM103451.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Mechanisms of Vascular Endothelial Dysfunction: The Problem with Sugar and Artificial Sweeteners

As diabetes becomes a growing worldwide heath concern there has been an increased awareness of environmental factors like diet that are contributing to the disease. In diabetic patients, a major causal factor contributing to progression of the disease is hyperglycemia. While we know that early intensive glycemic control reduces the risk of cardiovascular complications in humans and rodent models, there is a large gap in studies of the etiology of hyperglycemia‐induced alterations in the disease. To combat high sugar diets that contribute to diabetes and subsequent hyperglycemia, non‐caloric artificial sweeteners have become one of the most utilized food additives worldwide due to their consideration as a low caloric substitute. However, supporting scientific data as to the safety of these non‐caloric artificial sweeteners is limited and controversial. The negative implications of consuming a high sugar diet on overall health have long been linked to diabetes, obesity, and resulting systemic health problems; however, it was not until recently that the negative impact of consuming artificial sweeteners in the place of sugar had been increasingly recognized. This study focused on research to decipher the underlying molecular mechanisms of vascular dysfunction influenced by high glucose and artificial sweetener diets using a combination of high‐throughput molecular analyses and in vitro cell culture models. Initial characterization of the effects of hyperglycemia on in vitro tube formation assays exhibited impaired endothelial phenotypes (p<0.05). PNGaseF enzymatic removal of endothelial cell surface glycosylations was able to restore the healthy tube formation phenotypes (p<0.05) suggesting glycosylation plays an important role in high glucose induced vascular dysfunction. Further glycoproteomic analyses revealed 87 proteins significantly increased in N‐glycosylation and 143 in O‐glycosylation (p<0.05) on the endothelial cell surface following normal (4.5 mM) and high (25 mM) glucose treatments, including important endothelial cell surface receptors, a diverse array of ion channels, and immune regulators. The non‐caloric artificial sweetener aspartame also exhibited impaired endothelial phenotypes during an in vitro tube formation assay (p<0.05). However, insulin signaling gene expression analysis revealed global pathway downregulation as a result of aspartame, a phenomenon that was not observed with the high glucose treatment. Overall, results of this study suggest unique mechanisms of vascular impairment resulting from exposure to high glucose and artificial sweeteners that provide insights into their contribution to the onset and progression of diabetes and obesity.Support or Funding InformationThis work was supported by the National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases (K01DK105043 to BRH) and through the Mayo Clinic Metabolomics Resource Core pilot grant program (U24DK100469) originating from the National Institutes of Health Director's Common Fund.

Endothelial nitric oxide synthase uncoupling: A novel pathway in OSA induced vascular endothelial dysfunction

The mechanism of vascular endothelial dysfunction (VED) and cardiovascular disease in obstructive sleep apnea (OSA) is unknown. We performed a comprehensive evaluation of endothelial nitric oxide synthase (eNOS) function directly in the microcirculatory endothelial tissue of OSA patients who have very low cardiovascular risk status. Nineteen OSA patients underwent gluteal biopsies before, and after effective treatment of OSA. We measured superoxide (O2•−) and nitric oxide (NO) in the microcirculatory endothelium using confocal microscopy. We evaluated the effect of the NOS inhibitor l-Nitroarginine-Methyl-Ester (l-NAME) and the NOS cofactor tetrahydrobiopterin (BH4) on endothelial O2•− and NO in patient endothelial tissue before and after treatment. We found that eNOS is dysfunctional in OSA patients pre-treatment, and is a source of endothelial O2•− overproduction. eNOS dysfunction was reversible with the addition of BH4. These findings provide a new mechanism of endothelial dysfunction in OSA patients and a potentially targetable pathway for treatment of cardiovascular risk in OSA.

Kidney Disease in HIV-Infected Persons

Kidney disease is more prevalent among persons living with HIV, and may arise from a combination of comorbidities, co-infections, and medication-associated toxicities. Additional effects of HIV-1 viral replication, immunodeficiency and genetic factors also contribute to kidney disease. As is true in the general population, persons of African descent exhibit a disproportionate risk for severe kidney disease. Antiretroviral therapy (ART) modifies the natural history of HIV-associated nephropathy (HIVAN), and renal benefits of ART may not be limited to persons with HIVAN. Robust associations between proteinuria and cardiovascular disease imply that common mechanisms of vascular endothelial dysfunction may contribute to both processes.

Ендотелійзалежний фактор гіперполяризації як резервний захисний механізм регуляції судинного тонусу при дії іонізуючого опромінення

The goal of this study was to determine the cellular mechanisms of vascular endothelial dysfunction in rats irradiated with gamma-rays. Acetylcholine (Ach)-induced relaxation of rat thoracic aorta rings was measured as a test of endothelial integrity and function. The data obtained allow suggest that endothelial function is impaired in aorta from g-irradiated rats mainly due to the loss of EDRF/NO-dependent, but not EDHF-dependent relaxation. It has been shown that r-irradiation reduced the Ach-induced NO-release measured as nitrite anion content. Experiments on isolated rat aortic smooth muscle cells using whole-cell patch clamp technique demonstrated that irradiation led to a significant decrease in outward potassium currents. However, gamma-ray irradiation was without effect on K(+)-current carried through apamine-sensitive channels while the current through charybdotoxin-sensitive channels was increased as compared to cells from control animals. The data suggest that EDHF is resistant to ionized radiation and may constitute a crucial reserve mechanism for maintenance of blood flow under radiation. Therefore, it is likely that the subsequent studies related to EDHF identification will be important for new drugs development and targeted pharmacological intervention at endothelium dysfunction in case of radiation impact.

Comfortable lifestyle-induced imbalance of neuro-endocrineimmunity network: A possible mechanism of vascular endothelial dysfunction

To observe the changes of vascular endothelial functions and general neuro-endocrine-immunity (NEI) network under the state of qi-deficiency syndrome induced by excessive idleness and to approach their internal relevance and illuminate initially the pathophysiological mechanism of vascular lesion induced by excessive idleness. A total of 100 male Wistar rats were randomly divided into the control group and the qi-deficiency syndrome model group, 50 rats in each group. The qi-deficiency syndrome model was established by feeding the animals with hyper-alimentation diet in combination with restricting movement for 10 weeks. Changes of common chemical signal molecules related to NEI and vascular endothelial functions were measured by the end of the experiment. Furthermore, their internal relevance was analyzed by the method of canonical correlation analysis. The vascular endothelial structure and function were obviously injured in the model group. Compared with the control group, the chemical signal molecules, such as 5-hydroxytryptamine (5-HT), corticosterone (CORT), triiodothyronine (T3), tetraiodothyronine (T4), angiotensin II (Ang II), interleukin-1 (IL-1), and tumor necrosis factor-alpha (TNF-alpha) in peripheral blood of the model group (n=43) were changed significantly (P<0.05 or P<0.01). Canonical correlation analysis showed that vascular endothelial dysfunction was correlated to the changes of these signal molecules in the NEI network. Comfort-based lifestyle induced not only vascular endothelial dysfunction but also an imbalance of the NEI network. Vascular endothelial dysfunction and the imbalanced NEI network interacted with each other, and an imbalance of the NEI network may be the pathophysiologic basis for the genesis and development of vascular endothelial dysfunction, even diseases of the blood vessel.

Effect of serum from overfatigue rats on JNK/c-Jun/HO-1 pathway in human umbilical vein endothelial cells and the intervening effect of Tongxinluo (通心络) superfine powder

To cultivate human umbilical vein endothelial cells (HUVECs) in the serum of overfatigue rats with the intervention of Tongxinluo superfine powder (TXLSP). By examining the variation of the activity of JNK/c-Jun/HO-1 pathway, the possible mechanisms of vascular endothelial dysfunction under overfatigue conditions and the intervening effect of TXLSP were explored. The HUVECs were randomly divided into the normal control group, the model group, the SP600125 (a specific antagonist of JNK) group, the TXLSP group and the TXLSP + SP600125 group. The content of carboyhemoglobin (COHb) and the leak rate of lactic dehydrogenase (LDH) in different groups were measured. The mRNA and protein expression of JNK, c-Jun, HO-1 and the phosphorylation level of c-Jun (P-c-Jun) were detected using Western blot and PCR methods. Compared with the normal control group, the COHb level in supernatant was increased significantly in the model group, and the expression of HO-1, JNK, c-Jun mRNA and corresponding proteins and P-c-Jun were also increased remarkably. The increases in these parameters were significantly decreased by SP600125. TXLSP showed remarkable up-regulation on the expression of JNK, c-Jun, P-c-Jun and HO-1 mRNA and their protein expression. Compared with the SP600125 group, the expressions of JNK, c-Jun, P-c-Jun and HO-1 mRNA and its protein in the TXLSP+SP600125 group were significantly increased at different time points (P<0.05, P<0.01). The vascular endothelial dysfunction under overfatigue conditions is related to the activity of the JNK/c-Jun/HO-1 pathway. One of the mechanisms of TXLSP in improving the vascular endothelial function is to adjust the activity of the JNK/c-Jun/HO-1 pathway at gene and protein levels.

Mechanisms of aging-induced impairment of endothelium-dependent relaxation: role of tetrahydrobiopterin.

Oxidative stress has been implicated as an important mechanism of vascular endothelial dysfunction induced by aging. Previous studies suggested that tetrahydrobiopterin (BH4), an essential cofactor of endothelial NO synthase, could be a molecular target for oxidation. We tested the hypothesis that oxidative stress, in particular oxidation of BH4, may contribute to attenuation of endothelium-dependent relaxation in aged mice. Vasomotor function of isolated carotid arteries was studied using a video dimension analyzer. Vascular levels of BH4 and its oxidation products were measured via HPLC. In aged mice (age, 95 +/- 2 wk), endothelium-dependent relaxation to ACh (10(-5) to 10(-9) M) as well as endothelium-independent relaxation to the NO donor diethylammonium (Z)-1-(N,N-diethylamino)diazen-1-ium-1,2-diolate (DEA-NONOate, 10(-5) to 10(-9) M) were significantly reduced compared with relaxation detected in young mice (age, 23 +/- 0.5 wk). Incubation of aged mouse carotid arteries with the cell-permeable SOD mimetic Mn(III)tetra(4-benzoic acid)porphyrin chloride normalized relaxation to ACh and DEA-NONOate. Furthermore, production of superoxide anion in aorta and serum levels of amyloid P component, which is the murine analog of C-reactive protein, was increased in old mice. In aorta, neither the concentration of BH4 nor the ratio of reduced BH4 to the oxidation products were different between young and aged mice. Our results demonstrate that in mice, aging impairs relaxation mediated by NO most likely by increased formation of superoxide anion. Oxidation of BH4 does not appear to be an important mechanism underlying vasomotor dysfunction in aged mouse arteries.