scholarly journals Retinoic acid counteracts both the downregulation of thrombomodulin and the induction of tissue factor in cultured human endothelial cells exposed to tumor necrosis factor

Blood ◽  
1992 ◽  
Vol 80 (10) ◽  
pp. 2556-2562 ◽  
Author(s):  
H Ishii ◽  
S Horie ◽  
K Kizaki ◽  
M Kazama
Keyword(s):  
Endothelial Cells ◽  
Retinoic Acid ◽  
Tumor Necrosis Factor ◽  
Tissue Factor ◽  
Inflammatory Cytokines ◽  
Messenger Rna ◽  
Tumor Necrosis ◽  
Tnf Alpha ◽  
Mrna Levels ◽  
Necrosis Factor

Abstract Inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) shift the hemostatic balance of endothelial cell surfaces in favor of prothrombotic properties by downregulating thrombomodulin (TM) and inducing tissue factor (TF) expression. We investigated the effects of retinoic acid (RA) on the prothrombotic properties of cultured umbilical vein endothelial cells exposed to TNF-alpha. The approximate 50% downregulation of TM antigen and cofactor activity induced by TNF- alpha (10 U/mL for 24 hours) was completely prevented when the cells were coincubated with both TNF-alpha and 10 mumol/L RA. In accordance with changes in cell surface TM antigen levels, the 70% decrease in TM messenger RNA (mRNA) induced by TNF-alpha was also prevented by 10 mumol/L RA. TNF-alpha induced TF activity of lysed cells (100-fold greater than untreated controls), an effect prevented when the cells were coincubated with both the TNF-alpha and 10 mumol/L RA. The 34-fold increase in TF mRNA levels induced by TNF-alpha (10 U/mL for 3 hours) was only two-fold in the presence of both TNF-alpha and RA. The effects of RA on the regulation of TM and TF expression in the cells exposed to TNF-alpha was dose-dependent from 0.01 to 10 mumol/L RA. The present results suggest that RA may affect on the mRNA level to alter TM and TF expression, effectively counteracting expression of prothrombotic properties of endothelial cells induced by inflammatory cytokines such as TNF-alpha.

scholarly journals Retinoic acid counteracts both the downregulation of thrombomodulin and the induction of tissue factor in cultured human endothelial cells exposed to tumor necrosis factor

Blood ◽  
1992 ◽  
Vol 80 (10) ◽  
pp. 2556-2562 ◽  
Author(s):  
H Ishii ◽  
S Horie ◽  
K Kizaki ◽  
M Kazama
Keyword(s):  
Endothelial Cells ◽  
Retinoic Acid ◽  
Tumor Necrosis Factor ◽  
Tissue Factor ◽  
Inflammatory Cytokines ◽  
Messenger Rna ◽  
Tumor Necrosis ◽  
Tnf Alpha ◽  
Mrna Levels ◽  
Necrosis Factor

Inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) shift the hemostatic balance of endothelial cell surfaces in favor of prothrombotic properties by downregulating thrombomodulin (TM) and inducing tissue factor (TF) expression. We investigated the effects of retinoic acid (RA) on the prothrombotic properties of cultured umbilical vein endothelial cells exposed to TNF-alpha. The approximate 50% downregulation of TM antigen and cofactor activity induced by TNF- alpha (10 U/mL for 24 hours) was completely prevented when the cells were coincubated with both TNF-alpha and 10 mumol/L RA. In accordance with changes in cell surface TM antigen levels, the 70% decrease in TM messenger RNA (mRNA) induced by TNF-alpha was also prevented by 10 mumol/L RA. TNF-alpha induced TF activity of lysed cells (100-fold greater than untreated controls), an effect prevented when the cells were coincubated with both the TNF-alpha and 10 mumol/L RA. The 34-fold increase in TF mRNA levels induced by TNF-alpha (10 U/mL for 3 hours) was only two-fold in the presence of both TNF-alpha and RA. The effects of RA on the regulation of TM and TF expression in the cells exposed to TNF-alpha was dose-dependent from 0.01 to 10 mumol/L RA. The present results suggest that RA may affect on the mRNA level to alter TM and TF expression, effectively counteracting expression of prothrombotic properties of endothelial cells induced by inflammatory cytokines such as TNF-alpha.

scholarly journals Interleukin-1, tumor necrosis factor, and the production of colony- stimulating factors by cultured mesenchymal cells

Blood ◽  
1988 ◽  
Vol 72 (4) ◽  
pp. 1316-1323 ◽  
Author(s):  
CA Sieff ◽  
CM Niemeyer ◽  
SJ Mentzer ◽  
DV Faller
Keyword(s):  
Endothelial Cells ◽  
Tumor Necrosis Factor ◽  
Messenger Rna ◽  
Tumor Necrosis ◽  
Umbilical Vein ◽  
Interleukin 1 ◽  
Mesenchymal Cells ◽  
Colony Stimulating Factors ◽  
Gm Csf ◽  
Necrosis Factor

Abstract Although the genes for four hematopoietic colony-stimulating factors (CSFs) have been cloned, neither the mechanism of the regulation of their production nor their cellular origins have been established with certainty. Monocytes are known to produce colony-stimulating and burst- promoting activities, as well as several monokines such as interleukin- 1 (IL-1) and tumor necrosis factor (TNF). These monokines indirectly stimulate other mesenchymal cells to produce certain colony-stimulating factors such as granulocyte-macrophage CSF (GM-CSF). To determine whether monocytes produce other CSFs and if so, to compare the mechanism of regulation of production with that of endothelial cells and fibroblasts, we investigated the synthesis of CSFs by monocytes, human umbilical vein endothelial cells, and fibroblasts. We used total cellular RNA blot analysis to determine interleukin-3 (IL-3), GM-CSF, granulocyte CSF (G-CSF), and monocyte CSF (M-CSF) messenger RNA (mRNA) content and immunoprecipitation or bioassay to confirm the presence of the specific secreted proteins. The results indicate that M-CSF mRNA and protein are produced constitutively by all three cell types and their level of expression does not increase after induction. In contrast, GM-CSF and G-CSF mRNAs are barely detectable in uninduced monocytes and show an increase in expression after lipopolysaccharide treatment. Retrovirus-immortalized endothelial cells, unlike primary endothelial cells or both primary and immortalized fibroblasts, produce IL-1 constitutively; this correlates with their constitutive production of GM-CSF and G-CSF. IL-3 mRNA was not detectable in any of these cells either before or after induction. The results indicate that these mesenchymal cells can produce three CSFs: GM-CSF, G-CSF, and M-CSF; furthermore, the data suggest that the mechanism of regulation of M-CSF production is different from that of GM-CSF and G-CSF, and that the latter two inducible CSFs are regulated by different factors in monocytes compared with the other mesenchymal cells.

scholarly journals Tumor necrosis factor alpha induces endothelial galactosyl transferase activity and verocytotoxin receptors. Role of specific tumor necrosis factor receptors and protein kinase C

Blood ◽  
1995 ◽  
Vol 85 (3) ◽  
pp. 734-743 ◽  
Author(s):  
NC van de Kar ◽  
T Kooistra ◽  
M Vermeer ◽  
W Lesslauer ◽  
LA Monnens ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Protein Synthesis ◽  
Protein Kinase ◽  
Tumor Necrosis Factor ◽  
Tumor Necrosis ◽  
Tnf Alpha ◽  
Transferase Activity ◽  
Necrosis Factor Alpha ◽  
Galactosyl Transferase ◽  
Necrosis Factor

Infections with verocytotoxin (VT) producing Escherichia coli have been strongly implicated in the epidemic form of hemolytic uremic syndrome (HUS). Endothelial damage plays a central role in the pathogenesis of HUS. In vitro studies have shown that VT can damage endothelial cells after interaction with its cellular receptor globotriaosylceramide (GbOse3cer). Cytokines, such as tumor necrosis factor alpha (TNF alpha) and interleukin-1 (IL-1) can potentiate the toxic effect of VT by inducing a protein-synthesis dependent increase in VT receptors on endothelial cells. In this study, the mechanisms underlying the increase in endothelial VT receptors induced by TNF alpha were studied in more detail. To investigate which proteins were involved in this induction, endothelial cells were incubated with and without TNF alpha in the presence of 14C-galactose or 14C-glucose. Thin-layer chromatography (TLC) analysis of the glycolipid extracts of these cells demonstrated a markedly enhanced incorporation of 14C-galactose in GbOse3cer and other galactose-containing glycolipids, suggesting that TNF alpha enhanced galactosyl-transferase activity. To examine the role of the two recently cloned TNF-receptors (TNFR-p75 and TNFR-p55) in the TNF alpha-induced increase in GbOse3cer in human endothelial cells, cells were incubated with TNF alpha, the TNFR-p55 selective R32W-S86T- TNF alpha-mutant, or the TNFR-p75 selective D143N-A145R-TNF alpha- mutant. The effect of TNF alpha activation, determined by binding- experiments with 125I-VT-1, could be largely, but not completely mimicked by R32W-S86T-TNF alpha. Although incubation of cells with D143N-A145R-TNF alpha did not show an increase in VT-1 binding, the monoclonal antibody utr-1, which prevents binding to TNFR-p75, decreased the TNF alpha-induced VT-1 binding. Activation of protein kinase C (PKC) by phorbol ester increases the expression of VT-1 receptors; this effect was prevented by the PKC inhibitor Ro31–8220 and by homologous desensitization by pretreatment with phorbol ester. In contrast, the presence of the protein kinase inhibitor Ro31–8220 or desensitization of PKC activity reduced the TNF alpha-induced increase in VT-1 receptors maximally by 50% and 24%, respectively. Comparable reductions in overall protein synthesis and the synthesis of E-selectin and plasminogen activator inhibitor-1 (PAI-1) were observed. This suggests an effect on general protein synthesis rather than a specific effect of PKC in the signal transduction pathway, by which TNF alpha induces VT-1 receptors. Our results indicate that TNF alpha can increase the VT-1 receptors on endothelial cells by inducing galactosyl- transferase activity, that this action of TNF alpha mainly occurs via the TNFR-p55; and that PKC activation increases expression of VT-1 receptors by a separate mechanism that acts additively to the TNF alpha- induced increase in VT-1 receptors.

Colchicine has opposite effects on interleukin-1 beta and tumor necrosis factor-alpha production

1991 ◽  
Vol 261 (4) ◽  
pp. L315-L321 ◽  
Author(s):  
J. N. Allen ◽  
D. J. Herzyk ◽  
M. D. Wewers
Keyword(s):  
Tumor Necrosis Factor ◽  
Tumor Necrosis ◽  
Cytokine Production ◽  
Interleukin 1 ◽  
Tnf Alpha ◽  
Mrna Levels ◽  
Interleukin 1 Beta ◽  
Necrosis Factor Alpha ◽  
Factor Alpha ◽  
Necrosis Factor

To study the role of microtubules in cytokine production, the effect of the microtubule depolymerizing agent colchicine on lipopolysaccharide endotoxin (LPS)-induced interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) release by blood monocytes and alveolar macrophages were examined. Immunofluorescence microscopy demonstrated that LPS resulted in the appearance of microtubule-containing cytoplasmic appendages and that colchicine, which resulted in microtubule disruption in monocytes, blocked appendage formation. Colchicine resulted in approximately 50% increase in LPS-induced IL-1 beta release and a 50% decrease in LPS-induced TNF-alpha release by human monocytes at all doses of LPS tested. Although colchicine resulted in a statistically significant increase in LPS-stimulated human alveolar macrophage IL-1 beta release, the increase was not as great as that observed with monocytes. Northern blot analysis suggested that the colchicine effect occurs pretranslationally because colchicine caused an increase in LPS-stimulated IL-1 beta mRNA levels and a decrease in TNF-alpha mRNA levels. These results suggest that microtubules contribute to the regulation of endotoxin-stimulated mononuclear phagocyte cytokine production and that this regulation differs significantly between IL-1 beta and TNF-alpha.

scholarly journals Human serum IgA downregulates the release of inflammatory cytokines (tumor necrosis factor-alpha, interleukin-6) in human monocytes

Blood ◽  
1994 ◽  
Vol 83 (5) ◽  
pp. 1278-1288 ◽  
Author(s):  
HM Wolf ◽  
MB Fischer ◽  
H Puhringer ◽  
A Samstag ◽  
E Vogel ◽  
...  
Keyword(s):  
Tumor Necrosis Factor ◽  
Inflammatory Cytokines ◽  
Tumor Necrosis ◽  
Tnf Alpha ◽  
Human Monocytes ◽  
Necrosis Factor Alpha ◽  
Serum Iga ◽  
Iga Antibodies ◽  
Factor Alpha ◽  
Necrosis Factor

Abstract While the protective effect of IgA antibodies against infection of the mucosal surfaces is well documented, the mechanisms involved are not entirely clear. The aim of the current study is to investigate the effect of human serum IgA on the release of inflammatory cytokines in human monocytes activated with a particulate stimulus, Haemophilus influenzae type b (Hib), or soluble lipopolysaccharide (LPS) purified from Escherichia coli. Our results show that IgA downregulates tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) production, whereas IgG examined in parallel had no effect. IgA had no inhibitory effect on Hib-induced granulocyte-macrophage colony-stimulating factor release. TNF-alpha and IL-6 release were downmodulated if IgA was present during cytokine induction, and IgA was also inhibitory if added to Hib-pretreated monocytes during the phase of cytokine release. These findings indicate that there are at least two mechanisms whereby IgA antibodies can downregulate TNF-alpha and IL-6 release in human monocytes: by a mechanism acting during the time of monocyte activation, and a mechanism that downregulates the production and/or the release of these cytokines in activated monocytes. Regulation of TNF-alpha and IL-6 release by IgA may be among the antiinflammatory mechanisms preventing an uncontrolled release of potentially noxious levels of inflammatory cytokines during acute and/or chronic inflammation.

Polymorphisms in Coagulant and Inflammatory Genes Modify the Phenotype of Severe Hemophilia A and B.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1009-1009 ◽  
Author(s):  
G. Jayandharan ◽  
Mercy Devadharshini ◽  
Auro Viswabandya ◽  
Sukesh C. Nair ◽  
R.V. Shaji ◽  
...  
Keyword(s):  
Tumor Necrosis Factor ◽  
Tissue Factor ◽  
Plasminogen Activator ◽  
Protein C ◽  
Tumor Necrosis ◽  
Hemophilia A ◽  
Tnf Alpha ◽  
Severe Hemophilia ◽  
Tgf Beta ◽  
Necrosis Factor

Abstract Among patients with severe hemophilia (<1% factor level), 10–15% are known to have a clinically mild phenotype. The basis for this phenomenon is unclear. We hypothesized that functionally significant polymorphisms in the coagulant, inflammatory and immunoregulatory genes may affect the phenotype of severe hemophilia. A total 114 patients with hemophilia A (n=95) and hemophilia B (n=19) were studied. All these patients were on minimal on-demand treatment. Patients were evaluated for the frequency and site of hemorrhage. Their clinical and radiological joint scores were documented. They were categorized as ‘mild’ (<1 affected joint and < 5 bleeds in the preceding year, n=15) or ‘severe’ (>1 affected joint and >5bleeds, n=99). Functional polymorphisms in the coagulant system (human platelet alloantigen; tissue factor; fibrinogen; factors II; V; VII; XIIIA; thrombin activable fibrinolysis inhibitor (TAFI); endothelial protein C receptor; endothelial nitric oxide synthase 3; tissue plasminogen activator; plasminogen activator inhibitor; tissue factor pathway inhibitor; protein C and S; thrombomodulin), known procoagulant factors (methylene tetrahydrofolate reductase gene), inflammatory cytokine genes (tumor necrosis factor alpha; transforming growth factor beta; interleukin (IL) 10; IL 6; IL 1beta; IL 1 beta receptor antagonist; tumor necrosis factor beta), immunoregulatory cytokine genes (interferon gamma; HLA B27; FC gamma receptor), MDM2, angiotensin converting enzyme and HFE genes were genotyped. The mean age in the two groups was 18.5 & 14.85, p=0.124. The clinical features showing significant difference are shown in the table. Of the polymorphisms studied, the FVII RQ/QQ (lower levels) (RR-3.99, p=0.022, 95% CI 1.2–13.4), TNF alpha-308AA/AG (pro-inflammatory) (RR-3.4, p=0.037, 95% CI, 1.07–10.7), TGF beta Codon 10 CC/CT (pro-inflammatory) (RR-2.8, p=0.07, 95% CI, 0.91–8.3), have been associated with a severe phenotype while MDM2GG (anti-inflammatory, RR-0.3, p=0.038, 95% CI, 0.1–0.93) was associated with a milder phenotype. We hypothesize that the bleeding frequency in severe hemophilia may be increased due to relatively lower FVII levels and a combination of cytokine driven pro-inflammatory state involving TNF alpha, TGF beta and MDM2 would cause destruction of the cartilage resulting in elaboration of metalloproteinases from chondrocytes leading to the development of arthropathy. Parameter Severe, n=99 Median (Range) Mild, n=15 Median (Range) p Value Number of bleeds /yr 15(3–74) 2(0–5) 0.000 Number of joints /yr 3 (1–6) 1 (0–1) 0.000 Age at first clinical symptom (months) 21(1–300) 60(6–90) 0.056 WFH clinical score 10 (0–27) 4 (0–21) 0.000 Pettersson score 13 (0–57) 6 (0–20) 0.001

scholarly journals Differential expression of adrenomedullin and resistin in 3T3-L1 adipocytes treated with tumor necrosis factor-alpha

2003 ◽  
pp. 231-238 ◽  
Author(s):  
Y Li ◽  
K Totsune ◽  
K Takeda ◽  
K Furuyama ◽  
S Shibahara ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Tumor Necrosis Factor ◽  
Tumor Necrosis Factor Alpha ◽  
Tumor Necrosis ◽  
Tnf Alpha ◽  
Mrna Levels ◽  
Necrosis Factor Alpha ◽  
Factor Alpha ◽  
Necrosis Factor ◽  
Resistin Mrna

DESIGN: It has recently been shown that deficiency of adrenomedullin (AM), a potent vasodilator peptide, leads to insulin resistance. We studied expression of AM in NIH 3T3-L1 adipocytes and compared it with expression of resistin, an adipocyte-derived peptide hormone that is proposed to cause insulin resistance. Moreover, we studied the effects of tumor necrosis factor-alpha (TNF-alpha), a known mediator of insulin resistance, on the expression of AM and resistin in 3T3-L1 adipocytes. METHODS: 3T3-L1 cells were induced to differentiate to adipocytes by insulin, dexamethasone and 3-isobutyl-1-methylxanthine. Expression of AM mRNA and resistin mRNA was examined by Northern blot analysis. Immunoreactive AM in the medium was measured by RIA. RESULTS: AM mRNA was expressed in preadipocytes, but barely detectable in adipocytes. Immunoreactive AM was detected in the medium of both preadipocytes and adipocytes, with about 2.5 times higher levels found in preadipocytes. In contrast, resistin mRNA was expressed in adipocytes, whereas it was not detected in preadipocytes. Treatment with TNF-alpha increased AM expression in both adipocytes and preadipocytes, whereas it decreased resistin mRNA levels in adipocytes. CONCLUSIONS: The present study has shown that AM expression was down-regulated and resistin expression was up-regulated during adipocyte differentiation of 3T3-L1 cells. TNF-alpha acted as a potent negative regulator of resistin expression and a potent positive regulator of AM expression in adipocytes, raising the possibility that in addition to its known actions in causing insulin resistance, TNF-alpha may also have actions against insulin resistance through AM and resistin.

scholarly journals Human serum IgA downregulates the release of inflammatory cytokines (tumor necrosis factor-alpha, interleukin-6) in human monocytes

Blood ◽  
1994 ◽  
Vol 83 (5) ◽  
pp. 1278-1288 ◽  
Author(s):  
HM Wolf ◽  
MB Fischer ◽  
H Puhringer ◽  
A Samstag ◽  
E Vogel ◽  
...  
Keyword(s):  
Tumor Necrosis Factor ◽  
Inflammatory Cytokines ◽  
Tumor Necrosis ◽  
Tnf Alpha ◽  
Human Monocytes ◽  
Necrosis Factor Alpha ◽  
Serum Iga ◽  
Iga Antibodies ◽  
Factor Alpha ◽  
Necrosis Factor

While the protective effect of IgA antibodies against infection of the mucosal surfaces is well documented, the mechanisms involved are not entirely clear. The aim of the current study is to investigate the effect of human serum IgA on the release of inflammatory cytokines in human monocytes activated with a particulate stimulus, Haemophilus influenzae type b (Hib), or soluble lipopolysaccharide (LPS) purified from Escherichia coli. Our results show that IgA downregulates tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) production, whereas IgG examined in parallel had no effect. IgA had no inhibitory effect on Hib-induced granulocyte-macrophage colony-stimulating factor release. TNF-alpha and IL-6 release were downmodulated if IgA was present during cytokine induction, and IgA was also inhibitory if added to Hib-pretreated monocytes during the phase of cytokine release. These findings indicate that there are at least two mechanisms whereby IgA antibodies can downregulate TNF-alpha and IL-6 release in human monocytes: by a mechanism acting during the time of monocyte activation, and a mechanism that downregulates the production and/or the release of these cytokines in activated monocytes. Regulation of TNF-alpha and IL-6 release by IgA may be among the antiinflammatory mechanisms preventing an uncontrolled release of potentially noxious levels of inflammatory cytokines during acute and/or chronic inflammation.

scholarly journals Recombinant human tumor necrosis factor alpha regulates c-myc expression in HL-60 cells at the level of transcription

Blood ◽  
1987 ◽  
Vol 70 (1) ◽  
pp. 200-205
Author(s):  
A Tobler ◽  
D Johnston ◽  
HP Koeffler
Keyword(s):  
Tumor Necrosis Factor ◽  
Tumor Necrosis ◽  
Human Tumor ◽  
Tnf Alpha ◽  
Mrna Levels ◽  
Human Tumor Necrosis Factor ◽  
Mrna Accumulation ◽  
Necrosis Factor Alpha ◽  
Factor Alpha ◽  
Necrosis Factor

Recombinant human tumor necrosis factor alpha (TNF alpha) effectively inhibits clonal growth of leukemic cells from patients and several cell lines, including the promyelocytic HL-60 cells. Decreased expression of the c-myc oncogene is linked to growth arrest and terminal cellular differentiation. The present study characterizes the effect of TNF alpha on the regulation of the c-myc gene in HL-60 cells. TNF alpha (100 U/mL) rapidly inhibited messenger RNA (mRNA) accumulation of c-myc with a 50% reduction in less than one hour. Dose-response studies showed that a 50% reduction of c-myc mRNA occurred in the range of 15 U/mL. In vitro nuclear run-on experiments showed that this decrease of c-myc-mRNA accumulation was the result of a reduced rate of transcription of c-myc by TNF alpha. Further studies demonstrated that TNF alpha did not post-transcriptionally alter levels of c-myc mRNA, and the inhibitory action of TNF alpha on c-myc expression in HL-60 cells did not depend on new protein synthesis. In the conditions of all the experiments, TNF alpha did not affect cell viability. By contrast, TNF alpha (500 U/mL) did not decrease mRNA levels of c-myc in an HL-60 variant cell line whose growth was not inhibited by TNF alpha; also TNF alpha (500 U/mL) increased c-myc-mRNA levels in normal fibroblasts whose growth is known to be stimulated by TNF alpha. These findings, in concert with prior studies, show a close association between growth inhibition of HL-60 cells and decreased levels of mRNA coding for c-myc.

Fluid Shear Stress Attenuates Tumor Necrosis Factor-α–Induced Tissue Factor Expression in Cultured Human Endothelial Cells

Blood ◽  
1998 ◽  
Vol 91 (11) ◽  
pp. 4164-4172 ◽  
Author(s):  
Yutaka Matsumoto ◽  
Yohko Kawai ◽  
Kiyoaki Watanabe ◽  
Kazuo Sakai ◽  
Mitsuru Murata ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Shear Stress ◽  
Tumor Necrosis Factor ◽  
Tissue Factor ◽  
Shear Force ◽  
Tumor Necrosis ◽  
Shear Stresses ◽  
Dependent Manner ◽  
Tnf Α ◽  
Necrosis Factor

Abstract Hemodynamic forces modulate various endothelial cell functions under gene regulation. Previously, we have shown that fibrinolytic activity of endothelial cells is enhanced by the synergistic effects of shear stress and cytokines. In this study, we investigated the effect of shear stress on tumor necrosis factor (TNF)-α–induced tissue factor (TF) expression in cultured human umbilical vein endothelial cells (HUVECs), using a modified cone-plate viscometer. Shear stresses at physiological levels reduced TNF-α (100 U/mL)–induced TF expression at both mRNA and antigen levels, in a shear-intensity and exposure-time dependent manner, whereas shear stress itself did not induce TF expression in HUVECs. TF expressed on the cell surfaces measured by flow cytometry using an anti-TF monoclonal antibody (HTF-K180) was also decreased to one third by shear force applied at 18 dynes/cm2 for 15 hours before and 6 hours after TNF-α stimulation. Furthermore, functional activity of TF, as assessed by the activation of factor X in the presence of FVIIa and Ca2+, was also decreased by shear application. However, the stability of TF mRNA was not decreased in the presence of shear stress. These results suggest that shear force acts as an important regulator of TF expression in endothelium at the transcriptional level.

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