The proteasome pathway is required for cytokine-induced endothelial-leukocyte adhesion molecule expression (original) (raw)
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Endothelial adhesion molecule expression in an in vitro model of inflammation
Clinica Chimica Acta, 2002
Background: Cytokines influence the expression of adhesion molecules and hence, regulate the passage of leucocytes from the blood to the site of inflammation causing leucocyte accumulation and the modulation of the nature and progression of inflammatory responses. They form a complex communication network causing results which are not determined by the effects of a single cytokine but especially by the interaction of several cytokines. Method: For the determination of adhesion molecule expression on the surface of enzymatically detached endothelial cells, flow cytometry is applied. Fluorescence-conjugated mouse monoclonal antibodies directed against VCAM-1, ICAM-1, PECAM-1, CD34, E-and P-selectin are used. Results: We clearly demonstrate that ICAM-1, PECAM-1, P-selectin and CD34 are-in relation to an incubation cocktail containing solely TNF-a, IL-1h and IFN-g-altered antagonistically by the supplementary addition of the inflammatory cytokines IL-2 and IL-6 as well as the anti-inflammatory cytokines IL-4 and IL-10, whereas VCAM-1 is synergistically enhanced under the same test conditions. Conclusion: The results of our in vitro investigations show that the effects of a single cytokine within a multicomponent cytokine combination on endothelial adhesion molecule expression are strongly influenced by the nature of the other cytokines present in the combination tested.
Getting to the site of inflammation: the leukocyte adhesion cascade updated
Nature Reviews Immunology, 2007
Leukocyte rolling, adhesion and transmigration were all described by the pathologists of the nineteenth century 1,2. With the discovery of integrins, selectins and their respective ligands, and of chemokines and chemokine receptors, the leukocyte adhesion cascade emerged as a concept that began to explain the recruitment of leukocyte subsets to specific sites. The original model of leukocyte adhesion proposed that the cascade achieved combinatorial specificity 3,4 through the three steps of selectin-mediated rolling, chemokine-triggered activation and integrin-dependent arrest. However, recent evidence suggests that additional steps occur during integrin-mediated leukocyte adhesion, which remain incompletely understood 5,6. Transendothelial migration was first described almost 200 years ago 1 , but its molecular mechanisms were only discovered recently 7 and were not included in the classical adhesion cascade 3,4 .Integrin-mediated adhesion is characterized by at least two events-arrest from rolling, which is mediated by increased leukocyte avidity for the endothelium (BOX 1), and a post-binding phase of adhesion stabilization, the molecular basis of which is only now beginning to emerge, although it was correctly predicted to be important more than 10 years ago 4. In the past decade, new insights have been gained into the structures and signalling events that underlie integrin activation 5,6 , into the post-adhesion events that strengthen leukocyte attachment to the endothelium, and into the molecules that are involved in leukocyte transendothelial migration 7,8. These insights have led to an expanded version of the original three-step leukocyte adhesion cascade, which now includes slow rolling, adhesion strengthening, intraluminal crawling, paracellular and transcellular migration, and migration through the basement membrane (FIG. 1). Leukocyte rolling The role of selectins. Rolling is mediated by L-selectin, P-selectin and E-selectin 9 , which interact with P-selectin glycoprotein ligand 1 (PSGL1) 10 and other glycosylated ligands. L-selectin is expressed by most leukocytes, whereas E-selectin and P-selectin are expressed by inflamed endothelial cells. P-selectin is also expressed by activated platelets. PSGL1 has a dominant role as a ligand for all three selectins, although it was originally described as a P-selectin ligand. The binding of PSGL1 to L-selectin nucleates leukocyte-leukocyte interactions, by which adherent leukocytes 11 and leukocyte-derived fragments 12 facilitate secondary leukocyte capture or tethering, terms that are used synonymously. Secondary tethering also enables leukocytes that do not express ligands for E-selectin or P-selectin to reach sites of inflammation. Although PSGL1 is expressed on almost all leukocytes, it is functional only when glycosylated correctly (BOX 2). In addition to its expression by leukocytes, PSGL1 was recently found to be expressed by certain endothelial cells 13,14. In addition to PSGL1, E-selectin also binds to glycosylated CD44 and E-selectin ligand 1 (ESL1) 15 .
The Journal of Cell Biology, 1998
Previous studies have shown that polymorphonuclear leukocyte (PMN) adherence to endothelial cells (EC) induces transient increases in EC cytosolic free calcium concentration ([Ca 2 ϩ ] i ) that are required for PMN transit across the EC barrier (Huang, A.J., J.E. Manning, T.M. Bandak, M.C. Ratau, K.R. Hanser, and S.C. . J. Cell Biol. 120:1371-1380. To determine whether stimulation of [Ca 2 ϩ ] i changes in EC by leukocytes was induced by the same molecules that mediate leukocyte adherence to EC, [Ca 2 ϩ ] i was measured in Fura2-loaded human EC monolayers. Expression of adhesion molecules by EC was induced by a pretreatment of the cells with histamine or with Escherichia coli lipopolysaccharide (LPS), and [Ca 2 ϩ ] i was measured in single EC after the addition of mAbs directed against the EC adhesion proteins P-selectin, E-selectin, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), or platelet/endothelial cell adhesion molecule-1 (PECAM-1). Both anti-P-and anti-E-selectin mAb, as well as anti-VCAM-1 mAb, induced transient increases in EC [Ca 2 ϩ ] i that were comparable to those induced by 200 M histamine. In contrast, no effect was obtained by mAbs directed against the endothelial ICAM-1 or PECAM-1. PMN adherence directly stimulated increases in [Ca 2 ϩ ] i in histamine-or LPS-treated EC. mAbs directed against leukocyte CD18 or PECAM-1, the leukocyte counter-receptors for endo-thelial ICAM-1 and PECAM-1, respectively, did not inhibit PMN-induced EC activation. In contrast, mAb directed against sialyl Lewis x (sLe x ), a PMN ligand for endothelial P-and E-selectin, completely inhibited EC stimulation by adherent PMN. Changes in EC [Ca 2 ϩ ] i were also observed after adherence of peripheral blood monocytes to EC treated with LPS for 5 or 24 h. In these experiments, the combined addition of mAbs to sLe x and VLA-4, the leukocyte counter-receptor for endothelial VCAM-1, inhibited [Ca 2 ϩ ] i changes in the 5 h-treated EC, whereas the anti-VLA-4 mAb alone was sufficient to inhibit [Ca 2 ϩ ] i changes in the 24 h-treated EC. Again, no inhibitory effect was observed with an anti-CD18 or anti-PECAM-1 mAb. Of note, the conditions that induced changes in EC [Ca 2 ϩ ] i , i.e., mAbs directed against endothelial selectins or VCAM-1, and PMN or monocyte adhesion to EC via selectins or VCAM-1, but not via ICAM-1 or PECAM-1, also induced a rearrangement of EC cytoskeletal microfilaments from a circumferential ring to stress fibers. We conclude that, in addition to their role as adhesion receptors, endothelial selectins and VCAM-1 mediate endothelial stimulation by adhering leukocytes.
The Journal of Cell Biology
We have distinguished five TNF-alpha-inducible cell adhesion mechanisms on microvasculature-derived endothelioma cells of the mouse which mediate the binding of different types of leukocytes. Three of these mechanisms could be identified as the mouse homologs of ICAM-1, VCAM-1, and E-selectin, of which the latter was defined by the novel mAb 21KC10. The fourth TNF-alpha-inducible cell adhesion mechanism was blocked by antibodies specific for mouse P-selectin. We have recently shown that TNF-alpha stimulates the synthesis of P-selectin in mouse endothelioma cells (A. Weller, S. Isenmann, D. Vestweber. 1992. J. Biol. Chem. 267:15176-15183). Here we show that this stimulation leads to maximal cell surface expression levels within 4 h after stimulation while the same endothelioma cells are also able to upregulate P-selectin at the cell surface within minutes after stimulation with PMA. Both effects are additive. The fifth TNF-induced cell adhesion mechanism is defined by mediating the b...
Adhesion molecules and their role in vascular disease
American journal of hypertension, 2001
A variety of recently discovered glycoproteins have been implicated in cell-cell interactions that are critical for normal hemostasis, immune surveillance, and vascular wall integrity. These cell adhesion molecules (CAM) are known to mediate blood cell (leukocyte, platelet)-endothelial cell interactions that can occur in all segments of the microvasculature under certain physiological (eg, hemostasis) and pathological (eg, inflammation) conditions. The multistep process of leukocyte recruitment illustrates how the coordinated and regulated expression of structurally and functionally distinct families of CAM can elicit a highly reproducible vascular response to inflammation. Selectins mediate the initial, low-affinity leukocyte-endothelial cell interaction that is manifested as leukocyte rolling. This transient binding results in further leukocyte activation and subsequent firm adhesion and transendothelial migration of leukocytes, both of which are mediated by interactions between m...
Cell and Tissue Research, 1996
The time course of expression of the adhesion molecules E-selectin, VCAM-1, ICAM-1 and PECAM-1 was studied in interleukin-1β-stimulated human umbilical vein cells (HUVEC) and the subcellular sites of synthesis were determined by means of fluorescence immunohistochemistry. The , but was constitutively present for ICAM-1. In conclusion, each adhesion molecule shows a specific time-dependent course of appearance and disappearance in interleukin-1β-stimulated HUVECs in accordance with their physiological role in vivo. These morphological results confirm data obtained by flow cytometry and Western blotting, but they provide new information about the behaviour of individual cells with regard to the sites of synthesis and cellular localization of the adhesion molecules.