CD146 and its Soluble Form Regulate Monocyte Transendothelial Migration

Abstract

Objectives-During inflammation, cell adhesion molecules are modulated or redistributed for leukocyte transmigration.Among molecules at the interendothelial junction, CD146 is involved in cell-cell cohesion and permeability, but its role in monocyte transmigration is unknown. Methods and Results-TNF enhanced CD146 expression at the junction and apical membrane of human umbilical veins endothelial cells (HUVECs) through CD146 synthesis and intracellular store redistribution. In addition, TNF increased the release of a soluble form (sCD146) through a metalloproteinase-dependent mechanism. The redistribution of CD146 to the junction led us to investigate its role in monocyte transmigration using THP1 and freshly isolated monocytes.Evidence that CD146 contributes to monocyte transmigration was provided by inhibition experiments using anti-CD146 antibodies and CD146 siRNA in HUVECs. In addition, sCD146 specifically bound both monocytes and HUVECs and dose-dependently increased monocyte transmigration. Assessment of sCD146 binding on immobilized CD146 failed to evidence any homophilic interaction. Together, our data suggest endothelial CD146 binds heterophilically with a yet unknown ligand on monocytes. Conclusions-Our results demonstrate that CD146 is regulated by the inflammatory cytokine TNF and that CD146 and sCD146 are both involved in monocyte transendothelial migration during inflammation. Key Words: endothelial cells Ⅲ inflammation Ⅲ cytokines Ⅲ human Ⅲ adhesion molecules T he endothelial junctions play a fundamental role in endothelial integrity, vascular permeability, and cellular traffic. 1 At least 2 types of cell-to-cell junctional structures have been identified in the endothelium: adherens junctions (AJ) and tight junctions (TJ). 2 These junctions are tightly regulated structures composed of several adhesion molecules interacting with cytoskeletal proteins. 3 Among the adhesive molecules, endothelial VE-cadherin 4 is localized in AJ and junctional adhesion molecule (JAM) 5 in TJ, whereas other molecules such as PECAM-1/CD31 (platelet endothelial cell adhesion molecule-1) and CD99 are not restricted to 1 type of junctional structure. 6 The inflammatory response is characterized by leukocyte infiltration from the circulation toward the tissues, after a multistep process in which proinflammatory endothelial activation results in increased vascular permeability and then in leukocyte adhesion and transmigration. 7 Endothelial activation is mediated by several inflammatory cytokines. Among them, TNF␣ increases the expression of cell adhesion molecules like ICAM-1 or VCAM-1 and induces the redistribution of junctional adhesion molecules such as PECAM-1, JAM, VE-cadherin, and CD99 which, in turn, promote the transendothelial migration of leukocytes. 8 We have previously shown that CD146 (S-Endo1 Ag) is a component of the endothelial junction localized outside defined junctional structures. 9 CD146, also referred to as MUC18, is a member of the immunoglobulin superfamily (IgSF) constitutively expressed in all typ...

Soluble Melanoma Cell Adhesion Molecule (sMCAM/sCD146) Promotes Angiogenic Effects on Endothelial Progenitor Cells through Angiomotin

“…Altogether, these results suggest that both soluble and membrane CD146 are able to bind different proteins as a function of the cellular and physiopathological context but that heterophilic interactions are favored. Of interest, we found angiomotin mRNA expression (data not shown) not only in endothelial cells as HUVEC and EPC but also in the trophoblastic cell line HTR-8/SVneo, in L929 fibroblastic cells and in the monocytic cell line THP1, which does not express membrane CD146 but was activated by sCD146 during transmigration (4). Identifying angiomotin expressing cells will presumably provide new target cells for sCD146.…”

“…However, until recently, its physiological role was unknown. In a previous report, we have shown that sCD146 is involved in inflammation by specifically binding to monocytes and thereby stimulating transendothelial migration (4). We have further shown that sCD146 is also involved in angiogenesis (5).…”

“…Cell Culture of HUVEC and EPC-Human umbilical vein endothelial cells (HUVEC) were prepared from human umbilical cord samples collected in compliance with French legislation as described previously (4). Late EPC were prepared from human umbilical cord blood samples collected from donors, in compliance with French legislation as described previously (5,7).…”

“…Western Blot Experiments-Western blot analysis was performed as described previously (4,5). Briefly, cells were grown on plates treated or not for 24 h with rsCD146 50 ng/ml and then washed in PBS, scraped off of the plates, and extracted with 300 l of ice-cold lysis buffer (150 mM NaCl, 50 mM Tris HCl (pH 7.4), 2.4 mM EDTA, 1% Nonidet P40, 0.5 mM phenylmethylsulfonyl fluoride) for 30 min at 4°C.…”

Soluble CD146 and APS: a potential biomarker of obstetrical complications?

“…Indeed, we showed that sCD146 significantly increases the transmigration of monocytes across the monolayer of endothelial cells. 2 We also demonstrated the angiogenic properties of the molecule. Soluble CD146 increased endothelial proliferation, migration and vascular tube formation.…”