Human Endothelial-Cell Specific Molecule-1 Binds Directly to the Integrin CD11a/CD18 (LFA-1) and Blocks Binding to Intercellular Adhesion Molecule-1

Abstract

ICAMs are ligands for LFA-1, a major integrin of mononuclear cells involved in the immune and inflammatory processes. We previously showed that endothelial cell specific molecule-1 (ESM-1) is a proteoglycan secreted by endothelial cells under the control of inflammatory cytokines. Here, we demonstrate that ESM-1 binds directly to LFA-1 onto the cell surface of human blood lymphocytes, monocytes, and Jurkat cells. The binding of ESM-1 was equally dependent on Ca2+, Mg2+, or Mn2+ divalent ions, which are specific, saturable, and sensitive to temperature. An anti-CD11a mAb or PMA induced a transient increase in binding, peaking 5 min after activation. Direct binding of ESM-1 to LFA-1 integrin was demonstrated by specific coimmunoprecipitation by CD11a and CD18 mAbs. A cell-free system using a Biacore biosensor confirmed that ESM-1 and LFA-1 dynamically interacted in real time with high affinity (Kd = 18.7 nM). ESM-1 consistently inhibited the specific binding of soluble ICAM-1 to Jurkat cells in a dose-dependent manner. These results suggest that ESM-1 and ICAM-1 interact with LFA-1 on binding sites very close to but distinct from the I domain of CD11a. Through this mechanism, ESM-1 could be implicated in the regulation of the LFA-1/ICAM-1 pathway and may therefore influence both the recruitment of circulating lymphocytes to inflammatory sites and LFA-1-dependent leukocyte adhesion and activation.

Novel surface targets and serum biomarkers from the ovarian cancer vasculature

“…We chose 13 genes for detailed validation based on affinity reagents that could reliably identify the protein products. Most of these genes play important roles in processes that are in fact vital for tumor growth, such as regulation of endothelial permeability, leukocyte extravasation, 26 cell adhesion, 27,28 extracellular matrix degradation [29][30][31] and metastasis. 32 Nine of the genes (ADAM12, CDCP1, CSPG2, EGFL6, ESM1, FLJ46072, LGALS3BP, ST14 and TSG6) exhibited higher expression in ovarian cancer relative to normal tissues.…”

Expression of Versican V3 by Arterial Smooth Muscle Cells Alters Tumor Growth Factor β (TGFβ)-, Epidermal Growth Factor (EGF)-, and Nuclear Factor κB (NFκB)-dependent Signaling Pathways, Creating a Microenvironment That Resists Monocyte Adhesion

“…Lymphocyte Function-associated Antigen 1 (LFA1) and Very Late Antigen 4 (VLA4) Blocking Experiment-Calcein-labeled U937 cells were incubated in the presence of anti-integrin ␣ L (anti-LFA1, 4 g/ml; clone HI111, Biolegend) or anti-integrin ␣ 4 (anti-VLA4, 4 g/ml; clone 2B4, R&D Systems) in ice-cold RPMI medium for 1 h. These antibodies were previously demonstrated as blocking interactions between LFA1 and ICAM1 (26) or between VLA4 and VCAM1 (27). These cells were then used in monocyte adhesion assays as described above.…”

Endocan: A new marker for cancer and a target for cancer therapy

“…The results showed that endocan actively participates in the interaction of endothelial cells and leukocytes. The study by Béchard et al (3) confirmed that endocan acts on physical function or has a specific interaction with the LFA-1 integrin extracellular domain of Jurkat cells that rely on a combination of divalent cations, which are specificity, saturation and temperature sensitive. The binding sites of endocan and LFA-1 to ICAM-1 are different.…”

“…IdoA is an important component of the functional structure of endocan. In cancer patients, patients with sepsis and tissue samples of healthy volunteers, serum protein endocan is present in the form of a polysaccharide (1)(2)(3)(4). Studies of the HUVEC vascular endothelial cell model show that the endocan expression level is extremely low, which cannot meet the requirements of scientific research (4).…”