Altered Endothelial Function Research Articles

Preservation of epoxyeicosatrienoic acid bioavailability prevents renal allograft dysfunction and cardiovascular alterations in kidney transplant recipients

This study addressed the hypothesis that epoxyeicosatrienoic acids (EETs) synthesized by CYP450 and catabolized by soluble epoxide hydrolase (sEH) are involved in the maintenance of renal allograft function, either directly or through modulation of cardiovascular function. The impact of single nucleotide polymorphisms (SNPs) in the sEH gene EPHX2 and CYP450 on renal and vascular function, plasma levels of EETs and peripheral blood monuclear cell sEH activity was assessed in 79 kidney transplant recipients explored at least one year after transplantation. Additional experiments in a mouse model mimicking the ischemia–reperfusion (I/R) injury suffered by the transplanted kidney evaluated the cardiovascular and renal effects of the sEH inhibitor t-AUCB administered in drinking water (10 mg/l) during 28 days after surgery. There was a long-term protective effect of the sEH SNP rs6558004, which increased EET plasma levels, on renal allograft function and a deleterious effect of K55R, which increased sEH activity. Surprisingly, the loss-of-function CYP2C9*3 was associated with a better renal function without affecting EET levels. R287Q SNP, which decreased sEH activity, was protective against vascular dysfunction while CYP2C8*3 and 2C9*2 loss-of-function SNP, altered endothelial function by reducing flow-induced EET release. In I/R mice, sEH inhibition reduced kidney lesions, prevented cardiac fibrosis and dysfunction as well as preserved endothelial function. The preservation of EET bioavailability may prevent allograft dysfunction and improve cardiovascular disease in kidney transplant recipients. Inhibition of sEH appears thus as a novel therapeutic option but its impact on other epoxyfatty acids should be carefully evaluated.

Neutrophil extracellular traps are associated with altered human pulmonary artery endothelial barrier function

Introduction: Acute respiratory response syndrome (ARDS) leads to increased permeability of the endothelial-epithelial barrier, which in turn promotes edema formation and hypoxemic respiratory failure. Although activated neutrophils are thought to play a significant role in mediating ARDS, at present the contribution of neutrophil extracellular traps (NETs) to lung endothelial barrier function is unclear. Methods: To clarify their role, we co-cultured in vitro NETs induced by phorbol myristate acetate (PMA)–activated neutrophils with lung endothelial cell monolayers and examined the barrier function of lung endothelial cells by immunofluorescence microscopy and albumin permeability in a double-chamber culture method. Results: Co-culture with stimulated neutrophils increased the albumin permeability of the human pulmonary artery endothelial cell (HPAEC) monolayer and altered cytoskeleton F-actin and vascular endothelial-cadherin in cell-cell junctions. Hyperpermeability to albumin and histological alterations were prevented by inhibition of NET formation with peptidyl arginine deiminase inhibitor or a neutrophil elastase inhibitor and were also prevented by increased degradation of NET structure with DNase. Conclusion: This in vitro experiment shows that altered HPAEC barrier function and increased albumin permeability are caused by the direct effect of PMA-induced NETs and their components. NET formation may be involved in the increased vascular permeability of the lung, which is a common feature in ARDS of various etiologies. These insights may help generate novel approaches for medical interventions.

Myeloperoxidase mediated alteration of endothelial function is dependent on its cationic charge

Endothelial cell (EC) glycocalyx (GLX) comprise a multicomponent layer of proteoglycans and glycoproteins. Alteration of its integrity contributes to chronic vascular inflammation and leads to the development of cardiovascular diseases. Myeloperoxidase (MPO), a highly abundant enzyme released by polymorphonuclear neutrophils, binds to the GLX and deleteriously affects vascular EC functions. The focus of this study was to elucidate the mechanisms of MPO-mediated alteration of GLX molecules, and to unravel subsequent changes in endothelial integrity and function. MPO binding to GLX of human ECs and subsequent internalization was mediated by cell surface heparan sulfate chains. Moreover, interaction of MPO, which is carrying a cationic charge, with anionic glycosaminoglycans (GAGs) resulted in reduction of their relative charge. By means of micro-viscometry and atomic force microscopy, we disclosed that MPO can crosslink GAG chains. MPO-dependent modulation of GLX structure was further supported by alteration of wheat germ agglutinin staining. Increased expression of ICAM-1 documented endothelial cell activation by both catalytically active and also inactive MPO. Furthermore, MPO increased vascular permeability connected with reorganization of intracellular junctions, however, this was dependent on MPO's catalytic activity. Novel proteins interacting with MPO during transcytosis were identified by proteomic analysis. Altogether, these findings provide evidence that MPO through interaction with GAGs modulates overall charge of the GLX, causing modification of its structure and thus affecting EC function. Importantly, our results also suggest a number of proteins interacting with MPO that possess a variety of cellular localizations and functions.

Effect of β3-adrenergic receptor modulation on endothelial function

Understanding endothelial dysfunction is at the heart of current concerns due to its involvement in many cardiovascular diseases such as heart failure (HF). The β3-adrenergic receptor (β3-AR) could be at the origin of this endothelial dysfunction. Indeed, it is expressed at the level of the endothelial cell and induces vasorelaxation by the release of nitric oxide (NO), a central actor in endothelial dysfunction. Our objective was therefore to study the overexpression of the receptor in endothelial cells to understand its involvement in endothelial dysfunction. We used the Tgβ3 rat at 45 weeks of age, which overexpresses the human β3-AR gene in the endothelium. Endothelium-dependent aortic relaxation versus isoproterenol was measured with or without L-VNIO an inhibitor of nNOS at 10 μM. The protein expression of NOS was evaluated by Western-Blot and the production of NO and O2- was evaluated by EPR on aorta. Vascular reactivity was significantly reduced in response to isoproterenol in Tgβ3 aorta (−10% P < 0.05 vs. WT) indicating an alteration of endothelial function without alteration in systemic arterial pressure. With L-VNIO vasorelaxation was significantly reduce in Tgβ3 rat indicating a major implication of nNOS in vascular reactivity. nNOS expression was increased in aorta (+ 56% P < 0.05 vs. WT). Vascular production of NO was increased in Tgβ3 rats (+ 53% P < 0.05 vs. WT), possibly link to nNOS increase. This production was associated with an elevation of O2- and ONOO- in Tgβ3 rats (+ 340%, respectively P < 0.05 vs. WT). The increase in β3-AR expression induces endothelial dysfunction with a key role of eNOS and nNOS. Further studies will be conducted to understand the causal links between endothelial dysfunction and the alteration of the cardiac function.

Influenza A virus causes maternal and fetal pathology via innate and adaptive vascular inflammation in mice

Influenza A virus (IAV) infection during pregnancy causes severe maternal and perinatal complications, despite a lack of vertical transmission of IAV across the placenta. Here, we demonstrate a significant alteration in the maternal vascular landscape that underpins the maternal and downstream fetal pathology to IAV infection in mice. In IAV infection of nonpregnant mice, the local lung inflammatory response was contained to the lungs and was self-resolving, whereas in pregnant mice, virus dissemination to major maternal blood vessels, including the aorta, resulted in a peripheral "vascular storm," with elevated proinflammatory and antiviral mediators and the influx of Ly6Clow and Ly6Chigh monocytes, plus neutrophils and T cells. This vascular storm was associated with elevated levels of the adhesion molecules ICAM and VCAM and the pattern-recognition receptors TLR7 and TLR9 in the vascular wall, resulting in profound vascular dysfunction. The sequalae of this IAV-driven vascular storm included placental growth retardation and intrauterine growth restriction, evidence of placental and fetal brain hypoxia, and increased circulating cell free fetal DNA and soluble Flt1. In contrast, IAV infection in nonpregnant mice caused no obvious alterations in endothelial function or vascular inflammation. Therefore, IAV infection during pregnancy drives a significant systemic vascular alteration in pregnant dams, which likely suppresses critical blood flow to the placenta and fetus. This study in mice provides a fundamental mechanistic insight and a paradigm into how an immune response to a respiratory virus, such as IAV, is likely to specifically drive maternal and fetal pathologies during pregnancy.

Therapeutic Potential of Phosphodiesterase Inhibitors for Endothelial Dysfunction- Related Diseases

Cardiovascular diseases (CVD) are considered a major health problem worldwide, being the main cause of mortality in developing and developed countries. Endothelial dysfunction, characterized by a decline in nitric oxide production and/or bioavailability, increased oxidative stress, decreased prostacyclin levels, and a reduction of endothelium-derived hyperpolarizing factor is considered an important prognostic indicator of various CVD. Changes in cyclic nucleotides production and/ or signalling, such as guanosine 3', 5'-monophosphate (cGMP) and adenosine 3', 5'-monophosphate (cAMP), also accompany many vascular disorders that course with altered endothelial function. Phosphodiesterases (PDE) are metallophosphohydrolases that catalyse cAMP and cGMP hydrolysis, thereby terminating the cyclic nucleotide-dependent signalling. The development of drugs that selectively block the activity of specific PDE families remains of great interest to the research, clinical and pharmaceutical industries. In the present review, we will discuss the effects of PDE inhibitors on CVD related to altered endothelial function, such as atherosclerosis, diabetes mellitus, arterial hypertension, stroke, aging and cirrhosis. Multiple evidences suggest that PDEs inhibition represents an attractive medical approach for the treatment of endothelial dysfunction-related diseases. Selective PDE inhibitors, especially PDE3 and PDE5 inhibitors are proposed to increase vascular NO levels by increasing antioxidant status or endothelial nitric oxide synthase expression and activation and to improve the morphological architecture of the endothelial surface. Thereby, selective PDE inhibitors can improve the endothelial function in various CVD, increasing the evidence that these drugs are potential treatment strategies for vascular dysfunction and reinforcing their potential role as an adjuvant in the pharmacotherapy of CVD.

Vascular consequences of inflammation: a position statement from the ESH Working Group on Vascular Structure and Function and the ARTERY Society.

: Inflammation is a physiological response to aggression of pathogenic agents aimed at eliminating the aggressor agent and promoting healing. Excessive inflammation, however, may contribute to tissue damage and an alteration of arterial structure and function. Increased arterial stiffness is a well recognized cardiovascular risk factor independent of blood pressure levels and an intermediate endpoint for cardiovascular events. In the present review, we discuss immune-mediated mechanisms by which inflammation can influence arterial physiology and lead to vascular dysfunction such as atherosclerosis and arterial stiffening. We also show that acute inflammation predisposes the vasculature to arterial dysfunction and stiffening, and alteration of endothelial function and that chronic inflammatory diseases such as rheumatoid arthritis, inflammatory bowel disease and psoriasis are accompanied by profound arterial dysfunction which is proportional to the severity of inflammation. Current findings suggest that treatment of inflammation by targeted drugs leads to regression of arterial dysfunction. There is hope that these treatments will improve outcomes for patients.

Effects Of 10-days Bed-rest On Nitric Oxide Metabolites And Microvascular Function Assessed By Near-infrared Spectroscopy

PURPOSE: Prolonged periods of bed-rest (BR), experimental simulation of microgravity, greatly affect oxidative metabolism by acting at several levels of the O2 pathway. Short duration (10 days) of horizontal BR negatively affects in-vivo functional biomarkers related to skeletal muscle oxidative metabolism without affecting mitochondrial respiration ex-vivo. The impairment of muscle oxidative metabolism can partially derive from reduced O2 delivery, altered peripheral O2 diffusion and a mismatch between O2 delivery and O2 consumption, likely related to an altered nitric oxide signaling. Aim of this study was to evaluate the effects of 10 days of BR on microvascular reactivity indexes determined at skeletal muscle level by near infrared spectroscopy and nitric oxide metabolites. METHODS: Measurements were carried out on 10 recreationally active young males (age 23 ± 5 years [mean±SD]) before (PRE) and after (POST) 10 days of horizontal BR. Pulmonary O2 uptake (V̇O2) and other respiratory, cardiovascular and skeletal muscle variables were determined during an incremental exercise on a cycle ergometer. Microvascular endothelial function was assessed during vascular occlusion test (VOT) by evaluating the slope of re-oxygenation rate (SLOPE 2) and the area under the curve (AUC) over the baseline of 5min reperfusion phase of delta[oxy(Hb+Mb)] signal obtained from vastus lateralis muscle. Plasma nitrite concentration was determined by chemiluminescence. RESULTS: Peak V̇O2 was lower in POST (41.5±6.5 ml.kg-1.min-1) vs. PRE (44.5±7.4, P<0.01). SLOPE 2 was significantly slower in POST (5.3±0.8 %.s-1) compared to PRE (6.4±0.7, P<0.01). AUC was significantly reduced in POST (11025±2145 %.s) compared to PRE (13094±1940, P<0.01). Plasma nitrite concentration diminished from PRE (85.4±35.0 nM) to POST (65.5±45.6, P<0.01). CONCLUSIONS: These preliminary data suggest that after 10 days of horizontal BR whole-body impairment of oxidative metabolism during exercise is associated with reduced level of nitrite and an altered microvascular endothelial function. Further analyses of systemic functional variables as well as biochemical data obtained during the bed-rest campaign, and not yet analysed, will help us to define sites of limitation to muscle oxidative metabolism along the O2 pathway.

Basement Membrane Remodeling Controls Endothelial Function in Idiopathic Pulmonary Arterial Hypertension.

The extracellular matrix (ECM) increasingly emerges as an active driver in several diseases, including idiopathic pulmonary arterial hypertension (IPAH). The basement membrane (BM) is a specialized class of ECM proteins. In pulmonary arteries, the BM is in close contact and direct proximity to vascular cells, including endothelial cells. So far, the role of the BM has remained underinvestigated in IPAH. Here, we aimed to shed light on the involvement of the BM in IPAH, by addressing its structure, composition, and function. On an ultrastructural level, we observed a marked increase in BM thickness in IPAH pulmonary vessels. BM composition was distinct in small and large vessels and altered in IPAH. Proteoglycans were mostly responsible for distinction between smaller and larger vessels, whereas BM collagens and laminins were more abundantly expressed in IPAH. Type IV collagen and laminin both strengthened endothelial barrier integrity. However, only type IV collagen concentration dependently increased cell adhesion of both donor and IPAH-derived pulmonary arterial endothelial cells (PAECs) and induced nuclear translocation of mechanosensitive transcriptional coactivator of the hippo pathway YAP (Yes-activated protein). On the other hand, laminin caused cytoplasmic retention of YAP in IPAH PAECs. Accordingly, silencing of COL4A5 and LAMC1, respectively, differentially affected tight junction formation and barrier integrity in both donor and IPAH PAECs. Collectively, our results highlight the importance of a well-maintained BM homeostasis. By linking changes in BM structure and composition to altered endothelial cell function, we here suggest an active involvement of the BM in IPAH pathogenesis.

Improvement in Angiotensin 1-7 precedes and correlates with improvement in Arterial stiffness and endothelial function following Renin-Angiotensin system inhibition in type 2 diabetes with newly diagnosed hypertension

Background and aimStudies in cell cultures and animal models have revealed the possible pathophysiological factors associated with vascular endothelial dysfunction. However, the same in human subjects has not been clearly established. The current study uses a novel approach to identify the factors associated with endothelial function and arterial function by altering these vascular parameters using Angiotensin-Converting-Enzyme (ACE) inhibition. MethodsDiabetic patients with newly diagnosed hypertension (n = 60) were recruited for the study. Flow-mediated-dilation (FMD), carotid-femoral (cf), carotid-radial (cr) Pulse-wave-velocity (PWV), Augmentation-Index, Carotid-Intima-Media-Thickness (CIMT), serum levels of Renin, Angiotensin II (AngII), Angiotensin-Converting-Enzyme2 (ACE2), Angiotensin1-7 (Ang1-7), E-selectin, Vascular-Cell-Adhesion-Molecule-1 (VCAM-1), Highly-sensitive-C-Reactive-Protein (hsCRP) and Interleukin-10 were measured at baseline (V1), after 1 week (V2) and 3 months (V3) of ACE inhibition in patients of diabetes with newly diagnosed hypertension. The amplitude of change after 1 week (V2–V1) and 3 months (V3–V1) for the clinical and various parameters were correlated with the change in endothelial function and arterial stiffness. ResultsCarotid radial-PWVV2-V1 (p = 0.001) and Ang1-7V2–V1 (p = 0.01) emerged as independent predictors of FMDV2-V1. ReninV2-V1 and VCAM-1V2–V1 independently predicted E-selectinV2-V1 [(p = 0.01) and (p = 0.001), respectively]. ACE 2V2–V1 was the only independent predictor of cf-PWVV2-V1. The same parameters remained as independent predictors of the respective vascular factors after 3 months of ACE inhibition. ConclusionThe study highlights the role of AngII/Ang1-7 balance in alteration of endothelial function and central arterial stiffness in humans in addition to identifying the interrelationship between the renin-angiotensin-aldosterone-system components and clinically ascertainable parameters.

Overcoming Barriers: The Endothelium As a Linchpin of Coronavirus Disease 2019 Pathogenesis?

Objective:Coronavirus disease 2019 (COVID-19) is a global pandemic involving >5 500 000 cases worldwide as of May 26, 2020. The culprit is the severe acute respiratory syndrome coronavirus-2, which invades cells by binding to ACE2 (angiotensin-converting enzyme 2). While the majority of patients mount an appropriate antiviral response and recover at home, others progress to respiratory distress requiring hospital admission for supplemental oxygen. In severe cases, deterioration to acute respiratory distress syndrome necessitating mechanical ventilation, development of severe thrombotic events, or cardiac injury and dysfunction occurs. In this review, we highlight what is known to date about COVID-19 and cardiovascular risk, focusing in on the putative role of the endothelium in disease susceptibility and pathogenesis.Approach and Results:Cytokine-driven vascular leak in the lung alveolar-endothelial interface facilitates acute lung injury in the setting of viral infection. Given that the virus affects multiple organs, including the heart, it likely gains access into systemic circulation by infecting or passing from the respiratory epithelium to the endothelium for viral dissemination. Indeed, cardiovascular complications of COVID-19 are highly prevalent and include acute cardiac injury, myocarditis, and a hypercoagulable state, all of which may be influenced by altered endothelial function. Notably, the disease course is worse in individuals with preexisting comorbidities that involve endothelial dysfunction and may be linked to elevated ACE2 expression, such as diabetes mellitus, hypertension, and cardiovascular disease.Conclusions:Rapidly emerging data on COVID-19, together with results from studies on severe acute respiratory syndrome coronavirus-1, are providing insight into how endothelial dysfunction may contribute to the pandemic that is paralyzing the globe. This may, in turn, inform the design of biomarkers predictive of disease course, as well as therapeutics targeting pathogenic endothelial responses.

Bioactivity of Circulatory Factors After Pulmonary Exposure to Mild or Stainless Steel Welding Fumes.

Studies suggest that alterations in circulating factors are a driver of pulmonary-induced cardiovascular dysfunction. To evaluate, if circulating factors effect endothelial function after a pulmonary exposure to welding fumes, an exposure known to induce cardiovascular dysfunction, serum collected from Sprague Dawley rats 24 h after an intratracheal instillation exposure to 2 mg/rat of 2 compositionally distinct metal-rich welding fume particulates (manual metal arc welding using stainless steel electrodes [MMA-SS] or gas metal arc welding using mild steel electrodes [GMA-MS]) or saline was used to test molecular and functional effects of in vitro cultures of primary cardiac microvascular endothelial cells (PCMEs) or ex vivo organ cultures. The welding fumes elicited significant pulmonary injury and inflammation with only minor changes in measured serum antioxidant and cytokine levels. PCME cells were challenged for 4 h with serum collected from exposed rats, and 84 genes related to endothelial function were analyzed. Changes in relative mRNA patterns indicated that serum from rats exposed to MMA-SS, and not GMA-MS or PBS, could influence several functional aspects related to endothelial cells, including cell migration, angiogenesis, inflammation, and vascular function. The predictions were confirmed using a functional in vitro assay (scratch assay) as well as an ex vivo multicellular environment (aortic ring angiogenesis assay), validating the concept that endothelial cells can be used as an effective screening tool of exposed workers for determining bioactivity of altered circulatory factors. Overall, the results indicate that pulmonary MMA-SS fume exposure can cause altered endothelial function systemically via altered circulating factors.

Analysis of cerebrovascular dysfunction caused by chronic social defeat in mice

Psychological stress and affective disorders are clinically associated with hypertension and vascular disease, but the biological links between the conditions have not been fully explored. To examine this relationship, we used chronic social defeat (CSD) stress, which produces anxiety-like and depressive-like behavioral declines in susceptible mice. In such mice, CSD also produces cerebrovascular microbleeds in scattered locations. Here, we showed further evidence of vascular pathology and blood–brain barrier breakdown by visualizing plasma immunoglobulins and erythrocytes within the parenchyma and perivascular spaces of CSD brains. To further characterize the impact of stress on the cerebrovasculature, brain endothelial cells (bECs) were isolated, and global gene expression profiles were generated. Bioinformatic analysis of CSD-induced transcriptional changes in bECs showed enrichment in pathways that delineate the vascular response to injury. These pathways followed a temporal sequence of inflammation, oxidative stress, growth factor signaling, and wound healing (i.e., platelet aggregation, hemostasis, fibrinogen deposition, and angiogenesis). Immunohistochemical staining for markers of fibrinogen deposition and angiogenesis confirmed the existence of the markers at the sites of vascular disruptions. Recovery after CSD cessation was marked by recruitment of leukocytes perhaps participating in vascular repair. The data suggest that co-morbidity of affective disorders and vascular diseases may be attributed in part to a common link in altered endothelial cell function.

The uptake mechanism and intracellular fate of Paraoxonase-1 in endothelial cells

Paraoxonase-1 (PON1) is a high-density lipoprotein (HDL)-associated lactonase that plays a significant role in the anti-atherosclerotic activity of HDL. However, several studies have shown that PON1 localizes in cells, where it operates independently of HDL. Previously, we showed that PON1 localizes in endothelial cells (ECs), and impairs vasodilation mediated by the endothelium-derived hyperpolarizing factor (EDHF) 5,6-δ-DHTL. However, the internalization pathway of PON1 into ECs, and the intracellular fate of PON1 are unknown. Therefore, the present study aimed to elucidate the uptake mechanism, intracellular trafficking and the function of PON1 in ECs. ‏We conducted a series of inhibition experiments of fluorescently labeled recombinant PON1 (rePON1) in ECs, followed by FACS analyses. We found that rePON1 binds the EC membrane via specific binding sites located in lipid-rafts/caveolae microdomains that are shared with HDL, and internalized through dynamin-dependent endocytosis. Qualitative assessments of the intracellular trafficking of rePON1, using confocal z-stack images, showed colocalization of the labeled rePON1 with early and late endosome/lysosome markers. Accordingly, a “pulse-chase” incubation of rePON1, followed by lactonase activity measurement in EC lysate, revealed that rePON1 retains its lactonase activity after binding to the cells. However, this activity decreases over time. Finally, induction of endothelial dysfunction with high glucose, angiotensin II, or palmitic acid increased rePON1 uptake by ECs. In conclusion, these results indicate that free PON1 interacts with ECs via binding sites located in lipid-rafts/caveolae, where it is enzymatically active and regulates endothelial functions. However, once internalized, PON1 is degraded. Additionally, alteration in endothelial function affects PON1 uptake by ECs.

Isolation and Purification of Mouse Brain Endothelial Cells to Study Cerebral Cavernous Malformation Disease.

We describe a method to purify primary brain microvascular endothelial cells (BMEC) from mice bearing floxed alleles of Krit1 (Krit1fl/fl) or Pdcd10 (Pdcd10fl/fl) and an endothelial-specific tamoxifen-regulated Cre recombinase (Pdgfb-iCreERT2), and used these to delete Krit1 or Pdcd10 genes in a time-controlled manner. These BMEC culture models contain a high degree of purity and have been used to identify the major molecular processes involved in loss of Krit1/Pdcd10-induced altered brain endothelial phenotype and function. In addition, these in vitro models of cerebral cavernous malformations (CCMs) enable molecular, biochemical, and pharmacological studies that have contributed significantly to understand the pathogenesis of CCMs. The findings using this in vitro CCMs model have been validated in mouse CCM models and observed in human CCMs. In this chapter, we summarize procedures for isolation and purification of BMEC from transgenic mice, as well as our experience to genetically inactivate CCM genes in the brain endothelium.

Influence of Genetic Variation in PDE3A on Endothelial Function and Stroke.

We aimed to characterize the genetics of endothelial function and how this influences risk for cardiovascular diseases such as ischemic stroke. We integrated genetic data from a study of ultrasound flow-mediated dilatation of brachial artery in adolescents from ALSPAC (Avon Longitudinal Study of Parents and Children; n=5214) with a study of ischemic stroke (MEGASTROKE: n=60 341 cases and 452 969 controls) to identify variants that confer risk of ischemic stroke through altered endothelial function. We identified a variant in PDE3A (Phosphodiesterase 3A), encoding phosphodiesterase 3A, which was associated with flow-mediated dilatation in adolescents (9–12 years of age; β[SE], 0.38 [0.070]; P=3.8×10−8) and confers risk of ischemic stroke (odds ratio, 1.04 [95% CI, 1.02–1.06]; P=5.2×10−6). Bayesian colocalization analyses showed the same underlying variation is likely to lead to both associations (posterior probability, 97%). The same variant was associated with flow-mediated dilatation in a second study in young adults (age, 24–27 years; β[SE], 0.47 [0.23]; P=0.047) but not in older adults (β[SE], −0.012 [0.13]; P=0.89). We conclude that a genetic variant in PDE3A influences endothelial function in early life and leads to increased risk of ischemic stroke. Subtle, measurable changes to the vasculature that are influenced by genetics also influence risk of ischemic stroke.

Abstract 357: Cerebral Arterial Endothelial Dysfunction in the Post-Cardiac Arrest Period

Introduction: Cardiac arrest (CA) has a poor prognosis due to brain injury that progresses over time. Endothelial dysfunction may play an important role in the impairment of the cerebral circulation after CA. Aims: To investigate 1) whether endothelial dysfunction is present in cerebral arteries, and 2) if the altered endothelial function is caused by increased activity of calcium-activated potassium (K ca ) channels. Methods: Male Sprague-Dawley rats (403g±24g) were anaesthetized, intubated and ventilated. Four groups were examined; two CA groups observed for either 2 hours (2h-CA, n=10) or 4 hours (4h-CA, n=10) and two corresponding sham groups (2h-sham, n=10; 4h-sham, n=10). Following 7 minutes of asphyxial CA, the rats were resuscitated using adrenaline, ventilation, and chest compressions. Middle cerebral arteries were isolated and examined in wire-myographs. Results: Cerebral vasodilation was significantly enhanced in response to bradykinin in arteries from 4h-CA rats when compared to 4h-sham rats (4h-sham: E max 58% (5.57 of 9.69) ± 6% vs 4h-CA: E max 84% (6.16 of 7.32) ± 4%, p=0.007). Likewise, vasodilation induced by NS309 (K Ca -channel activator) was increased in CA rats when compared to sham rats. In the presence of L-NAME (NO synthase inhibitor), bradykinin induced vasodilation was significantly augmented in 4h-CA rats when compared to 4h-sham rats, whereas SNP (NO donor) induced vasodilation was similar between groups. In the presence of L-NAME and K Ca -channel blockers (UCL1684 and ICA-17043), bradykinin induced vasodilation was abolished in cerebral arteries in all four groups. Conclusion: Our findings demonstrate an enhanced endothelial-dependent vasodilation in cerebral arteries in the post-cardiac arrest period. The increased vasodilatory response may be explained by increased endothelial K Ca -channel activity and bioavailability of NO, and may contribute to dysregulation of cerebral blood flow after CA.

Role of endothelial dysfunction in heart failure.

Coronary artery disease is a major underlying etiology for heart failure. The role of coronary microvascular disease, and endothelial dysfunction, in the pathophysiology of heart failure is poorly appreciated. Endothelial dysfunction, induced by oxidative stress, contributes to the development of heart failure. Alterations of endothelial function and nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathway are involved in the pathophysiology of heart failure with both reduced and preserved ejection fraction. Indeed, an altered endothelium dependent vasodilatation, causing repeated episodes of ischemia/reperfusion, can induce a chronic stunned myocardium with systolic dysfunction and an increased diastolic stiffness with diastolic dysfunction. Moreover, the altered NO-cGMP pathway directly affects myocardial homeostasis. Endothelial dysfunction is associated with worse prognosis and higher rate of cardiovascular events. Potential therapeutic strategies targeting the NO-cGMP pathway in patients with HF will be discussed in this review article. Although clinical data are still inconclusive, the NO-cGMP pathway represents a promising target for therapy.

Android Fat Deposition and Its Association With Cardiovascular Risk Factors in Overweight Young Males.

ObjectiveExcess adiposity increases the risk of type-2 diabetes and cardiovascular disease development. Beyond the simple level of adiposity, the pattern of fat distribution may influence these risks. We sought to examine if higher android fat distribution was associated with different hemodynamic, metabolic or vascular profile compared to a lower accumulation of android fat deposits in young overweight males.MethodsForty-six participants underwent dual-energy X-ray absorptiometry and were stratified into two groups. Group 1: low level of android fat (<9.5%) and group 2: high level of android fat (>9.5%). Assessments comprised measures of plasma lipid and glucose profile, blood pressure, endothelial function [reactive hyperemia index (RHI)] and muscle sympathetic nerve activity (MSNA).ResultsThere were no differences in weight, BMI, total body fat and lean mass between the two groups. Glucose tolerance and insulin resistance (fasting plasma insulin) were impaired in group 2 (p < 0.05). Levels of plasma triglycerides and 5 lipid species were higher in group 2 (p < 0.05). Endothelial function was less in group 2 (RHI: 1.64 vs. 2.26, p = 0.003) and heart rate was higher (76 vs. 67 bpm, p = 0.004). No difference occurred in MSNA nor blood pressure between the 2 groups.ConclusionPreferential fat accumulation in the android compartment is associated with increased cardiovascular and metabolic risk via alteration of endothelial function.

Flow-mediated dilation shows impaired endothelial function in patients with mastocytosis

Mastocytosis is a rare disease characterized by clonal proliferation of mast cells (MCs) in different organs. Clinical manifestations of mastocytosis are mostly due to release of mediators from MCs and, in many cases, such as urticaria, flushing, angioedema, and anaphylaxis, are an expression of the biological effects of mediators on endothelial cells. Chronic secretion of mediators in patients with mastocytosis can lead to alteration of endothelial function. We sought to investigate endothelial function in patients with mastocytosis using a noninvasive technique of flow-mediated dilation (FMD). Twenty-five adult patients with indolent and advanced forms of mastocytosis and 20 healthy control subjects were enrolled in the study. Ultrasound assessment of FMD was performed by measuring changes in the diameter of the brachial artery after 5minutes of arterial occlusion. Changes in FMD were correlated with clinical parameters and serum tryptase levels. Patients with mastocytosis had lower FMD compared with healthy control subjects (P<.001). Advanced and smoldering forms showed a lower FMD compared with indolent forms (P<.001). FMD inversely correlated with age and serum tryptase levels and directly with median arterial pressure and recurrent flushing episodes. No correlation was found between FMD and osteoporosis, recurrent anaphylaxis, presence of skin lesions, and long-term antihistamine treatment. Endothelial dysfunction, as demonstrated by FMD reduction, is detectable in patients with mastocytosis and is more severe in patients with high tryptase levels and advanced disease. Endothelial function appears to be negatively influenced by MC proliferation rather than by the severity of mediator-related symptoms.