Platelet endothelial cell adhesion molecule-1 is expressed in adenoidal crypt epithelial cells

The adenoidal epithelial crypt is a potential site of antigen transport from pharyngeal lumen to adenoidal tissue. The base of the crypt is consistently infiltrated with leucocytes, forming a reticular lymphoepithelial structure. To evaluate mechanisms that possibly mediate leucocyte infiltration, expressions of leucocyte adhesion molecules, such as platelet endothelial cell adhesion molecule-1 (PECAM-1) (CD31), vascular cell adhesion molecule-1 (VCAM-1) (CD106) and intercellular adhesion molecule-1 (ICAM-1) (CD54), were studied in the adenoidal epithelial crypt. Epithelial cells in the outer opening of the adenoidal crypt were positive for VCAM-1, whereas epithelial cells at the base of the crypt were positive for PECAM-1. Isolated ICAM-1-expressing cells were found throughout the epithelial crypt. Double immunofluorescence staining revealed that the epithelial cells positive for PECAM-1 or VCAM-1 were positive for cytokeratin. The expression of PECAM-1 in the base and VCAM-1 at the orifice of the adenoidal epithelial crypt implies that the base and the orifice of the crypt have a distinct ability to recruit leucocytes. Epithelial cells expressing PECAM-1 may have a role in the formation of the reticular lymphoepithelial structure in the epithelial crypt.     

Intercellular cell adhesion molecule-1, vascular cell adhesion molecule-1, and regulated on activation normal T cell expressed and secreted are expressed by human breast carcinoma cells and support eosinophil adhesion and activation

Eosinophils are usually associated with parasitic and allergic diseases; however, eosinophilia is also observed in several types of human tumors, including breast carcinomas. In this study we examined several human breast carcinoma cell lines for adhesion molecule expression and the ability to bind and activate eosinophils. MDA-MB-435S and MDA-MB-468 cells constitutively expressed both intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) and this expression was enhanced by treatment with tumor necrosis factor-alpha (TNF-alpha). BT-20 and SK-BR-3 cells only expressed ICAM-1 or VCAM-1 after stimulation with TNF-alpha. Eosinophils constitutively bound to MDA-MB-435S cells, but not to BT-20 cells. Stimulation with TNF-alpha slightly enhanced eosinophil adhesion to MDA-MB-435S cells and dramatically increased adhesion to BT-20 cells. Greater than 80% of eosinophil adhesion to these cell lines was blocked with an anti-alpha4-integrin monoclonal antibody. Both MDA-MB-435S and BT-20 cells also released eosinophil activator(s). Supernatants from TNF-alpha-treated, but not control-treated, cell lines increased eosinophil adhesion to fibronectin and increased eosinophil transmigration across fibronectin-coated transwell plates. Enzyme-linked immunosorbent assays showed that TNF-alpha-stimulated breast carcinoma cells released the chemokine regulated on activation, T cell expressed and secreted (RANTES). Addition of an anti-RANTES antibody to breast carcinoma cell supernatants partially blocked eosinophil activation suggesting that RANTES in these supernatants was participating in eosinophil activation. These data show that TNF-alpha-stimulated breast carcinoma cells express mediators that can both bind and activate eosinophils, suggesting a mechanism for eosinophil localization to breast carcinoma sites.     

Disturbed homeostasis of lung intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 during sepsis

Cecal ligation and puncture (CLP)-induced sepsis in mice was associated with perturbations in vascular adhesion molecules. In CLP mice, lung vascular binding of (125)I-monoclonal antibodies to intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 revealed sharp increases in binding of anti-ICAM-1 and significantly reduced binding of anti-VCAM-1. In whole lung homogenates, intense ICAM-1 up-regulation was found (both in mRNA and in protein levels) during sepsis, whereas very little increase in VCAM-1 could be measured although some increased mRNA was found. During CLP soluble VCAM-1 (sVCAM-1) and soluble ICAM-1 (sICAM-1) appeared in the serum. When mouse dermal microvascular endothelial cells (MDMECs) were incubated with serum from CLP mice, constitutive endothelial VCAM-1 fell in association with the appearance of sVCAM-1 in the supernatant fluids. Under the same conditions, ICAM-1 cell content increased in MDMECs. When MDMECs were evaluated for leukocyte adhesion, exposure to CLP serum caused increased adhesion of neutrophils and decreased adhesion of macrophages and T cells. The progressive build-up in lung myeloperoxidase after CLP was ICAM-1-dependent and independent of VLA-4 and VCAM-1. These data suggest that sepsis disturbs endothelial homeostasis, greatly favoring neutrophil adhesion in the lung microvasculature, thereby putting the lung at increased risk of injury.     

Expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in human crescentic glomerulonephritis

AIMS: In glomerulonephritis, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) may play important roles in the formation of crescents. These studies are designed to evaluate the expression patterns of ICAM-1 and VCAM-1 in human crescentic glomerulonephritis and to determine the cellular origin of adhesion molecules in the crescentic lesions. METHODS AND RESULTS: We examined the expression of ICAM-1 and VCAM-1 proteins in renal biopsies with cellular (n=7), fibrocellular (n=9) or fibrous (n=4) crescentic glomerulonephritis, and six controls by immunohistochemistry. mRNA expression of ICAM-1 and VCAM-1 was further evaluated by RNA in-situ hybridization. Cytokeratin or CD68 immunohistochemistry was performed on the same sections, where in-situ hybridization had been carried out. In cellular crescents, ICAM-1 and VCAM-1 proteins were over-expressed to a similar extent. Of the three types of crescents, the extent of ICAM-1 immunopositivity was the greatest in the cellular crescents and decreased towards the fibrous crescents (P < 0.05). Yet the extent of VCAM-1 immunoreactivity was not different between the types. Fibrous crescents still contained some epithelial cells and showed only VCAM-1 expression. In the glomeruli with cellular or fibrocellular crescents, the extent of ICAM-1 immunopositivity in the glomerular tufts was significantly larger than that of VCAM-1 (P < 0.05). In an in-situ hybridization study, the mRNA expression patterns of ICAM-1 and VCAM-1 paralleled their protein expressions. A double-labelling study showed that the signal for ICAM-1 and VCAM-1 mRNAs was mainly present in cytokeratin-positive and CD68-negative cells in the crescentic lesions. CONCLUSIONS: These results suggest that glomerular parietal epithelial cells in cellular crescents up-regulate both ICAM-1 and VCAM-1, and that some epithelial cells retained in fibrous crescents persistently over-express VCAM-1, but not ICAM-1. They also suggest that ICAM-1 is involved in early leucocyte recruitment into glomeruli in crescentic glomerulonephritis.     

Platelet-endothelial cell adhesion molecule-1 (PECAM-1/CD31) tyrosine phosphorylation state changes during vasculogenesis in the murine conceptus.

Vasculogenesis, the differentiation of mesodermal cells to angioblasts and the subsequent formation of blood islands and blood vessels by angioblasts in the conceptus, is a dynamic process modulated, in part, by cell-extracellular matrix and cell-cell interactions in the presence of a variety of growth factors and morphogens. In this report we demonstrate differential tyrosine phosphorylation of platelet-endothelial cell adhesion molecule-1 (PECAM-1) during the formation of blood islands and vessels from clusters of extraembryonic and embryonic angioblasts in the murine conceptus. In addition, we identify the phosphorylation of a particular tyrosine residue in the PECAM-1 cytoplasmic domain, Tyr686, which has the potential of mediating binding to Src homology 2 domain-containing proteins, affecting PECAM-1 cellular localization and endothelial cell migration.     

Vascular cell adhesion molecule-1 is a key adhesion molecule in melanoma cell adhesion to the leptomeninges

Leptomeningeal metastases occur in up to 8% of patients with systemic malignancies and have a poor prognosis. A better understanding of the pathophysiologic processes underlying leptomeningeal metastases is needed for more effective treatment strategies. We hypothesized that tumor cells will have to adhere to the well-vascularized leptomeninges, because the cerebrospinal fluid lacks nutrients and growth factors for efficient tumor cell proliferation. Specific receptor-ligand interactions, which are unknown until now, will mediate this adhesion process. We determined the growth characteristics of B16F-10 melanoma cells in cerebrospinal fluid. The expression levels of specific adhesion molecules on both mouse leptomeningeal cells (MLMC) and murine B16F-10 melanoma cells were measured by immunofluorescence flow cytometry. We used mAbs to determine the function of these specific adhesion molecules on B16F-10 melanoma cell adhesion to a leptomeningeal cell layer under static and (cerebrospinal fluid-like) flow conditions. B16F-10 melanoma cells did not proliferate in cerebrospinal fluid because of a lack of nutrients and growth factors. MLMC expressed low levels of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), beta1- and beta3-integrin subunits, and CD44. VCAM-1 expression on MLMC was shown to be up-regulated by TNF-alpha. Blocking VCAM-1 on the MLMC with a mAb resulted in a 60% inhibition of melanoma cell adhesion to a leptomeningeal cell layer under flow but not under static conditions. No additive inhibitory effect on melanoma cell adhesion was found by concomitant blocking of the beta1- and beta3-integrin subunits and CD44 with mAbs. Our experiments indicate that cerebrospinal fluid does not support B16F-10 melanoma cell proliferation, suggesting the need for melanoma cell adhesion to the well-vascularized leptomeninges. VCAM-1, expressed on MLMC, is an important mediator of in vitro melanoma cell adhesion under (cerebrospinal fluid-like) flow conditions.     

Nerve-mast cell and smooth muscle-mast cell interaction mediated by cell adhesion molecule-1, CADM1.

Mast cells are a native composer of connective tissue of the skin dermis and intestinal and respiratory mucosa. Independent lines of accumulated evidence indicate the existence of an intensive bidirectional crosstalk between mast cells and sensory nerves and suggest that mast cells and sensory nerves may be viewed as a functional unit, which could be of crucial importance in neuroimmunological pathways. Mast cells appear to have a property of influencing smooth muscle function via not only such nerve-mast cell effects, but also direct pathways. In bronchial asthma, mast cells infiltrate the airway smooth muscle layer, and interact directly with smooth muscle cells, suggesting pathogenic roles for mast cells in airway obstruction. Current studies on mast cell biology identified a novel adhesion molecule of mast cells, namely cell adhesion molecule-1, CADM1. This molecule is unique, because it serves as not only simple glue but also appears to promote functional communication between nerve and mast cells and between smooth muscle and mast cells.     

Platelet-endothelial cell adhesion molecule-1 (CD31) redistributes from the endothelial junction and is not required for the transendothelial migration of melanoma cells

We have examined the role of platelet-endothelial cell adhesion molecule-1 (PECAM-1/CD31) during the transendothelial migration of melanoma cells using a novel in vitro system. Comparable studies have suggested the involvement of PECAM-1 in leukocyte transendothelial migration. Such studies have been confirmed using in vivo models of inflammation. These studies prompted us to examine the role of PECAM-1 in tumor cell transendothelial migration. Anti-PECAM-1 monoclonal antibodies, known to block leukocyte transendothelial migration, were tested in co-cultures of human melanoma cells seeded on a monolayer of human lung microvascular endothelial cells. None of these antibodies inhibited the transmigration of melanoma cells. Moreover, confocal microscopy revealed the dissolution of the PECAM-1 adhesion complexes in the endothelial junctions associated with melanoma cells and the lack of PECAM-1 in heterotypic contacts between transmigrating melanoma cells and adjacent endothelial cells. These data, therefore, indicate that PECAM-1 is not required for the transendothelial migration of melanoma cells. This revised version was published online in July 2006 with corrections to the Cover Date.     

Cyclic stretching of mesangial cells up-regulates intercellular adhesion molecule-1 and leukocyte adherence: a possible new mechanism for glomerulosclerosis

Intraglomerular hypertension is a primary causal factor in the progressive glomerulosclerosis that characterizes diabetic nephropathy or severe renal ablation. However, inflammation of the glomerular mesangium also participates in at least the early phase of these diseases. In glomerulonephritis, where inflammation is thought to be the predominant causal factor, intraglomerular hypertension is also often present. Mesangial cells (MCs) are critical in orchestrating key functions of the glomerulus including extracellular matrix metabolism, cytokine production, and interaction with leukocytes. Because MCs are subject to increased stretching when intraglomerular hypertension is present, and in glomerulonephritis MC/leukocyte interactions seem to be mediated primarily via the up-regulation of intercellular adhesion molecule-1 (ICAM-1), we examine the possibility that cyclic stretching is a stimulus for increased MC ICAM-1 activity. We demonstrate that the normal low levels of MC ICAM-1 mRNA and protein are dramatically up-regulated by even short intervals of cyclic stretch. This effect is dose- and time-dependent, and requires little amplitude and a brief period of elongation for significant induction. Stretch-induced MC ICAM-1 also leads to a marked elevation in phagocytic leukocyte adherence. This stimulated adherence is equal or greater than that induced by the inflammatory cytokine tumor necrosis factor-alpha, whereas an additive effect occurs when both are applied in combination. Our results indicate that stretch-induced ICAM-1 may provide a direct link between hypertension and inflammation in the progression of injury and glomerulosclerosis in diabetes, renal ablation, and other forms of glomerulonephritis.     

Human mucosal addressin cell adhesion molecule-1 is preferentially expressed in intestinal tract and associated lymphoid tissue.

Lymphocyte homing to normal tissues and recruitment to inflammatory tissue sites are controlled, in part, by the selective expression of chemokines, pro-inflammatory cytokines and mediators, and various adhesion proteins and molecules. In the mouse, mucosal addressin cell adhesion molecule-1 (MAdCAM-1) is selectively expressed on endothelium of high endothelial venules in gut and gut-associated lymphoid tissue. By interaction with its integrin ligand, alpha 4 beta 7, lymphocytes presumed to be involved in mucosal immunity are selectively recruited to these intestinal sites. After generating monoclonal antibodies against a murine cell line expressing recombinant human MAdCAM-1, we qualitatively and semiquantitatively assessed MAdCAM-1 expression in human tissue sections from various normal and inflammatory disorders. We found that human MAdCAM-1, as in the mouse, is expressed in a tissue-selective manner. In normal tissues, MAdCAM-1 is constitutively expressed to endothelium of venules of intestinal lamina propria. Interestingly, using computer-assisted morphometric analysis, the proportion of venular endothelium within lamina propria that expresses MAdCAM-1 is increased, compared with normal tissues, at inflammatory foci associated with ulcerative colitis and Crohn's disease. Moreover, for the most part, MAdCAM-1 is not detected in the majority of normal or inflamed extra-intestinal tissues, including those with mucosal surfaces. These results are consistent with a role, as originally defined in the mouse, for human MAdCAM-1 in the localization of alpha 4 beta 7+ lymphocytes in the gastrointestinal tract and associated lymphoid tissue. As such, the pathway defined by MAdCAM-1/alpha 4 beta 7 may be a relevant tissue-specific therapeutic target for the modulation of inflammatory bowel disease activity.     

Expression of endothelial intercellular adhesion molecule-1 is determined by genotype: effects on efficiency of leukocyte adhesion to human endothelial cells

Two biallelic polymorphisms, previously described in the human intercellular adhesion molecule (ICAM)-1 gene at codon 241 (glycine [G] to arginine [R] substitution) and codon 469 (glutamic acid [E] to lysine [K] substitution) have been associated with a number of diseases including myocardial infarction, transplant rejection, and diabetes. However, the functional significance of these polymorphisms has not been determined. ICAM-1 cell surface expression and ICAM-1-mediated leukocyte adhesion were investigated using Cos7 transfected with ICAM-1 polymorphic variants or human umbilical vein endothelial cells (HUVEC) of different ICAM-1 genotypes. There was significantly higher expression of surface ICAM-1 on Cos7 transfected with a plasmid encoding the GE (G241/E469) ICAM-1 variant or untreated HUVEC of GEGE (G241/E469 homozygous genotype). ICAM-1-mediated adhesion of peripheral blood mononuclear cells (PBMC) to GE-Cos7 cells or TNF-treated GEGE HUVEC was significantly increased. However, there was no significant difference in adhesion of PBMC to recombinant ICAM-1 of each polymorphic variant plated onto plastic wells. We conclude that the GE genotype of ICAM-1 is associated with greater cell surface expression of ICAM-1, which in turn leads to greater adhesion of leukocytes. This may explain the previously described associations of ICAM-1 polymorphisms with chronic inflammatory disease.     

Intercellular adhesion molecule-1 on cultured human epithelial cell lines: influence of proinflammatory cytokines

Paolieri F, Battifora M, Riccio AM, Pesce G, Canonica GW, Bagnasco M. Intercellular adhesion molecule-1 on cultured human epithelial cell lines: influence of proinflammatory cytokines.
The expression of intercellular adhesion molecule-1 'CD54 or ICAM-1' on epithelial cells during acute or chronic inflammation may favor the interaction between epithelial cells and leukocytes expressing the natural ligands of ICAM-1, LFA-1 'CD11a/CD18', and Mac-1 'CD11b/CD18'. We have evaluated in vitro the expression of ICAM-1 by a conjunctival 'WK' and an intestinal '1407' human continuous epithelial cell line. Cells were cultured for 24 h in the presence or absence of IFN-γ, TNF-α, IL-1β, IL-4, IL-6, IL-8, IL-10, and TGF-Jβ1. Both epithelial cell lines showed a constitutive expression of ICAM-1. IFN-γ at 500 U/ml and TNF-α at 200 ng/ml upregulated ICAM-1 expression; IL-1β at 100 pg/ml upregulated ICAM-1 on WK cells only. Cells cultured in the presence of both IFN-γ and TNF-α exhibited a mean fluorescence intensity far greater than those cultured with IFN-γ or TNF-α alone. 1407 and WK cells were able to release soluble ICAM-1. IFN-γ and TNF-α enhanced the release of sICAM-1. IL-4, IL-6, IL-8, IL-10, and TGF-β1 did not affect either ICAM-1 expression or sICAM-1 release. In conclusion, continuously cultured human epithelial cells may express ICAM-1 on their surface and release it in culture medium. These phenomena are upregulated by proinflammatory cytokines.     

Vascular cell adhesion molecule-1 expression and signaling during disease: regulation by reactive oxygen species and antioxidants

The endothelium is immunoregulatory in that inhibiting the function of vascular adhesion molecules blocks leukocyte recruitment and thus tissue inflammation. The function of endothelial cells during leukocyte recruitment is regulated by reactive oxygen species (ROS) and antioxidants. In inflammatory sites and lymph nodes, the endothelium is stimulated to express adhesion molecules that mediate leukocyte binding. Upon leukocyte binding, these adhesion molecules activate endothelial cell signal transduction that then alters endothelial cell shape for the opening of passageways through which leukocytes can migrate. If the stimulation of this opening is blocked, inflammation is blocked. In this review, we focus on the endothelial cell adhesion molecule, vascular cell adhesion molecule-1 (VCAM-1). Expression of VCAM-1 is induced on endothelial cells during inflammatory diseases by several mediators, including ROS. Then, VCAM-1 on the endothelium functions as both a scaffold for leukocyte migration and a trigger of endothelial signaling through NADPH oxidase-generated ROS. These ROS induce signals for the opening of intercellular passageways through which leukocytes migrate. In several inflammatory diseases, inflammation is blocked by inhibition of leukocyte binding to VCAM-1 or by inhibition of VCAM-1 signal transduction. VCAM-1 signal transduction and VCAM-1-dependent inflammation are blocked by antioxidants. Thus, VCAM-1 signaling is a target for intervention by pharmacological agents and by antioxidants during inflammatory diseases. This review discusses ROS and antioxidant functions during activation of VCAM-1 expression and VCAM-1 signaling in inflammatory diseases.     

可溶性血管细胞粘附分子1(sVCAM-1)在紫癜性肾炎发病中的作用探讨

目的:探讨血管细胞粘附分子-1(VCAM-1)在过敏性紫癜性肾炎(HSPN)发病中的作用,并观察其与白介素-6(IL-6)、免疫球蛋白E(IgE)在HSPN发病中的关系。方法:采用酶联免疫吸附法(ELISA)检测27例过敏性紫癜、35例紫癜性肾炎患儿(其中急性期16例,恢复期10例)及20例健康对照儿童的血清sVCAM-1、IL-6、IgE水平。结果:①紫癜性肾炎组较单纯过敏性紫癜组、正常对照组血清sVCAM-1均明显升高,且急性期高于恢复期及正常对照组,差异均有显著性意义(P均<0.001),肾炎组、单纯组分别与对照组比较,血清IL-6、IgE水平升高,差异有显著性意义(P<0.01),恢复期较正常对照组血清sVCAM-1、IL-6水平无很大变化,差异无显著性意义(P均>0.05)。②紫癜性肾炎组、单纯过敏性紫癜组sVCAM-1水平随血清IL-6、IgE水平升高而增加(相关系数分别为0.35、0.38,P均<0.01)。结论:sVCAM-1参与了过敏性紫癜、紫癜性肾炎的发病过程,且可反映其病情程度。     

Lack of stimulatory effect of dienogest on the expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 by endothelial cell as compared with other synthetic progestins

Objectives: Monocyte adhesion to endothelial cells is an important initial event at the onset of atherosclerosis. It is partially mediated by the expression of adhesion molecules on the endothelial cell surface. While estrogens inhibit the development of atherosclerosis, the effect of co-administered progestin remains controversial. We examined the effect of progestins on cytokine-stimulated human umbilical venous endothelial cell (HUVEC) expression of adhesion molecules. Methods: In HUVECs, mRNA expression of progesterone receptors (PRs) and androgen receptors (AR) was determined by RT-PCR. HUVECs were stimulated by interleukin-1β (IL-1β) for 24 h with or without various steroids, and then the cell-surface expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) was semiquantified by ELISA. Results: In all preparations of HUVECs used in this study, RT-PCR confirmed mRNA expression of both isoforms of PR, PR-A and PR-B, as well as AR. Addition of progesterone (10⁻¹⁰–10⁻⁷ M) or dienogest (DNG) (10⁻¹⁰–10⁻⁸ M) did not affect IL-1β-stimulated ICAM-1 or VCAM-1 expression. In contrast, medroxyprogesterone acetate, norethindrone acetate and levonorgestrel (10⁻¹⁰–10⁻⁸ M) dose-dependently increased cell adhesion molecules. The progestin-induced increase was blocked by the concomitant addition of mifepristone, a PR antagonist, but not by hydroxyflutamide, an AR antagonist, indicating that the progestin stimulation was mediated predominantly via PR. Conclusions: These results suggest that DNG, unlike other synthetic progestins, lacks stimulation of cell adhesion molecules. For the prevention of atherosclerosis, estrogen in combination with DNG may be a suitable regimen in hormone replacement therapy in postmenopausal women.     

Functional evidence that intercellular adhesion molecule-1 (ICAM-1) is a ligand for LFA-1-dependent adhesion in T cell-mediated cytotoxicity

Although intercellular adhesion molecule-1 (ICAM-1) has been implicated as a ligand in some LFA-1-dependent adhesion, its importance to T cell function has not been established. The present studies investigate the importance of ICAM-1 for human cytotoxic T lymphocytes (CTL), both in their formation of antigen-independent conjugates (AIC) and in their lysis of targets. Analysis of monoclonal antibody (mAb) inhibition of AIC formation indicate that ICAM-1 mAb 1 blocks (a) AIC formation with some but not all targets; (b) the LFA-1 pathway but not the CD2/LFA-3 pathway of adhesion; (c) by binding to the target cell, not the T cell. In studies of cell-mediated lysis (CML) ICAM-1 mAb inhibited lysis of some targets, such as U-937, that use ICAM-1 predominantly in AIC formation; CML on some other targets is not inhibited by ICAM-1 mAb. These data indicate that ICAM-1 is a ligand for AIC formation, antigen-specific CTL recognition and cytolysis of particular target cells. The data also indicate that ICAM-1 is not used in LFA-1-dependent CTL interactions with all kinds of target cells, suggesting the existence of alternative ligands for LFA-1.     

Up-regulation of the endothelial cell adhesion molecule intercellular adhesion molecule-1 (ICAM-1) by autoantibodies in autoimmune vasculitis

Autoimmune vasculitis is characterized by the presence of autoantibodies, particularly anti-neutrophil cytoplasmic antibodies (ANCA) and anti-nuclear antibodies (ANA), in patient sera. These autoantibodies have an incompletely understood role in development of vascular injury. The expression or up-regulation of cell adhesion molecules is an early phase in the development of an inflammatory vascular lesion. Autoantibody-positive sera from patients with vasculitis were assessed for their ability to modulate adhesion molecule expression by human umbilical vein endothelial cells (HUVEC). Autoantibody-positive serum samples from 11 out of 21 patients with primary vasculitis produced substantial up-regulation of ICAM-1 on HUVEC. Autoantibody-negative samples did not produce adhesion molecule up-regulation. Up-regulation of adhesion molecules on HUVEC was observed with samples positive for ANA, a phenomenon not previously reported. Preincubation of the sera with purified antigens recognized by ANCA failed to block this activation. In addition, MoAbs to ANCA antigens were ineffective at inducing ICAM-1 up-regulation, suggesting that activation is independent of the molecular specificity of the antibody. This capacity of ANCA- and ANA-positive sera to up-regulate adhesion molecules on endothelial cells may be a factor in the vessel wall inflammation seen in ANCA-associated vasculitis.     

Neural cell adhesion molecule is expressed by smooth muscle cells during the development of the rat vascular system

Summary The presence and distribution of neural cell adhesion molecule (N-CAM) was examined by light and electron microscopical immunocytochemistry in the descending thoracic aorta, the superior mesenteric artery and mesenteric arteries from fetal and adult rats (embryonic day 15 to post-natal day 90). In embryonic and early post-natal rats, N-CAM immunoreactivity was localized in perivascular nerves, in the smooth muscle cell plasma membrane and basal lamina. In nerves, N-CAM-immunoreactive sites were found associated with both the axon and Schwann cell membranes. N-CAM immunoreactivity was also found associated with the surface of adventitial fibroblast-like cells and with collagen fibrils, in regions where these fibrils were in contact with smooth muscle cells. In mature vessels N-CAM immunoreactivity was found to be restricted to the perivascular innervation and the surface of fibroblast-like cells. These observations indicate that N-CAM is expressed transiently in rat vascular tissues during development and is localized not only on the surface of smooth muscle cells but also in association with extracellular matrix components.     

Monocyte adhesion to endothelium in simian immunodeficiency virus-induced AIDS encephalitis is mediated by vascular cell adhesion molecule-1/alpha 4 beta 1 integrin interactions.

Because the mechanisms associated with recruitment of monocytes to brain in AIDS encephalitis are unknown, we used tissues from rhesus monkeys infected with simian immunodeficiency virus (SIV) to examine the relative contributions of various adhesion pathways in mediating monocyte adhesion to endothelium from encephalitic brain. Using a modified Stamper and Woodruff tissue adhesion assay, we found that the human monocytic cell lines, THP-1 and U937, and the B cell line, Ramos, preferentially bound to brain vessels from monkeys with AIDS encephalitis. Using a combined tissue adhesion/immunohistochemistry approach, these cells only bound to vessels expressing vascular cell adhesion molecule-1 (VCAM-1). Furthermore, pretreatment of tissues with antibodies to VCAM-1 or cell lines with antibodies to VLA-4 (CD49d) inhibited adhesion by more than 70%. Intercellular adhesion molecule-1 (ICAM-1)/beta 2 integrin interactions were not significant in mediating cell adhesion to the vasculature in encephalitic simian brain using a cell line (JY) capable of binding rhesus monkey ICAM-1. In addition, selectin-mediated interactions did not significantly contribute to cell binding to encephalitic brain as there was no immunohistochemical expression of E-selectin and P-selectin in either normal or encephalitic brain, nor was there a demonstrable adhesive effect from L-selectin using L-selectin-transfected 300.19 cells on simian encephalitic brain. These results demonstrate that using the tissue adhesion assay, THP-1, U937, and Ramos cells bind to vessels in brain from animals with AIDS encephalitis using VCAM-1/alpha 4 beta 1 integrin interactions and suggest that VCAM-1 and VLA-4 may be integral for monocyte recruitment to the central nervous system during the development of AIDS encephalitis.