The leukocyte adhesion molecule LFA-1 mediates a wide range of lymphocyte, monocyte, natural killer cell, and granulocyte interactions with other cells in immunity and inflammation. LFA-1 (CD11a/CD18) is a receptor for intercellular adhesion molecule 1 (ICAM-1, CD54), a surface molecule which is constitutively expressed on some tissues and induced on other in inflammation. Induction of ICAM-1 on epithelial cells, endothelial cells and fibroblasts mediates LFA-1-dependent adhesion of lymphocytes. Several lines of evidence have suggested the existence of a second LFA-1 ligand: homotypic adhesion of one cell line was inhibited by a monoclonal antibody to LFA-1, but not by one to ICAM-1; there exists an LFA-1-dependent, ICAM-1-independent pathway of adhesion to endothelial cells; and also, there are some types of target cells in which LFA-1-dependent T-lymphocyte adhesion and lysis are independent of ICAM-1. We have cloned this second ligand, designated ICAM-2, using a novel method for identifying ligands of adhesion molecules. ICAM-2 is an integral membrane protein with two immunoglobulin-like domains, whereas ICAM-1 has five. Remarkably, ICAM-2 is much more closely related to the two most N-terminal domains of ICAM-1 (34% identity) than either ICAM-1 or ICAM-2 is to other members of the immunoglobulin superfamily, demonstrating the existence of a subfamily of immunoglobulin-like ligands that bind the same integrin receptor.
"Adhesion molecules are divided into three subgroups: selectins, integrins and members of the immunoglobulin superfamily of molecules (Dustin et al. 1988). Two subtypes of ICAM coexist: ICAM-1, which is inducible, and ICAM-2, which is constitutively and inducibly expressed on endothelial cells (Staunton et al. 1989). "
[Show abstract][Hide abstract] ABSTRACT: We present an ultrasound technique for the detection of inflammatory changes in developing atheromas. We used contrast-enhanced ultrasound imaging with (i) microbubbles targeted to intercellular adhesion molecule-1 (ICAM-1), a molecule of adhesion involved in inflammatory processes in lesions of atheromas in New Zealand White rabbits, and (ii) pretreatment with nitric oxide-loaded microbubbles and ultrasound activation at the site of the endothelium to enhance the permeability of the arterial wall and the penetration of ICAM-1-targeted microbubbles. This procedure increases acoustic enhancement 1.2-fold. Pretreatment with nitric oxide-loaded echogenic liposomes and ultrasound activation can potentially facilitate the subsequent penetration of targeted echogenic liposomes into the arterial wall, thus allowing improved detection of inflammatory changes in developing atheromas.
Ultrasound in medicine & biology 06/2014; 40(6). DOI:10.1016/j.ultrasmedbio.2013.12.013 · 2.21 Impact Factor
"In contrast, anti-MAC-1 mAb treatment partially reduced adhesion in both WT and ICAM-2 KO mice, and substantially inhibited extravasation in WT animals. The contribution of ICAM-1, which has overlapping ligand specificities with ICAM-2 (Ding et al., 1999; Li et al., 1993; Staunton et al., 1989; Xie et al., 1995), was also investigated. Although ICAM-2 blockade or genetic deletion had no effect on adhesion, ICAM-1 blockade had a profound inhibitory effect on neutrophil adhesion as a result of which neutrophil extravasation was almost totally abolished. "
[Show abstract][Hide abstract] ABSTRACT: Intercellular adhesion molecule-2 (ICAM-2) is expressed on endothelial cells (ECs) and supports neutrophil extravasation. The full details of its role remain unknown however, and the present study investigates the functional mechanisms of ICAM-2 in neutrophil-endothelial cell interactions. Initial studies showed expression of ICAM-2 at both EC junctions and on the EC body. In line with the observed expression profile analysis of neutrophil-vessel wall interactions using real-time in vivo confocal microscopy identified numerous functional roles for ICAM-2 within the vascular lumen and at the stage of neutrophil extravasation. Functional or genetic blockade of ICAM-2 significantly reduced neutrophil crawling velocity, increased frequency of crawling with a disrupted stop-start profile, and prolonged interaction of neutrophils with EC junctions prior to transendothelial cell migration (TEM), collectively resulting in significantly reduced extravasation. Pharmacological blockade of the leukocyte integrin MAC-1 indicated that some ICAM-2-dependent functions may be mediated through ligation of this integrin. These findings highlight novel roles for ICAM-2 in mediating luminal neutrophil crawling and the effect on subsequent levels of extravasation.
"endothelial and epithelial cells, platelets, lymphocytes, and monocytes) that are known to mediate homo-and heterophilic interactions. Of these, ICAM2 is a well-studied protein possessing an extracellular domain, a transmembrane domain, and a cytoplasmic domain (Staunton et al. 1989). Initially described as a receptor for lymphocyte function-associated antigen-1 (LFA1, a b 2 integrin), ICAM2 is known to be critical for cell adhesion and cell movement. "
[Show abstract][Hide abstract] ABSTRACT: In this study, we investigated the role of intercellular adhesion molecule-2 (ICAM-2) in the testis. ICAM-2 is a cell adhesion protein having important roles in cell migration, especially during inflammation when leukocytes cross the endothelium. Herein, we showed ICAM-2 to be expressed by germ and Sertoli cells in the rat testis. When a monospecific antibody was used for immunolocalization experiments, ICAM-2 was found to surround the heads of elongating/elongated spermatids in all stages of the seminiferous epithelial cycle. To determine if ICAM-2 is a constituent of the apical ectoplasmic specialization (ES), co-immunoprecipitation (co-IP) and dual immunofluorescence staining were performed. Interestingly, ICAM-2 was found to associate with β1-integrin, nectin-3, afadin, Src, proline-rich tyrosine kinase 2 (Pyk2), annexin II and actin. Following CdCl2 treatment, ICAM-2 was found to be up-regulated during restructuring of the seminiferous epithelium, with round spermatids becoming increasingly immunoreactive for ICAM-2 by 6-16 h. Interestingly, there was a loss in the binding of ICAM-2 to actin during CdCl2-induced germ cell loss, suggesting that a loss of ICAM-2-actin interactions might have facilitated junction restructuring. Taken collectively, these results illustrate that ICAM-2 plays an important role in apical ES dynamics during spermatogenesis.
Journal of Endocrinology 10/2012; 216(1). DOI:10.1530/JOE-12-0434 · 3.72 Impact Factor
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