Monocyte-endothelial Cell Adhesion Research Articles

Hematopoietic Growth Factors Regulate the Entry of Monocytes into the Adult Brain via Chemokine Receptor CCR5.

Monocytes are circulating macrophage precursors generated from bone marrow hematopoietic stem cells. In adults, monocytes continuously replenish cerebral border-associated macrophages under physiological conditions. Monocytes also rapidly infiltrate the brain in pathological settings. The mechanisms of recruiting monocyte-derived macrophages into the brain under pathological conditions have been extensively studied. However, it remains unclear how monocytes enter the brain to renew border-associated macrophages under physiological conditions. Using both in vitro and in vivo approaches, this study reveals that a combination of two hematopoietic growth factors, stem cell factor (SCF) and granulocyte colony-stimulating factor (G-CSF), complementarily and synergistically enhances the adhesion of monocytes to cerebral endothelial cells in a dose-dependent manner. Cysteine-cysteine chemokine receptor 5 (CCR5) in brain endothelial cells, but not the cell adhesion molecules mediating neuroinflammation-related infiltration of monocyte-derived macrophages, modulates SCF+G-CSF-enhanced monocyte-endothelial cell adhesion. Blocking CCR5 or genetically deleting CCR5 reduces monocyte-endothelial cell adhesion induced by SCF+G-CSF. The SCF+G-CSF-enhanced recruitment of bone marrow-derived monocytes/macrophages into the cerebral perivascular space is also reduced in adult CCR5 knockout mice. This study demonstrates the role of SCF and G-CSF in regulating the entry of monocytes into the adult brain to replenish perivascular macrophages.

Genome-Wide Search Links Senescence-Associated Secretory Proteins With Susceptibility for Coronary Artery Disease in Mouse and Human.

Advanced age is an independent risk factor for coronary artery disease (CAD), the leading global cause of mortality. Senescent vascular cells in the atherosclerotic plaques exhibit senescence-associated secretory phenotype (SASP). How SASP contributes to atherosclerosis and CAD, however, remains unclear. Here, we integrated RNA-array datasets of senescent human coronary arterial endothelial cells (HCAECs) and aortic smooth muscle cells (HASMCs) as well as genome-wide association data for CAD. We identified 26 genes from HCAECs and 6 genes from HASMCs related to SASP and CAD in both in-house and published datasets. Of which, Cystatin C (CST3), a CAD susceptibility gene, was found to be expressed in both HCAECs and HASMCs, thus, it was prioritized for further investigation. We demonstrated it was significantly elevated in senescent vascular cells, aged arteries, and early atherosclerosis. In vitro experiments showed that CST3 enhances the monocyte-endothelial cell adhesion. Additionally, ligand-receptor pairing analyses revealed two important pathways, COL4A1-ITGA1 and LPL-LRP1 pathways, linked to the critical processes in the development of atherosclerosis, including cell adhesion, inflammation response, extracellular matrix organization, and lipid metabolism. We further demonstrated a reduced monocyte-endothelial cell adhesion following the knockdown of COL4A1 or ITGA1 and a significantly increased expression of COL4A1, ITGA1, and LPL in arterial intima of aged mice and ApoE-/- mice. Our findings demonstrate that vascular cell-derived SASP proteins increase the CAD susceptibility and identify CST3 functionally contributing to atherosclerosis.

Tyrosol attenuates lipopolysaccharide‑induced inflammation in HUVECs to promote vascular health against atherosclerosis challenge.

The role of vascular endothelial cells in acute and chronic vascular inflammatory response has long been recognized. Therefore, persistent vascular inflammation may lead to endothelial dysfunction, thus resulting in the release of pro-inflammatory cytokines and the expression of adhesion molecules, which in turn promote monocyte/macrophage adhesion. Inflammation serves a key role in the development of vascular diseases, such as atherosclerosis. Tyrosol is a natural polyphenolic compound with diverse biological functions, found in large quantities in olive oil or in Rhodiola rosea. The current study aimed to investigate the regulatory in vitro effects of tyrosol on pro-inflammatory phenotypes using Cell Counting Kit-8, cell adhesion assay, wound healing, ELISA, western blotting, duel-luciferase, reverse transcription-quantitative PCR and flow cytometry. The results showed that tyrosol significantly inhibited the adhesion of THP-1 human umbilical vein endothelial cells, reduced lipopolysaccharide-induced cell migration and decreased the release of pro-inflammatory factors and the expression levels of adhesion-related molecules, such as TNF-α, monocyte chemotactic protein-1, intercellular adhesion molecule-1 and vascular cell adhesion molecule-1. Previous studies indicate that NF-κB could serve a pivotal role in initiating the inflammatory responses of endothelial cells and particularly in regulating the expression of adhesion molecules and inflammatory factors. The results of the current study demonstrated that tyrosol was associated with decreased expression of adhesion molecules and monocyte-endothelial cell adhesion, thus suggesting that tyrosol could be a novel pharmacological approach for treating inflammatory vascular diseases.

Acetylcholine suppresses LPS-induced endothelial cell activation by inhibiting the MAPK and NF-κB pathways.

Endothelial cell activation plays a critical role in leukocyte recruitment during inflammation and infection. We previously found that cholinergic stimulation (via vagus nerve stimulation) attenuates vascular endothelial impairment and reduces the inflammatory profile in ovariectomized rats. However, the specific molecular mechanism is unclear. This study was designed to explore the effects and molecular mechanisms of cholinergic agonists (acetylcholine [ACh]) on lipopolysaccharide (LPS)-induced endothelial cell activation in vitro. Human umbilical vein endothelial cells (HUVECs) were treated with different concentrations of LPS (10/100/1000ng/mL) to activate endothelial cells. HUVECs were untreated, treated with ACh (10-5 M) alone, treated with 100ng/mL LPS alone, or treated with different concentrations of ACh (10-9/10-8/10-7/10-6/10-5 M) before LPS stimulation. HUVECs were also pre-treated with 10-6 M ACh with or without mecamylamine (an nAChR blocker) (10μΜ) and methyllycaconitine (a specific α7 nAChR blocker) (10μΜ) and incubated with or without LPS. ELISA, western blotting, cell immunofluorescence, and cell adhesion assays were used to examine inflammatory cytokine production, adhesion molecule expression, monocyte-endothelial cell adhesion and activation of the MAPK/NF-κB pathways. LPS (at 10ng/mL, 100ng/mL and 1,000ng/mL) increased VCAM-1 expression in HUVECs in a dose-dependent manner (with no significant difference between LPS at 100ng/mL and 1,000ng/mL). ACh (10-9 M-10-5 M) blocked adhesion molecule expression (VCAM-1, ICAM-1, and E-selectin) and inflammatory cytokine production (TNF-α, IL-6, MCP-1, IL-8) in response to LPS in a dose-dependent manner (with no significant difference between 10-5 and 10-6 M Ach). LPS was also shown to significantly enhance monocyte-endothelial cell adhesion, which was largely abrogated by treatment with ACh (10-6M). VCAM-1 expression was blocked by mecamylamine rather than methyllycaconitine. Lastly, ACh (10-6 M) significantly reduced LPS-induced phosphorylation of NF-κB/p65, IκBα, ERK, JNK and p38MAPK in HUVECs, which was blocked by mecamylamine. ACh protects against LPS-induced endothelial cell activation by inhibiting the MAPK and NF-κB pathways, which are mediated by nAChR, rather than α7 nAChR. Our results may provide novel insight into the anti-inflammatory effects and mechanisms of ACh.

The proatherosclerotic function of BCAT1 in atherosclerosis development of aged-apolipoprotein E-deficient mice

Atherosclerosis (AS) is an inflammatory vascular disease. Branched-chain amino acid transaminase 1 (BCAT1) has been implicated in inflammatory diseases, while its role in AS is unclear yet. In ApoE−/− mice with a high fat diet (HDF), BCAT1 was highly up-regulated and more pronounced in aged than in young ApoE−/− mice, which was abundantly expressed in macrophages located in AS lesions. The function of BCAT1 in AS was explored using lentivirus-mediated BCAT1 overexpression. ApoE−/− mice fed a HFD with BCAT1 overexpression exhibited the worsening lipid deposition and pathological injury of aortic tissues, accompanied by aggravated hyperlipidemia as proved by increased serum triglyceride, total cholesterol, and low-density lipoprotein-cholesterol levels. Immunohistochemical staining of vascular cell adhesion molecule-1 (VCAM-1), monocyte chemoattractant protein-1 (MCP-1), and CD68 in the aortic root plaque suggested that BCAT1 overexpression could induce monocyte-endothelial cell adhesion and macrophages infiltration, thereby contributing inflammatory response by promoting TNF-α, IL-6, and IL-1β expression. Further, in vivo experiments, lipid accumulation, and inflammatory response induced by oxidized-LDL in RAW267.4 cells were also intensified or alleviated by BCAT1 overexpression or knockdown. Finally, BCAT1 overexpression aggravated AS development. These adverse effects of BCAT1 on hyperlipidemia, lipid accumulation, foaming cell formation, and inflammation suggested that the modulation of BCAT1 might be a potential approach to prevent AS disease.

7-Methoxyisoflavone suppresses vascular endothelial inflammation by inhibiting the expression of endothelial adhesion molecules

Endothelial cells (ECs) are vital regulators of inflammatory processes, there is the potential for inhibition of EC inflammation to be a therapeutic target in chronic inflammatory diseases. This study aimed to investigate the effect of 7-methoxyisoflavone (7-Mif) on endothelial inflammation. Our results showed that 7-Mif have no cytotoxicity on HUVECs. Pretreatment with 5 μM, 10 μM and 50 μM 7-Mif significantly reduced IL-1β-induced ICAM-1 (28.1% ± 4.1%, 25.9 ± 2.5% and 32.0% ± 3.2%, respectively) and VCAM-1 (48.0% ± 5.6%, 40.1 ± 3.1% and 39.6% ± 3.1%, respectively) mRNA expression. And pretreatment with 10 μM and 50 μM 7-Mif significantly reduced IL-1β-induced ICAM-1 (45.1% ± 4.4% and 33.6 ± 4.4%, respectively) and VCAM-1 (53.0% ± 3.7% and 53.7 ± 5.1%, respectively) protein levels. Furthermore, pretreatment with 50 μM 7-Mif inhibited monocyte-endothelial cell adhesion (50.2% ± 4.2%). Mechanistically, our results showed that 7-Mif reversed IL-1β-induced NF-κB activation and p65 translocation to the nucleus, therefore inhibiting endothelial cell inflammation. In addition, we confirmed that 7-Mif 10 mg/kg and 20 mg/kg reduced LPS-induced ICAM-1 (47.3% ± 1.3% and 39.0% ± 3.2%, respectively) and VCAM-1 (56.5 ± 2.8% and 47.8 ± 4.3%, respectively) expression and attenuated inflammatory injury in mice. In conclusion, we showed the inhibitory effect of 7-Mif on endothelial inflammation by suppressing the expression of endothelial adhesion molecules and monocyte adhesion. Our data illustrated that 7-Mif could positively regulate the process of endothelial inflammation.

EPSTI1 promotes monocyte adhesion to endothelial cells in vitro via upregulating VCAM-1 and ICAM-1 expression.

Atherosclerosis is a chronic inflammatory disease of arterial wall, and circulating monocyte adhesion to endothelial cells is a crucial step in the pathogenesis of atherosclerosis. Epithelial-stromal interaction 1 (EPSTI1) is a novel gene, which is dramatically induced by epithelial-stromal interaction in human breast cancer. EPSTI1 expression is not only restricted to the breast but also in other normal tissues. In this study we investigated the role of EPSTI1 in monocyte-endothelial cell adhesion and its expression pattern in atherosclerotic plaques. We showed that EPSTI1 was dramatically upregulated in human and mouse atherosclerotic plaques when compared with normal arteries. In addition, the expression of EPSTI1 in endothelial cells of human and mouse atherosclerotic plaques is significantly higher than that of the normal arteries. Furthermore, we demonstrated that EPSTI1 promoted human monocytic THP-1 cell adhesion to human umbilical vein endothelial cells (HUVECs) via upregulating VCAM-1 and ICAM-1 expression in HUVECs. Treatment with LPS (100, 500, 1000 ng/mL) induced EPSTI1 expression in HUVECs at both mRNA and protein levels in a dose- and time-dependent manner. Knockdown of EPSTI1 significantly inhibited LPS-induced monocyte-endothelial cell adhesion via downregulation of VCAM-1 and ICAM-1. Moreover, we revealed that LPS induced EPSTI1 expression through p65 nuclear translocation. Thus, we conclude that EPSTI1 promotes THP-1 cell adhesion to endothelial cells by upregulating VCAM-1 and ICAM-1 expression, implying its potential role in the development of atherosclerosis.

Interleukin-1β enhances cell adhesion in human endothelial cells via microRNA-1914–5p suppression

Atherosclerosis is a chronic inflammatory disease and the underlying cause of most cardiovascular diseases. Interleukin (IL)-1β facilitates early atherogenic lesion formation by increasing monocyte adhesion to endothelial cells via upregulation of adhesion molecules, including intercellular adhesion molecule-1 (ICAM-1). MicroRNAs (miRNAs) have been shown to be associated with inflammatory conditions in the vascular system. The expression of circulating miR-1914–5p is reportedly downregulated in patients with cardiovascular diseases. However, the role of miR-1914–5p downregulation in IL-1β–induced endothelial cell dysfunction and the effect of miR-1914–5p on lesion formation remain unclear. Therefore, we investigated whether miR-1914–5p is associated with monocyte adhesion in human endothelial cells. IL-1β decreased miR-1914–5p expression in EA.hy926 cells. In addition, miR-1914–5p depletion enhanced ICAM-1 expression and monocyte adhesion in EA.hy926 cells. Moreover, miR-1914–5p mimic suppressed monocyte adhesion and ICAM-1 expression induced by IL-1β in endothelial cells. These results suggest that suppression of miR-1914–5p expression by IL-1β may be an important regulator in mediating monocyte adhesion in endothelial cells. Further investigation of miR-1914–5p may lead to the development of novel therapeutic strategies for atherosclerosis.

Role of Low-Density Lipoprotein in Early Vascular Aging Associated With Systemic Lupus Erythematosus.

Patients with systemic lupus erythematosus (SLE) often have atherosclerotic complications at a young age but normal low-density lipoprotein (LDL) levels. This study was undertaken to investigate the role of LDL composition in promoting early vascular aging in SLE patients. Plasma LDL from 45 SLE patients (SLE-LDL) and from 37 normal healthy controls (N-LDL) was chromatographically divided into 5 subfractions (L1-L5), and the subfraction composition was analyzed. Correlations between subfraction levels and signs of early vascular aging were assessed. Mechanisms of lipid-mediated endothelial dysfunction were explored using in vitro assays and experiments in apoE-/- mice. The L5 percentage was increased 3.4 times in the plasma of SLE patients compared with normal controls. This increased percentage of SLE-L5 was positively correlated with the mean blood pressure (r = 0.27, P = 0.04), carotid intima-media thickness (IMT) (right carotid IMT, r = 0.4, P = 0.004; left carotid IMT, r = 0.36, P = 0.01), pulse wave velocity (r = 0.29, P = 0.04), and blood levels of CD16+ monocytes (r = 0.35, P = 0.004) and CX3CL1 cytokines (r = 0.43, P < 0.001) in SLE patients. Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry analysis revealed that plasma levels of lysophosphatidylcholine (LPC) and platelet-activating factor (PAF) were increased in SLE-LDL and in the SLE-L5 plasma subfraction. Injecting SLE-LDL, SLE-L5, or LPC into young, male apoE-/- mice caused increases in plasma CX3CL1 levels, aortic fatty-streak areas, aortic vascular aging, and macrophage infiltration into the aortic wall, whereas injection of N-LDL or SLE-L1 had negligible effects (n = 3-8 mice per group). In vitro, SLE-L5 lipid extracts induced increases in CX3CR1 and CD16 expression in human monocytes; synthetic PAF and LPC had similar effects. Furthermore, lipid extracts of SLE-LDL and SLE-L5 induced the expression of CX3CL1 and enhanced monocyte-endothelial cell adhesion in assays with bovine aortic endothelial cells. An increase in plasma L5 levels, not total LDL concentration, may promote early vascular aging in SLE patients, leading to premature atherosclerosis.

Involvement of Senescence and Mitochondrial Fission in Endothelial Cell Pro-Inflammatory Phenotype Induced by Angiotensin II.

Angiotensin II (AngII) has a crucial role in cardiovascular pathologies, including endothelial inflammation and premature vascular aging. However, the precise molecular mechanism underlying aging-related endothelial inflammation induced by AngII remains elusive. Here, we have tested a hypothesis in cultured rat aortic endothelial cells (ECs) that the removal of AngII-induced senescent cells, preservation of proteostasis, or inhibition of mitochondrial fission attenuates the pro-inflammatory EC phenotype. AngII stimulation in ECs resulted in cellular senescence assessed by senescence-associated β galactosidase activity. The number of β galactosidase-positive ECs induced by AngII was attenuated by treatment with a senolytic drug ABT737 or the chemical chaperone 4-phenylbutyrate. Monocyte adhesion assay revealed that the pro-inflammatory phenotype in ECs induced by AngII was alleviated by these treatments. AngII stimulation also increased mitochondrial fission in ECs, which was mitigated by mitochondrial division inhibitor-1. Pretreatment with mitochondrial division inhibitor-1 attenuated AngII-induced senescence and monocyte adhesion in ECs. These findings suggest that mitochondrial fission and endoplasmic reticulum stress have causative roles in endothelial senescence-associated inflammatory phenotype induced by AngII exposure, thus providing potential therapeutic targets in age-related cardiovascular diseases.

(−)-Epicatechin metabolites promote vascular health through epigenetic reprogramming of endothelial-immune cell signaling and reversing systemic low-grade inflammation

Ingestion of (−)-epicatechin flavanols reverses endothelial dysfunction by increasing flow mediated dilation and by reducing vascular inflammation and oxidative stress, monocyte-endothelial cell adhesion and transendothelial monocyte migration in vitro and in vivo. This involves multiple changes in gene expression and epigenetic DNA methylation by poorly understood mechanisms. By in silico docking and molecular modeling we demonstrate favorable binding of different glucuronidated, sulfated or methylated (−)-epicatechin metabolites to different DNA methyltransferases (DNMT1/DNMT3A). In favor of this model, genome-wide DNA methylation profiling of endothelial cells treated with TNF and different (−)-epicatechin metabolites revealed specific DNA methylation changes in gene networks controlling cell adhesion-extravasation endothelial hyperpermeability as well as gamma-aminobutyric acid, renin-angiotensin and nitric oxide hypertension pathways. Remarkably, blood epigenetic profiles of an 8 weeks intervention with monomeric and oligomeric flavanols (MOF) including (−)-epicatechin in male smokers revealed individual epigenetic gene changes targeting similar pathways as the in vitro exposure experiments in endothelial cells. Furthermore, epigenetic changes following MOF diet intervention oppose atherosclerosis associated epigenetic changes. In line with biological data, the individual epigenetic response to a MOF diet is associated with different vascular health parameters (glutathione peroxidase 1 and endothelin-1 expression, acetylcholine-mediated microvascular response), in part involving systemic shifts in blood immune cell types which reduce the neutrophil–lymphocyte ratio (NLR). Altogether, our study suggests that different (−)-epicatechin metabolites promote vascular health in part via epigenetic reprogramming of endothelial-immune cell signaling and reversing systemic low-grade inflammation.

Innate Immune Dysfunction in Rosacea Promotes Photosensitivity and Vascular Adhesion Molecule Expression

Rosacea is a chronic skin disease characterized by photosensitivity, abnormal dermal vascular behavior, inflammation, and enhanced expression of the antimicrobial peptide LL-37. We observed that dermal endothelial cells in rosacea had an increased expression of VCAM1 and hypothesized that LL-37 could be responsible for this response. The digestion of double-stranded RNA from keratinocytes exposed to UVB blocked the capacity of these cells to induce adhesion molecules on dermal microvascular endothelial cells. However, a synthetic noncoding snoU1RNA was only capable of increasing adhesion molecules on endothelial cells in the presence of LL-37, suggesting that the capacity of UVB exposure to promote both double-stranded RNA and LL-37 was responsible for the endothelial response to keratinocytes. Sequencing of RNA from the endothelial cells uncovered the activation of Gene Ontology (GO) pathways relevant to the human disease, such as type I and II interferon signaling, cell-cell adhesion, leukocyte chemotaxis, and angiogenesis. Functional relevance was demonstrated as double-stranded RNA and LL-37 promoted adhesion and transmigration of monocytes across the endothelial cell monolayers. Gene knockdown of TLR3, RIGI, or IRF1 decreased monocyte adhesion in endothelial cells, confirming the role of the double-stranded RNA recognition pathways. These observations show how the expression of LL-37 can lead to enhanced sensitivity to UVB radiation in rosacea.

Yak-Kong Soybean (Glycine max) Fermented by a Novel Pediococcus pentosaceus Inhibits the Oxidative Stress-Induced Monocyte–Endothelial Cell Adhesion

Yak-Kong (YK), a small black soybean (Glycine max) in Korea, contained higher concentrations of antioxidants than ordinary black soybean or yellow soybean in our previous study. We prepared the fermented YK extract by using a novel lactic acid bacterium, Pediococcus pentosaceus AOA2017 (AOA2017) isolated from Eleusine coracana, and found that the antioxidant ability was enhanced after fermentation. In order to investigate the cause of the enhanced antioxidant ability in the fermented YK extract, we conducted a phenolic composition analysis. The results show that proanthocyanidin decreased and phenolic acids increased with a statistical significance after fermentation. Among the phenolic acids, p-coumaric acid was newly produced at about 11.7 mg/100 g, which did not exist before the fermentation. Further, the fermented YK extract with increased p-coumaric acid significantly inhibited the lipopolysaccharide-induced THP-1 monocyte–endothelial cell adhesion compared to the unfermented YK extract. The fermented YK extract also suppressed the protein expression levels of vascular cell adhesion molecule (VCAM)-1 in human umbilical vein endothelial cells (HUVECs). Together with the previous studies, our results suggest that the extract of YK fermented by AOA2017 has potential to be a new functional food material with its enhanced bioactive compounds which may help to prevent atherosclerosis caused by oxidative stress.

Visfatin Promotes Monocyte Adhesion by Upregulating ICAM-1 and VCAM-1 Expression in Endothelial Cells via Activation of p38-PI3K-Akt Signaling and Subsequent ROS Production and IKK/NF-κB Activation.

Visfatin is known to act as a mediator in several metabolic disorders, such as obesity, diabetes, and cardiovascular diseases. This study aimed to investigate the effect of visfatin on the adhesion of THP-1 monocytes to human vascular endothelial cells and the underlying mechanism. Monocytes adhesion to endothelial cells was determined by using fluorescence-labeled monocytes. ICAM-1 and VCAM-1 expression in endothelial cells were measured by western blotting. Production of reactive oxygen species (ROS) was measured by using a fluorescent dye. The amounts of nuclear factor-kappa B (NF-κB) and phosphorylation of inhibitory factor of NF-κB (IκB) were determined by using western blot analysis. The translocation of NF-κB from the cytoplasm to the nucleus was determined by using immunofluorescence. Here we showed that visfatin significantly caused the upregulation of intercellular cell adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in endothelial cells, as well as enhanced monocyte adhesion to endothelial cells. Moreover, we found that inhibition of PI3K, Akt, and p38 MAPK activation significantly prevented visfatin-enhanced expression of ICAM-1 and VCAM-1 and monocyte adhesion to endothelial cells. Visfatin enhanced ROS production and IKK/NF-кB activation and then led to upregulation of ICAM-1 and VCAM-1 and enhanced monocyte adhesion to endothelial cells. These effects were also p38/PI3K/Akt-dependent. These results demonstrated that visfatin promoted monocyte-endothelial cell adhesion by increasing ICAM-1 and VCAM-1 expression via the activation of p38/PI3K/Akt signaling and downstream ROS production and IKK/NF-кB activation.

Retraction: Homocysteinylated Albumin Promotes Increased Monocyte-Endothelial Cell Adhesion and Up-Regulation of MCP1, Hsp60 and ADAM17

Retraction: Homocysteinylated Albumin Promotes Increased Monocyte-Endothelial Cell Adhesion and Up-Regulation of MCP1, Hsp60 and ADAM17

Glucose-6-phosphate dehydrogenase deficiency increases cell adhesion molecules and activates human monocyte-endothelial cell adhesion: Protective role of l-cysteine

Glucose-6-phosphate dehydrogenase is a major enzyme that supplies the reducing agent nicotinamide adenine dinucleotide phosphate hydrogen (NADPH), which is required to recycle oxidized/glutathione disulfide (GSSH) to reduced glutathione (GSH). G6PD-deficient cells are susceptible to oxidative stress and a deficiency of GSH. Endothelial dysfunction is characterized by the loss of nitric oxide (NO) bioavailability, which regulates leukocyte adhesion to endothelium. G6PD-deficient endothelial cells (EC) demonstrate reduced expression of endothelial nitric oxide synthase (eNOS) and NO levels along with reduced GSH. Whether G6PD deficiency plays any role in EC dysfunction is unknown. The chronic inflammation commonly seen in those with metabolic syndrome, characterized by elevated levels of tumor necrosis factor (TNF) and monocyte chemoattractant protein 1 (MCP-1), provided an incentive for investigation of these cytokines as well. A GSH/G6PD-deficient model was created using human umbilical vein endothelial cells (HUVEC) treated with either buthionine sulfoximine (BSO), a pharmacological inhibitor of the rate-limiting enzyme of GSH biosynthesis (γ-glutamylcysteine synthetase), or with 6-aminonicotinamide (6-AN), an inhibitor of G6PD or G6PD siRNA. Normal and G6PD-deficient cells were also treated with pro-atherosclerotic stimuli such as high glucose, TNF, and MCP-1. After inhibiting or knocking down G6PD/GSH, the capacity of endothelial cells for monocyte recruitment was assessed by determining the expression of the adhesion molecules intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1), which was upregulated by G6PD deficiency and accompanied by the presence of the oxidative stress markers NADPH oxidase 4 (NOX4), inducible nitric oxide synthase (iNOS), and reactive oxygen species (ROS). Treatment with the inhibitors BSO and 6-AN caused increased levels of adhesion molecule mRNA and monocyte-EC adhesion. Following treatment with high glucose, G6PD-deficient cells showed an increase in levels of ICAM-1 and VCAM-1 mRNA, as well as monocyte-EC adherence, compared with results seen in control cells. Treatment with l-cysteine (a precursor of GSH) protected endothelial cells by increasing GSH and attenuating ROS, ICAM-1, VCAM-1, and monocyte-EC adhesion. These results suggest that G6PD/GSH deficiency plays a role in endothelial dysfunction and that supplementation with l-cysteine can restore GSH levels and reduce the EC activation markers in G6PD-deficient conditions.

Decarbromodiphenyl ether (BDE-209) promotes monocyte–endothelial adhesion in cultured human aortic endothelial cells through upregulating intercellular adhesion molecule-1

There is growing evidence that exposure to persistent organic pollutants (POPs) is statistically associated with incidence of cardiovascular disease (CVD) or its risk factors. Decarbromodiphenyl ether (BDE-209) is a new POP which exists extensively in human tissues, but its potential effects on CVD have so far received less focus. The adhesion of circulating monocytes to endothelial cells is one of the critical underlying steps in the initiation and development of CVD. In the present study, we investigated the effect of BDE-209 on the adhesion of THP-1 monocytes to human aortic endothelial cells (HAECs) and identified the molecular mechanisms involved. Our results showed that 6.25, 12.5 and 25 µM of BDE-209 exposures caused significant increases in monocyte–endothelial cell adhesion, in a dose-dependent manner. Mechanistically, BDE-209 exposure increased the expression of intercellular adhesion molecule-1 (ICAM-1). Moreover, the up-regulation of ICAM-1 was accompanied by a decrease in the expression of microRNA-141 (miR-141). Furthermore, the up-regulation of ICAM-1 and the increased adhesion induced by BDE-209 could be reversed by miR-141 supplement. Taken together, our results show that BDE-209 potentiates monocyte–endothelial cell interaction via miR-141/ICAM-1 pathway in HAECs.

Peridinin Is an Exceptionally Potent and Membrane-Embedded Inhibitor of Bilayer Lipid Peroxidation.

Antilipoperoxidant protein dysfunction is associated with many human diseases, suggesting that bilayer lipid peroxidation may contribute broadly to pathogenesis. Small molecule inhibitors of this membrane-localized chemistry could in theory enable better understanding and/or treatment of such diseases, but currently available compounds have important limitations. Many biological questions thus remain unanswered, and clinical trials have largely been disappointing. Enabled by efficient, building block-based syntheses of three atypical carotenoid natural products produced by microorganisms that thrive in environments of extreme oxidative stress, we found that peridinin is a potent inhibitor of nonenzymatic bilayer lipid peroxidation in liposomes and in primary human endothelial cells. We also found that peridinin blocks monocyte-endothelial cell adhesion, a key step in atherogenesis. A series of frontier solid-state NMR experiments with a site-specifically 13C-labeled isotopolog synthesized using the same MIDA boronate building block-based total synthesis approach revealed that peridinin is completely embedded within and physically spans the hydrophobic core of POPC membranes, maximizing its effective molarity at the site of the targeted lipid peroxidation reactions. Alternatively, the widely used carotenoid astaxanthin is significantly less potent and was found to primarily localize extramembranously. Peridinin thus represents a promising and biophysically well-characterized starting point for the development of small molecule antilipoperoxidants that serve as more effective biological probes and/or therapeutics.

Microparticles from \u03b2-thalassaemia/HbE patients induce endothelial cell dysfunction

Thromboembolic complication occurs frequently in β-thalassaemia/HbE patients, particularly in splenectomised patients. Endothelial cells play an important role in thrombosis. There is strong evidence of endothelial cell activation and dysfunction in β-thalassaemia. Microparticles (MPs) are associated with thrombosis and endothelial cell dysfunction in many diseases including β-thalassaemia. However, the effect of thalassaemic-MPs on endothelial cells mediating thrombus formation has not been elucidated. In this study, the effects of circulating MPs from β-thalassaemia/HbE patients on endothelial cell functions were investigated. The results showed that MPs directly induce tissue factor, interleukin (IL)-6, IL-8, intracellular adhesion molecule-1, vascular cell adhesion molecule-1 and E-selectin expression in human umbilical vein endothelial cells (HUVECs). Notably, the levels of these endothelial cell activation markers were significantly increased in HUVECs treated with MPs obtained from splenectomised β-thalassaemia/HbE patients when compared to MPs from non-splenectomised patients or normal subjects. The increased endothelial cell activation ultimately lead to increased monocyte-endothelial cell adhesion. THP-1 and HUVECs adhesion induced by MPs from normal subjects, non-splenectomised and splenectomised patients increased to 2.0 ± 0.4, 2.3 ± 0.4 and 3.8 ± 0.4 fold, respectively when compared to untreated cells. This finding suggests that MPs play an important role on thrombosis and vascular dysfunction in β-thalassaemia/HbE disease, especially in splenectomised cases.

ESM-1 promotes adhesion between monocytes and endothelial cells under intermittent hypoxia.

Intermittent hypoxia (IH), the key property of obstructive sleep apnea (OSA), is closely associated with endothelial dysfunction. Endothelial-cell-specific molecule-1 (ESM-1, Endocan) is a novel, reported molecule linked to endothelial dysfunction. The aim of this study is to evaluate the effect of IH on ESM-1 expression and the role of ESM-1 in endothelial dysfunction. We found that serum concentration of ESM-1, inter-cellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) is significantly higher in patients with OSA than healthy volunteers (p < 0.01). The expression of ESM-1, hypoxia-inducible factor-1 alpha (HIF-1α), and vascular endothelial growth factor (VEGF) was significantly increased in human umbilical vein endothelial cells (HUVECs) by treated IH in a time-dependent manner. HIF-1α short hairpin RNA and vascular endothelial growth factor receptor (VEGFR) inhibitor inhibited the expression of ESM-1 in HUVECs. ICAM-1 and VCAM-1 expressions were significantly enhanced under IH status, accompanied by increased monocyte-endothelial cell adhesion rate ( p < 0.001). Accordingly, ESM-1 silencing decreased the expression of ICAM-1 and VCAM-1 in HUVECs, whereas ESM-1 treatment significantly enhanced ICAM-1 expression accompanied by increasing adhesion ability. ESM-1 is significantly upregulated by the HIF-1α/VEGF pathway under IH in endothelial cells, playing a critical role in enhancing adhesion between monocytes and endothelial cells, which might be a potential target for IH-induced endothelial dysfunction.