Primary Human Aortic Endothelial Cells Research Articles

Cytoprotective effects of berry anthocyanins against induced oxidative stress and inflammation in primary human diabetic aortic endothelial cells

Type 2 diabetes is associated with oxidative stress and low-grade inflammation resulting in endothelial dysfunction (ED). This study determined to explore the protective effects of berry-derived anthocyanins (AC) with potent antioxidant and anti-inflammatory activities in human diabetic endothelial cells upon oxidative and inflammatory stressors. Cultured healthy human aortic endothelial cells (HAEC) and diabetic human aortic endothelial cells (D-HAEC) exposed to oxidative stress by hydrogen peroxide (H2O2, 75 μM) and lipopolysaccharide (LPS, 1 μg/mL) as an inflammatory inducer before treatment with AC (50 μl/ml). The results from cytotoxicity assays showed that AC had no significant effects in cell viability (P-value < 0.0001), and exposure to H2O2 75 μM had a less toxic effect (P-value < 0.05). Although, AC significantly decreased H2O2-induced cytotoxicity and oxidative stress in both HAEC and D-HAEC cell lines (P-value < 0.0001), no positive impact of AC was found on the GSSG/GSH ratios (P-value < 0.05). Exposure to the LPS increased the production of IL-6 in both HAEC and D-HAEC cell lines (P-value < 0.0001), whereas AC treatment reduced LPS‐induced IL‐6 production in both cell lines with a more robust impact on D-HAEC (P-value < 0.0001). While LPS increased inflammasome assembling and caspase-1 activation, AC treatment inhibited caspase-1 activation in D-HAEC (P ≤ 0.05). This study indicated that berry anthocyanins reduced oxidative stress and inflammation via the inhibition of the NF-ƙB signaling pathway, which contributes to mitigating the diabetes-induced up-regulation of NF-ƙB.

Bach1 Inhibitors Reduce Stasis in Townes Sickle Cell Mouse Model

In sickle cell disease (SCD) excessive release of Hb and heme into the vasculature can activate innate immune toll-like receptor 4 (TLR4) signaling in the vasculature leading to inflammation and vaso-occlusion. Heme-mediated TLR4 signaling can be interrupted by inducing heme oxygenase 1 (HO-1) to degrade heme or ferritin heavy chain (FTH1) to sequester iron. Globin synthesis, HO-1 expression, heme/iron homeostasis, and antioxidant levels are regulated in part by antioxidant response genes, which is a set of hundreds of genes that possess antioxidant response elements (ARE) in their promoter regions. Bach1 complexes bind to ARE sites and dominantly repress Nrf2 transcriptional activity. This transcriptional repression can be inactivated by heme binding to Bach1. We have discovered small molecule BACH1 inhibitors that increase HO-1 and FTH1 mRNA in HepG2 cells. Additionally, they restore glutathione levels and inhibit VCAM-1 expression in human primary aortic endothelial cells upon hemin or TNFα challenge. To investigate if Bach1 inhibitors could have an effect on vaso-occlusion in vivo, microvascular stasis was examined in Townes-SS mice with implanted dorsal skin-fold chambers. Townes-SS mice were orally gavaged with vehicle or Bach1 inhibitors at different doses once daily for 8 days. Microvascular stasis was determined in 20-25 preselected flowing subcutaneous venules in response to intravenous infusion of hemin (3.2 μmol/kg). Stasis was significantly inhibited by Bach1 inhibitors in a dose responsive manner. After stasis measurement, blood was collected and the F-cells were stained using the Kleihauer-Betke Test. F-cell % was significantly increased by Bach1 inhibitor treatment at all doses tested. Disclosures Belcher: Mitobridge, an Astellas Company: Consultancy, Research Funding. Biddle:Mitobrige, an Astellas Company: Employment, Membership on an entity's Board of Directors or advisory committees, Patents &amp; Royalties. Stickens:Mitobridge, an Astellas Company: Employment, Membership on an entity's Board of Directors or advisory committees, Patents &amp; Royalties. Olson:Mitobridge, an Astellas Company: Employment. Bell:Mitobridge, an Astellas Company: Employment. Vercellotti:Mitobridge, an Astellas Company: Consultancy, Research Funding.

Biliverdin reductase deficiency triggers an endothelial-to-mesenchymal transition in human endothelial cells

Endothelial dysfunction accompanied by the loss of endothelial cell phenotype plays an essential role in cardiovascular diseases. Here, we report that knockdown of biliverdin reductase (BVR), the enzyme of the heme degradation pathway converting biliverdin to bilirubin, shifts endothelial phenotype of the primary human aortic endothelial cells (HAECs) to mesenchymal-like one. It is reflected by the loss of endothelial markers and angiogenic response, with concomitant acquiring of mesenchymal markers, increased migratory capacity and metalloproteinase activity. BVR-deficiency induces the activity of Nrf2 transcription factor and increases heme oxygenase-1 (HO-1) level, which is accompanied by the reduction of cellular heme content, increase in a free iron fraction and oxidative stress. Accordingly, the phenotype of BVR-deficient cells can be mimicked by hemin or iron overload. Depletion of HO-1 in BVR-deficient ECs abrogates the increase in intracellular free iron and oxidative stress, preventing the loss of endothelial markers. Treatment of BVR-deficient cells with bilirubin does not rescue the endothelial phenotype of HAECs. Unlike BLVRA mRNA level, the expression of HMOX1, HMOX1:BLVRA ratio and HO-1 protein level positively correlate with abdominal aortic aneurysm size in clinical samples. Collectively, the non-enzymatic activity of BVR contributes to the maintenance of healthy endothelial phenotype through the prevention of HO-1-dependent iron-overload, oxidative stress and subsequent endothelial-to-mesenchymal transition (EndMT).

A key role for the novel coronary artery disease gene JCAD in atherosclerosis via shear stress mechanotransduction.

AimsGenome-wide association studies (GWAS) have consistently identified an association between coronary artery disease (CAD) and a locus on chromosome 10 containing a single gene, JCAD (formerly KIAA1462). However, little is known about the mechanism by which JCAD could influence the development of atherosclerosis.Methods and resultsVascular function was quantified in subjects with CAD by flow-mediated dilatation (FMD) and vasorelaxation responses in isolated blood vessel segments. The JCAD risk allele identified by GWAS was associated with reduced FMD and reduced endothelial-dependent relaxations. To study the impact of loss of Jcad on atherosclerosis, Jcad−/− mice were crossed to an ApoE−/− background and fed a high-fat diet from 6 to16 weeks of age. Loss of Jcad did not affect blood pressure or heart rate. However, Jcad−/−ApoE−/− mice developed significantly less atherosclerosis in the aortic root and the inner curvature of the aortic arch. En face analysis revealed a striking reduction in pro-inflammatory adhesion molecules at sites of disturbed flow on the endothelial cell layer of Jcad−/− mice. Loss of Jcad lead to a reduced recovery perfusion in response to hind limb ischaemia, a model of altered in vivo flow. Knock down of JCAD using siRNA in primary human aortic endothelial cells significantly reduced the response to acute onset of flow, as evidenced by reduced phosphorylation of NF-КB, eNOS, and Akt.ConclusionThe novel CAD gene JCAD promotes atherosclerotic plaque formation via a role in the endothelial cell shear stress mechanotransduction pathway.

2182Sirtuin 5 regulates arterial thrombosis by modulating endothelial plasminogen activator inhibitor-1

Abstract Introduction Arterial thrombosis as a result of plaque rupture or erosion is a crucial event in myocardial infarction and stroke. Oxidative stress and inflammation promote endothelial dysfunction and play a pivotal role in destabilization of the atherosclerotic plaque. Sirtuin 5 (SIRT5) is a member of the sirtuin protein family with function as a NAD+-dependent protein desuccinylase and demalonylase. Being implicated in the regulation of different pathophysiological processes among which production of reactive oxygen species and transcription of inflammatory mediators, SIRT5 plays a role in the development of several cardiovascular diseases such as myocardial infarction and stroke. To date, the possible involvement of SIRT5 as a mediator of arterial thrombosis remains to be investigated. Purpose In this study we investigate the putative role of this protein in arterial thrombosis by using an established in vivo mouse model. The translational value of animal findings as well as the molecular mechanism underlying the observed effect will be investigated also in primary human aortic endothelial cells (HAECs). Methods SIRT5 knockout (KO) as well as SIRT5 transgenic (TG) animals were used for in vivo experiments. HAECs treated with SIRT5 silencing RNA (si-SIRT5) and stimulated with tumor necrosis factor (TNF)-α were used for in vitro assays. Results When compared to WT animals, SIRT5 KO mice display blunted carotid artery thrombus formation as underlined by delayed time to occlusion in a photochemical injury model. Oppositely, in SIRT5 TG mice the formation of an occlusive thrombus is accelerated (Fig 1). Mechanistically, SIRT5 KO and WT animals show no difference in terms of vascular tissue factor (TF) activity, TF concentration in plasma and expression of TF pathway inhibitor (TFPI) in the aorta. In line with the observed reduced thrombogenicity, SIRT5 KO animal express reduced level of the pro-thrombotic plasminogen activator-1 (PAI-1), as assessed by western blot in aorta lysate. Of interest, SIRT5 genetic deletion does not affect platelet aggregation, as assessed by ex-vivo collagen-induced aggregometry. In HAECs, SIRT5-silencing inhibits PAI-1 expression in response to TNF-α. Real-time polymerase chain reaction revealed that inhibition of PAI-1 expression occurs at the mRNA level. This effect is mediated by reduced activation of the MAP kinase Erk 1/2, but not JNK (Fig 1). Conclusions SIRT5 mediates arterial thrombosis by increasing endothelial PAI-1 expression. Hence, SIRT5 may be an effective therapeutic target in the context of atherothrombosis.

Cilostazol ameliorates high free fatty acid (FFA)-induced activation of NLRP3 inflammasome in human vascular endothelial cells

Cardiovascular disease is recognized as a leading cause of death worldwide, but the risk of death is 2–3 times higher for individuals with diabetes. NLRP3 inflammasome activation is a leading pathway of vascular damage, and new treatment methods are needed to reduce NLRP3 inflammasome expression, along with a detailed understanding of how those treatments work. In a series of assays on human vascular endothelial cells that were exposed to high concentrations of free fatty acids (FFA) to induce a diabetes-like environment, we found a significant impact of cilostazol, a vasodilator widely used to treat blood flow problems and well-tolerated medication. To our knowledge, this study is the first to demonstrate the effects of cilostazol in primary human aortic endothelial cells. We found that cilostazol significantly reduced NLRP3 inflammasome activation, as well as the activity of other related and harmful factors, including oxidative stress, expression of NADPH oxidase 4 (NOX-4), thioredoxin-interacting protein (TxNIP), high mobility group box 1 (HMGB-1), interleukin 1β (IL-1β) and IL-18. Cilostazol also protected the functionality of sirtuin 1 (SIRT1), which serves to restrict NLRP3 inflammasome activity, when exposure to FFAs would have otherwise impaired its function. Thus, it appears that cilostazol’s mechanism of action in reducing NLRP3 inflammasome activation is an indirect one; it protects SIRT1, which then allows SIRT1 to perform its regulatory job. Cilostazol has potential as an already-available, well-tolerated preventive medication that may alleviate some of the adverse vascular effects of living with diabetes. The findings of the present study lay the groundwork for further research on the potential of cilostazol as a safe and effective treatment against diabetic endothelial dysfunction and vacular disease.

A Rapid Array-Based Approach to N-Glycan Profiling of Cultured Cells.

Typically, N-glycosylation studies done on cultured cells require up to millions of cells followed by lengthy preparation to release, isolate, and profile N-glycans. To overcome these limitations, we report a rapid array-based workflow for profiling N-glycan signatures from cells, adapted from imaging mass spectrometry used for on-tissue N-glycan profiling. Using this approach, N-glycan profiles from a low-density array of eight cell chambers could be reported within 4 h of completing cell culture. Approaches are demonstrated that account for background N-glycans due to serum media. Normalization procedures are shown. The method is robust and reproducible, requiring as few as 3000 cells per replicate with a 3-20% coefficient of variation to capture label-free profiles of N-glycans. Quantification by stable isotopic labeling of N-glycans in cell culture is demonstrated and adds no additional time to preparation. Utility of the method is demonstrated by measurement of N-glycan turnover rates due to induction of oxidative stress in human primary aortic endothelial cells. The developed method and ancillary tools serve as a foundational launching point for rapid profiling of N-glycans ranging from high-density arrays down to single cells in culture.

Tofacitinib inhibits ox-LDL-induced adhesion of THP-1 monocytes to endothelial cells

Atherosclerosis is a chronic inflammatory disease of the blood vasculature. Endothelial dysfunction is an early event in the development of atherosclerosis and the endothelium plays an important role in the innate immune defense in the pathology of cardiovascular diseases. New therapies are being developed based on the involvement of the immune system in atherosclerosis. In this study, we demonstrate that a commonly used anti-rheumatic drug, tofacitinib, possesses vascular protective properties in cultured primary human aortic endothelial cells (HAECs). Tofacitinib ameliorates oxidized low-density lipoprotein (ox-LDL)-induced adhesion of THP-1 cells to HAECs, suppresses the expression of vascular adhesion molecules and production of cytokines, including vascular cell adhesion molecule 1 (VCAM-1), intercellular cell adhesion molecule-1 (ICAM-1), tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β). Moreover, tofacitinib inhibits elevation of endothelial lectin-like ox-LDL receptor-1 (LOX-1) and production of reactive oxygen species (ROS) triggered by ox-LDL. As a result, the presence of tofacitinib reduces ox-LDL-induced cytotoxicity and improves endothelial viability. Mechanistically, we demonstrate that tofacitinib suppresses ox-LDL-mediated activation of NF-κB inhibitor α (IκB-α), accumulation of nuclear p65 and activation of nuclear factor κB (NF-κB) promoter, indicating that tofacitinib inhibits NF-κB activation. Collectively, our data support that tofacitinib possesses a novel protective function in endothelial cells, implying that tofacitinib could have the therapeutic potential to modulate inflammation in cardiovascular diseases.

Inflammation induces endothelial‐to‐mesenchymal transition and promotes vascular calcification through downregulation of BMPR2

Endothelial‐to‐mesenchymal transition (EndMT) has been unveiled as a common cause for a multitude of human pathologies, including cancer and cardiovascular disease. Vascular calcification is a risk factor for ischemic vascular disorders and slowing calcification may reduce mortality in affected patients. The absence of early biomarkers hampers the identification of patients at risk. EndMT and vascular calcification are induced upon cooperation between distinct stimuli, including inflammatory cytokines and transforming growth factor beta (TGF‐β) family members. However, how these signaling pathways interplay to promote cell differentiation and eventually vascular calcification is not well understood. Using in vitro and ex vivo analysis in animal models and patient‐derived tissues, we have identified that the pro‐inflammatory cytokines tumor necrosis factor alpha (TNF‐α) and interleukin‐1 beta (IL‐1β) induce EndMT in human primary aortic endothelial cells, thereby sensitizing them for BMP‐9‐induced osteogenic differentiation. Downregulation of the BMP type II receptor BMPR2 is a key event in this process. Rather than compromising BMP canonical signal transduction, loss of BMPR2 results in decreased JNK signaling in ECs, thus enhancing BMP‐9‐induced mineralization. Altogether, our results point at the BMPR2–JNK signaling axis as a key pathway regulating inflammation‐induced EndMT and contributing to calcification. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Downregulation of GATA6 in mTOR-inhibited human aortic endothelial cells: effects on TNF-α-induced VCAM-1 expression and monocytic cell adhesion.

Increased expression of vascular cell adhesion molecule 1 (VCAM-1) on the aortic endothelium is an early marker of atherogenesis, promoted in part by elevated levels of inflammatory cytokines such as TNF-α. Mammalian target of rapamycin (mTOR) is a ubiquitous signaling molecule that has been considered to contribute to diverse cellular processes through mTOR complex 1 (mTORC1) or complex 2 (mTORC2). This study aimed to elucidate the role of mTOR signaling in TNF-α-induced VCAM-1 expression by the arterial endothelium. Primary human aortic endothelial cells (HAECs) were treated with low-dose (0.1 ng/ml) TNF-α, and VCAM-1 expression was measured by real-time quantitative PCR, Western blot analysis, and flow cytometry. Inhibition of mTOR through siRNA-mediated depletion or treatment with chemical inhibitors rapamycin or torin 1 suppressed VCAM1 transcription, which translated to inhibition of VCAM-1 surface expression by HAECs and concomitant decreased adhesion of monocytes. A promoter luciferase assay and chromatin immunoprecipitation indicated that mTOR regulated VCAM1 transcription through a mechanism involving transcription factor GATA6. Activation of PKC-α and an increase in miR-200a-3p expression, caused by mTOR inhibition but not disruption of mTORC1 or mTORC2 singly or together, decreased TNF-α-induced GATA6 expression and its enrichment at the VCAM1 promoter. In conclusion, mTOR inhibition activates PKC-α independently of disruption of mTORC1 and/or mTORC2, which challenges the conventional wisdom regarding mTOR signaling. Moreover, mTOR signals through transcriptional and posttranscriptional mechanisms to elicit maximal cytokine-induced endothelial inflammation that precedes atherosclerosis. NEW & NOTEWORTHY Both mammalian target of rapamycin (mTOR) complex 1 (mTORC1) and mTORC2 contribute to PKC-α activation in the human aortic endothelium. Inhibition of mTOR is not equivalent to disruption of mTORC1 and/or mTORC2 in affecting human aortic endothelial cell signaling. Specifically, inhibition of mTOR causes PKC-α activation and miR-200a-3p upregulation, which independently suppresses TNF-α-induced transcription factor GATA6 expression and subsequently inhibits VCAM-1 expression and monocytic cell adhesion onto the aortic endothelium.

Vildagliptin protects endothelial cells against high glucose-induced damage.

Hyperglycemia or high blood sugar is one of the major pathological characteristics of diabetes. The endothelium is the inner layer of the vascular wall and is directly exposed to various stimuli in blood vessels. As a characteristic of diabetes, chronic high glucose is known to be harmful to endothelial cells. In this study, we found that vildagliptin, an available type 2 diabetes agent, protects primary human aortic endothelial cells (HAECs) against damage induced by high glucose. Our data indicate that vildagliptin improves the decrease in endothelial viability and reduces the release of lactate dehydrogenase (LDH) induced by high glucose. Vildagliptin potently suppresses high glucose-induced generation of reactive oxygen species (ROS) and production of vascular inflammatory factors including tumor necrosis factor-α (TNF-α), interleukin-8 (IL-8), intercellular cell adhesion molecule-1 (ICAM-1) and monocyte chemotactic protein 1 (MCP-1). Moreover, vildagliptin suppresses adhesion of monocytes to endothelial cells and induction of toll-like receptor 4 (TLR-4) in HAECs caused by high glucose. Mechanistically, we found that the cellular protective effects mediated by vildagliptin involve suppression of nuclear factor-kappa B (NF-κB) nuclear signals. Collectively, our data indicate that vildagliptin possesses a protective function in vascular cells.

Very small superparamagnetic iron oxide nanoparticles: Long-term fate and metabolic processing in atherosclerotic mice

We investigated the biotransformation of very small superparamagnetic iron oxide nanoparticles (VSOP) in atherosclerotic LDLR−/− mice. Transmission electron microscopy revealed an uptake of VSOP not only by macrophages but also by endothelial cells in liver, spleen, and atherosclerotic lesions and their accumulation in the lysosomal compartment. Using magnetic particle spectroscopy (MPS), we show that the majority of VSOP's superparamagnetic iron was degraded within 28 days. MPS spectrum shape indicated changes in the magnetic properties of VSOP during the biodegradation process. Experiments with primary murine bone marrow derived macrophages, primary murine liver sinusoidal endothelial cells, and primary human aortic endothelial cells demonstrated that loading with VSOP induced a differential response of cellular iron homeostasis mechanisms with increased levels of ferritin and iron transport proteins in macrophages and increased levels of ferritin in endothelial cells.

The histone methyltransferase SETD1A regulates thrombomodulin transcription in vascular endothelial cells

Thrombomodulin (TM, encoded by the THBD gene) expressed in vascular endothelial cells plays pivotal roles maintaining the equilibrium of coagulation and anti-coagulation. TM levels can be regulated at the transcriptional level although the epigenetic mechanism is underexplored. Here we report that transcriptional activation of TM in both immortalized vascular endothelial cells (EAhy926) and primary human aortic endothelial cells (HAEC) by all-trans retinoic acid (RA) paralleled accumulation of trimethylated histone H3K4, a prominent marker for active chromatin, surrounding the THBD promoter. RA treatment up-regulated the expression of SETD1A (SET1), a dedicated H3K4 methyltransferase, and augmented SETD1A occupancies on the THBD promoter. Further analysis revealed that the sequence-specific transcription factor Kruppel-like factor 4 (KLF4) interacted with and recruited SETD1A to the THBD promoter. Interestingly, SETD1A was recruited to the KLF4 promoter by retinoic acid receptor (RAR) and mediated the up-regulation of KLF4 expression by RA stimulation. In summary, our data illustrate a previously unrecognized pathway in which SETD1A contributes to RA-induced TM expression in vascular endothelial cells by modulating the activity and expression of KLF4.

Cell-Specific Functions of ADAM17 Regulate the Progression of Thoracic Aortic Aneurysm.

ADAM17 (a disintegrin and metalloproteinase-17) is a membrane-bound enzyme that regulates bioavailability of multiple transmembrane proteins by proteolytic processing. ADAM17 has been linked to several pathologies, but its role in thoracic aortic aneurysm (TAA) has not been determined. The objective of this study was to explore the cell-specific functions of vascular ADAM17 in the pathogenesis and progression of TAA. In aneurysmal thoracic aorta from patients, ADAM17 was increased in tunica media and intima. To determine the function of ADAM17 in the major cells types within these regions, we generated mice lacking ADAM17 in smooth muscle cells (SMC; Adam17f/f/Sm22Cre/+ ) or endothelial cells (Adam17f/f/Tie2Cre/+ ). ADAM17 deficiency in either cell type was sufficient to suppress TAA dilation markedly and adverse remodeling in males and females (in vivo) although through different mechanisms. ADAM17 deficiency in SMCs prevented the contractile-to-synthetic phenotypic switching in these cells after TAA induction, preventing perivascular fibrosis, inflammation, and adverse aortic remodeling. Loss of ADAM17 in endothelial cells protected the integrity of the intimal barrier by preserving the adherens junction (vascular endothelial-cadherin) and tight junctions (junctional adhesion molecule-A and claudin). In vitro studies on primary mouse thoracic SMCs and human primary aortic SMCs and endothelial cells (±ADAM17 small interfering RNA) confirmed the cell-specific functions of ADAM17 and demonstrated the cross-species validity of these findings. To determine the impact of ADAM17 inhibition in treating TAA, we used an ADAM17-selective inhibitor (PF-548) before or 3 days after TAA induction. In both cases, ADAM17 inhibition prevented progression of aneurysmal growth. We have identified distinct cell-specific functions of ADAM17 in TAA progression, promoting pathological remodeling of SMC and impairing integrity of the intimal endothelial cell barrier. The dual impact of ADAM17 deficiency (or inhibition) in protecting 2 major cell types in the aortic wall highlights the unique position of this proteinase as a critical treatment target for TAA.

Abstract 667: Endothelial Cell “Memory”: Rapid Recall of Chemokines After Prior Exposure to Inflammatory Stimuli

Background: Surprisingly little has been studied on the capacity of cytokine-primed endothelial cells (EC) to respond upon secondary challenge. The principal hypothesis is that EC store and rapidly recall chemokines after upon secondary challenge. Methods: Confluent primary human aortic (AEC), dermal microvascular (DMVEC), umbilical vein (UVEC), and renal glomerular (RGEC) endothelial cells were pre-exposed to TNFα or IL-1β (10ng/mL, 18hr), allowed to rest (4-24hr), and re-challenged with the secretagogues PMA or histamine. The repertoire of rapidly recalled soluble mediators was determined by ELISA, and cell surface P-selectin by cell-based ELISA. Total P-selectin content was measured by Western Blot. Results: Priming with TNFα or IL-1β overnight increased IL-8 secretion by all EC. 4hr after removal of TNFα or IL-1β, IL-8 was still in all supernatants. After 7hr rest, IL-8 was detectable from RGEC but undetectable in other EC. After 24hr, IL-8 was undetectable in the supernatants from all EC. Secondary challenge with secretagogues 24hr after removal of TNFα or IL-1β stimulated rapid secretion of IL-8, but not from unprimed endothelium. P-selectin was rapidly externalized at the cell surface of unprimed cells after 20min exposure to PMA or 10min Histamine. TNFα-primed EC exhibited significantly lower P-selectin induction, mirrored by profoundly reduced total intracellular P-selectin expression. mRNA expression of LAMP3 (CD63, a tetraspanin critical for P-selectin sorting to Weibel-Palade bodies) was highest in microvascular EC and lowest in larger vessel EC. LAMP3 might be important for controlling WPb content as well as durability of exocytosis upon type 1 activation and sorting of newly synthesized type II mediators to WPb for rapid recall. Conclusions: The data confirm that prior exposure of EC to inflammatory stimuli evokes storage of IL-8 that can be rapidly secreted upon exposure to a second stimulus. Moreover, constitutive expression of P-selectin is suppressed by TNFα exposure, but not IL-1β. Thus, EC exhibit a chronic inflammatory phenotype after cytokines have been encountered and removed, due to storage of chemokines within Weibel-Palade bodies or other granules.

Transcriptomic profiling of mitochondrial dysfunction induced apoptosis in accelerated cardiovascular disease

IntroductionVascular calcification is a significant contributor to accelerated cardiovascular disease and mortality in patients with chronic kidney disease (CKD). We previously reported that heat shock protein 70 (HSP70) induction can inhibit human aortic smooth muscle cell (HA‐SMC) calcification in CKD. In addition, our data indicated mitochondrial complexes II, IV, NADH cytochrome c reductase (NCCR), succinate cytochrome c reductase (SCCR), and cytochrome c oxidase (CCO) activities were preserved by HSP70 induction leading to reduced apoptosis. Apoptosis occurs with either receptor mediated extrinsic pathway or the mitochondrial‐dependent intrinsic pathway. The molecular mechanisms of HSP70 vasculo‐protective effects involving mitochondrial dysfunction induced apoptosis are currently unknown.HypothesisThe goal of the present study was to investigate the transcriptomic profile of genes involved in mitochondrial function and vasculo‐protective mechanisms of HSPs in apoptosis induced vascular calcification.MethodsHuman arteries were collected from healthy and CKD patients. Human aortic endothelial cells (HAECs) was treated in calcification medium (CM: 5mM β‐glycerolphosphate and 5mM CaCl2) in time‐course experiments (0–48 hours), in vitro. Total RNA from human arteries and HAECs was extracted using the Nucleospin RNA isolation kit. cDNA was synthesized and fragmented using SMART‐seq2 and Nextera XT (Illumina), respectively to generate libraries for sequencing on Hi‐seq 2000 (Illumina). Five million single‐ended raw reads from each sample were mapped to the human reference genome consortium GRCh38 by Burrows‐Wheeler Aligner (BWA). Gene analysis were performed by the combinations of fold‐changes on log 2 ratio, and p value &lt; 0.05.ResultsIn healthy human arteries, we found that HSPA5 (fold change, FC, 3.85), HSPA1 (FC=3.64), and HSPA9 (FC=3.85) expression was preserved and Bcl2 associated Athanogene 1 (BAG1) (FC=7.44) was upregulated. However, mitochondrial fusion regulation genes MFN1 (FC=1.83) and OPA1 (FC=2.33) were down‐regulated in CKD arteries together with downregulation of downstream anti‐apoptotic gene Bcl2 (FC=4.52) and up‐regulation of pro‐apoptotic gene BAX (FC=2.77) and P53 (FC=5.35). Lastly, caspase 3 (FC=2.6) and cytochrome c (FC=2.29) expression were significantly increased in CKD arteries compared to control. In the primary HAECs, our data indicates that BAG1 was significantly increased at 6 hours prior to upregulation of Bcl2 at 12 hours in HAECs after CM treatment. BAG1 is a co‐chaperone for heat‐shock protein 70 (HSP70) that coordinates signals for cell growth in response to stress. Stress respondent genes, DNAJB6 (HSP40) and HSPA5 (HSP70 member5) was significantly increased at 24 hours and 12 hours respectively in CM‐treated HAECs.ConclusionComplex differential gene regulation involving preservation of mitochondrial function and cell apoptosis may be involved in the pathogenesis of accelerated vascular calcification. Decreased HSPs in CKD arteries may play the key role in mitochondrial dysfunction induced endothelial cells' apoptosis, which further leading to vascular calcification. Our findings may serve to inform the rational development of therapeutic strategies for vascular calcification involving therapeutic targeting of HSPs.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Thioredoxin-interacting protein promotes high-glucose-induced macrovascular endothelial dysfunction

Thioredoxin-interacting protein (TXNIP) emerges as a central regulator for glucose homeostasis, which goes awry in diabetic subjects. Endothelial dysfunction is considered the earliest detectable stage of cardiovascular disease (CVD), a major complication of diabetes. Here, we hypothesize that TXNIP may promote endothelial dysfunction seen in Type 1 diabetes mellitus (T1D). Using a T1D-like rat model, we found that diabetic rats showed significantly higher TXNIP mRNA and protein levels in peripheral blood, compared to their non-diabetic counterparts. Those changes were accompanied by decreased production of nitric oxide (NO) and vascular endothelial growth factor (VEGF), concurrent with increased expression of reactive oxygen species (ROS) and vascular cell adhesion molecule 1 (VCAM-1) in the aortic endothelium. In addition, TXNIP overexpression in primary human aortic endothelial cells (HAECs) induced by either high glucose or overexpression of carbohydrate response element binding protein (ChREBP), a major transcriptional activator of TXNIP, promoted early apoptosis and impaired NO bioactivity. The correlation between TXNIP expression levels and endothelial dysfunction suggests that TXNIP may be a potential biomarker for vascular complications in T1D patients.

Human aortic endothelial cells respond to shear flow in well-plate microfluidic devices.

Although chronic progressive cardiovascular diseases such as atherosclerosis are often challenging to fully model in vitro, it has been shown that certain in vitro methods can effectively evaluate some aspects of disease progression. This has been demonstrated in in vitro and in vivo studies of endothelial cells that have illustrated the effects of nitric oxide (NO) production, filamentous actin (F-actin) formation, and cell and actin angle alignment on vascular function and homeostasis. Systems utilising shear flow have been established, in order to create a physiologically relevant environment for cells that require shear flow for homeostasis. Here, we investigated the use of a well-plate microfluidic system and associated devices (0-20dyn/cm²) to demonstrate applied shear effects on primary Human Aortic Endothelial Cells (HAECs). Changes in cell and actin alignment in the direction of flow, real-time production of NO and gross cell membrane shape changes in response to physiological shear flow were observed. These commercial systems have a range of potential applications, including within the consumer and pharmaceutical industries, thereby reducing the dependency on animal testing for regulatory safety assessments.

Abstract 078: Ox-LDL Leads to Increases of Endothelial Lysine Acetylation Linking Metabolic Memory to Diabetic Vascular Dysfunction

Around 70% of type 2 diabetic (T2DM) patients will die due to sustained vascular complications, including hypertension. Evidence from clinical trials has shown that even under proper glycemic control, diabetic patients exhibit persistent vascular dysfunction. This phenomenon referred as “metabolic memory” (MM) is a major problem in treating diabetic patients. A current gap in knowledge of how MM contributes to diabetic vascular dysfunction needs to be addressed. Elevated serum ox-LDL levels are frequently found in T2DM. Whether ox-LDL is linked with MM remains undefined. We hypothesize that transient ox-LDL exposure increases endothelial lysine acetylation which in turn may contribute to persistent vascular dysfunction. Using a model of MM in cultured primary human aortic endothelial cells (HAEC), we found that 16h stimulation with ox-LDL (40 μg/mL) significantly increased lysine acetylation in the total cellular proteins (2.2 fold of increase vs unstimulated cells, p&lt;0.01, n=4). Moreover, ox-LDL increased vascular cellular adhesion molecule-1 protein (VCAM-1, 1.8-fold increase, p&lt;0.05, n=3), and superoxide production detected by dihydroethidium (2.5-fold increase, p&lt;0.001, n=4) in comparison to unstimulated HAEC. When HAEC stimulated with ox-LDL were returned to a regular medium for 48h, VCAM-1 expression markedly decreased, whereas superoxide and lysine acetylation levels remained unchanged, suggesting that transient ox-LDL exposure generates MM. To determine whether increased endothelial lysine acetylation correlates with vascular dysfunction, we assessed endothelium-depend relaxation through concentration-dependent responses to acetylcholine using wire myograph in freshly isolated mice superior mesenteric arteries in organ culture. Vasorelaxation was impaired in vessels incubated with 40 μg/mL ox-LDL for 8h (66.3 ± 3.4 vs 90.1 ± 2.2 % control, p&lt;0.05, n=4). This impairment was ameliorated when vessels exposed to ox-LDL were returned to regular medium for 12h (75.5 ± 2.0 vs 66.3 ± 2.4 %, p&lt;0.01, n=4). These results indicate that transient ox-LDL causes persistent endothelial dysfunction and augmented endothelial lysine acetylation which may be an epigenetic modification driving MM and diabetic vascular dysfunction.

Transcriptional networks specifying homeostatic and inflammatory programs of gene expression in human aortic endothelial cells.

Endothelial cells (ECs) are critical determinants of vascular homeostasis and inflammation, but transcriptional mechanisms specifying their identities and functional states remain poorly understood. Here, we report a genome-wide assessment of regulatory landscapes of primary human aortic endothelial cells (HAECs) under basal and activated conditions, enabling inference of transcription factor networks that direct homeostatic and pro-inflammatory programs. We demonstrate that 43% of detected enhancers are EC-specific and contain SNPs associated to cardiovascular disease and hypertension. We provide evidence that AP1, ETS, and GATA transcription factors play key roles in HAEC transcription by co-binding enhancers associated with EC-specific genes. We further demonstrate that exposure of HAECs to oxidized phospholipids or pro-inflammatory cytokines results in signal-specific alterations in enhancer landscapes and associate with coordinated binding of CEBPD, IRF1, and NFκB. Collectively, these findings identify cis-regulatory elements and corresponding trans-acting factors that contribute to EC identity and their specific responses to pro-inflammatory stimuli.