Fibrin induction of ICAM-1 expression in human vascular endothelial cells

In acute and chronic inflammatory processes, fibrin deposition, and leukocyte accumulation are classic histopathologic hallmarks. Previous studies have shown that fibrin and fibrin degradation products can have biologic effects on vascular endothelial cells and can induce the expression of several endothelial cell-derived factors that may be important in regulating inflammation and tissue repair. We now demonstrate that coculture of human vascular endothelial cells (EC) with fibrin results in the up-regulation of intercellular adhesion molecule-1 (ICAM-1), thus providing a first link between fibrin deposition and adhesion molecule expression, which may lead subsequently to leukocyte accumulation and extravasation. Increased ICAM-1 expression was demonstrated by ELISA, flow cytometry, and functional adhesion assays. EC ICAM-1 expression increased in a time and dose response fashion. Cell surface levels of ICAM-1 induced by fibrin were comparable to, or exceeded, levels induced by IL-1beta. ICAM-1 expression increased beginning at 4 h post-fibrin formation with sustained elevated expression at 48 h. Fibrin-stimulated EC also bound increased numbers of polymorphonuclear neutrophils in cellular adhesion assays. This increase in adhesion could be blocked by Ab to ICAM-1. Inhibition of fibrin polymerization also inhibited the up-regulation of ICAM-1. Culture medium from fibrin-stimulated EC contained elevated levels of soluble ICAM-1. These data suggest that fibrin deposition on vascular EC, in addition to other reported effects on EC metabolism, may also lead to leukocyte accumulation and extravasation through the induction of leukocyte adhesion molecules such as ICAM-1.     

Intercellular adhesion molecule-3 on endothelial cells. Expression in tumors but not in inflammatory responses

Intercellular adhesion molecule-3 (ICAM-3) was identified as the third counter-receptor for lymphocyte function-associated antigen-1. ICAM-3 is absent on endothelial cells in normal tissues but found on endothelial cells in lymphomas. Here, we examined ICAM-3 expression on vascular endothelial cells in lymphomas, nonlymphoid malignancies, benign tumors, and inflammatory diseases. We compared the expression of ICAM-3 on endothelial cells with the severity of inflammatory infiltrates and with the presence of E-selectin and VCAM-1. We found that ICAM-3 expression on endothelial cells was high on both benign and malignant tumors whereas it was low in inflammatory diseases. In contrast to E-selectin, ICAM-3 expression on endothelial cells was not correlated to the severity of inflammatory infiltrates. In hemangiomas, we showed by Northern blot analysis and immunocytochemistry that ICAM-3 expression was induced and that it was localized in immature areas that sustain the early stages of angiogenesis. Therefore, expression of ICAM-3 on blood vessels does not seem to play a role in the recruitment of leukocytes during inflammation but rather is correlated with angiogenesis and tumor development.     

Intercellular adhesion molecule 1 is the major adhesion molecule expressed during schistosome granuloma formation

Endothelial cell adhesion molecules play a key role in inflammation by initiating leukocyte trafficking. One of the most complex inflammatory responses is the formation of a cellular granuloma. Expression of adhesion molecules during granuloma formation was investigated by using the murine host reaction to schistosome parasite eggs deposited in the liver as a model. By both immunohistochemistry and lymphocyte adhesion assays, the predominant interaction identified was between intercellular adhesion molecule 1 (ICAM-1) and its cognate integrin, leukocyte functional antigen 1 (LFA-1). ICAM-1 expression on sinusoidal endothelium was induced when eggs were first deposited in the liver, peaked in parallel with granuloma size, and was downregulated with modulation of the granuloma. Polyacrylamide beads coated with soluble parasite egg antigens could induce ICAM-1 expression on endothelial cells in vitro only in the presence of tumor necrosis factor alpha, a cytokine previously shown to be key to granuloma formation. A role for ICAM-1 in recruiting lymphocytes to the hepatic granuloma was also supported by the observation that lymphocytes preincubated with anti-LFA-1 antibody did not bind to granulomas in tissue sections. While ICAM-1 is the predominant adhesion molecule in schistosome egg granuloma formation in wild-type mice, when the ICAM-1 gene is knocked out, vascular cell adhesion molecule 1 is upregulated and granuloma formation is preserved.     

Rickettsia conorii infection enhances vascular cell adhesion molecule-1- and intercellular adhesion molecule-1-dependent mononuclear cell adherence to endothelial cells

Leukocyte adherence to the endothelium is an essential component of the inflammatory response during rickettsial infection. In vitro, Rickettsia conorii infection of endothelial cells enhances the expression of adhesive molecules E-selectin, intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) in a time- and dose-dependent manner. Rickettsial lipopolysaccharide does not seem to be involved, because polymyxin B does not reduce their expression. The intracellular presence of the organism and de novo host protein synthesis are required for expression of cell adhesive molecules, since rickettsial inactivation by formol and pretreatment of cells with cycloheximide inhibits an increase in expression. The contribution of interleukin-1alpha (IL-1alpha) to this endothelial adhesive phenotype was shown by inhibitory experiments 8 and 24 h after infection with IL-1 receptor antagonist and IL-1alpha blocking antibodies. Enhanced adherence of mononuclear cells to infected endothelial cells involved VCAM-1- and ICAM-1-dependent mechanisms at the late phase of the inflammatory response. This endothelial adhesive phenotype may constitute a key pathophysiologic mechanism in R. conorii-induced vascular injury.     

Anti-adhesion molecule therapy in Theiler's murine encephalomyelitis virus-induced demyelinating disease

We examined the role of leukocyte function-associated antigen (LFA)-1 and its counter-receptor intercellular adhesion molecule (ICAM)-1, one of the most important pairs of adhesion molecules, in the development of Theiler's murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD). Immunohistochemical study showed hyper-expression of ICAM-1 on vascular endothelial cells and expression of LFA-1 on mononuclear infiltrating cells in the spinal cords of TMEV-infected mice. Treatment with mAb to ICAM-1 and/or LFA-1 molecules resulted in significant suppression of the development of demyelinating disease, both clinically and histologically, with down-regulation in the CNS of the respective adhesion molecules after treatment. In mice treated with these mAb, the specific delayed-type hypersensitivity and T cell proliferative responses for TMEV were decreased. The production of tumor necrosis factor-alpha and IFN-gamma in spleen cells was also decreased, but IL-4 production remained unchanged. These data suggest that ICAM-1/LFA-1 interaction is critically involved in the pathogenesis of TMEV-IDD and that antibodies to these adhesion molecules could be a novel therapeutic approach to the treatment of demyelinating diseases such as human multiple sclerosis.     

Activation of peripheral blood T cells by interaction and migration through endothelium: role of lymphocyte function antigen-1/intercellular adhesion molecule-1 and interleukin-15

Cell adhesion molecules have a key role in the migration of T cells to inflammatory foci. However, the effect of the endothelial-lymphocyte interaction on the activation of the latter cells remains unresolved. We have studied the effect of resting and stimulated endothelial cells (ECs) on the activation of peripheral blood T cells (PBTLs), as assessed by the expression of CD69 and CD25 activation antigens. The incubation of PBTLs with tumor necrosis factor-alpha-activated EC monolayers, either alive or fixed, induced the expression of CD69 but not CD25, preferentially in the CD8(+) CD45RO+ cell subset. Furthermore, it induced the production of cytokines such as IFN-gamma, but not that of interleukin-2 (IL-2) and IL-4. EC treated with other stimuli such as IL-1beta, IFN-gamma, or lipopolysaccharide also showed the same proactivatory effect on T cells. Lymphocyte activation was almost completely inhibited by blocking anti-CD18 and anti-intercellular adhesion molecule-1 (anti-ICAM-1) monoclonal antibodies (MoAbs), but only slightly affected by MoAbs against CD49d, vascular cell adhesion molecule-1, and anti-IL-15. In addition, the interaction of PBTL with immobilized ICAM-1 induced CD69 expression in the same memory T-cell subset. IL-15 induced T-cell activation with expression of CD69 and CD25, and production of IFN-gamma, and its effect was additive with that triggered by cell adhesion to either EC or immobilized ICAM-1. The transmigration of PBTLs through either confluent EC monolayers or ICAM-1-coated membranes also induced efficiently the expression of CD69. When IL-15 was used as chemoattractant in these assays, a further enhancement in CD69 expression was observed in migrated cells. Together these results indicate that stimulated endothelium may have an important role in T-cell activation, through the lymphocyte function antigen-1/ICAM-1 pathway, and that IL-15 efficiently cooperates in this phenomenon. These observations could account for the abundance of CD69(+) cells in the lymphocytic infiltrates of several chronic inflammatory diseases.     

Ibuprofen inhibits pyrogen-dependent expression of VCAM-1 and ICAM-1 on human endothelial cells

Leukocyte adhesion and transmigration through the endothelial cell (EC) layer plays a crucial role in inflammation. IL-1 alpha and TNF alpha increase EC-adhesiveness for leukocytes by stimulating surface expression of ICAM-1 (intercellular adhesion molecule 1, CD54), VCAM-1 (vascular cell adhesion molecule 1, CD106) and E-selectin (CD62E). In this study, the effects of ibuprofen on IL-1 alpha and TNF alpha-induced expression of ICAM-1, VCAM-1 and E-selectin on cultured human umbilical vein EC (HUVEC) were analyzed. Exposure to IL-1 alpha or TNF alpha resulted in an increased expression of VCAM-1, ICAM-1, and E-selectin. Ibuprofen was identified as a potent inhibitor of IL-1 alpha and TNF alpha-induced surface expression of VCAM-1 and a less potent inhibitor of pyrogen-induced expression of ICAM-1, whereas no effect on E-selectin was found. The effects of ibuprofen on VCAM-1 expression were dose-dependent (IC50 [IL-1 alpha]: 0.5 mM; IC50 [TNF alpha]: 0.5 mM) and time-dependent with maximum responses observed after 18 h. Moreover, ibuprofen abrogated pyrogen-dependent adhesion of leukocytes to HUVEC. Ibuprofen also inhibited VCAM-1 mRNA expression in pyrogen activated EC. VCAM-1-downregulation on EC by ibuprofen may contribute to the anti-inflammatory actions of the drug.     

In vitro correlates of the L. casei animal model of Kawasaki disease

The induction of coronary arteritis in mice by Lactobacillus casei cell wall (CW) is thought to represent an animal model of Kawasaki disease. Treatment of vascular endothelial cells (EC) in vitro with supernatants from CW stimulated human mononuclear cells (MNC) enhanced adherence of human polymorphonuclear leukocyte (PMN) to human EC, and EC expression of intercellular adhesion molecule-1 (ICAM-1) but not HLA-DR. Supernatants contained high concentrations of tumor necrosis factor-alpha (TNF-alpha) and PMN adherence correlated directly with the concentration of TNF-alpha. Intravenous human gamma globulin (IVGG) preparations did not block the effect of cytokine containing MNC supernates upon EC, ICAM-1 expression by EC, or PMN adherence to prestimulated EC. However, both EC ICAM-1 expression and enhanced PMN adherence to EC by CW induced MNC supernatants were blocked by anti-TNF-alpha treatment. The initial coronary inflammatory reaction in the mouse model appears to involve PMN adherence to vascular EC that have been activated by TNF-alpha released by MNC after stimulation with CW.     

Release of soluble intercellular adhesion molecule 1 into bile and serum in murine endotoxin shock

Neutrophil-induced liver injury during endotoxemia is dependent on the adhesion molecules Mac-1 (CD11b/CD18) on neutrophils and its counterreceptor on endothelial cells and hepatocytes, intercellular adhesion molecule 1 (ICAM-1). To investigate a potential release of a soluble form of ICAM-1 (sICAM-1), animals received 100 micrograms/kg Salmonella abortus equi endotoxin alone or in combination with 700 mg/kg galactosamine. In endotoxin-sensitive mice (C3Heb/FeJ), injection of endotoxin did not cause liver injury but induced a time-dependent increase of sICAM-1 in serum (300%) and in bile (615%) without affecting bile flow. In galactosamine/endotoxin-treated animals, which developed liver injury, the increase in both compartments was only 97% and 104%, respectively. In either case, the increase in sICAM-1 concentrations paralleled the enhanced ICAM-1 expression in the liver. The endotoxin-resistant strain (C3H/HeJ) did not show elevated sICAM-1 levels in serum or bile after endotoxin administration. In contrast, the intravenous injection of murine tumor necrosis factor alpha (TNF-alpha), interleukin-1 alpha (IL-1 alpha) or IL-1 beta (13-23 micrograms/kg) into endotoxin-resistant mice induced a 225% to 364% increase in serum sICAM-1 and a 370% elevation of the biliary efflux of sICAM-1, again independent of changes in bile flow. These data indicate that cytokines are major inducers of sICAM-1 formation during endotoxemia in vivo. The described experimental model can be used to investigate the role of sICAM-1 in the pathophysiology of inflammatory liver disease.     

Cytokine-induced beta-galactoside alpha-2,6-sialyltransferase in human endothelial cells mediates alpha 2,6-sialylation of adhesion molecules and CD22 ligands

Sialic acids decorating blood and cell surface proteins can play important roles in various biological processes. The inflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin-1, as well as bacterial lipopolysaccharide, can activate vascular endothelium, increasing expression of several surface glycoproteins. Here we show that treatment of cultured human endothelial cells (HEC) with TNF-alpha, interleukin-1, or lipopolysaccharide causes increased expression of the enzyme beta-galactoside alpha-2,6-sialytransferase (alpha 2-6STN). TNF-alpha was most effective, inducing a 3.5-fold enhancement of cell-associated sialytransferase activity by 72 h. In addition, activated HEC secreted a large portion of the induced sialyltransferase activity into the medium. Analysis of labeled HEC showed both a relative and an absolute increase of alpha 2,6-linked sialic acid on N-linked oligosaccharides after TNF-alpha stimulation. This coincided with increased expression of endothelial glycoproteins bearing N-linked glycans with alpha 2,6-linked sialic acid detected by the lectin Sambucus nigra agglutinin. The cytokine-inducible endothelial cell adhesion molecules E-selectin, ICAM-1, and VCAM-1 are among these glycoprotein substrates for alpha 2-6STN. These changes also correlated with a substantial increase in binding sites for CD22 beta, a mammalian lectin known to recognize oligosaccharides carrying multiple copies of alpha 2,6-linked sialic acid. Northern analysis revealed increased levels of mRNA encoding alpha 2-6STN. Thus, activation of endothelial cells during inflammatory and immunological processes may induce alpha 2-6STN, which can participate in sialylation of other activation-dependent molecules.     

Identification of childhood vaccine providers in Maryland

Chronic inflammation seems to play a major role in skin and muscle cell damage in dermatomyositis. Adhesion molecules and their ligands are fundamental in regulating inflammation. We have carried out an immunohistochemical analysis of different activation-inducible adhesion markers in 15 biopsy specimens from dermatomyositis skin lesions. Consistent findings were the increased expression of intercellular adhesion molecule-1 (ICAM-1) on endothelial cells, inflammatory cells and focally grouped keratinocytes in contact with subepidermal inflammatory infiltrates. Immunoreactivity for vascular cell adhesion molecule-1 (VCAM-1) was predominant on endothelial cells of the upper reticular dermis and dermal stellate-shaped cells. E-selectin (endothelial leukocyte adhesion molecule-1) immunoreactivity was less extensive, detected mostly on segments of vessels of the papillary dermis and upper reticular dermis, and sometimes independent of inflammation. This pattern of adhesion molecule expression is similar to that described in other immunemediated dermatoses. The up-regulation of the adhesion molecules appears to play a role in the development and perpetuation of dermatomyositis skin lesions.     

Soluble E-selectin enhances intercellular adhesion molecule-1 (ICAM-1) expression in human tumor cell lines

E-selectin mediates neovascularization via its soluble form, while its membrane-bound form initiates binding of tumor cells to vascular endothelium. Therefore, it was studied whether soluble E-selectin regulates further adhesion molecules on tumor cells. In tumor cells but not in related nonmalignant cells, intercellular adhesion molecule (ICAM)-1 expression was strikingly increased from 5 to 68% positive cells by in vitro inoculation of a recombinant E-selectin-IgG1 within 24 h, as analyzed by flow cytometry. The absence of changes in the expression of vascular cell adhesion molecule, integrin ligands (CD11a, CD18, integrin alpha 4), and sialyl-Lewis X indicates a specific effect of soluble E-selectin on ICAM-1. A cell adhesion assay revealed that the enhanced adhesion on T-cells to tumor cells mediated by soluble E-selectin-induced ICAM-1 expression was at a maximum after a 12-h incubation period. Therefore, ICAM-1 regulation on tumor cells might be a mechanism of immune escape.