Essential Role for Activated Leukocyte Cell Adhesion Molecule in Transendothelial Migration.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3691-3691
Author(s):  
Solomon F. Ofori-Acquah

Abstract Activated leukocyte cell adhesion molecule (ALCAM/CD166) is a member of the immunoglobulin cell adhesion super family, which has been implicated in diverse physiological and pathophysiological events involving cell migration. Hitherto, ALCAM’s role in inflammation has not been determined. In this study, we show ALCAM is involved in controlling migration of mononuclear leukocytes across the pulmonary endothelium. We demonstrated that ALCAM is localized at intercellular junctions in pulmonary microvascular endothelial cells in vitro and in vivo. ALCAM co-localized with multiple adherens junction molecules including cadherins, catenins and Dlg, as determined by confocal microscopy, and these observations were confirmed by co-immunoprecipitation and co-distribution assays. Treatment of endothelial cultures with EGTA and cytochalasin D translocated ALCAM from intercellular junctions to the cytosol indicating a requirement for homotypic cadherin adhesion and an intact endothelial cytoskeleton for maintaining ALCAM at endothelial cell junctions. Collectively, these data supports the conclusion that ALCAM contributes to the adherens junction complex in endothelial cells. To determine ALCAM’s role in leukocyte-endothelial cell interactions, adult Sprague Dawley rats were intratracheally instilled with macrophage inflammatory protein-1, and this treatment caused acute expression of ALCAM exclusively in newly recruited mononuclear but not polymorphonuclear leukocytes in the alveolar airway. Given that no ALCAM reactivity was observed in peripheral blood leukocytes, we concluded ALCAM is activated as part of the phenotypic switch by mononuclear leukocytes transitioning from circulation to interstitial tissue compartments. To determine the physiological relevance of this finding we examined whether ALCAM was required for transendothelial migration using monocyte chemoattractant protein 1 (MCP-1). MCP-1 dose- and time-dependently increased the number of transmigrated THP-1 monocytes across pulmonary microvascular endothelial monolayers. Recombinant soluble ALCAM dose-dependently reduced the number of transmigrated THP-1 monocytes, whereas in control experiments recombinant soluble vascular endothelial cadherin had no effect on transmigration. This study shows for the first time that ALCAM is located at endothelial cell junctions where it is intimately involved in controlling the number of monocytes that pass through endothelial barriers. ALCAM may therefore play an essential role in the response to inflammation by enhancing recruitment of mononuclear leukocytes by inflamed tissues.

1991 ◽  
Vol 114 (5) ◽  
pp. 1059-1068 ◽  
Author(s):  
S M Albelda ◽  
W A Muller ◽  
C A Buck ◽  
P J Newman

PECAM-1 is a 130-120-kD integral membrane glycoprotein found on the surface of platelets, at endothelial intercellular junctions in culture, and on cells of myeloid lineage. Previous studies have shown that it is a member of the immunoglobulin gene superfamily and that antibodies against the bovine form of this protein (endoCAM) can inhibit endothelial cell-cell interactions. These data suggest that PECAM-1 may function as a vascular cell adhesion molecule. The function of this molecule has been further evaluated by transfecting cells with a full-length PECAM-1 cDNA. Transfected COS-7, mouse 3T3 and L cells expressed a 130-120-kD glycoprotein on their cell surface that reacted with anti-PECAM-1 polyclonal and monoclonal antibodies. COS-7 and 3T3 cell transfectants formed cell-cell junctions that were highly enriched in PECAM-1, reminiscent of its distribution at endothelial cell-cell borders. In contrast, this protein remained diffusely distributed within the plasma membrane of PECAM-1 transfected cells that were in contact with mock transfectants. Mouse L cells stably transfected with PECAM-1 demonstrated calcium-dependent aggregation that was inhibited by anti-PECAM antibodies. These results demonstrate that PECAM-1 mediates cell-cell adhesion and support the idea that it may be involved in some of the interactive events taking place during thrombosis, wound healing, and angiogenesis.


1991 ◽  
Vol 114 (3) ◽  
pp. 557-565 ◽  
Author(s):  
K Miyake ◽  
K Medina ◽  
K Ishihara ◽  
M Kimoto ◽  
R Auerbach ◽  
...  

Two new mAbs (M/K-1 and M/K-2) define an adhesion molecule expressed on stromal cell clones derived from murine bone marrow. The protein is similar in size to a human endothelial cell adhesion molecule known as VCAM-1 or INCAM110. VCAM-1 is expressed on endothelial cells in inflammatory sites and recognized by the integrin VLA-4 expressed on lymphocytes and monocytes. The new stromal cell molecule is a candidate ligand for the VLA-4 expressed on immature B lineage lymphocytes and a possible homologue of human VCAM-1. We now report additional similarities in the distribution, structure, and function of these proteins. The M/K antibodies detected large cells in normal bone marrow, as well as rare cells in other tissues. The antigen was constitutively expressed and functioned as a cell adhesion molecule on cultured murine endothelial cells. It correlated with the presence of mRNA which hybridized to a human VCAM-1 cDNA probe. Partial NH2 terminal amino acid sequencing of the murine protein revealed similarities to VCAM-1 and attachment of human lymphoma cells to murine endothelial cell lines was inhibited by the M/K antibodies. All of these observations suggest that the murine and human cell adhesion proteins may be related. The antibodies selectively interfered with B lymphocyte formation when included in long term bone marrow cultures. Moreover, they caused rapid detachment of lymphocytes from the adherent layer when added to preestablished cultures. The VCAM-like cell adhesion molecule on stromal cells and VLA-4 on lymphocyte precursors may both be important for B lymphocyte formation.


2006 ◽  
Vol 80 (23) ◽  
pp. 11539-11555 ◽  
Author(s):  
Gretchen L. Bentz ◽  
Marta Jarquin-Pardo ◽  
Gary Chan ◽  
M. Shane Smith ◽  
Christian Sinzger ◽  
...  

ABSTRACT Human cytomegalovirus (HCMV) pathogenesis is dependent on the hematogenous spread of the virus to host tissue. While data suggest that infected monocytes are required for viral dissemination from the blood to the host organs, infected endothelial cells are also thought to contribute to this key step in viral pathogenesis. We show here that HCMV infection of endothelial cells increased the recruitment and transendothelial migration of monocytes. Infection of endothelial cells promoted the increased surface expression of cell adhesion molecules (intercellular cell adhesion molecule 1, vascular cell adhesion molecule 1, E-selectin, and platelet endothelial cell adhesion molecule 1), which were necessary for the recruitment of naïve monocytes to the apical surface of the endothelium and for the migration of these monocytes through the endothelial cell layer. As a mechanism to account for the increased monocyte migration, we showed that HCMV infection of endothelial cells increased the permeability of the endothelium. The cellular changes contributing to the increased permeability and increased naïve monocyte transendothelial migration include the disruption of actin stress fiber formation and the decreased expression of lateral junction proteins (occludin and vascular endothelial cadherin). Finally, we showed that the migrating monocytes were productively infected with the virus, documenting that the virus was transferred to the migrating monocyte during passage through the lateral junctions. Together, our results provide evidence for an active role of the infected endothelium in HCMV dissemination and pathogenesis.


1997 ◽  
Vol 8 (7) ◽  
pp. 1329-1341 ◽  
Author(s):  
N Sheibani ◽  
P J Newman ◽  
W A Frazier

Expression of thrombospondin-1 (TS1) in polyoma middle-sized T (tumor)-transformed mouse brain endothelial cells (bEND.3) restores a normal phenotype and suppresses their ability to form hemangiomas in mice. We show that TS1 expression results in complete suppression of platelet-endothelial cell adhesion molecule-1 (PECAM-1) expression and altered cell-cell interactions in bEND.3 cells. To further investigate the role of PECAM-1 in regulation of endothelial cell-cell interactions and morphogenesis, we expressed human (full length) or murine (delta 15) PECAM-1 isoforms in TS1-transfected bEND.3 (bEND/TS) cells. Expression of either human or murine PECAM-1 resulted in an enhanced ability to organize and form networks of cords on Matrigel, an effect that was specifically blocked by antibodies to PECAM-1. Anti-PECAM-1 antibodies also inhibited tube formation in Matrigel by normal human umbilical vein endothelial cells. However, PECAM-1-transfected bEND/TS cells did not regain the ability to form hemangiomas in mice and the expressed PECAM-1, unlike the endogenous PECAM-1 expressed in bEND.3 cells, failed to localize to sites of cell-cell contact. This may be, in part, attributed to the different isoforms of PECAM-1 expressed in bEND.3 cells. Using reverse transcription-polymerase chain reaction, we determined that bEND.3 cells express mRNA encoding six different PECAM-1 isoforms, the isoform lacking both exons 14 and 15 (delta 14&15) being most abundant. Expression of the murine delta 14&15 PECAM-1 isoform in bEND/TS cells resulted in a similar phenotype to that described for the full-length human or murine delta 15 PECAM-1 isoform. The delta 14&15 isoform, despite the lack of exon 14, failed to localize to sites of cell-cell contact even in clones that expressed it at very high levels. Thus, contrary to recent reports, lack of exon 14 is not sufficient to result in junctional localization of PECAM-1 isoforms in bEND/TS cells.


2004 ◽  
Vol 286 (5) ◽  
pp. C1195-C1202 ◽  
Author(s):  
Peter J. Kuhlencordt ◽  
Eva Rosel ◽  
Robert E. Gerszten ◽  
Manuel Morales-Ruiz ◽  
David Dombkowski ◽  
...  

The objective of this study was to determine whether absence of endothelial nitric oxide synthase (eNOS) affects the expression of cell surface adhesion molecules in endothelial cells. Murine lung endothelial cells (MLECs) were prepared by immunomagnetic bead selection from wild-type and eNOS knockout mice. Wild-type cells expressed eNOS, but eNOS knockout cells did not. Expression of neuronal NOS and inducible NOS was not detectable in cells of either genotype. Upon stimulation, confluent wild-type MLECs produced significant amounts of NO compared with Nω-monomethyl-l-arginine-treated wild-type cells. eNOS knockout and wild-type cells showed no difference in the expression of E-selectin, P-selectin, intracellular adhesion molecule-1, and vascular cell adhesion molecule-1 as measured by flow cytometry on the surface of platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31)-positive cells. Both eNOS knockout and wild-type cells displayed the characteristics of resting endothelium. Adhesion studies in a parallel plate laminar flow chamber showed no difference in leukocyte-endothelial cell interactions between the two genotypes. Cytokine treatment induced endothelial cell adhesion molecule expression and increased leukocyte-endothelial cell interactions in both genotypes. We conclude that in resting murine endothelial cells, absence of endothelial production of NO by itself does not initiate endothelial cell activation or promote leukocyte-endothelial cell interactions. We propose that eNOS derived NO does not chronically suppress endothelial cell activation in an autocrine fashion but serves to counterbalance signals that mediate activation.


1998 ◽  
Vol 9 (4) ◽  
pp. 701-713 ◽  
Author(s):  
Nader Sheibani ◽  
William A. Frazier

bEND.3 cells are polyoma middle T-transformed mouse brain endothelial cells that express very little or no thrombospondin-1, a natural inhibitor of angiogenesis, but express high levels of platelet endothelial cell adhesion molecule-1 (PECAM-1) that localizes to sites of cell–cell contact. Here, we have examined the role of PECAM-1 in regulation of bEND.3 cell proliferation, migration, morphogenesis, and hemangioma formation. We show that down-regulating PECAM-1 expression by antisense transfection of bEND.3 cells has a dramatic effect on their morphology, proliferation, and morphogenesis on Matrigel. There is an optimal level for PECAM-1 expression such that high levels of PECAM-1 inhibit, whereas moderate levels of PECAM-1 stimulate, endothelial cell morphogenesis. The down-regulation of PECAM-1 in bEND.3 cells resulted in reexpression of endogenous thrombospondin-1 and its antiangiogenic receptor CD36. The expression of the vascular endothelial growth factor receptors flk-1 and flt-1, as well as integrins and metalloproteinases (which are involved in angiogenesis), were also affected. These observations are consistent with the changes observed in proliferation, migration, and adhesion characteristics of the antisense-transfected bEND.3 cells as well as with their lack of ability to form hemangiomas in mice. Thus, a reciprocal relationship exists between thrombospondin-1 and PECAM-1 expression, such that these two molecules appear to be constituents of a “switch” that regulates in concert many components of the angiogenic and differentiated phenotypes of endothelial cells.


2005 ◽  
Vol 73 (2) ◽  
pp. 1209-1213 ◽  
Author(s):  
Lena Serghides ◽  
Kevin C. Kain

ABSTRACT Peroxisome proliferator-activated receptor γ-retinoid X receptor (PPARγ-RXR) agonists had minimal effects on the surface levels of CD36, intercellular cell adhesion molecule-1, or platelet-endothelial cell adhesion molecule-1 and had no effect on the cytoadherence of infected erythrocytes to either human umbilical vein endothelial cells or human microvascular endothelial cells or on malaria-induced interleukin-6 secretion from these cells. PPARγ-RXR agonists do not significantly modify malaria-infected erythrocyte-endothelial cell interactions in vitro.


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