INHIBITION OF ENDOTHELIAL CELL PROLIFERATION BY NORMAL HUMAN MONOCYTES

1987 ◽  
Author(s):  
F Liote ◽  
M P Wautier ◽  
E Savariau ◽  
H Setiadi ◽  
J L Wautier

Human peripheral blood monocytes and macrophages possess factors which are capable of inhibiting or stimulating endothelial cell proliferation. We have further explored if such activity is due to cytotoxic effects of monocytes. Normal mononuclear cells were isolated first by density gradient. Monocytes were then purified by three different techniques: 1) counter centrifugation elutriation (CCE) (Beckman) 2) selective adhesion to gelatin-plasma (GPI) 3) selective adhesion to fibronectin (Fn). Cytotoxicity was estimated by counting the release of 51cr used to label the human umbilical vein endothelial cells (HUVE) prior to the addition of monocytes. Whilst [3H] thymidine incorporation by HUVE permitted us to measure the effect of monocytes on the growth of the endothelial cells. Monocytes were incubated with HUVE (12×103) for 24 to 36h at various concentrations '(1.5-12×103). No cytotoxic effect could be demonstrated but an inhibition of [3h] thymidine uptake was observed and was dependent upon monocytes concentration. Monocytes isolated on GP1 exhibited a significantly higher inhibitory effect (p<0.05) compared to those purified on Fn or by CCE.(GP1: 85±6%, Fn:58±6%, CCE:67±5%). These results indicated t*hat normal monocytes can inhibit endothelial cell proliferation. This activity appeared to be higher when monocytes were isolated on GP1 which suggest that the adhesion on this surface could stimulate monocytes not only by its fibronectin receptor. This inhibitory activity of monocyte on endothelial cells proliferation could be different in patients with vascular disorders.

Blood ◽  
1994 ◽  
Vol 83 (8) ◽  
pp. 2145-2152 ◽  
Author(s):  
VC Broudy ◽  
NL Kovach ◽  
LG Bennett ◽  
N Lin ◽  
FW Jacobsen ◽  
...  

Stem cell factor (SCF) is a hematopoietic growth factor produced by fibroblasts and endothelial cells that stimulates the growth of primitive hematopoietic cells. SCF triggers cell growth by binding to the c-kit receptor. Because endothelial cells can respond to certain hematopoietic growth factors, we tested human umbilical vein endothelial cells for display of the c-kit receptor and examined the effect of SCF on endothelial cell proliferation, adhesion molecule expression, and production of tissue factor. Quantitative binding experiments with 125I-SCF showed both high-affinity (Kd = 42 pmol/L) and low-affinity (Kd = 1.7 nmol/L) c-kit receptors. There were approximately 1,100 high-affinity c-kit receptors, and 5,400 low- affinity c-kit receptors per endothelial cell. Enzyme immunoassays showed that endothelial cells released soluble c-kit receptor and SCF. The transmembrane form of SCF was detected by indirect immunofluorescence analysis using monoclonal or polyclonal anti-SCF receptor antibodies. The addition of SCF (100 ng/mL) did not alter endothelial cell proliferation over a 7-day period. Similarly, there was no change in the release of tissue factor or expression of inducible endothelial adhesion molecules (intercellular adhesion molecule-1, endothelial-leukocyte adhesion molecule-1, and vascular cell adhesion molecule-1) measured by enzyme-linked immunosorbant assay at 4 and 24 hours after SCF addition. The neutralizing anti-c-kit receptor monoclonal antibody SR-1 blocked binding of 125I-SCF to the c- kit receptor by 98% but did not alter endothelial cell proliferation or adhesion-molecule expression. c-kit receptors were also detected on adult endothelial cells lining small blood vessels in normal human lymph nodes. These data indicate that normal human endothelial cells produce SCF and show high-affinity c-kit receptors that have the capacity to dimerize. The lack of response to exogenous SCF may be because of intracellular activation of the c-kit receptor via autocrine production of SCF. Alternatively, SCF and c-kit may play a role other than stimulation of proliferation, adhesion-molecule display, or tissue factor production by endothelial cells. The production of soluble c-kit receptors by normal human endothelial cells may serve to regulate the bioactivity of SCF within the bone marrow microenvironment.


2011 ◽  
Vol 301 (5) ◽  
pp. C1086-C1092 ◽  
Author(s):  
A. M. Porter ◽  
C. M. Klinge ◽  
A. S. Gobin

Angiogenesis is an important biological response known to be involved in many physiological and pathophysiological situations. Cellular responses involved in the formation of new blood vessels, such as increases in endothelial cell proliferation, cell migration, and the survival of apoptosis-inducing events, have been associated with vascular endothelial growth factor isoform 165 (VEGF165). Current research in the areas of bioengineering and biomedical science has focused on developing polyethylene glycol (PEG)-based systems capable of initiating and sustaining angiogenesis in vitro. However, a thorough understanding of how endothelial cells respond at the molecular level to VEGF165 incorporated into these systems has not yet been established in the literature. The goal of the current study was to compare the upregulation of key intracellular proteins involved in angiogenesis in human umbilical vein endothelial cells (HUVEC) and human microvascular endothelial cells (HMEC) seeded on PEG hydrogels containing grafted VEGF165 and adhesion peptides Arg-Gly-Asp-Ser (RGDS). Our data suggest that the covalent incorporation of VEGF165 into PEG hydrogels encourages the upregulation of signaling proteins responsible for increases in endothelial cell proliferation, cell migration, and the survival after apoptosis-inducing events.


Blood ◽  
1994 ◽  
Vol 83 (8) ◽  
pp. 2145-2152 ◽  
Author(s):  
VC Broudy ◽  
NL Kovach ◽  
LG Bennett ◽  
N Lin ◽  
FW Jacobsen ◽  
...  

Abstract Stem cell factor (SCF) is a hematopoietic growth factor produced by fibroblasts and endothelial cells that stimulates the growth of primitive hematopoietic cells. SCF triggers cell growth by binding to the c-kit receptor. Because endothelial cells can respond to certain hematopoietic growth factors, we tested human umbilical vein endothelial cells for display of the c-kit receptor and examined the effect of SCF on endothelial cell proliferation, adhesion molecule expression, and production of tissue factor. Quantitative binding experiments with 125I-SCF showed both high-affinity (Kd = 42 pmol/L) and low-affinity (Kd = 1.7 nmol/L) c-kit receptors. There were approximately 1,100 high-affinity c-kit receptors, and 5,400 low- affinity c-kit receptors per endothelial cell. Enzyme immunoassays showed that endothelial cells released soluble c-kit receptor and SCF. The transmembrane form of SCF was detected by indirect immunofluorescence analysis using monoclonal or polyclonal anti-SCF receptor antibodies. The addition of SCF (100 ng/mL) did not alter endothelial cell proliferation over a 7-day period. Similarly, there was no change in the release of tissue factor or expression of inducible endothelial adhesion molecules (intercellular adhesion molecule-1, endothelial-leukocyte adhesion molecule-1, and vascular cell adhesion molecule-1) measured by enzyme-linked immunosorbant assay at 4 and 24 hours after SCF addition. The neutralizing anti-c-kit receptor monoclonal antibody SR-1 blocked binding of 125I-SCF to the c- kit receptor by 98% but did not alter endothelial cell proliferation or adhesion-molecule expression. c-kit receptors were also detected on adult endothelial cells lining small blood vessels in normal human lymph nodes. These data indicate that normal human endothelial cells produce SCF and show high-affinity c-kit receptors that have the capacity to dimerize. The lack of response to exogenous SCF may be because of intracellular activation of the c-kit receptor via autocrine production of SCF. Alternatively, SCF and c-kit may play a role other than stimulation of proliferation, adhesion-molecule display, or tissue factor production by endothelial cells. The production of soluble c-kit receptors by normal human endothelial cells may serve to regulate the bioactivity of SCF within the bone marrow microenvironment.


2001 ◽  
Vol 281 (1) ◽  
pp. H396-H403 ◽  
Author(s):  
Larry J. Thompson ◽  
Jihong Jiang ◽  
Nageswara Madamanchi ◽  
Marschall S. Runge ◽  
Cam Patterson

The vascular endothelium is a dynamic interface between the blood vessel and circulating factors and, as such, plays a critical role in vascular events like inflammation, angiogenesis, and hemostasis. Whereas specific protein tyrosine kinases have been identified in these processes, less is known about their protein tyrosine phosphatase (PTP) counterparts. We utilized a RT-PCR/differential hybridization assay to identify PTP-ε as a highly abundant endothelial cell PTP. PTP-ε mRNA expression is growth factor responsive, suggesting a role for this enzyme in endothelial cell proliferation. Overexpression of PTP-ε decreases proliferation by 60% in human umbilical vein endothelial cells (HUVEC) but not in smooth muscle cells or fibroblasts. In contrast, overexpression of PTP-ε (D284A), a catalytically inactive mutant, has no significant effect on HUVEC proliferation. These data provide the first functional characterization of PTP-ε in endothelial cells and identify a novel pathway that negatively regulates endothelial cell growth. Such a pathway may have important implications in vascular development and angiogenesis.


2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Luke Hoeppner ◽  
Sutapa Sinha ◽  
Ying Wang ◽  
Resham Bhattacharya ◽  
Shamit Dutta ◽  
...  

Vascular permeability factor/vascular endothelial growth factor A (VEGF) is a central regulator of angiogenesis and potently promotes vascular permeability. VEGF plays a key role in the pathologies of heart disease, stroke, and cancer. Therefore, understanding the molecular regulation of VEGF signaling is an important pursuit. Rho GTPase proteins play various roles in vasculogenesis and angiogenesis. While the functions of RhoA and RhoB in these processes have been well defined, little is known about the role of RhoC in VEGF-mediated signaling in endothelial cells and vascular development. Here, we describe how RhoC modulates VEGF signaling to regulate endothelial cell proliferation, migration and permeability. We found VEGF stimulation activates RhoC in human umbilical vein endothelial cells (HUVECs), which was completely blocked after VEGF receptor 2 (VEGFR-2) knockdown indicating that VEGF activates RhoC through VEGFR-2 signaling. Interestingly, RhoC knockdown delayed the degradation of VEGFR-2 compared to control siRNA treated HUVECs, thus implicating RhoC in VEGFR-2 trafficking. In light of our results suggesting VEGF activates RhoC through VEGFR-2, we sought to determine whether RhoC regulates vascular permeability through the VEGFR-2/phospholipase Cγ (PLCγ) /Ca 2+ /eNOS cascade. We found RhoC knockdown in VEGF-stimulated HUVECs significantly increased PLC-γ1 phosphorylation at tyrosine 783, promoted basal and VEGF-stimulated eNOS phophorylation at serine 1177, and increased calcium flux compared with control siRNA transfected HUVECs. Taken together, our findings suggest RhoC negatively regulates VEGF-induced vascular permeability. We confirmed this finding through a VEGF-inducible zebrafish model of vascular permeability by observing significantly greater vascular permeability in RhoC morpholino (MO)-injected zebrafish than control MO-injected zebrafish. Furthermore, we showed that RhoC promotes endothelial cell proliferation and negatively regulates endothelial cell migration. Our data suggests a scenario in which RhoC promotes proliferation by upregulating -catenin in a Wnt signaling-independent manner, which in turn, promotes Cyclin D1 expression and subsequently drives cell cycle progression.


1999 ◽  
Vol 112 (10) ◽  
pp. 1599-1609 ◽  
Author(s):  
B.M. Kraling ◽  
D.G. Wiederschain ◽  
T. Boehm ◽  
M. Rehn ◽  
J.B. Mulliken ◽  
...  

Vessel maturation during angiogenesis (the formation of new blood vessels) is characterized by the deposition of new basement membrane and the downregulation of endothelial cell proliferation in the new vessels. Matrix remodeling plays a crucial, but still poorly understood role, in angiogenesis regulation. We present here a novel assay system with which to study the maturation of human capillary endothelial cells in vitro. When human dermal microvascular endothelial cells (HDMEC) were cultured in the presence of dibutyryl cAMP (Bt2) and hydrocortisone (HC), the deposition of a fibrous lattice of matrix molecules consisting of collagens type IV, type XVIII, laminin and thrombospondin was induced. In basal medium (without Bt2 and HC), HDMEC released active matrix metalloproteinases (MMPs) into the culture medium. However, MMP protein levels were significantly reduced by treatment with Bt2 and HC, while protein levels and activity of endogenous tissue inhibitor of MMPs (TIMP) increased. This shift in the proteolytic balance and matrix deposition was inhibited by the specific protein kinase A inhibitors RpcAMP and KT5720 or by substituting analogues without reported glucocorticoid activity for HC. The addition of MMP inhibitors human recombinant TIMP-1 or 1,10-phenanthroline to cultures under basal conditions induced matrix deposition in a dose-dependent manner, which was not observed with the serine protease inhibitor epsilon-amino-n-caproic acid (ACA). The deposited basement membrane-type of matrix reproducibly suppressed HDMEC proliferation and increased HDMEC adhesion to the substratum. These processes of matrix deposition and downregulation of endothelial cell proliferation, hallmarks of differentiating new capillaries in the end of angiogenesis, were recapitulated in our cell culture system by decreasing the matrix-degrading activity. These data suggest that our cell culture assay provides a simple and feasible model system for the study of capillary endothelial cell differentiation and vessel maturation in vitro.


2017 ◽  
Vol 37 (12) ◽  
Author(s):  
Ying Zhang ◽  
Rony Chidiac ◽  
Chantal Delisle ◽  
Jean-Philippe Gratton

ABSTRACT Nitric oxide (NO) produced by endothelial NO synthase (eNOS) modulates many functions in endothelial cells. S-nitrosylation (SNO) of cysteine residues on β-catenin by eNOS-derived NO has been shown to influence intercellular contacts between endothelial cells. However, the implication of SNO in the regulation of β-catenin transcriptional activity is ill defined. Here, we report that NO inhibits the transcriptional activity of β-catenin and endothelial cell proliferation induced by activation of Wnt/β-catenin signaling. Interestingly, induction by Wnt3a of β-catenin target genes, such as the axin2 gene, is repressed in an eNOS-dependent manner by vascular endothelial growth factor (VEGF). We identified Cys466 of β-catenin as a target for SNO by eNOS-derived NO and as the critical residue for the repressive effects of NO on β-catenin transcriptional activity. Furthermore, we observed that Cys466 of β-catenin, located at the binding interface of the β-catenin–TCF4 transcriptional complex, is essential for disruption of this complex by NO. Importantly, Cys466 of β-catenin is necessary for the inhibitory effects of NO on Wnt3a-stimulated proliferation of endothelial cells. Thus, our data define the mechanism responsible for the repressive effects of NO on the transcriptional activity of β-catenin and link eNOS-derived NO to the modulation by VEGF of Wnt/β-catenin-induced endothelial cell proliferation.


Blood ◽  
2008 ◽  
Vol 111 (8) ◽  
pp. 4145-4154 ◽  
Author(s):  
Nelly A. Abdel-Malak ◽  
Coimbatore B. Srikant ◽  
Arnold S. Kristof ◽  
Sheldon A. Magder ◽  
John A. Di Battista ◽  
...  

Abstract Angiopoietin-1 (Ang-1), ligand for the endothelial cell–specific Tie-2 receptors, promotes migration and proliferation of endothelial cells, however, whether these effects are promoted through the release of a secondary mediator remains unclear. In this study, we assessed whether Ang-1 promotes endothelial cell migration and proliferation through the release of interleukin-8 (IL-8). Ang-1 elicited in human umbilical vein endothelial cells (HUVECs) a dose- and time-dependent increase in IL-8 production as a result of induction of mRNA and enhanced mRNA stability of IL-8 transcripts. IL-8 production is also elevated in HUVECs transduced with retroviruses expressing Ang-1. Neutralization of IL-8 in these cells with a specific antibody significantly attenuated proliferation and migration and induced caspase-3 activation. Exposure to Ang-1 triggered a significant increase in DNA binding of activator protein-1 (AP-1) to a relatively short fragment of IL-8 promoter. Upstream from the AP-1 complex, up-regulation of IL-8 transcription by Ang-1 was mediated through the Erk1/2, SAPK/JNK, and PI-3 kinase pathways, which triggered c-Jun phosphorylation on Ser63 and Ser73. These results suggest that promotion of endothelial migration and proliferation by Ang-1 is mediated, in part, through the production of IL-8, which acts in an autocrine fashion to suppress apoptosis and facilitate cell proliferation and migration.


Author(s):  
Sanghamitra Sahoo ◽  
Yao Li ◽  
Daniel de Jesus ◽  
John Charles Sembrat II ◽  
Mauricio M Rojas ◽  
...  

Pulmonary arterial hypertension (PAH) is a fatal cardiopulmonary disease characterized by increased vascular cell proliferation with resistance to apoptosis and occlusive remodeling of the small pulmonary arteries in humans. The Notch family of proteins are proximal signaling mediators of an evolutionarily conserved pathway that effect cell proliferation, fate determination, and development. In endothelial cells (ECs), Notch receptor 2 (Notch2) has been shown to promote endothelial apoptosis. However, a pro- or anti-proliferative role for Notch2 in pulmonary endothelial proliferation and ensuing PAH is unknown. Herein, we postulated that suppressed Notch2 signaling drives pulmonary endothelial proliferation in the setting of PAH. We observed that levels of Notch2 are ablated in lung and PA tissue samples from PAH patients compared to non-PAH controls. Interestingly, Notch2 expression was attenuated in human pulmonary artery endothelial cells (hPAECs) exposed to vasoactive factors including hypoxia, TGFβ, ET-1, and IGF-1. Gene silencing of Notch2 increased EC proliferation and reduced apoptosis. At the molecular level, Notch2-deficient hPAECs activated Akt, Erk1/2 and anti-apoptotic protein Bcl-2, and reduced levels of p21cip and Bax. Intriguingly, loss of Notch2 elicits a paradoxical activation of Notch1 and transcriptional upregulation of canonical Notch target genes Hes1, Hey1 and Hey2. Further, reduction in Rb and increased E2F1 binding to the Notch1 promoter appear to explain the upregulation of Notch1. In aggregate, our results demonstrate that loss of Notch2 derepresses Notch1 and elicits aberrant EC hallmarks of PAH. The data underscore a novel role for Notch in the maintenance of endothelial cell homeostasis.


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