Inflammatory responses of endothelial cells experiencing reduction in flow after conditioning by shear stress

Division of Medical Sciences, The Medical School, University of Birmingham, UK.
Journal of Cellular Physiology (Impact Factor: 3.84). 09/2008; 216(3):732-41. DOI: 10.1002/jcp.21457
Source: PubMed


Exposure of endothelial cells (EC) to shear stress reduces their response to tumour necrosis factor-alpha (TNF). We tested how shear-conditioned EC responded to reduction in flow, either by spontaneously binding leukocytes, or by increasing sensitivity to TNF. Human umbilical vein EC were exposed to shear stress of 2.0 Pa (20 dyn/cm(2)) for 24 h. Shear was then reduced to stasis (30 sec perfusion each hour to exchange medium) or 0.003 Pa (creeping flow). At chosen times, neutrophils were perfused over the EC at 0.1 Pa (effective reperfusion). EC developed an ability to capture flowing neutrophils that lasted from 1 to 3 h after flow reduction, which was reduced by antibody against P-selectin or pre-treatment of EC with an inhibitor of NADPH-oxidase. Adhesion of neutrophils to TNF-treated EC was greatly suppressed by shear-conditioning, remained suppressed immediately after cessation of flow and then took 48 h to approach the level in static cultures. Interestingly, the response to TNF remained suppressed in cultures switched to creeping flow. Gene array analysis confirmed that differently recovered cells had separate phenotypes. Thus, an acute response of EC to reduction in shear may contribute to leukocyte recruitment, along with hypoxia, in ischaemia and reperfusion. Prolonged cessation of flow may increase the sensitivity of EC to inflammatory stimuli, but this effect may be suppressed by residual flow.

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    • "ECs are first exposed to fluid shear stress (i.e. pre-conditioned) and then subjected to chemical stimuli under static conditions [21]. Additionally, simultaneous shear-cytokine induced EC response is typically observed in limited time frames [22], [23], [24]. "
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    ABSTRACT: Endothelial cells (ECs) are continuously exposed to hemodynamic forces imparted by blood flow. While it is known that endothelial behavior can be influenced by cytokine activation or fluid shear, the combined effects of these two independent agonists have yet to be fully elucidated. We investigated EC response to long-term inflammatory cues under physiologically relevant shear conditions via E-selectin expression where monolayers of human umbilical vein ECs were simultaneously exposed to laminar fluid shear and interleukin-1ß (shear-cytokine activation) in a parallel plate flow chamber. Naïve ECs exposed to shear-cytokine activation display significantly higher E-selectin expression for up to 24 hr relative to ECs activated in static (static-cytokine). Peak E-selectin expression occurred after 8-12 hr of continuous shear-cytokine activation contrary to the commonly observed 4-6 hr peak expression in ECs exposed to static-cytokine activation. Cells with some history of high shear conditioning exhibited either high or muted E-selectin expression depending on the durations of the shear pre-conditioning and the ensuing shear-cytokine activation. Overall, the presented data suggest that a high laminar shear enhances acute EC response to interleukin-1ß in naïve or shear-conditioned ECs as may be found in the pathological setting of ischemia/reperfusion injury while conferring rapid E-selectin downregulation to protect against chronic inflammation.
    PLoS ONE 02/2012; 7(2):e31874. DOI:10.1371/journal.pone.0031874 · 3.23 Impact Factor
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    • "Graphical representation: solid black (0 h), open (12 h) and solid grey (24 h). CLEC14A is a novel tumor endothelial marker M Mura et al Topper, 2004; Matharu et al., 2008). Around 3% of genes expressed in endothelial cells appear to be regulated by shear stress (Chu and Peters, 2008). "
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    ABSTRACT: Tumor endothelial markers (TEMs) that are highly expressed in human tumor vasculature compared with vasculature in normal tissue hold clear therapeutic potential. We report that the C-type lectin CLEC14A is a novel TEM. Immunohistochemical and immunofluorescence staining of tissue arrays has shown that CLEC14A is strongly expressed in tumor vasculature when compared with vessels in normal tissue. CLEC14A overexpression in tumor vessels was seen in a wide range of solid tumor types. Functional studies showed that CLEC14A induces filopodia and facilitates endothelial migration, tube formation and vascular development in zebrafish that is, CLEC14A regulates pro-angiogenic phenotypes. CLEC14A antisera inhibited cell migration and tube formation, suggesting that anti-CLEC14A antibodies may have anti-angiogenic activity. Finally, in endothelial cultures, expression of CLEC14A increased at low shear stress, and we hypothesize that low shear stress due to poor blood flow in the disorganized tumor vasculature induces expression of CLEC14A on tumor vessels and pro-angiogenic phenotypes.
    Oncogene 06/2011; 31(3):293-305. DOI:10.1038/onc.2011.233 · 8.46 Impact Factor
    • "Graphical representation: solid black (0 h), open (12 h) and solid grey (24 h). CLEC14A is a novel tumor endothelial marker M Mura et al Topper, 2004; Matharu et al., 2008). Around 3% of genes expressed in endothelial cells appear to be regulated by shear stress (Chu and Peters, 2008). "

    Cancer Research 01/2011; 70(8 Supplement):1589-1589. DOI:10.1158/1538-7445.AM10-1589 · 9.33 Impact Factor
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