Mediator Of Endothelial Dysfunction Research Articles

Inhibition of nuclear factor-κB activation improves non-nitric oxide-mediated cutaneous microvascular function in reproductive-aged healthy women.

The transcriptional regulator nuclear factor-κB (NF-κB) is a mediator of endothelial dysfunction. Inhibiting NF-κB with salsalate is used to investigate inflammatory mechanisms contributing to accelerated cardiovascular disease risk. However, in the absence of disease, inhibition of NF-κB can impact redox mechanisms, resulting in paradoxically decreased endothelial function. This study aimed to measure microvascular endothelial function during inhibition of the transcriptional regulator NF-κB in reproductive-aged healthy women. In a randomized, single-blind, crossover, placebo-controlled design, nine healthy women were randomly assigned oral salsalate (1,500 mg, twice daily) or placebo treatments for 5 days. Subjects underwent graded perfusion with the endothelium-dependent agonist acetylcholine (ACh, 10-10 to 10-1 M, 33°C) alone and in combination with 15 mM NG-nitro-l-arginine methyl ester [l-NAME; nonselective nitric oxide (NO) synthase inhibitor] through intradermal microdialysis. Laser-Doppler flux was measured over each microdialysis site, and cutaneous vascular conductance (CVC) was calculated as flux divided by mean arterial pressure and normalized to site-specific maximum (CVC%max; 28 mM sodium nitroprusside + 43°C). The l-NAME sensitive component was calculated as the difference between the areas under the dose-response curves. During the placebo and salsalate treatments, the l-NAME sites were reduced compared with the control sites (both P < 0.0001). Across treatments, there was a significant difference between the control and l-NAME sites, where both sites shifted upward following salsalate treatment (both P < 0.0001), whereas the l-NAME-sensitive component was not different (P = 0.94). These data demonstrate that inhibition of the transcriptional regulator NF-κB improves cutaneous microvascular function in reproductive-aged healthy women through non-NO-dependent mechanisms.NEW & NOTEWORTHY The transcription factor nuclear factor-κB (NF-κB) regulates multiple aspects of innate and adaptive immunity by encoding for genes that participate in inflammation and impact endothelial function following NF-κB inhibition with salsalate treatment. Our results show that cutaneous microvascular function is increased through non-nitric oxide (NO)-dependent mechanisms following salsalate treatment in reproductive-aged healthy women.

Evaluation of Oxidative Stress and Endothelial Dysfunction in COVID-19 Patients.

Background and Objectives: Heat shock proteins (HSPs) are stress proteins. The endogenous nitric oxide (NO) synthase inhibitor asymmetric dimethyl arginine (ADMA) is a mediator of endothelial dysfunction. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus causes endothelial dysfunction and coagulopathy through severe inflammation and oxidative stress. Using these markers, we analyzed the prognostic value of serum ADMA and HSP-90 levels for early prediction of severe coronavirus disease (COVID-19) patients. Materials and Methods: A total of 76 COVID-19 patients and 35 healthy control subjects were included in this case-control study. COVID-19 patients were divided into two groups: mild and severe. Results: Serum ADMA and HSP-90 levels were significantly higher in the COVID-19 patients compared to the control subjects (p < 0.001). Additionally, serum ADMA and HSP-90 levels were determined to be higher in a statistically significant way in severe COVID-19 compared to mild COVID-19 (p < 0.001). Univariable logistic regression analysis revealed that ADMA and HSP-90, respectively, were independent predictors of severe disease in COVID-19 patients (ADMA (OR = 1.099, 95% CI = 1.048-1.152, p < 0.001) and HSP-90 (OR = 5.296, 95% CI = 1.719-16.316, p = 0.004)). When the cut-off value for ADMA was determined as 208.94 for the prediction of the severity of COVID-19 patients, the sensitivity was 72.9% and the specificity was 100% (AUC = 0.938, 95%CI = 0.858-0.981, p < 0.001). When the cut-off value for HSP-90 was determined as 12.68 for the prediction of the severity of COVID-19 patients, the sensitivity was 88.1% and the specificity was 100% (AUC = 0.975, 95% CI= 0.910-0.997, p < 0.001). Conclusions: Increased levels of Heat shock proteins-90 (HSP-90) and ADMA were positively correlated with increased endothelial damage in COVID-19 patients, suggesting that treatments focused on preventing and improving endothelial dysfunction could significantly improve the outcomes and reduce the mortality rate of COVID-19. ADMA and HSP-90 might be simple, useful, and prognostic biomarkers that can be utilized to predict patients who are at high risk of severe disease due to COVID-19.

Red blood cell-derived extracellular vesicles from type 2 diabetes patients induce endothelial dysfunction through a mechanism involving arginase 1

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Foundation for Geriatric Diseases Karolinska Institutet (2023-01860). Swedish Heart and Lung Foundation (20220210) Background The mechanisms driving the development of cardiovascular injury in type 2 diabetes (T2D) remain incompletely understood. We have recently demonstrated that red blood cells (RBCs) from patients with T2D (T2D-RBCs) act as mediators of endothelial dysfunction through the upregulation of arginase 1 and attenuation of nitric oxide bioavailability. However, the underlying mechanisms of this interaction remain unknown. It is increasingly clear that extracellular vesicles (EVs) are actively secreted by practically all cell types, including RBCs, and represent a novel mechanism of intercellular communication. However, the involvement of RBC-derived EVs in the development of endothelial dysfunction in T2D remains to be elucidated. Purpose To test the hypothesis that EVs are secreted by RBCs and transfer signalling to induce endothelial dysfunction in T2D through arginase 1. Methods EVs released from T2D-RBCs (T2D-RBCs EVs) and RBCs from age-matched healthy controls (H-RBCs EVs) were isolated using sequential ultracentrifugation or a membrane affinity column, co-incubated with mouse aortae to evaluate endothelium-dependent relaxation (EDR), and with human carotid artery endothelial cells (HCtAEC) to study the EV uptake and alteration in gene expression. EVs were characterized based on morphology, size and particle number, uptake in endothelial cells, and arginase 1 content. Functional involvement of EV uptake and arginase were investigated using pharmacological interventions. Arginase 1 was measured in EVs, HCtAEC, and mouse aortae after co-incubation with H-RBCs EVs and T2D-RBCs EVs. Results The uptake of T2D-RBCs EVs by endothelial cells was greater than that of EVs from H-RBCs (Fig. 1A, B) despite the reduced formation of EVs by T2D-RBCs (Fig. 1C). T2D-RBCs EVs significantly impaired EDR (Fig. 1D), and this impairment was prevented by inhibiting uptake of EVs with heparin (Fig. 1E). Arginase 1 was detected in RBC-derived EVs (Fig. 2A), and endothelial function was rescued by blocking arginase activity in EVs by the arginase inhibitor 2(S)-amino-6-boronohexanoic acid (ABH; Fig. 2B). Immunohistochemical staining revealed upregulation of arginase 1 in the vasculature following incubation with T2D-RBCs EVs (Fig. 2C, D). Additionally, co-incubation of HCtAEC and EVs derived from T2D-RBCs significantly increased endothelial cell arginase 1 (Fig. 2E, F). Administration of ABH to the aortae following the co-incubation also attenuated the impairment of EDR induced by T2D-RBCs EVs, suggesting the involvement of vascular arginase 1 (Fig. 2G). Conclusion T2D-RBCs EVs induce endothelial dysfunction. In addition to increased uptake of EVs in endothelial cells, the signalling behind this effect of EVs is mediated by arginase 1 to induce endothelial dysfunction. These results shed new important light on the mechanism underlying vascular injury mediated by RBCs in T2D.

Asymmetric and symmetric dimethylarginine as markers of endothelial dysfunction in cerebrovascular disease: A prospective study

Background and aimAsymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) have been proposed as mediators of endothelial dysfunction. In this study, we aimed to investigate the diagnostic and prognostic role of ADMA and SDMA in acute cerebrovascular disease. Methods and resultsA prospective case-control study was performed, enrolling 48 patients affected by ischemic stroke with no cardioembolic origin, 20 patients affected by TIA, 40 subjects at high cardiovascular risk and 68 healthy subjects.ADMA levels were significantly lower in high-risk subjects (18.85 [11.78–22.83] μmol/L) than in patients with brain ischemic event, both transient (25.70 [13.15–40.20] μmol/L; p = 0.032) and permanent (24.50 [18.0–41.33] μmol/L; p = 0.001). SDMA levels were different not only between high-risk subjects and ischemic patients, but also between TIA and stroke patients, reaching higher levels in TIA group and lower levels in stroke group (1.15 [0.90–2.0] vs 0.68 [0.30–1.07] μmol/L; p < 0.001). SDMA was also correlated with short-term prognosis, with lower levels in case of adverse clinical course, evaluated by type of discharge (p = 0.009) and need of prolonged rehabilitation (p = 0.042). ConclusionsThe present study highlights the relationship between l-arginine, ADMA, SDMA and acute cerebrovascular events. Therefore, our results suggested a potential role of SDMA as a specific marker of transient ischemic damage and as a short-term positive prognostic marker.

Evaluation of Uric Acid to Albumin Ratio as a Marker of Coronary Artery Disease Severity in Acute Coronary Syndrome: A Cross-Sectional Study.

Coronary artery disease (CAD) is a widespread cause of morbidity and mortality. Serum uric acid, a mediator of endothelial dysfunction and inflammation in vascular disease, can increase the risk of atherosclerosis, contributing to CAD. As serum albumin inhibits platelet activation and aggregation, low levels of it can contribute to platelet-induced coronary artery stenosis. Limited studies have been conducted worldwide in evaluating the role of uric acid to albumin ratio (UAR) in predicting severity or poor outcomes in acute coronary syndrome (ACS) patients. This study was undertaken to assess the role of UAR as a predictor of CAD severity, which can facilitate the identification of high-risk patients. A hospital-based analytical cross-sectional study was conducted in an urban tertiary healthcare center for a period of two months between June and August of 2022. A total of 100 ACS patients were included in the study. The study population included patients above the age of 18 years diagnosed with ACS who underwent a coronary angiography. Coronary angiograms were used to diagnose the presence of CAD, and its severity was assessed using Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery (SYNTAX) scores (SS). The correlation of UAR with CAD severity using SS was studied and compared between three varieties of ACS: ST-elevation myocardial infarction (STEMI), non-ST-elevation myocardial infarction (NSTEMI), and unstable angina (UA). Chi-squared tests were used to determine statistical significance for qualitative data.Independent t-tests were used to identify the mean difference between two quantitative variables. Receiver operating characteristic (ROC) curves were constructed for UAR and high SS. A comparison between UAR and neutrophil to lymphocyte ratio (NLR) as a predictor of disease severity was done.ROC and optimal cutoff points were chosen to calculate sensitivity, specificity, and positive and negative predictive values. Microsoft Excel (Microsoft, Redmond, WA, USA) and SPSS V22.0(IBM Corp., Armonk, NY, USA) were used to analyze the data. A total of 100 ACS patients were included in the study and divided into two groups on the basis of SS, with 74% showing low severity and 26% showing intermediate-high severity. There was a statistically significant difference found between older age and SS (p=0.017). Our study showed 74% (n=74) of the patients were male and 26% (n=26) were female. It also revealed that 75.7% (n=56) of the male patients were in the low-severity group, and 24.3% (n=18) of males were in the intermediate-high severity group. 69.2% (n=18) of the female patients were in the low-severity group, and 30.8% (n=8) were in the intermediate-high severity group. Of the 100 patients, 55% were diagnosed with STEMI, of which 69.1% were in the low-severity group, and 30.9% were in the intermediate-high severity group. Among all the patients 33% of the patients were diagnosed as NSTEMI, of which 72.7% were in the low-severity group, and 27.3% were in the intermediate-high severity group. Twelve percent of the patients were diagnosed with UA, and 100% of these patients were in the low-severity group. The mean UAR was 1.40 ± 0.38 in the low-severity group and 1.29 ± 0.46 in the intermediate-high severity group (p=0.22). Our study yielded no statistically significant difference in UAR among varying severities of CAD.

Erythrocyte-derived extracellular vesicles from type 2 diabetes patients induce endothelial dysfunction through arginase 1

Abstract Background The mechanisms driving the development of cardiovascular injury in type 2 diabetes (T2D) remain incompletely understood. We recently demonstrated that red blood cells (RBCs) from patients with T2D (T2D-RBCs) act as mediators of endothelial dysfunction, but the mechanisms underlying this interaction are not clarified. We found that RBCs via upregulation of arginase 1 attenuate nitric oxide bioavailability and endothelial function. It is increasingly clear that extracellular vesicles (EVs) are actively secreted by practically all cell types, including RBCs, and represent a novel mechanism of intercellular communication. Purpose This study aimed to determine whether EVs derived from T2D-RBCs are involved as mediators in vascular injury through the signalling of arginase 1. Methods T2D-RBCs and RBCs from age-matched healthy controls (H-RBCs) were isolated and incubated with Krebs-Henseleit buffer (20% haematocrit). Following 18h incubation, the conditioned medium was collected for EV isolation using sequential ultracentrifugation and membrane affinity column. EV concentration was measured by nanoparticle tracking analysis. Aortas isolated from wild-type mice were incubated with EVs derived from T2D-RBCs and H-RBCs for 18h. Endothelium-dependent and -independent relaxations (EDR and EIDR, respectively) of the aortae were evaluated in a wire myograph. The involvement of arginase was investigated by the addition of the arginase inhibitor 2(S)-amino-6-boronohexanoic acid (ABH) either to the 18h co-incubation of EVs with the aortic segments to selectively investigate the contribution of EV-derived arginase (ABH, 10 mM) or to the aortae following the 18h co-incubation to selectively target vascular arginase (ABH, 100 µM). All animal experiments were performed according to the principles of laboratory animal care (NIH Publication no. 85-23 revised 1985) and human procedures according to the declaration of Helsinki and approved by the Swedish Ethical Review Authority. Results T2D-RBCs had a ten times lower EV concentration compared to H-RBCs. T2D-RBC-derived EVs isolated using both methods significantly impaired EDR (Fig. 1A-C), whereas EIDR was not affected. This effect was observed irrespective of if the same volume or concentration of EVs were administered. Inhibition of arginase with ABH during the co-incubation with EVs derived from T2D-RBCs completely prevented the impairment of EDR induced by the EVs (Fig. 1D). Administration of ABH to the aortae following the co-incubation also attenuated the impairment of EDR. Immunohistochemical staining revealed upregulation of arginase 1 (Fig. 2A-B) but not arginase 2 (Fig. 2C-D) in the vasculature following incubation with EVs from T2D-RBCs. Conclusion EVs derived from T2D-RBCs induce endothelial dysfunction, and arginase 1 derived from these EVs mediates this endothelial dysfunction. These results shed new important light on the mechanism underlying vascular injury mediated by RBCs in T2D.

Effect of magnesium sulfate treatment on mediators of endothelial dysfunction and electrolytes in mild and severe preeclampsia: A case-control study.

Magnesium sulfate (MgSO4) treatment is widely used for the prevention of eclamptic seizures. However, its effect on mediators of endothelial dysfunction (ED) and electrolytes remains unclear. We evaluated the effects of MgSO4 treatment on mediators of ED and electrolytes. We recruited 100 women comprising 50 severe, 50 mild preeclampsia (PE) as cases and 50 normotensive pregnant women as controls from the Sampa Government Hospital, Ghana. We estimated for adrenomedullin (AM),calcitonin gene-related peptide (CGRP),soluble forms of intercellular adhesion molecule-1 (sICAM-1), Na+, K+, and Mg2+ before MgSO4 treatment, 24 h after MgSO4 treatment, and 48 h after delivery. p < 0.05 were considered significant for statistical analyses. Levels of AM, sICAM-1, and Na+ decreased significantly at 24 h after MgSO4 treatment and 48 h after delivery among PEwomen compared to the AM levels before treatment (p < 0.0001). The levels of CGRP and Mg2+ increased significantly after 24 h of MgSO4 treatment and 48 h after delivery among PE compared to the AM levels before treatment (p < 0.0001). The changes in AM, sICAM-1, CGRP, and Mg2+ at 24 h after treatment and 48 h after delivery were significantly higher in severe compared to mild PE (p < 0.0001). AM levels reduced significantly by 14.7% in mild and 42.7% in severe PE after MgSO₄ treatment (p < 0.05). sICAM-1 levels reduced significantly by 20.9% in mild and 25% in severe PE after MgSO₄ treatment. After MgSO₄ treatment, there was significant increase of 42.1% and >100% in CGRP levels in mild and severe PE, respectively (p < 0.05). After MgSO₄ treatment, Mg²⁺ levels increased significantly by 67.0% and 63.8% in mild and severe PE, respectively (p < 0.05). MgSO₄ treatment reduces AM, sICAM-1, and sodium levels but improves magnesium and CGRP in severe than mild PE thus have more beneficial role in severe PE.

The red blood cell as a mediator of endothelial dysfunction in patients with familial hypercholesterolemia and dyslipidemia.

Patients with familial hypercholesterolemia (FH) display high levels of low-density lipoprotein cholesterol (LDL-c), endothelial dysfunction, and increased risk of premature atherosclerosis. We have previously shown that red blood cells (RBCs) from patients with type 2 diabetes induce endothelial dysfunction through increased arginase 1 and reactive oxygen species (ROS). To test the hypothesis that RBCs from patients with FH (FH-RBCs) and elevated LDL-c induce endothelial dysfunction. FH-RBCs and LDL-c >5.0 mM induced endothelial dysfunction following 18-h incubation with isolated aortic rings from healthy rats compared to FH-RBCs and LDL-c <2.5 mM or RBCs from healthy subjects (H-RBCs). Inhibition of vascular but not RBC arginase attenuated the degree of endothelial dysfunction induced by FH-RBCs and LDL-c >5.0 mM. Furthermore, arginase 1 but not arginase 2 was elevated in the vasculature of aortic segments after incubation with FH-RBCs and LDL-c >5.0 mM. A superoxide scavenger, present throughout the 18-h incubation, attenuated the degree of endothelial dysfunction induced by FH-RBCs and LDL-c >5.0 mM. ROS production was elevated in these RBCs in comparison with H-RBCs. Scavenging of vascular ROS through various antioxidants also attenuated the degree of endothelial dysfunction induced by FH-RBCs and LDL-c >5.0 mM. This was corroborated by an increase in the lipid peroxidation product 4-hydroxynonenal. Lipidomic analysis of RBC lysates did not reveal any significant changes across the groups. FH-RBCs induce endothelial dysfunction dependent on LDL-c levels via arginase 1 and ROS-dependent mechanisms.

Extracellular cyclophilins A and C induce dysfunction of pancreatic microendothelial cells.

Extracellular cyclophilins (eCyps) A and B are chemotactic mediators in several illnesses in which inflammation plays an important role such as diabetes and cardiovascular diseases. Recently, eCypC has been reported as a potential biomarker for coronary artery disease but its effect in endothelium has not been determined. Moreover, there is a lack of studies with all these proteins in the same model, which makes difficult a direct comparison of their effects. In this work, MS1 pancreatic microendothelial cells were treated with eCyps A, B and C and their impact on endothelial function was analysed. eCyps A and C stimulated the release of IL-6 and MCP-1 and increased the expression of the receptor CD147, but eCypB did not affect these pro-inflammatory markers. Moreover, eCypC activated the translocation of NFkB-p65 to the nucleus. All these effects were reversed by pre-treatment with cyclosporine A. eCyps also produced endothelial dysfunction, as evidenced by the decrease in eNOS activation. Finally, the crosstalk among eCyps addition and their protein and gene expression was evaluated. eCypA generated a depletion in its protein and gene levels, whilst eCyps B and C upregulated their own protein expression. Moreover, each eCyp altered the intracellular expression of other Cyps, including cyclophilin D. This work is the first report of eCyps influence on iCyps expression, as well as the first description of eCypC as an activator of CD147 receptor and a mediator of endothelial dysfunction, which points to a potential role of this protein in vascular complications associated to diabetes.

Abstract 048: Extracellular Endothelial Microvesicles Causative Agents In Hypertension-related Endothelial Dysfunction

We have previously demonstrated that endothelial cell-derived microvesicles (EMVs) are elevated with hypertension and are associated with endothelial dysfunction. However, it is unknown whether EMVs play a causative role in blood pressure-related endothelial dysfunction. The experimental aim of this study was to determine the effects of EMVs isolated from hypertensive adults on endothelial cell inflammation, apoptosis and nitric oxide (NO) production. Twenty middle-aged adults were studied: 10 normotensive (NT: 8M/2F; 57 + 2 yr; BP: 113/71 + 2/2 mmHg; EMVs: 64 + 10 EMV/μL) and 10 hypertensive (HT: 6M/4F; 56 + 2 yr; 137/82 + 2/2 mmHg; 115 + 17 EMV/μL). All subjects were sedentary, non-smokers, non-medicated and free of overt cardiometabolic diseases. EMVs (CD144+) were identified, sorted and collected from plasma by flow cytometry. Human umbilical vein endothelial cells were cultured and treated with EMVs from either NT or HT adults. EMVs from HT induced significantly greater release of interleukin (IL)-6 (38.9±1.5 vs 31.5±0.9 pg/mL) and IL-8 (38.1±2.7 vs 30.3±1.8 pg/mL) compared with EMVs from NT. Concordantly, HT-related EMVs induced ~25% higher (P&lt;0.05) expression of phosphorylated-NF-kB p65 (Ser536; active NF-kB) (168.5 + 12.1 vs 136.8 + 7.0 AU). HT EMVs induced significantly higher activation of the apoptotic proteins p38-MAPK (26.0 + 4.5 vs 12.4 + 1.2 AU) and caspase-3 (243.1±36.7 vs 150.8±17.0 AU) than NT EMVs. Although total eNOS expression was not significantly altered; active eNOS (pSer1177) (221.02 + 34.8 vs 331.5 + 30.4 AU) and, in turn, NO production (6.2 + 0.4 vs 9.4 + 0.6 υmol/L) were significantly lower (~30%) in the cells treated with EMVs from HT adults. Increased inflammation, apoptosis susceptibility and decreased NO production are central features of endothelial dysfunction. Circulating EMVs represent both a biomarker and mediator of endothelial dysfunction with hypertension.

Interferon-stimulated gene 15 pathway is a novel mediator of endothelial dysfunction and aneurysms development in angiotensin II infused mice through increased oxidative stress.

Interferon-stimulated gene 15 (ISG15) encodes a ubiquitin-like protein that induces a reversible post-translational modification (ISGylation) and can also be secreted as a free form. ISG15 plays an essential role as host-defence response to microbial infection; however, its contribution to vascular damage associated with hypertension is unknown. Bioinformatics identified ISG15 as a mediator of hypertension-associated vascular damage. ISG15 expression positively correlated with systolic and diastolic blood pressure and carotid intima-media thickness in human peripheral blood mononuclear cells. Consistently, Isg15 expression was enhanced in aorta from hypertension models and in angiotensin II (AngII)-treated vascular cells and macrophages. Proteomics revealed differential expression of proteins implicated in cardiovascular function, extracellular matrix and remodelling, and vascular redox state in aorta from AngII-infused ISG15-/- mice. Moreover, ISG15-/- mice were protected against AngII-induced hypertension, vascular stiffness, elastin remodelling, endothelial dysfunction, and expression of inflammatory and oxidative stress markers. Conversely, mice with excessive ISGylation (USP18C61A) show enhanced AngII-induced hypertension, vascular fibrosis, inflammation and reactive oxygen species (ROS) generation along with elastin breaks, aortic dilation, and rupture. Accordingly, human and murine abdominal aortic aneurysms showed augmented ISG15 expression. Mechanistically, ISG15 induces vascular ROS production, while antioxidant treatment prevented ISG15-induced endothelial dysfunction and vascular remodelling. ISG15 is a novel mediator of vascular damage in hypertension through oxidative stress and inflammation.

Amelioration of Endothelial Dysfunction in Diabetes: Role of Takeda G Protein-Coupled Receptor 5.

Diabetes mellitus (DM) eventually leads to chronic vascular complications, resulting in cardiovascular diseases. DM-associated endothelial dysfunction (ED) plays an important role in the development of chronic vascular complications. Low endothelial nitric oxide synthase (eNOS) activity, inflammation, and oxidative stress all contribute to ED. The G protein–coupled receptor Takeda G protein–coupled receptor 5 (TGR5) is a membrane receptor for bile acids that plays an important role in the regulation of glucose metabolism. Recent studies have shown that TGR5 is involved in the regulation of various mediators of ED, which suggests that TGR5 may represent a target for the treatment of DM-associated ED. In this review, we summarize the principal mechanisms of DM-associated ED, then propose TGR5 as a novel therapeutic target on the basis of its mechanistic involvement, and suggest potential directions for future research.

Erythrocytes Induce Vascular Dysfunction in COVID-19

Background: Vascular injury has been implicated as a major cause of clinical complications in patients with coronavirus disease 2019 (COVID-19) based on autopsy studies showing destruction of the endothelial architecture. Red blood cells (RBCs) are affected by COVID-19 with alterations in their structure and function, possibly altering disease progress. Objectives: This study was designed to test the hypothesis of persistent endothelial dysfunction and that RBCs act as mediators of endothelial dysfunction in COVID-19. Methods and results: COVID-19 patients displayed profound endothelial dysfunction in vivo assessed with pulse amplitude tonometry, both in the acute phase and at follow-up four months later. RBCs but not plasma from COVID-19 patients in the acute phase incubated with healthy rat aorta induced severe endothelial dysfunction ex vivo compared to RBCs from healthy subjects. Further, these RBCs induced vascular arginase 1 and oxidative stress. Consequently, inhibition of vascular arginase or superoxide attenuated endothelial dysfunction induced by RBCs from COVID-19 patients. These RBCs were characterized by increased production of reactive oxygen species and reduced export of the nitric oxide metabolite nitrate. RBCs from COVID-19 patients at follow-up did not affect vascular function. Pre-incubation of RBCs from healthy subjects with interferon-γ impaired endothelial function.Conclusions: This study demonstrates the presence of persistent endothelial dysfunction in an otherwise mainly healthy population hospitalized for COVID-19, and implicates a role of RBCs as mediators of endothelial injury. These data shed light on a new pathological mechanism underlying vascular dysfunction in COVID-19 and lay the foundation for future therapeutic developments.

Streptolysin O: a novel mediator of endothelial dysfunction

Streptolysin O: a novel mediator of endothelial dysfunction

Abstract P069: Microvesicles From Enos-suppressed Endothelial Cells Induce Endothelial Cell Dysfunction

Introduction: Endothelial nitric oxide synthase (eNOS) activity is critical to vascular health. Impaired eNOS activity and diminished NO production are common characteristics of a proatherogenic, dysfunctional endothelial phenotype that is associated with cardiovascular risk factors and disease. Extracellular microvesicles, particularly endothelial cell derived microvesicles (EMVs) represent novel mechanistic mediators of endothelial dysfunction and vascular disease. It is unknown whether eNOS suppression affects EMV number and function. We tested the following hypotheses: 1) eNOS blockade increases EMV release; and 2) EMVs derived from eNOS-suppressed cells adversely affect endothelial cell inflammation, apoptosis and NO production. Methods: Human umbilical vein endothelial cells (HUVECs) were treated with the eNOS inhibitor, L-N G -Nitroarginine methyl ester (L-NAME; 300mM) for 24 h. EMVs (CD144 + ) released into the supernatant from cells treated with L-NAME or vehicle were isolated and quantified by flow cytometry. Fresh HUVECs were then treated with either L-NAME-derived or control EMVs for 24 h. To evaluate the role of endocytosis on the endothelial effects of EMVs, HUVECs were pre-incubated (12 h) with EIPA, filipin and chlorpromazine for 2 h, and all experiments repeated. Results: EMV release was markedly higher (~100%; P&lt;0.05) in cells treated with L-NAME compared with control (81±6 vs. 40±7 EMV/μL). L-NAME-generated EMVs induced significantly higher release of IL-6 (38.4±5.1 vs. 21.0±1.9 pg/mL) and IL-8 (38.9±3.5 vs. 27.2±3.1 pg/mL) as well as greater active NF-κB p65 (Ser-536) (9.7±0.7 vs. 6.1±0.6 AU) expression than control EMVs. The expression of activated-caspase-3 was significantly higher in the cells treated with L-NAME (9.5±1.1 vs. 6.4±0.4 AU). Total eNOS (97.1±8.2 vs. 157.5±15.6 AU), activated eNOS (4.9±1.2 vs. 9.1±1.3 AU) and NO production (5.0±0.8 vs. 7.0±0.6 μmol/L) were significantly lower in endothelial cells treated with EMVs from eNOS suppressed cells. Endocytosis blockers mitigated the deleterious endothelial effects of EMVs. Conclusion: eNOS-suppression increases EMV release. Moreover, EMVs from eNOS-suppressed cells increase endothelial cell inflammation and apoptosis and decrease NO production.

Resistin and Cardiac Arrest-A Prospective Study.

The systemic response to ischemia-reperfusion that occurs after a cardiac arrest (CA) followed by the return of spontaneous circulation leads to endothelial toxicity and cytokine production, both responsible for the subsequent occurrence of severe cardiocirculatory dysfunction and early death. Resistin is emerging as a biomarker of proinflammatory status and myocardial ischemic injury and as a mediator of endothelial dysfunction. The study aimed to analyze the possible associations between several clinical and biological variables and the serum levels of resistin in CA survivors. Forty patients with out-of-hospital resuscitated CA, were enrolled in the study. Demographic, clinical and laboratory data (including serum resistin measurements at admission and at 6, 12, 24, 48 and 72 h) were recorded. For resistin, we calculated the area under the curve (AUC) using the trapezoidal method with measurements from 0 to 12 h, 0 to 24 h, 0 to 48 h and 0 to 72 h. Fifteen (37.5%) patients died in the first 72 h after CA. Cardiovascular comorbidities were present in 65% of patients. The majority of patients had post-CA shock (29 (72.5%)). Resistin serum levels rose in the first 12–24 h and decreased in the next 48–72 h. In univariate analysis, advanced age, longer duration of resuscitation, high sequential organ failure assessment score, high lactate levels, presence of cardiovascular comorbidities and the post-CA shock were associated with higher resistin levels. In multivariate analysis, post-CA shock or cardiovascular comorbidities were independently associated with higher AUCs for resistin for 0–12 h and 0–24 h. The only identified variable to independently predict higher AUCs for resistin for 0–48 h and 0–72 h was the presence of post-CA shock. Our data demonstrate strong independent correlation between high serum resistin levels, cardiac comorbidities and post-CA shock. The impact of the post-CA shock on serum concentration of resistin was greater than that of cardiac comorbidities.

Induction of endothelial dysfunction by oxidized low-density lipoproteins via downregulation of Erk-5/Mef2c/KLF2 signaling: Amelioration by fisetin

Extra-cellular signal regulated kinase-5 (Erk-5), a transcriptional activator and regulator of endothelial cells (ECs) homeostasis, has been implicated in shear stress-induced endothelial dysfunction (ED), however its role in oxidized low-density lipoprotein (oxLDL)- induced ED during metabolic stress is not known. Herein, regulation and function of Erk-5 in oxLDL-induced EC death, inflammation and dysfunction has been investigated. Primary Human Umbilical Vein Endothelial Cells (pHUVECs) were stimulated with oxLDL. MTT and Trypan blue exclusion assays to assess cell viability, RT-qPCR and Western blotting assays to determine expression of endothelial and inflammatory markers and ED mediators at mRNA and protein levels, respectively were performed. Monocyte adhesion assay was performed to examine monocytes adherence to oxLDL-stimulated pHUVECs. The exposure of oxLDL induced a dose- and time-dependent decrease in pHUVECs viability, which concurred with decreased Erk-5 expression. Further, oxLDL (100 μg/ml) decreased the expression of endothelial markers eNOS and vWF, and increased the expression of ICAM-1, at both mRNA and protein levels. SiRNA-mediated silencing of Erk-5 or its inhibition showed that changes in eNOS, vWF and ICAM-1 expression could be mediated through Erk-5. Furthermore, oxLDL decreased the levels of Erk-5's upstream regulator MEK5 and downstream regulators Mef2c and KLF2, which were similar to their expressions in Erk-5 silenced cells. Fisetin, a phytochemical and bioflavonoid, could reduce the effect of oxLDL in ECs by upregulating the expression of endothelial markers including Erk-5, and downregulating the expression of inflammation markers. These results suggest that Erk-5 could be a critical regulator of oxLDL-induced EC death, inflammation and dysfunction via downregulation of Erk-5/Mef2c-KLF2 signaling pathway, which can be ameliorated by a bioflavonoid, fisetin.

MEDIATORS OF ENDOTHELIAL DYSFUNCTION IN CEREBRAL ISCHEMIA IN PREMATURE INFANTS

N preterm infants with cerebral ischemia, the blood level of such mediators of endothelial dysfunction (MED), as endothelin-1, nitric oxide, angiotensin II, homocysteine, neurotrophic factors, tissue type plasminogen activator and von Willebrand factor was quantified. The established patterns of changes in the blood level of these mediators, depending on the degree of prematurity and severity of cerebral ischemia, reflect the severity of impairment of the functional state of the endothelial system. The quantitative data on the blood MED level in premature infants can be considered as criteria for the assessment of the degree of endothelial dysfunction, as in choosing modes for adequate timely correction of cerebrovascular disorders in newborns.

P593Endoplasmic reticulum protein thioredoxin domain containing 5 (TXNDC5) is a novel mediator of endothelial dysfunction and atherosclerosis

P593Endoplasmic reticulum protein thioredoxin domain containing 5 (TXNDC5) is a novel mediator of endothelial dysfunction and atherosclerosis

Abstract 690: Endothelial-Specific Krüppel-Like Factor 2 Inactivation Promotes Endothelial Dysfunction in the Setting of Uremia

Background: Uremic solutes that accumulate in end-stage renal disease (ESRD) contribute to endothelial dysfunction and subsequent cardiovascular disease in ESRD patients. However, the specific mechanisms which mediate uremia-induced endothelial dysfunction in ESRD are not understood. Kruppel-like factors (KLFs) are important regulators of endothelial homeostasis which may be affected by the uremic milieu. In this study, we examined the role and regulation of endothelial KLF2 in mediating endothelial dysfunction in the setting of uremia. Methods and Results: First, we assessed the impact of the uremic milieu on endothelial gene expression utilizing serum from uremic and non-uremic pigs with chronic renal insufficiency. We demonstrate that KLF2 expression was dose-dependently decreased with uremic serum in human umbilical vein endothelial cells (HUVECS) versus normal serum which was reversed by prolonged serum dialysis or the application of laminar shear stress. Carboxymethyl-lysine (CML) modified albumin, a uremic advanced glycation end-product (AGE), also inhibited KLF2 expression. This effect was completely abrogated by receptor for AGE (RAGE) siRNA, as well as by a constitutively active form of IκBα, implicating a role for RAGE activation and the NF-κB signaling pathway. KLF2 suppression also promoted endothelial dysfunction in vitro, as adenoviral overexpression of KLF2 inhibited reactive oxygen species production and leukocyte adhesion in HUVECs treated with uremic serum or CML-AGE. For in vivo translation, we utilized high-frequency ultrasound and quantified flow-mediated dilation of the femoral artery in endothelial-specific KLF2 conditional knockout (cKO) mice after 5 minutes of hindlimb ischemia and demonstrated a 50% reduction in vasodilation in KLF2 cKO mice compared to controls. The lack of femoral artery vasodilation in KLF2 cKO mice was also accompanied by attenuated return of wall shear stress to baseline independent of blood velocity. Conclusions: Collectively, these observations implicate loss of endothelial KLF2 as mediator of endothelial dysfunction in the setting of uremia and suggest that elevating KLF2 expression may be a novel strategy for prevention and treatment of cardiovascular disease in ESRD.