Hemodynamic Regulation of Inflammation at the Endothelial–Neutrophil Interface

Department of Bioengineering, Institute for Medicine and Engineering, University of Pennsylvania, 1024 Vagelos Research Laboratory, 3340 Smith Walk, Philadelphia, PA 19104, USA.
Annals of Biomedical Engineering (Impact Factor: 3.23). 05/2008; 36(4):586-95. DOI: 10.1007/s10439-008-9465-4
Source: PubMed


Arterial shear stress can regulate endothelial phenotype. The potential for anti-inflammatory effects of shear stress on TNFalpha-activated endothelium was tested in assays of cytokine expression and neutrophil adhesion. In cultured human aortic endothelial cells (HAEC), arterial shear stress of 10 dyne/cm(2) blocked by >80% the induction by 5 ng/mL TNFalpha of interleukin-8 (IL-8) and IL-6 secretion (50 and 90% reduction, respectively, in the presence of nitric oxide synthase antagonism with 200 microM nitro-L-arginine methylester, L-NAME). Exposure of TNFalpha-stimulated HAEC to arterial shear stress for 5 h also reduced by 60% (p < 0.001) the conversion of neutrophil rolling to firm arrest in a venous flow assay conducted at 1 dyne/cm(2). Also, neutrophil rolling lengths at 1 dyne/cm(2) were longer when TNFalpha-stimulated HAEC were presheared for 5 h at arterial stresses. In experiments with a synthetic promoter that provides luciferase induction to detect cis interactions of glucocorticoid receptor (GR) and NFkappaB, shear stress caused a marked 40-fold induction of luciferase in TNFalpha-treated cells, suggesting a role for GR pathways in the anti-inflammatory actions of fluid shear stress. Hemodynamic force exerts anti-inflammatory effects on cytokine-activated endothelium by attenuation of cytokine expression and neutrophil firm arrest.

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    • "We show for the first time that the co-stimulation of naïve ECs (not previously exposed to shear in vitro) with flow-induced shear and IL-1β induces the expression of significantly higher levels of functional E-selectin molecules up to 24 hr when compared with monolayers stimulated under static condition only (Figure 1). This is interesting since E-selectin expression by ECs is typically not inducible by laminar shear alone [35], [47], [48] as was shown in Figure 1 though one report showed a 4 fold increase in E-selectin mRNA in human aortic ECs in response to 4.5 dyn cm−2 (but not at >10 dyn cm−2) of laminar shear [49]. Similarly, peak E-selectin expression is well-documented to occur between 4–6 hr in static-cytokine stimulated cells compared to the 8–12 hr peak observed with naïve cells under shear-cytokine activation (Figure 2A). "
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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.
    Full-text · Article · Feb 2012 · PLoS ONE
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    • "The expression of adhesion molecules, such as VCAM-1, in response to chemokines and cytokines is essential in the acute inflammatory response and represents a clear sign of an activated endothelial phenotype [35,37-39]. Unidimensional and bidimensional western blots analysis [40,41] revealed that TSFZR75.30 was able to induce the expression of VCAM-1a (Mr 81 kDa/pI 5.1) [NCBI access number NP_001069] and VCAM-1b (Mr 71 kDa/pI 5.0) [NCBI access number NP_542413] in HUVECs in a similar magnitude as TNF (Figure 2A). "
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    ABSTRACT: Several common aspects of endothelial phenotype, such as the expression of cell adhesion molecules, are shared between metastasis and inflammation. Here, we analyzed VCAM-1 variants as biological markers of these two types of endothelial cell activation. With the combination of 2-DE and western blot techniques and the aid of tunicamycin, we analyzed N-glycosylation variants of VCAM-1 in primary human endothelial cells stimulated with either TNF or tumoral soluble factors (TSF's) derived from the human breast cancer cell line ZR75.30. Treatments induced a pro-adhesive endothelial phenotype. 2D western blots analysis of cells subjected to both treatments revealed the expression of the two known VCAM-1 isoforms and of previously unknown isoforms. In particular TSFZR75.30 induced an isoform with a relative molecular mass (Mr) and isoelectric point (pI) of 75-77 kDa and 5.0, respectively. The unknown isoforms of VCAM-1 that were found to be overexpressed after treatment with TSF's compared with TNF, could serve as biomarkers to discriminate between inflammation and metastasis. 2D western blots revealed three new VCAM-1 isoforms expressed in primary human endothelial cells in response to TSF stimulation. Each of these isoforms varies in Mr and pI and could be the result of differential glycosylation states.
    Full-text · Article · Nov 2009 · BMC Chemical Biology
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    ABSTRACT: The effects of ethanol at physiological concentrations on neutrophil membrane tether pulling, adhesion lifetime, rolling, and firm arrest behavior were studied in parallel-plate flow chamber assays with adherent 1-microm-diameter P-selectin-coated beads, P-selectin-coated surfaces, or IL-1-stimulated human endothelium. Ethanol (0.3% by volume) had no effect on P-selectin glycoprotein ligand-1 (PSGL-1), L-selectin, or CD11b levels but caused PSGL-1 redistribution. Also, ethanol prevented fMLP-induced CD11b up-regulation. During neutrophil collisions with P-selectin-coated beads at venous wall shear rates of 25-100 s(-1), ethanol increased membrane tether length and membrane growth rate by 2- to 3-fold but reduced the adhesion efficiency (detectable bonding per total collisions) by 2- to 3-fold, compared with untreated neutrophils. Without ethanol treatment, adhesion efficiency and adhesion lifetime declined as wall shear rate was increased, whereas ethanol caused the adhesion lifetime over all events to increase from 0.1 s to 0.5 s as wall shear rate was increased, an example of pharmacologically induced hydrodynamic thresholding. Consistent with this increased membrane fluidity and reduced capture, ethanol reduced rolling velocity by 37% and rolling flux by 55% on P-selectin surfaces at 100 s(-1), compared with untreated neutrophils. On IL-1-stimulated endothelium, rolling velocity was unchanged by ethanol treatment, but the fraction of cells converting to firm arrest was reduced from 35% to 24% with ethanol. Overall, ethanol caused competing biophysical and biochemical effects that: 1) reduced capture due to PSGL-1 redistribution, 2) reduced rolling velocity due to increased membrane tether growth, and 3) reduced conversion to firm arrest.
    Preview · Article · Sep 2008 · The Journal of Immunology
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