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.     

Simvastatin modulates TNFalpha-induced adhesion molecules expression in human endothelial cells

Adhesion and transendothelial migration of leukocytes into the vascular wall is a crucial step in atherogenesis. Expression of cell adhesion molecules by endothelial cells plays a leading role in this process. We investigated the effect of simvastatin, an inhibitor of HMG-CoA reductase administered to reduce plasma levels of LDL-cholesterol, on the expression of vascular cell adhesion molecule-1 (VCAM-1) and intracellular cell adhesion molecule-1 (ICAM-1) by human umbilical vein endothelial cells (HUVEC) stimulated with tumor necrosis factor alpha (TNFalpha). We found the expression to be significantly inhibited by the drug in a time and concentration-dependent manner and to a greater extent in the case of VCAM-1 as compared with ICAM-1. In TNFalpha-stimulated HUVEC, simvastatin decreased VCAM-1 and ICAM-1 mRNA levels, inhibited TNFalpha-induced activation of nuclear factor kappaB (NF-kappaB) and enhanced expression of peroxisome proliferator-activated receptor alpha (PPARalpha). These effects were associated with reduction of adherence of monocytes and lymphocytes to HUVEC. The present findings suggest that the benefits of statins in vascular disease may include the inhibition of expression of VCAM-1 and ICAM-1 through effects on NF-kappaB.     

Intercellular adhesion molecule-1 and vascular endothelial growth factor expression kinetics in macrophage-derived foam cells

Macrophage-derived foam cells seem to play an important role during inflammatory response of atherosclerosis, in which the overexpression of intercellular adhesion molecule-1 (ICAM-1) and vascular endothelial growth factor (VEGF) are associated with the early and later pathological changes in foam cell formation. In this study, we investigated the expression kinetics of ICAM-1 and VEGF in macrophage-derived foam cells. The foam cell model was established through incubating the human monocyte line (U937 cells) with oxidized-low density lipoprotein (ox-LDL). Up-regulated expressions of ICAM-1 and VEGF were analyzed in protein and mRNA levels in U937 foam cells by flow cytometry, ELISA, and Northern blot. Kinetic studies showed the deferent kinds of expression curves in dose response and time course. The expression dose-kinetics demonstrated that the ICAM-1 showed the peak expression induced by ox-LDL 50 mg/L, while VEGF levels increased in a dose-dependent manner with the maximum level induced by ox-LDL 200 mg/L. Time-kinetic studies revealed that the ICAM-1 levels showed the peak expression in 12 h while VEGF expression increased in a time-dependent manner with the maximum level in 48 h. These results proved that both ICAM-1 and VEGF expressions were enhanced in the macrophage-derived foam cells, but ICAM-1 expression increased earlier than the up-regulation of VEGF; low dose of ox-LDL mainly up regulated ICAM-1 expression, while high dose mainly increased the VEGF expression.     

Monocyte adhesion and spreading on human endothelial cells is dependent on Rho-regulated receptor clustering.

The GTPase Rho is known to mediate the assembly of integrin-containing focal adhesions and actin stress fibers. Here, we investigate the role of Rho in regulating the distribution of the monocyte-binding receptors E-selectin, ICAM-1, and VCAM-1 in human endothelial cells. Inhibition of Rho activity with C3 transferase or N19RhoA, a dominant negative RhoA mutant, reduced the adhesion of monocytes to activated endothelial cells and inhibited their spreading. Similar effects were observed after pretreatment of endothelial cells with cytochalasin D. In contrast, dominant negative Rac and Cdc42 proteins did not affect monocyte adhesion or spreading. C3 transferase and cytochalasin D did not alter the expression levels of monocyte-binding receptors on endothelial cells, but did inhibit clustering of E-selectin, ICAM-1, and VCAM-1 on the cell surface induced by monocyte adhesion or cross-linking antibodies. Similarly, N19RhoA inhibited receptor clustering. Monocyte adhesion and receptor cross-linking induced stress fiber assembly, and inhibitors of myosin light chain kinase prevented this response but did not affect receptor clustering. Finally, receptor clusters colocalized with ezrin/moesin/ radixin proteins. These results suggest that Rho is required in endothelial cells for the assembly of stable adhesions with monocytes via the clustering of monocyte-binding receptors and their association with the actin cytoskeleton, independent of stress fiber formation.     

Endothelial intercellular cell adhesion molecule 1 contributes to cell aggregate formation in CHO cells cultured in serum-free media

Chinese hamster ovary (CHO) cells have been adapted to grow in serum-free media and in suspension culture to facilitate manufacturing needs. Some CHO cell lines, however, tend to form cell aggregates while being cultured in suspension. This can result in reduced viability and capacity for single cell cloning (SCC) via limiting dilution, and process steps to mitigate cell aggregate formation, for example, addition of anti-cell-aggregation agents. In this study, we have identified endothelial intercellular cell adhesion molecule 1 (ICAM-1) as a key protein promoting cell aggregate formation in a production competent CHO cell line, which is prone to cell aggregate formation. Knocking out (KO) the ICAM-1 gene significantly decreased cell aggregate formation in the culture media without anti-cell-aggregation reagent. This trait can simplify the process of transfection, selection, automated clone isolation, and so on. Evaluation in standard cell line development of ICAM-1 KO and wild-type CHO hosts did not reveal any noticeable impacts on titer or product quality. Furthermore, analysis of a derived nonaggregating cell line showed significant reductions in expression of cell adhesion proteins. Overall, our data suggest that deletion of ICAM-1 and perhaps other cell adhesion proteins can reduce cell aggregate formation and improve clonality assurance during SCC.     

Cholesterol increases adhesion of monocytes to endothelium by moving adhesion molecules out of caveolae

Caveolae and its structural protein caveolin-1 (Cav-1) are abundant in vascular endothelial cells (ECs). We examined whether caveolae are involved in monocyte adhesion to ECs responding to a synergy of hypercholesterolemia and inflammation. Treating human umbilical vein ECs with cholesterol enhanced endotoxin lipopolysaccharide (LPS)-induced monocyte adhesion. Use of isolated caveolae-enriched membranes revealed that cell adhesion molecules (CAMs), including intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), co-localized with Cav-1 in caveolae. LPS upregulated CAMs expression and increased the co-localization. Cholesterol exposure decreased the level of CAMs in the caveolae. Co-immunoprecipitation and confocal microscopy revealed that ICAM-1 interacted with Cav-1. Electron microscopy showed that ICAM-1 was mainly located in caveolae. Cholesterol exposure decreased this interaction and drove ICAM-1 out of caveolae. Knockdown of Cav-1 reduced the synergistic effects of cholesterol and inflammation. In vivo, ICAM-1 and Cav-1 co-localization was lower in the aortic endothelium of ApoE^−/− mice than in that of wild-type controls. Cav-1 negatively regulates monocyte adhesion by the co-localization of CAMs in caveolae, which is disturbed by cholesterol. Thus, our study suggests a molecular basis underlying the synergistic effects of hypercholesterolemia and inflammation in atherogenesis.     

C-reactive protein induced expression of adhesion molecules in cultured cerebral microvascular endothelial cells

Ischemic stroke can trigger an acute phase response resulting in a rise of plasma concentration of C-reactive protein (CRP). Clinical data about the relationship between CRP and prognosis suggest that CRP might be involved in the pathogenesis of cerebral ischemia. In the present work, a significant increase of circulating level of CRP was observed in an vivo rat brain ischemia model of middle cerebral artery occlusion. To determine the possible effects of CRP on brain microvessel endothelium, we performed a dose-dependent experiment in mouse brain microvascular endothelial cells (bEnd.3 cells) with emphasis on its relation to cell adhesions molecules. Incubation with CRP (1-75 mg/L) for 24 h significantly increased Lactate dehydrogenase (LDH) leakage from bEnd.3 cells (P<0.01) in a dose-dependent manner, and induced significant up-regulations of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expressions analyzed by Western blotting (P<0.01). In contrast to earlier report, CRP also induced significant increase in ICAM-1 expression in the absence of serum (P<0.01). In conclusion, the present results suggest that CRP may be involved directly in the development of inflammation in response to cerebral ischemia.     

Effects of TNF-alpha on leukocyte adhesion molecule expressions in cultured human lymphatic endothelium.

TNF-alpha alters leukocyte adhesion molecule expression of cultured endothelial cells like human umbilical vein endothelial cells (HUVEC). This study was designed to investigate the changes in vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and platelet endothelial cell adhesion molecule-1 (PECAM-1) expression with TNF-alpha stimulation in cultured human neonatal dermal lymphatic endothelial cells (HNDLEC). The real-time quantitative PCR analysis on HNDLEC showed that TNF-alpha treatment leads to increases of VCAM-1 and ICAM-1 mRNAs to the 10.8- and 48.2-fold levels of untreated cells and leads to a reduction of PECAM-1 mRNA to the 0.42-fold level of untreated cells. Western blot and immunohistochemical analysis showed that TNF-alpha leads to VCAM-1 and ICAM-1 expressions that were inhibited by antiserum to human TNF receptor or by AP-1 inhibitor nobiletin. In flow cytometry analysis, the number of VCAM-1- and ICAM-1-positive cells increased, and PECAM-1-positive cells decreased with TNF-alpha treatment. Regarding protein amounts produced in cells and amounts expressed on the cell surface, VCAM-1 and ICAM-1 increased in HNDLEC and HUVEC, and PECAM-1 decreased in HNDLEC in a TNF-alpha concentration-dependent manner. VCAM-1, ICAM-1, and PECAM-1 protein amounts in TNF-alpha-stimulated cells were lower in HNDLEC than in HUVEC. This suggests that the lymphatic endothelium has the TNF-alpha-induced signaling pathway, resulting in increased VCAM-1 and ICAM-1 expression to a weaker extent than blood endothelium and PECAM-1 reduction to a stronger extent than blood endothelium.     

Cardiotrophin-1 stimulates intercellular adhesion molecule-1 and monocyte chemoattractant protein-1 in human aortic endothelial cells

Intercellular adhesion molecule-1 (ICAM-1) and monocyte chemoattractant protein-1 (MCP-1) play critical roles in mediating monocyte adhesion to the vascular endothelium and monocyte migration into the subendothelial regions of the vessels. Inasmuch as cardiotrophin-1 (CT-1), an IL-6-type cytokine, was expressed in human atherosclerotic plaque, we examined whether CT-1 induces monocyte adhesion and migration by stimulating gene and protein expressions of ICAM-1 and MCP-1 in human aortic endothelial cells (HAECs). Immunocytochemistry revealed that CT-1 increased intensity of ICAM-1 and MCP-1 immunoreactivity in HAECs. Adhesion assay and chemotaxis assay revealed that CT-1 increased human monocytic THP-1 cell adhesion to HAECs and promoted chemotaxis in THP-1 cells, which were attenuated by anti-ICAM-1 and anti-MCP-1 antibody, respectively. Western blot analysis showed that CT-1 increased phosphorylation of ERK1/2 MAP kinase, p38 MAP kinase, and Akt and that their inhibitors, PD-98059, SB-203580, and LY-294002, respectively, inhibited phosphorylation. RNase protection assay and ELISA demonstrated that CT-1 increased gene and protein expressions of ICAM-1 and MCP-1. EMSA revealed that CT-1 enhanced NF-kappaB DNA-binding activity. CT-1-mediated upregulation of ICAM-1 and MCP-1 was suppressed by PD-98059, SB-203580, LY-294002, and parthenolide. The present study demonstrates that CT-1 promotes monocyte adhesion and migration by stimulating ICAM-1 and MCP-1 through mechanisms that involve ERK1/2 MAP kinase, p38 MAP kinase, phosphatidylinositol 3-kinase, and NF-kappaB pathways and suggests that CT-1 plays an important role in the pathophysiology of vascular inflammation and atherosclerosis.     

Effect of irradiation-induced intercellular adhesion molecule-1 expression on natural killer cell-mediated cytotoxicity toward human cancer cells

Background aims

Irradiation enhances the adhesion between natural killer (NK) cells and target cells by up-regulating intercellular adhesion molecule-1 (ICAM-1) on target cells. Therefore, we investigated the effect of irradiation-induced ICAM-1 expression on human cancer cells on NK cell–mediated cytotoxicity.

Identification of peptides inhibiting adhesion of monocytes to the injured vascular endothelial cells through phage-displaying screening

Using oxidized low-density lipoprotein (LDL)-injured vascular endothelial cells (ECs) as target cells, peptides specifically binding to the injured ECs were screened from a phage-displaying peptide library by using the whole-cell screening technique after three cycles of the ““““““““““““““““““““““““““““““““““““““““““““““““““““““““““““““““adsorption-elution-amplification““““““““““““““““““““““““““““““““““““““““““““““““““““““““““““““““ procedure. Positive phage clones were identified by ELISA, and the inserted amino acid sequences in the displaying peptides were deduced from confirmation with DNA sequencing. The adhesion rate of ECs to monocytes was evaluated by cell counting. The activity of endothelial nitric oxide synthase (eNOS), and the expression levels of caveolin-1 and intercellular adhesion molecule-1 (ICAM-1) were determined by Western blotting. Six positive clones specifically binding to injured ECV304 endothelial cells were selected from fourteen clones. Interestingly, four phages had peptides with tandem leucine, and two of these even shared an identical sequence. Functional analysis demonstrated that the YCPRYVRRKLENELLVL peptide shared by two clones inhibited the expression of ICAM-1, increased nitric oxide concentration in the culture media, and upregulated the expression of caveolin- 1 and eNOS. As a result, the adhesion rate of monocytes to ECV304 cells was significantly reduced by 12.1%. These data suggest that the anti-adhesion effect of these novel peptides is related to the regulation of the caveolin- 1/nitric oxide signal transduction pathway, and could be of use in potential therapeutic agents against certain cardiovascular diseases initiated by vascular endothelial cell damage.     

Inhibition of the α-mannosidase Man2c1 gene expression enhances adhesion of Jurkat cells

Protein N-glycosylation plays very important roles in immunity and α-mannosidase is one of the key enzymes in Nglycosylation. This paper reports that inhibition of α-mannosidase Man2c1 gene expression enhances adhesion of Jurkat T cells. In comparison to the controls with normal expression of the enzyme, Jurkat cells with the inhibition of Man2c1 gene expression （AS cell） formed larger aggregates in culture, indicating an enhancement of adhesion between the cells. mRNA differential display analysis discovered up-regulation of several adhesion molecule genes in the AS cell. Because of the pivotal role played by CD54-LFA-1 interaction in immune cell interaction, this study focused on the contribution of enhanced expression of CD54 and LFA-1 to the enhanced adhesion of AS Jurkat cells. These facts, including increased binding of AS cells to ICAM-1-Fc, Mg^2＋ activation of the binding of AS cells to ICAM-1-Fc and enhanced aggregation of AS cells, together with the inhibiting effect of a blocking CD1 la mAb on the binding to ICAM-1-Fc and aggregation of the cells demonstrate an important contribution of enhanced CD54-LFA-1 interaction to increased adhesion between AS cells. The enhanced CD54-LFA-1 interaction also resulted in increased adhesion between AS Jurkat T cells and Raji B cells. In addition, AS cells showed cytoskeletal rearrangement. The data imply a biological significance of MAN2C1 in T-cell functioning.     

The role of the cytoskeleton in cellular adhesion molecule expression in tumor necrosis factor-stimulated endothelial cells

Leukocyte infiltration is a hallmark of the atherosclerotic lesion. These cells are captured by cellular adhesion molecules (CAMs), including vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), platelet-endothelial cell adhesion molecule (PECAM), and E-selectin, on endothelial cells (EC). We examined the role of the actin cytoskeleton in tumor necrosis factor-alpha (TNF-alpha)-induced translocation of CAMs to the cell surface. Human aortic EC were grown on 96-well plates and an ELISA was used to assess surface expression of the CAMs. TNF-alpha increased VCAM-1, ICAM-1, and E-selectin by 4 h but had no affect on the expression of PECAM. A functioning actin cytoskeleton was important for VCAM-1 and ICAM-1 expression as both cytochalasin D, an actin filament disruptor, and jasplakinolide, an actin filament stabilizer, attenuated the expression of these CAMs. These compounds were ineffective in altering E-selectin surface expression. Myosin light chains are phosphorylated in response to TNF-alpha and this appears to be regulated by Rho kinase instead of myosin light chain kinase. However, the Rho kinase inhibitor, Y27632, had no affect on TNF-alpha-induced CAM expression. ML-7, a myosin light chain kinase inhibitor, had a modest inhibitory effect on the translocation of VCAM-1 but not on ICAM-1 or E-selectin. These data suggest that the surface expression of VCAM-1 and ICAM-1 is dependent on cycling of the actin cytoskeleton. Nevertheless, modulation of actin filaments via myosin light chain phosphorylation is not necessary. The regulation of E-selectin surface expression differs from that of the other CAMs.     

Respiratory syncytial virus infection of human lung endothelial cells enhances selectively intercellular adhesion molecule-1 expression

Respiratory syncytial virus (RSV) is worldwide the most frequent cause of bronchiolitis and pneumonia in infants requiring hospitalization. In the present study, we supply evidence that human lung microvascular endothelial cells, human pulmonary lung aorta endothelial cells, and HUVEC are target cells for productive RSV infection. All three RSV-infected endothelial cell types showed an enhanced cell surface expression of ICAM-1 (CD54), which increased in a time- and RSV-dose-dependent manner. By using noninfectious RSV particles we verified that replication of RSV is a prerequisite for the increase of ICAM-1 cell surface expression. The up-regulated ICAM-1 expression pattern correlated with an increased cellular ICAM-1 mRNA amount. In contrast to ICAM-1, a de novo expression of VCAM-1 (CD106) was only observed on RSV-infected HUVEC. Neither P-selectin (CD62P) nor E-selectin (CD62E) was up-regulated by RSV on human endothelial cells. Additional experiments performed with neutralizing Abs specific for IL-1alpha, IL-1beta, IL-6, and TNF-alpha, respectively, excluded an autocrine mechanism responsible for the observed ICAM-1 up-regulation. The virus-induced ICAM-1 up-regulation was dependent on protein kinase C and A, PI3K, and p38 MAPK activity. Adhesion experiments using polymorphonuclear neutrophil granulocytes (PMN) verified an increased ICAM-1-dependent adhesion rate of PMN cocultured with RSV-infected endothelial cells. Furthermore, the increased adhesiveness resulted in an enhanced transmigration rate of PMN. Our in vitro data suggest that human lung endothelial cells are target cells for RSV infection and that ICAM-1 up-regulated on RSV-infected endothelial cells might contribute to the enhanced accumulation of PMN into the bronchoalveolar space.     

Effect of selenium supplementation in asthmatic subjects on the expression of endothelial cell adhesion molecules in culture

Endothelial cells play a major role in immunologic reactions, in which cellular adhesion molecules P-selectin, ICAM-1, VCAM-1, and ELAM-1 are important mediators in the recruitment of leukocytes in pulmonary inflammation. Selenium (Se) is known to modulate immunological mechanisms of asthma. The aim of our investigation was to examine whether Se supplementation in cortico-dependent asthmatic patients may modulate adhesion molecule expression in cultured endothelium. Our findings indicated that P-selectin, VCAM-1, and ELAM-1 expression on human umbilical vein endothelial cells stimulated with peripheral blood mononuclear cells obtained from asthmatics before supplementation with Se was significantly higher than from healthy donors (p < 0.05). The production of ICAM-1 showed only slight augmentation. The levels of VCAM-1 and ELAM-1 expression were significantly decreased after 3 mo of Se supplementation (p < 0.05). After 6 mo of intervention period the intensity of P-selectin and ICAM-1 expression was also significantly reduced (p < 0.05 andp < 0.01, respectively). The inhibitory effect of Se on the adhesion molecule expression was studied in cultured endothelial cells after interferon-γ stimulation. Our data suggest that Se affects the expression of P-selectin, ICAM-1, VCAM-1, and ELAM-1 in a dosedependent manner and the half-maximal inhibitory concentrations were 3.4, 0.5, 4, and 3.8 μg/mL, respectively. The maximal inhibitions (greater than 80%) were observed in vitro with 10 μg/mL Se (p < 0.01). Regulation of adhesion molecule expression may be an important mechanism through which the inflammation may be controlled.