Initial tract formation in the brain of the chick embryo: selective expression of the BEN/SC1/DM-GRASP cell adhesion molecule

This study reports the spatio-temporal pattern of BEN expression (a molecule of the immunoglobulin superfamily) during early stages of the first axonal tract formation, in the fore- and midbrain of chick embryos [Hamburger and Hamilton (HH) stages 12-22]. The expression of BEN has been analysed using immunohistochemistry and non-radioactive in situ hybridization. Furthermore, double labelling experiments (combining anti-class III beta-tubulin, a pan-neuronal marker, and anti-BEN antibodies) have been carried out to determine whether BEN is expressed by all first axonal tracts. The first neurons expressing BEN appear around stage HH13-14, in the caudal diencephalon. They belong to the interstitial nucleus of Cajal, and their axons are the first components of the medial longitudinal fasciculus. By HH14, two other early axonal tracts appear: the tract of the postoptic commissure and the descending root of the mesencephalic nucleus of the trigeminal nerve. Only the latter expresses BEN. At later stages of development numerous new axonal tracts appear in the telencephalic, diencephalic and mesencephalic domains. Only a few of them (the fourth nerve, the lemniscus lateralis, the tectobulbar and habenulopeduncular tracts) express BEN. In all BEN positive systems, the cell bodies, axons and growth cones are uniformly labelled by the antibody. We have found that none of the early axonal tracts grows preferentially at interneuromeric boundaries. Moreover, each tract is formed by several thin fascicles rather than a single one. The expression of BEN is transient and disappears shortly before hatching. These results suggest that BEN may serve to promote axonal outgrowth of precise neuronal systems involved in 'axonal scaffolding'.     

Expression of the cell adhesion proteins BEN/SC1/DM-GRASP and TAG-1 defines early steps of axonogenesis in the human spinal cord

We have studied the expression pattern of two cell adhesion proteins of the immunoglobin (Ig) superfamily, BEN/SC1/DM-GRASP (BEN) and the transient axonal glycoprotein TAG-1, during the development of the human nervous system. This study was performed by immunocytochemistry on sections of human embryos ranging from 4 to 13 weeks postconception. The overall distribution of the two proteins during development is very similar to that reported in other vertebrate species, but several important differences have been observed. Both proteins exhibit a transient expression on selected neuronal populations, which include the motor and the sensory neurons. In addition, BEN was also detected on virtually all neurons derived from the neural crest as well as in nonneuronal tissues. A major difference of expression with the chick embryo is that, in the motor neurons, BEN expression was not observed at early stages of development, thus arguing against a role of this molecule in pathfinding and fasciculation. BEN was observed to be restricted to subsets of motor neurons, such as the medial column at the upper limb level. Expression was also detected in a laterodorsal population of the ventral horn cells, which are likely to correspond to migrating preganglionic neurons that originate from the motor pool at the thoracic level. TAG-1 was found on commissural neurons and weakly on the sympathetic neurons; it was also detected on restricted nonneuronal populations. In addition, we observed TAG-1 expression in fibers that could correspond either to subsets of dorsal root ganglia (DRGs) central afferences (including the Ia fibers) or to the axons of association interneurons and in scattered motoneurons likely to correspond either to preganglionic neurons, to gamma-motoneurons, or to late-born motoneurons. Therefore, our results indicate that the molecular strategies used to establish the axonal scaffolding of the nervous system in humans are extremely conserved among the different vertebrates.     

Spatio-temporal diversity in the microenvironments for neural cell adhesion molecule, neural cell adhesion molecule-polysialic acid, and L1-cell adhesion molecule expression by sensory neurons and their targets during cochleo-vestibular innervation

Sixteen phases in the microenvironments were defined for the structural development and innervation of the cochleo-vestibular ganglion and its targets. In each phase the cell adhesion molecules, neural cell adhesion molecule, neural cell adhesion molecule-polysialic acid, and L1-cell adhesion molecule, were expressed differentially by cochleo-vestibular ganglion cells, their precursors, and the target cells on which they synapse. Detected by immunocytochemistry in staged chicken embryos, in the otocyst, neural cell adhesion molecule, but not L1-cell adhesion molecule, was localized to the ganglion and hair cell precursors. Ganglionic precursors, migrating from the otocyst, only weakly expressed neural cell adhesion molecule. Epithelial hair cell precursors, remaining in the otocyst, expressed neural cell adhesion molecule, but not L1-cell adhesion molecule. Post-migratory ganglion cell processes expressed both molecules in all stages. The cell adhesion molecules were most heavily expressed by axons penetrating the otic epithelium and accumulated in large amounts in the basal lamina. In the basilar papilla (cochlea), cell adhesion molecule expression followed the innervation gradient. Neural cell adhesion molecule and L1 were heavily concentrated on axonal endings peripherally and centrally. In the rhombencephalon, primitive epithelial cells expressed neural cell adhesion molecule, but not L1-cell adhesion molecule, except in the floorplate. The neuroblasts and their axons expressed L1-cell adhesion molecule, but not neural cell adhesion molecule, when they began to migrate and form the dorsal commissure. There was a stage-dependent, differential distribution of the cell adhesion molecules in the floorplate. Commissural axons expressed both cell adhesion molecules, but their polysialic acid disappeared within the floorplate at later stages. In conclusion, the cell adhesion molecules are expressed by the same cells at different times and places during their development. They are positioned to play different roles in migration, target penetration, and synapse formation by sensory neurons. A multiphasic model provides a morphological basis for experimental analyses of the molecules critical for the changing roles of the microenvironment in neuronal specification.     

Platelet endothelial cell adhesion molecule-1 expression during mouse postimplantation development

The proteasome is an unusually large multisubunit proteolytic complex, consisting of a central catalytic machine (equivalent to the 20S proteasome) and two terminal regulatory subcomplexes, termed PA700 or PA28, that are attached to both ends of the central portion in opposite orientations to form the enzymatically active proteasome. Totally about 40 subunits with sizes of 20-110 kDa are assembled to form two types of the proteasomal complexes with the same catalytic core and different regulatory modules. To date, cDNAs or genes encoding almost all subunits of human and the budding yeast proteasomes have been isolated by molecular-biological techniques. In this minireview, I summarize briefly available information on the structure-function relationships of the proteasome acting as a protein death machinery.     

Multiple roles of neural cell adhesion molecule, neural cell adhesion molecule-polysialic acid, and L1 adhesion molecules during sensory innervation of the otic epithelium in vitro

To explore the role of cell adhesion molecules in the innervation of the inner ear, antibody perturbation was used on histotypic co-cultures of the ganglionic and epithelial anlagen derived from the otocyst. When unperturbed, these tissues survived and differentiated in this culture system with outgrowth of fasciculated neuronal fibers which expressed neural cell adhesion molecule and L1. The fibers exhibited target choice and penetration, then branching and spreading within the otic epithelium as individual axons. Treatment of the co-cultures, or of the ganglionic anlagen alone, with anti-neural cell adhesion molecule or anti-L1 Fab fragments produced a defasciculation of fibers but did not affect neurite outgrowth. In the co-cultures this defasciculation was accompanied by a small increase in the number of fibers found in inappropriate tissues. However, the antibodies did not prevent fiber entry to the otic epithelium. In contrast, removal of polysialic acid from neural cell adhesion molecule with endoneuraminadase-N, while producing a similar fiber defasciculation, also increased the incidence of fibers entering the epithelium. Nevertheless, once within the target tissue, the individual fibers responded to either Fab or to desialylation by spreading out more rapidly, branching, and growing farther into the epithelium. The findings suggest that fasciculation is not essential for specific sensory fibers to seek out and penetrate the appropriate target, although it may improve their tracking efficiency. Polysialic acid on neural cell adhesion molecule appears to limit initial penetration of the target epithelium. Polysialic acid as well as neural cell adhesion molecule and L1 function are involved in fiber-target interactions that influence the arborization of sensory axons within the otic epithelium.     

The neural restrictive silencer element can act as both a repressor and enhancer of L1 cell adhesion molecule gene expression during postnatal development

The cell adhesion molecule L1 mediates axonal guidance during neural development and mutations in its gene result in severe neurological defects. In previous studies, we identified the promoter for the L1 gene and showed that a neural restrictive silencer element (NRSE) was critical for preventing ectopic expression of L1 during early embryonic development. In the present study, we have investigated the role of the NRSE in the regulation of L1 expression during postnatal development. In gel mobility shift experiments, the NRSE formed DNA-protein complexes with nuclear extracts prepared from the brains of postnatal mice. To examine the influence of the NRSE on postnatal patterns of L1 expression in vivo, we compared the expression of two lacZ transgene constructs, one containing the native L1 gene regulatory sequences (L1lacZ) and another (L1lacZDeltaN) lacking the NRSE. Newborn mice carrying the L1lacZDeltaN showed enhanced beta-galactosidase expression relative to L1lacZ in the brain and ectopic expression in nonneural tissues. In contrast to L1lacZ mice, however, L1lacZDeltaN mice showed an unexpected loss, during postnatal development and in the adult, of beta-galactosidase expression in several neural structures, including the neural retina, cerebellum, cortex, striatum, and hippocampus. These data support the conclusion that the NRSE not only plays a role in the silencing of L1 expression in nonneural tissues during early development but also can function as a silencer and an enhancer of L1 expression in the nervous system of postnatal and adult animals.     

Influence of adhesion molecule expression by human brain microvessel endothelium on cancer cell adhesion

Cultures of endothelial (En) cells derived from human brain microvessels were established in order to characterize adhesion molecule expression and to assay the adhesion properties of neoplastic cell lines to monolayers of En cells. Low constitutive expression of beta1 integrin (CD29), and ICAM-2 (CD102) was detected on human brain microvessel En cells. The beta1 chain of the VLA integrin family, ICAM-1, E-selectin (CD62E) and VCAM-1 (CD106) but not ICAM-2 and PECAM-1 (CD31) expression was upregulated by IL1-alpha, and TNF-alpha proinflammatory cytokines. High expression of PECAM-1 was found on non-activated human brain EN cells. In order to study the potential role of adhesion molecules in neoplastic cell adhesion two tumor cell lines were chosen. Adhesion of a cell line (DU145) derived from a cerebral metastasis of prostate carcinoma to human brain microvessel En cell monolayers was less pronounced compared to adhesion of a primary prostate carcinoma cell line (ND1). Adhesion of cerebral metastatic neoplastic cell line (DU145) was not significantly influenced by incubation of endothelial cells with different proinflammatory cytokines. The adhesion capability of primary prostate carcinoma line (NDI) was significantly upregulated by TNF-alpha proinflammatory cytokine. Furthermore, the adhesion of ND1 was partly inhibited using anti-E-selectin and VCAM-1 monoclonal antibodies. There was no significant effect of anti-adhesion antibodies on the adhesion characteristics of the cerebral metastatic (DU145) cell line. Our data demonstrate that different mechanisms are involved in the adhesion of neoplastic cells to cerebral En cells and turn our attention to the importance of adhesion molecule expression in the formation of metastases.     

Novel redistribution of the Ca(2+)-dependent cell adhesion molecule DdCAD-1 during development of Dictyostelium discoideum

Dictyostelium discoideum cells express DdCAD-1, a Ca(2+)-dependent cell-cell adhesion molecule, soon after the initiation of development. DdCAD-1 is a soluble protein which shares a significant degree of sequence similarity with E-cadherin. Laser scanning confocal microscopy of the subcellular localization of DdCAD-1 has revealed a nonrandom pattern of DdCAD-1 distribution. DdCAD-1 is present mostly as diffusely stained material in the cytoplasm during the initial stage of development. However, a drastic redistribution takes place before the onset of cell aggregation, when DdCAD-1 become localized predominantly at the cell periphery and an enrichment of DdCAD-1 occurs on membrane ruffles. A high concentration of DdCAD-1 also becomes associated with lamellipodia and filopodia, which often appear to participate in cell contact formation. Although DdCAD-1 is present in high concentrations in contact regions during early development, it disappears rapidly from these areas during cell aggregation. This redistribution is accompanied by an accumulation of the Ca(2+)-independent cell adhesion molecule gp80 in contact regions. During chemotactic migration, DdCAD-1 is present primarily on cells at the tip and on the outer margin of cell streams. In contrast, gp80 is concentrated in contact regions among cells within well-developed streams. This dynamic redistribution suggests a unique role for DdCAD-1 in the recruitment of cells into streams and in the formation of initial contacts, but it may not be required to maintain stable contacts in the presence of gp80.     

Lymphocytes mediate TNF-alpha-induced endothelial cell adhesion molecule expression: studies on SCID and RAG-1 mutant mice

TNF-alpha is known to elicit a rapid increase in the expression of specific endothelial cell adhesion molecules (ECAMs) within different vascular beds. The aim of this study was to determine whether lymphocytes contribute to the increased ECAM expression elicited by TNF-alpha. A dual radiolabeled mAb technique was used to quantify constitutive and TNF-alpha-induced expression of ICAM-1, VCAM-1, E-selectin, and P-selectin in different vascular beds (lung, heart, stomach, mesentery, small intestine, large intestine, and muscle) in wild-type and SCID mice. In reconstitution experiments, either whole splenocytes, T cell-enriched splenocytes, or B cell-enriched splenocytes were injected into SCID mice 48 h before TNF-alpha administration. Although the constitutive expression of ECAMs differed only slightly between wild-type and SCID mice, TNF-alpha-induced ECAM expression was markedly blunted in SCID mice compared with wild-type mice. This blunted response to TNF-alpha was also demonstrated for VCAM-1 in recombination activating gene (RAG)-1 mutant mice. Reconstitution studies revealed that administration of 50 x 10(6) splenocytes in SCID mice at 48 h before cytokine treatment restored the TNF-alpha-induced expression of VCAM-1 to levels normally observed in wild-type mice. Reconstitution with T cell- but not B cell-enriched splenocytes, also restored the TNF-alpha-induced expression of VCAM-1 in SCID mice to wild-type levels. These results implicate circulating T lymphocytes as modulators of the increased ECAM expression elicited by TNF-alpha.     

Differential regulation of endothelial cell adhesion molecule expression by nitric oxide donors and antioxidants

Although nitric oxide (NO) and antioxidants inhibit adhesion molecule expression, their inhibitory effects on nuclear factor kappaB (NF-kappaB) activation may differ. The NO donors, but not 8-bromo-cGMP, decreased tumor necrosis factor alpha (TNF-alpha)-induced VCAM-1, ICAM-1, and E-selectin expression by 11-70%. In contrast, NAC completely abolished VCAM-1 and E-selectin expression and decreased ICAM-1 expression by 56%. Gel shift assays demonstrate that NF-kappaB activation was inhibited by both NO and antioxidants. The activation of NF-kappaB involves the phosphorylation and degradation of its cytoplasmic inhibitor IkappaB-alpha by 26S proteasomes. The 26S proteasome inhibitor MG132 prevented the degradation of phosphorylated IkappaB-alpha. NAC inhibited IkappaB kinase (IKK) activity and prevented IkappaB-alpha phosphorylation and degradation. In contrast, NO did not inhibit IKK activity, IkappaB-alpha phosphorylation, or IkappaB-alpha degradation. However, NO, but not antioxidants, induced IkappaB-alpha promoter activity. The inhibitory effects of NO on adhesion molecule expression, therefore, differs from that of antioxidants in terms of the mechanism by which NF-kappaB is inactivated.     

Neurite fasciculation mediated by complexes of axonin-1 and Ng cell adhesion molecule

Neural cell adhesion molecules composed of immunoglobulin and fibronectin type III-like domains have been implicated in cell adhesion, neurite outgrowth, and fasciculation. Axonin-1 and Ng cell adhesion molecule (NgCAM), two molecules with predominantly axonal expression exhibit homophilic interactions across the extracellular space (axonin- 1/axonin-1 and NgCAM/NgCAM) and a heterophilic interaction (axonin-1-NgCAM) that occurs exclusively in the plane of the same membrane (cis-interaction). Using domain deletion mutants we localized the NgCAM homophilic binding in the Ig domains 1-4 whereas heterophilic binding to axonin-1 was localized in the Ig domains 2-4 and the third FnIII domain. The NgCAM-NgCAM interaction could be established simultaneously with the axonin-1-NgCAM interaction. In contrast, the axonin-1-NgCAM interaction excluded axonin-1/axonin-1 binding. These results and the examination of the coclustering of axonin-1 and NgCAM at cell contacts, suggest that intercellular contact is mediated by a symmetric axonin-12/NgCAM2 tetramer, in which homophilic NgCAM binding across the extracellular space occurs simultaneously with a cis-heterophilic interaction of axonin-1 and NgCAM. The enhanced neurite fasciculation after overexpression of NgCAM by adenoviral vectors indicates that NgCAM is the limiting component for the formation of the axonin-12/NgCAM2 complexes and, thus, neurite fasciculation in DRG neurons.     

Identification and characterization of glycosylation-dependent cell adhesion molecule 1-like protein expression in the ovine uterus

We cloned the dbl-1 gene, a C. elegans homolog of Drosophila decapentaplegic and vertebrate BMP genes. Loss-of-function mutations in dbl-1 cause markedly reduced body size and defective male copulatory structures. Conversely, dbl-1 overexpression causes markedly increased body size and partly complementary male tail phenotypes, indicating that DBL-1 acts as a dose-dependent regulator of these processes. Evidence from genetic interactions indicates that these effects are mediated by a Smad signaling pathway, for which DBL-1 is a previously unidentified ligand. Our study of the dbl-1 expression pattern suggests a role for neuronal cells in global size regulation as well as male tail patterning.     

The cell adhesion molecule L1 is developmentally regulated in the renal epithelium and is involved in kidney branching morphogenesis

We immunopurified a surface antigen specific for the collecting duct (CD) epithelium. Microsequencing of three polypeptides identified the antigen as the neuronal cell adhesion molecule L1, a member of the immunoglobulin superfamily. The kidney isoform showed a deletion of exon 3. L1 was expressed in the mesonephric duct and the metanephros throughout CD development. In the adult CD examined by electron microscopy, L1 was not expressed on intercalated cells but was restricted to CD principal cells and to the papilla tall cells. By contrast, L1 appeared late in the distal portion of the elongating nephron in the mesenchymally derived epithelium and decreased during postnatal development. Immunoblot analysis showed that expression, proteolytic cleavage, and the glycosylation pattern of L1 protein were regulated during renal development. L1 was not detected in epithelia of other organs developing by branching morphogenesis. Addition of anti-L1 antibody to kidney or lung organotypic cultures induced dysmorphogenesis of the ureteric bud epithelium but not of the lung. These results suggest a functional role for L1 in CD development in vitro. We further postulate that L1 may be involved in the guidance of developing distal tubule and in generation and maintenance of specialized cell phenotypes in CD.     

Increased expression of intercellular adhesion molecule 1, CD11/CD18 cell surface adhesion glycoproteins and alpha 4 beta 1 integrin in a rat model of chronic interstitial lung fibrosis

The expression of the intercellular adhesion molecule 1 (ICAM-1), and the integrins CD49, CD11b/c, and CD11a (LFA-1 alpha chain) was analyzed in an experimental model of pulmonary fibrosis. Adult rats were exposed to 75% oxygen during 10 weeks, and to 2.0 mg/kg of paraquat twice weekly. Rats were sacrificed at 2 days, and at 2 and 10 weeks after the first injection of paraquat. Lungs were fixed in 4% paraformaldehyde and used for histology and immunohistochemistry. At 2 days the lungs showed a diffuse inflammation composed of a mixed polymorphonuclear and mononuclear cell infiltrate. Afterwards, the inflammatory process was predominantly mononuclear, and an increasing fibroblast proliferation was observed. Early inflammatory events (48 h) correlated with a moderate increased expression of ICAM-1, LFA, and CD11b/c in epithelial cells as well as a pronounced expression of ICAM-1 and CD11b/c in macrophages. At 2 and 10 weeks, there was a progressive increased expression of CD11b/c and ICAM-1 by macrophages, as well as of LFA in epithelial cells, and of ICAM-1 and CD49 by epithelial and interstitial cells. Lymphocytes showed a slight increased expression of LFA at 2 weeks, and of CD49 at 2 and 10 weeks. These results suggest that macrophages expressing ICAM-1, CD11b/c, and CD49 are involved in the earlier and late phases of the disease whereas fibroblast and epithelial cells expressing ICAM-1 and CD49 might play a role in the cell interactions involved in the fibrotic phase.     

Adenovirus-mediated gene transfer in neurons: construction and characterization of a vector for heterologous expression of the axonal cell adhesion molecule axonin-1

A case control study was undertaken to compare the distribution of apolipoprotein (a) phenotypes in patients suffering from atherosclerosis and undergoing coronary bypass surgery with the distribution observed in adequately selected controls. Cases differed from controls for triglycerides (1.90 +/- 0.88 mmol l-1 and 1.16 +/- 0.79 mmol l-1, P < 0.0001, respectively), HDL cholesterol (1.15 +/- 0.34 mmol l-1 and 1.69 +/- 0.42 mmol l-1, P < 0.0001, respectively), apolipoprotein AI (1.31 +/- 0.24 g l-1 and 1.70 +/- 0.29 g l-1, P < 0.0001, respectively) and lipoprotein a (Lp(a)) (0.32 +/- 0.30 g l-1 and 0.19 +/- 0.20 g l-1, P < 0.0001, respectively). The apolipoprotein (a) phenotypes were distributed differently in cases and controls (chi 2 = 25.26, P < 0.0001) with a lower percentage of isoforms of larger size and a higher percentage of isoforms of smaller size in patients. The Lp(a) concentration remained significantly higher in patients than in controls for most of the phenotypes, suggesting that both a high Lp(a) concentration and a different apolipoprotein (a) size distribution could be involved in the development of atherosclerosis in this population. In addition, patients exhibiting the highest Lp(a) concentrations had higher levels of LDL cholesterol and apolipoprotein B than patients exhibiting the lowest Lp(a) concentrations. This feature was not observed in controls. By contrast, controls with the highest Lp(a) concentration had significantly higher triglyceride levels than controls with the lowest Lp(a) concentration. This feature was not observed in patients. Our results indicate that patients undergoing bypass surgery have higher Lp(a) concentrations than controls, this increase being not completely explained by the difference in apolipoprotein (a) phenotype distribution. The high Lp(a) concentration seems to be associated with different lipid profiles in patients than in controls.     

Hematopoietic progenitor cell rolling in bone marrow microvessels: parallel contributions by endothelial selectins and vascular cell adhesion molecule 1

1,2-Naphthoquinones, such as beta-lapachone, 4-alkoxy-1,2-naphthoquinones, and tetrahydrofuran-1,2-naphthoquinones, react rapidly with 2-mercaptoethanol in benzene to give 1,4-, 1,2-, 1,3- and 1,6-Michael-type adducts that are formed by the addition of the thiol group to the quinone ring. Menadione (2-methyl-1,4-naphthoquinone) reacts with the thiol reagent very slowly under the same reaction conditions. Although the formation of the adducts can be followed by 1H-NMR, attempts to isolate the adducts failed due to their retroconversion to the starting products. On addition of a Lewis acid, however, the adducts undergo cyclization reactions that give stable derivatives that can be isolated and characterized. Determination of the structures of the derivatives allowed for the identification of the adducts from which they originated. Thus, beta-lapachone and 2,3-dinordunnione underwent 1,4- and 1,2-Michael type additions to the quinone ring, while 4-pentyloxy-1,2-naphthoquinone underwent two simultaneous Michael additions to the quinone ring of the naphthoquinone. Menadione underwent a single 1,3-addition. The alkylation rates of the thiol group of 2-mercaptoethanol by the naphthoquinones parallel the naphthoquinones efficiencies in inducing DNA cleavage through DNA-bound topoisomerase II. These results support our hypothesis that the cytotoxic effect of the naphthoquinones derive, at least in part, from their alkylation of exposed thiol residues on the topoisomerase II-DNA complex.     

Detection of altered adhesion molecule expression in experimental tumors by a radiolabeled monoclonal antibody

Adhesion molecules play a major role in the processes of invasion and metastasis of malignant tumors. Their expression within tumors has been reported to be quantitatively and qualitatively altered according to the invasiveness and metastatic potential of the tumor. The present study tested whether the intratumoral expression of integrin alpha 3 can be detected by a radiolabeled monoclonal antibody. The in vitro binding study with four different human cancer cells showed that radioiodinated GA17 antibody recognizing integrin alpha 3 bound specifically to these cells to varying degrees, according to the antigen density on each cell. The biodistribution study with 125I- and 111In-labeled antibodies showed specific localization of radiolabeled GA17 to the xenografts. However, the in vivo tumor localization was not proportional to the antigen density calculated in vitro, and antibody metabolism varied among the tumors, as was also confirmed by in vitro radionuclide retention assay. The intratumoral distribution of radioactivities varied reflecting the antigen expression within the tumor. These results indicate that 1) integrin alpha 3 was expressed in various kinds of tumors and could be localized by the radiolabeled antibody, and 2) the expression of integrin alpha 3 and the metabolism of the radiolabeled antibody after binding to the antigen within the tumor were variable among the tumors, which affected the radionuclide distribution characteristics. The expression of adhesion molecules within these tumors was noninvasively detected by a radiolabeled antibody. It may be possible to use integrin alpha 3, when it is overexpressed, as a target of therapy with antibodies radiolabeled with alpha or beta emitters.     

Interference of nonsteroidal antiinflammatory drugs with very late activation antigen 4/vascular cells adhesion molecule 1-mediated lymphocyte-endothelial cell adhesion

OBJECTIVE: To study the effect of nonsteroidal antiinflammatory drugs (NSAIDs) on the adhesion of peripheral blood lymphocytes (PBL) to activated human umbilical vein endothelial cells (HUVEC) under conditions that resemble blood flow. METHODS: Assays of adhesion of PBL to HUVEC or recombinant vascular cell adhesion molecule 1 (rVCAM-1), intercellular adhesion molecule 1 (ICAM-1), and E-selectin were performed under continuous rotation at 37 degrees C. The phenotype of PBL subpopulations attached was characterized by flow cytometry. Lymphocytes were pretreated with different doses (5-100 microg/ml) of aceclofenac, diclofenac, indomethacin, or piroxicam or with inhibitory monoclonal antibodies (MAb) prior to the adhesion assays. The effect of NSAIDs on lymphocyte adhesion molecules was assessed by flow cytometry. To determine whether NSAIDs interfere with the affinity state of very late activation antigen 4 (VLA-4) integrin, we studied the effect of these drugs on the appearance of a beta1 activation-dependent epitope recognized by the HUTS21 MAb both on human T lymphoblasts and on synovial fluid lymphocytes (SFL). RESULTS: In the flow-resembling model, PBL-HUVEC adhesion was mainly mediated by the VLA-4/ VCAM-1 adhesion pathway. The major PBL subset attached was the CD3+, CD45RO+ memory T cell, with CD49d(high) expression. Aceclofenac, diclofenac, and indomethacin, but not piroxicam, were able to inhibit PBL adhesion to HUVEC or rVCAM-1. However, the quantitative expression of VLA-4 was not affected by treatment of PBL with any of the NSAIDs studied. On T lymphoblasts and SFL, mostly CD45RO+ cells, the expression of the beta1 activation-dependent epitope detected by HUTS21 MAb was significantly decreased by aceclofenac, diclofenac, and indomethacin. CONCLUSION: Some NSAIDs are able to inhibit the adhesion of PBL to HUVEC under conditions that resemble blood flow by interfering with the conformational change in VLA-4 that increases its affinity for VCAM-1.