Proteasome inhibitors block VCAM-1 and ICAM-1 gene expression in endothelial cells without affecting nuclear translocation of nuclear factor-ϰB

Endothelial cells play a major role in recruiting leukocytes to sites of inflammation. This is accomplished, at least in part, by up-regulation of cell surface adhesion molecules, including VCAM-1 and ICAM-1, in response to cytokines. In this report, we investigated the role of the proteasome complex in mediating the interleukin (IL)-1β induction of VCAM-1 and ICAM-1 gene expression in human endothelial cells. We present evidence that a proteasome inhibitor, n-acetyl-leucinyl-leucinyl-norleucinal (norLEU), as well as specific protease inhibitors, n-tosyl-Lys-chloromethylketone and n-tosyl-Phe-chloromethylketone, blocked IL-1β induction of VCAM-1 and ICAM-1 promoter-driven reporter gene expression in stably transfected endothelial cells. These inhibitors also blocked cytokine induced cell surface expression of VCAM-1 and ICAM-1 by human umbilical vein endothelial cells. As expected, the protease inhibitors blocked the activation of nuclear factor (NF)-?B in response to IL-1β stimulation. In contrast, norLEU did not prevent IL-1β-induced nuclear translocation of NF-?B. The effects of norLEU were specific because it did not inhibit the IL-1β induction of plasminogen activator inhibitor type 1 gene expression. This study demonstrates that inhibition of the proteolytic activity of the proteasome blocks IL-1β induction of VCAM-1 and ICAM-1 gene expression in human endothelial cells.     

High expression of human 15-lipoxygenase induces NF-kappaB-mediated expression of vascular cell adhesion molecule 1, intercellular adhesion molecule 1, and T-cell adhesion on human endothelial cells

Expression of 15-lipoxygenase (15-LO) is induced over 100-fold in early fatty streak lesions. 15-LO activity leads to the production of specific lipid hydroperoxides, which can have major effects on the expression of proinflammatory genes involved in atherogenesis. We have used retrovirus-mediated gene transfer to achieve stable high expression of 15-LO in human endothelial ECV304 cells. These cells were used to study the effects of 15-LO on the expression of vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1), activation of nuclear factor kappa B (NF-kappaB), and T-cell adhesion on endothelial cells. NF-kappaB activation was greatly potentiated by increased 15-LO activity in the stably transduced cells, and both VCAM-1 and ICAM-1 were significantly induced in these cells in response to tumor necrosis factor-alpha (TNF-alpha) and phorbol 12-myristate 13-acetate (PMA) stimulation, as studied by flow cytometry. The induction of ICAM-1 was sensitive to antioxidants in a dose-dependent manner. The adherence of Jurkat T cells on the 15-LO-expressing endothelial cells was markedly induced after PMA stimulation. These results indicate that 15-LO activity may be involved in the early pathogenesis of atherosclerosis by inducing VCAM-1 and ICAM-1 expression and by increasing T-cell adhesion on the endothelium.     

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.     

EXPRESSION OF ICAM-1 AND VCAM-1 IN HUMAN MALIGNANT MESOTHELIOMA

Intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) are cytokine-inducible adhesion molecules which recognize ligands that are highly expressed on leukocytes. Expression of ICAM-1 and VCAM-1 was investigated in tissue sections of 16 cases of malignant mesothelioma (seven epithelial, eight biphasic, and one sarcomatoid) using immunohistochemistry. Neoplastic cells were diffusely and intensely stained for ICAM-1 in all cases. VCAM-1 was detected in 14 of 16 cases. The percentage of VCAM-1-positive tumour cells was more than 50 per cent in eight cases and the staining was observed mainly in epithelial-like cells. VCAM-1 was rarely expressed in other malignant tumours of epithelial origin, being present in only 1 of 58 cases of carcinoma originating from different anatomical sites. At the cellular level, ICAM-1 and VCAM-1 appeared co-distributed, the staining for both being cytoplasmic with a membrane reinforcement. The regulation of VCAM-1 expression by neoplastic mesothelial cells was investigated in vitro using 14 mesothelioma cell lines. ICAM-1 was expressed by cultured cells of all mesothelioma cell lines, even in the absence of cytokines. VCAM-1 was detected in 10–50 per cent of the cells in three non-stimulated mesothelioma cell lines (mero-95, mero-96, and mero-134), and was absent or poorly expressed in the remaining 11. Exposure of a negative cell line (mero-48a) to an optimal concentration of tumour necrosis factor alpha (TNFα) or interleukin-13 (IL-13) for 6–18 h resulted in the induction of VCAM-1 mRNA synthesis and in VCAM-1 expression at the membrane level in 60–70 per cent of the cells. These findings are consistent with the possibility that TNFα, IL-13, or other activating signals are released in the tumour micro-environment and regulate the expression of VCAM-1 in malignant mesothelioma cells.     

Intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression and function on cultured human glomerular epithelial cells.

Glomerular epithelial cells are involved in extracapillary inflammation (crescents) but the mechanisms of this extracapillary accumulation of macrophages, epithelial cells and occasional lymphocytes are unknown. Human glomerular parietal epithelial cells express ICAM-1 and VCAM-1 on immunohistological stains of renal biopsies. We studied the expression of these cell adhesion molecules on cultured human glomerular epithelial cells (HGEC), their regulation by pro-inflammatory cytokines, and their role in mediating the adhesion of concanavalin A (Con A)-activated peripheral blood mononuclear cells. Human glomerular epithelial cells in culture constitutively express ICAM-1 and VCAM-1. The expression of ICAM-1 was not significantly altered by tumour necrosis factor-alpha (TNF-alpha) (P = 0.32), IL-1 beta (P = 0.24), interferon-gamma (IFN-gamma) (P = 0.66) or IL-4 (P = 0.85). VCAM-1 expression was increased by all four cytokines, but only significantly so by IL-4 (P = 0.0001). Con A-stimulated, monocyte-depleted peripheral blood lymphocytes bound to human glomerular epithelial cells, median 28.9% (range 14.5-37.9%). This adherence was significantly inhibited by anti-ICAM-1 (P = 0.03) and anti-LFA-1 (P = 0.02), but not by anti-VCAM-1 (P = 0.13) or by antibody to von Willebrand factor (P = NS). The interaction between ICAM-1 on HGEC and LFA-1 on mononuclear cells may be important in the pathogenesis of extracapillary inflammation in glomerulonephritis.     

Human intestinal epithelial cells down-regulate IL-8 expression in human intestinal microvascular endothelial cells; role of transforming growth factor-beta 1 (TGF-β1)

Cytokines produced from intestinal epithelial cells may function as signals to neighbouring immune cells. In the present study we analysed the effects of colonic epithelial cell lines (HT-29, Caco-2, HCT-116, Colo-320) and freshly isolated intestinal epithelial cells on IL-8 expression in the SV-40T transfected human microvascular endothelial cell line (HMEC-1). Epithelial cell-conditioned media and transwells preventing physical contact between epithelial and endothelial cells were used. TGF-β1 and IL-8 levels were determined by ELISA and Northern blot analysis. Increasing concentrations of IL-1β led to increasing production of IL-8. The addition of epithelial cell-conditioned medium or epithelial cells to HMEC-1 cells in a two-compartment co-culture system resulted in a strong decrease in IL-8 at the protein and mRNA level. Decrease of IL-8 was markedly stronger when epithelial cells were co-cultured in contact with HMEC-1 cells, indicating that not only soluble factor(s) play a role in the induction of IL-8 suppression in HMEC-1 cells. MoAbs against TGF-β1 partially inhibited down-regulation of endothelial IL-8 expression. In further studies, IL-8 expression in freshly isolated human intestinal microvascular endothelial cells (HIMEC) was also down-regulated by intestinal epithelial cells. Our results demonstrate that intestinal epithelial cells down-regulate IL-8 expression in HMEC-1 cells. TGF-β1 is a candidate factor of epithelial–endothelial communication in the colonic mucosa.     

Keratinocyte growth factor (KGF) decreases ICAM-1 and VCAM-1 cell expression on bronchial epithelial cells

Activation of leucocytes during airway inflammatory reaction involves adhesion to bronchial epithelial cells (BEC), a process implicating specific interactions between glycoproteins with epithelial cell surface proteins, mainly intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). In this study, the effect of keratinocyte growth factor (KGF), a growth factor involved in pulmonary epithelium repair, was evaluated on adhesion molecule expression with BEAS-2B cells and BEC and granulocyte adherence to BEAS-2B. The modulation by KGF of membrane and mRNA expression of ICAM-1 and VCAM-1 was studied on confluent cells stimulated or not with tumour necrosis factor-alpha (TNF) (200 UI/ml) or TNF and interleukin (IL)-4 (50 UI/ml and 10 ng/ml). Levels of soluble-(s)ICAM-1 and sVCAM-1 were measured by ELISA. Although moderately, KGF significantly decreased membrane ICAM-1 expression in unstimulated BEAS-2B cells (24% inhibition at 100 ng/ml) or in TNF- or TNF + IL-4-stimulated cells (22.5 and 18.7% inhibition, respectively). Treatment with KGF tended to decrease VCAM-1 expression in TNF- and TNF + IL-4-stimulated BEAS-2B (P = n.s. and P < 0.05, 14 and 15% inhibition, respectively). In primary culture of BEC, adhesion molecule expression was also reduced. ICAM-1 and VCAM-1 mRNA expression were also inhibited by KGF. Levels of sICAM-1 and sVCAM-1 were not significantly increased in supernatants from KGF-treated cells (30% and 24% increase at 100 ng/ml, respectively) compared to controls. Moreover, KGF decreased by 31% the adherence of neutrophils to TNF-activated BEAS-2B. In conclusion, KGF decreases ICAM-1 and VCAM-1 expression and neutrophil adherence in BEC. These suggest its involvement in the resolution of the inflammatory reaction.     

Expression and regulation of intercellular adhesion molecule-1 on airway parasympathetic nerves

BACKGROUND: Eosinophils cluster along airway nerves in patients with asthma and release eosinophil major basic protein, an antagonist of inhibitory M2 muscarinic receptors on nerves. Blocking M2 function increases bronchoconstriction, leading to airway hyperreactivity. Intercellular adhesion molecule-1 (ICAM-1) mediates eosinophil adhesion to nerves. OBJECTIVE: We investigated mechanisms of ICAM-1 expression by parasympathetic nerves. METHODS: ICAM-1 expression was examined by immunocytochemistry of lung sections from ovalbumin-sensitized and challenged guinea pigs. ICAM-1 was measured in parasympathetic nerves isolated from subjects and guinea pigs and in human neuroblastoma cells by real-time RT-PCR, immunocytochemistry, and Western blot. RESULTS: ICAM-1 was not detected in control airway parasympatheric nerves in vivo or in cultured cells. ICAM-1 was expressed throughout antigen-challenged guinea pig lung tissue and was selectively decreased by dexamethasone only in nerves. ICAM-1 was induced in human and guinea pig parasympathetic nerves by TNF-alpha and IFN-gamma and was inhibited by dexamethasone and by an inhibitor of nuclear factor-kappaB (NF-kappaB). In neuroblastoma cell lines TNF-alpha and IFN-gamma-induced ICAM-1 was blocked by an inhibitor of NF-kappaB but not by inhibitors of mitogen-activated protein kinases. Dexamethasone did not inhibit ICAM-1 expression in neuroblastoma cells. CONCLUSIONS: ICAM-1 induced in nerves by antigen challenge and proinflammatory cytokines is sensitive to dexamethasone. ICAM-1 expression is also sensitive to inhibitors of NF-kappaB. Neuroblastoma cells mimic many, but not all, characteristics of ICAM-1 expression in parasympathetic nerves. CLINICAL IMPLICATIONS: Dexamethasone and NF-kappaB inhibitors could prevent eosinophils from adhering to nerves by blocking ICAM-1 expression on parasympathetic nerves, thus protecting inhibitory M2 muscarinic receptors and making this pathway a potential target for asthma treatment.     

Morphological aspects of LFA-1/ICAM-1 and VLA4/VCAM-1 adhesion pathways in human lymph nodes

Monoclonal antibodies specific for the adhesion molecules participating in lymphocyte homing, lymphocyte function associated antigen-1 (LFA-1) and very late antigen 4 (VLA4), and their respective ligands, intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1), were used to characterize their expression pattern in human lymph nodes by immunohistochemical and immunoelectron microscopic techniques. The location of LFA-1-positive lymphocytes and selective expression of ICAM-1 on the luminal plasma membrane of high endothelial venule endothelium suggested that the LFA-1/ICAM-1 adhesion pathway participates only in the initial step of the lymphocyte migration process. Lymphocytes passing through endothelium appear not to be influenced by this pathway. VCAM-1 was detected occasionally on the endothelium of high endothelial venules in the hyperplastic lymph nodes in the mesentery, but not in peripheral lymph nodes. VLA4-positive lymphocytes tended to be more frequently observed within high endothelial venules in mesenteric lymph nodes than in peripheral ones. Strong expression of both ligands, ICAM-1 and VCAM-1, was noted on the plasma membrane of follicular dendritic cells, and was especially prominent on their labyrinthine folding, and on the interdigitating cells in the paracortex. Furthermore, both LFA-1-and VLA4-positive lymphocytes localized around these cells. This suggests that LFA-1/ICAM-1 and VLA4/VCAM-1 adhesion pathways play an important role in the lymphocyte recognition of antigen-presenting cells.     

Increased expression of mucosal addressin cell adhesion molecule-1 (MAdCAM-1) and lymphocyte recruitment in murine gastritis induced by Helicobacter pylori

Although T cell involvement in Helicobactor pylori-induced gastritis is known, mechanism about T cell recruitment is not understood. In this study we examined how mucosal addressin cell adhesion -molecule-1 (MAdCAM-1) is involved in lymphocyte recruitment in murine chronic gastritis induced by H. pylori. C57 BL/6 mice were infected with Sydney strain (SS1). Six months after infection, the stomach was removed. The expression of adhesion molecules, MAdCAM-1, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), and the cell surface antigens CD4, CD8, CD45R/B220 or beta7-integrin were determined by immunohistochemistry. A significant increase in CD4 lymphocytes was observed in the body portion of stomach in SS1-infected mice and most of these CD4 cells express beta7-integrin, a known counter ligand for MAdCAM-1 molecule. Strong MAdCAM-1 expression was observed adjacent to these cells in the lamina propria as well as in the submucosa of SS1-infected stomach. Quantitative analysis showed that the area of MAdCAM-1 expression well correlated with the infiltration of beta7-integrin positive lymphocytes. On the other hand, expression of ICAM-1 or VCAM-1 in the lamina propria was few even in the SS1-infected stomach. Increased expression of MAdCAM-1 was well correlated to the location of lymphocytes, which express CD4 and beta7-integrin. These results suggest the possibility that MAdCAM-1 may be largely involved in the lymphocyte recruitment in the gastritis mucosa with H. pylori.     

ICAM-1, VCAM-1, and MAdCAM-1 are expressed on choroid plexus epithelium but not endothelium and mediate binding of lymphocytes in vitro.

The expression of cell adhesion molecules (CAMs) in the choroid plexus was studied in normal brain and during experimental autoimmune encephalomyelitis (EAE) in the SJL/J mouse during inflammation induced by intracerebral injection of killed Corynebacterium parvum in the C3H/He mouse. Both ICAM-1 and VCAM-1, but not MAdCAM-1, were constitutively expressed on choroid plexus epithelium but not on the fenestrated capillary endothelial cells within the choroid plexus. During EAE, we observed an up-regulation of ICAM-1 and VCAM-1 and de novo expression of MAdCAM-1 on choroid plexus epithelial cells. In contrast, endothelial cells in the choroid plexus were not induced to express any of the investigated CAMs. In in situ hybridization analysis we demonstrated that ICAM-1, VCAM-1, and MAdCAM-1 were locally synthesized and that the amount of their mRNAs increased in the inflamed choroid plexus. In vitro, primary choroid plexus epithelial cells could be induced to express ICAM-1, VCAM-1, and MAdCAM-1 on their surface after treatment with proinflammatory cytokines such as tumor necrosis factor-alpha, interleukin-1, interferon-gamma, and lipopolysaccharide. To investigate the functional status of the expressed CAMs we performed Stamper-Woodruff binding assays on frozen sections of inflamed and naive brains. ICAM-1, VCAM-1, and MAdCAM-1 expressed in choroid plexus epithelial cells mediated binding of lymphocytes via their known ligands LFA-1 and alpha4-integrin, respectively. The expression of ICAM-1, VCAM-1, and MAdCAM-1 on choroid plexus epithelial cells together with the lack of their expression on the fenestrated choroid plexus endothelium raises the possibility that the epithelial blood-cerebrospinal-fluid barrier plays an important role in the immunosurveillance of the central nervous system.     

Hypoxia-induced mitogenic factor promotes vascular adhesion molecule-1 expression via the PI-3K/Akt-NF-kappaB signaling pathway

Hypoxia-induced mitogenic factor (HIMF), also known as FIZZ1 (found in inflammatory zone 1), is an important player in lung inflammation. However, the effects of HIMF on cell adhesion molecules involved in lung inflammation remain largely unknown. In the present work, we tested whether HIMF modulates vascular adhesion molecule (VCAM)-1 expression, and dissected the possible signaling pathways that link HIMF to VCAM-1 upregulation. Recombinant HIMF protein, instilled intratracheally into adult mouse lungs, results in a significant increase of VCAM-1 production in vascular endothelial, alveolar type II, and airway epithelial cells. In cultured mouse endothelial SVEC 4-10 and lung epithelial MLE-12 cells, we demonstrated that HIMF induces VCAM-1 expression via the phosphatidylinositol-3 kinase (PI-3K)/Akt-nuclear factor (NF)-kappaB signaling pathway. Knockdown of HIMF expression by small interference RNA attenuated LPS-induced VCAM-1 expression in vitro. We showed that HIMF induced phosphorylation of the IkappaB kinase signalsome and, subsequently, IkappaBalpha, leading to activation of NF-kappaB. Meanwhile, VCAM-1 production was correspondingly upregulated. Blocking NF-kappaB signaling pathway by expression of dominant-negative mutants of IkappaB kinase and IkappaBalpha suppressed HIMF-induced VCAM-1 upregulation. HIMF also strongly induced phosphorylation of Akt. A dominant-negative mutant of PI-3K, Deltap85, as well as PI-3K inhibitor, LY294002, also blocked HIMF-induced NF-kappaB activation and attenuated VCAM-1 production. Furthermore, LY294002 pretreatment abolished HIMF-enhanced mononuclear cells adhesion to endothelial and epithelial cells. Our findings connect HIMF to signaling pathways that regulate inflammation, and thus reveal the critical roles that HIMF plays in lung inflammation.     

Mice with neonatally induced inactivation of the vascular cell adhesion molecule-1 fail to control the parasite in Toxoplasma encephalitis

Under various inflammatory conditions, cell adhesion molecules are up-regulated in the central nervous system (CNS) and may contribute to the recruitment of leukocytes to the brain. In the present study, the functional role of vascular cell adhesion molecule (VCAM)-1 in Toxoplasma encephalitis (TE) was addressed using VCAM(flox/flox MxCre) mice. Neonatal inactivation of the VCAM-1 gene resulted in a lack of induction of VCAM-1 on cerebral blood vessel endothelial cells, whereas the constitutive expression of VCAM-1 on choroid plexus epithelial cells and the ependyma was unaffected; in these animals, resistance to T. gondii was abolished, and VCAM(flox/flox MxCre) mice died of chronic TE caused by a failure to control parasites in the CNS. Although leukocyte recruitment to the CNS was unimpaired, the B cell response was significantly reduced as evidenced by reduced serum levels of anti-T. gondii-specific IgM and IgG antibodies. Furthermore, the frequency and activation state of intracerebral T. gondii-specific T cells were decreased, and microglial activation was markedly reduced. Taken together, these data demonstrate the crucial requirement of VCAM-1-mediated immune reactions for the control of an intracerebral infectious pathogen, whereas other cell adhesion molecules can efficiently compensate for VCAM-1-mediated homing across cerebral blood vessels.     

Subcellular Localization of Intercellular Adhesion Molecule-1 in Colonic Mucosa in Ulcerative Colitis

Intercellular adhesion molecule-1 (ICAM-1) mediates the firm adhesion of leukocytes to endothelial cells. In ulcerative colitis (UC), ICAM-1 is suggested also to be involved in the further migration of leukocytes toward the epithelial lining, and in colonic tissue it has been reported to be expressed by cell types other than endothelial cells. This study aimed at determining the ultrastructural localization of ICAM-1 on cells belonging to the colonic mucosa from patients with UC. Colonic biopsies from 3 UC patients and 3 control subjects were examined ultrastructurally by immunogold labeling of ICAM-1. ICAM-1 was expressed on the luminal cell membranes of endothelial cells in both controls and inflamed and noninflamed UC colon, although the density was significantly increased in UC ( p <. 0001). Labeling was observed on the basal endothelial cell membranes and on macrophages and plasma cells in inflamed UC colon only. Epithelial cells did not express ICAM-1. ICAM-1 appears to be constitutively upregulated on the luminal endothelial membrane in UC, and the expression on basal endothelial membranes in active UC only suggests that ICAM-1 is more extensively involved in the leukocyte migration than previously acknowledged.     

Quantification of mucosal leucocyte endothelial cell interaction by in vivo fluorescence microscopy in experimental colitis in mice.

Leucocyte recruitment to sites of intestinal inflammation is a crucial, multi-step process that leads ultimately to the accumulation of cells in the inflamed tissue. We established a new in vivo model system of experimental colitis to quantify leucocyte-endothelial cell interaction and leucocyte extravasation in the inflamed mucosa of the colon. Furthermore, we investigated the pathophysiological role of ICAM-1 in the intestinal microcirculation in vivo. Using the model of dextran sodium sulphate (DSS)-induced acute and chronic colitis in mice, in vivo microscopy was performed in the colonic submucosal postcapillary venules and the submucosal collecting venules in normal or inflamed murine colonic segments. ICAM-1 expression was blocked by an anti-ICAM-1 monoclonal antibody or by suppressing NF-kappaB activation by gliotoxin. Significant increases in leucocyte adhesiveness (51-fold in postcapillary venules, 30-fold in collecting venules, P < 0.01) and extravasation (6.5-fold) could be demonstrated as early as day 2 of DSS-application in acute colitis (P < 0.01). This was paralleled by increases in both the histological damage scores and myeloperoxidase activities. In chronic dextran sodium sulphate-induced colitis significant increases in leucocyte-endothelium interactions and leucocyte extravasation were observed. Blocking ICAM-1 expression with a monoclonal antibody or gliotoxin, leucocyte sticking and extravasation were significantly down-regulated in vivo compared to controls (> 70%; P < 0.01). This new model system offers the possibility to specifically assess the role of adhesion molecules in the colonic mucosa in vivo as well as to investigate and quantify the effectiveness of experimental therapeutic approaches in acute or chronic intestinal inflammation.     

VCAM-1, but not ICAM-1 or MAdCAM-1, immunoblockade ameliorates DSS-induced colitis in mice

Adhesion molecule immunoneutralization is envisioned as a promising therapy for inflammatory bowel disease, but the relative value of selective blockade of different adhesion molecules has not been established. The aims of this study were to measure expression and functional relevance of endothelial intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), and mucosal addressin cell adhesion molecule 1 (MAdCAM-1) in leukocyte recruitment in experimental colitis and to compare the therapeutic effectiveness of their selective blockade. For this purpose, cell adhesion molecule expression was measured by the dual radiolabeled antibody technique in mice with dextran sulfate sodium-induced colitis and controls. Leukocyte-endothelial cell interactions were determined in colonic venules by fluorescence intravital microscopy. Therapeutic effects of chronic treatment with anti-ICAM-1, anti-VCAM-1, or anti-MAdCAM-1 antibodies were also assessed. Whereas colonic endothelial ICAM-1 was constitutively expressed and had a mild up-regulation in colitic animals, constitutive expression of VCAM-1 and MAdCAM-1 was low, but markedly increased after induction of colitis. Leukocyte adhesion was abrogated by immunoneutralization of VCAM-1 or MAdCAM-1 but not by treatment with an anti-ICAM-1 antibody. Chronic administration of anti-VCAM-1 antibody, but not anti-ICAM-1 or anti-MAdCAM-1, resulted in significant attenuation of colitis in terms of disease activity index, colon length, ratio of colon weight to length, and myeloperoxidase activity. In conclusion, VCAM-1 plays a central role in leukocyte recruitment in colitis and blockade of this adhesion molecule has higher therapeutic effect than immunoneutralization of ICAM-1 or MAdCAM-1 in this experimental model.     

Expression of E-selectin, intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 in non-small-cell lung carcinoma

Vascular cell adhesion molecules (VCAM) play an important part in the regulation of inflammation and are considered to be important in the process of malignant tumour growth. The present study describes the immunohistochemical staining patterns of E-selectin, intercellular adhesion molecule (ICAM)-1 and VCAM-1 on endothelial cells of the vessels in tumour stroma and other cell types in non-small-cell lung carcinoma (NSCLC; n=43) in association with inflammatory cells. Expression of E-selectin was dominant on endothelial cells in the stromal areas of the tumour, especially at the borders, and was confined to endothelial cells. Moderate to strong staining for ICAM-1 was demonstrated on endothelial cells irrespective of size or localization of the vessels. Compared with ICAM-1, fewer vessels were positive for VCAM-1, and stained with lesser intensity. ICAM-1 expression was demonstrated on NSCLC cells, the basal cells of bronchial epithelium, type II pneumocytes, lymphocytes and fibroblasts. VCAM-1 was clearly expressed on NSCLC cells in 4 of the 43 cases and on lymphocytes and fibroblasts. The staining patterns observed on endothelial cells support the idea of an active status of NSCLC vessels. This phenotypic pattern looks similar to the vascular component of inflammation. The presence of ICAM-1 and VCAM-1 on NSCLC cells suggests a functional role in the process of chemotaxis for tumour cells.