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C W Smith

Publications and source records attributed to C W Smith.

At least 235 records · Page 13Linked to original sources

Induction of ICAM-1 expression on human airway epithelial cells by inflammatory cytokines: effects on neutrophil-epithelial cell adhesion.

Inflammation of the human airways in diseases such as chronic bronchitis, cystic fibrosis with Pseudomonas endobronchial infection, and possibly asthma during late-phase reactions involves a local influx of neutrophils (PMN) that may participate in airway epithelial injury. PMN-mediated cellular injury is most efficient under conditions of PMN-target cell adhesion. PMN express adhesive glycoproteins of the CD11/CD18 family that are counter-receptors for intercellular adhesion molecule-1 (ICAM-1), found on various cell types. We proposed that adherence by PMN to human airway epithelial cells via ICAM-1 might be an important mechanism in inflammatory airway diseases. We found that although PMN adhere poorly (less than 5%) to monolayers of human tracheal epithelial cells (TEC) in primary culture, they adhere readily (45 to 50%) to an SV40-immortalized line of human TEC, designated 9HTEo-. We also found 6-fold greater surface expression of ICAM-1 on 9HTEo- compared with primary TEC. Blocking surface ICAM-1 on 9HTEo- cells with specific monoclonal antibody inhibited PMN adherence by about 50%. Thus, ICAM-1 plays a major role in this adherence, although it is possible that other epithelial ligands contribute also. Antibodies to CD11a, CD11b, and CD18 on PMN also inhibited PMN-epithelial adherence. Treatment of primary TEC monolayers with the proinflammatory cytokines interleukin-1 (IL-1) or tumor necrosis factor-alpha (TNF-alpha) caused a 3- to 4-fold increase in both cell surface ICAM-1 expression and support of PMN adhesion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Neutrophil adherence to isolated adult cardiac myocytes. Induction by cardiac lymph collected during ischemia and reperfusion.

Canine neutrophils can be induced to adhere in vitro to isolated adult cardiac myocytes by stimulation of the neutrophils with chemotactic factors such as zymosan-activated serum (ZAS) only if the myocytes have been previously exposed to cytokines such as interleukin 1 (IL-1) or tumor necrosis factor-alpha. These cytokines induce synthesis and surface expression of intercellular adhesion molecule-1 (ICAM-1) on the myocyte, and neutrophil adhesion is almost entirely CD18 and ICAM-1 dependent. The present study examines cardiac-specific lymph collected from awake dogs during 1-h coronary occlusion and 3 d of reperfusion for its ability to induce both ICAM-1 expression in cardiac myocytes, and neutrophil-myocyte adherence. Reperfusion lymph induced ICAM-1 expression in isolated myocytes, and myocyte adherence to ZAS-stimulated neutrophils that was completely inhibited by anti-CD18 and anti-ICAM-1 monoclonal antibodies. This activity peaked at 90 min of reperfusion and persisted for up to 72 h. Preischemic lymph was not stimulatory. IL-1 appeared not to be a stimulating factor in lymph in that dilutions of lymph were found to inhibit the stimulatory effects of recombinant IL-1 beta. However, investigation of interleukin 6 (IL-6) revealed that recombinant IL-6 stimulated myocyte adhesiveness for ZAS-stimulated neutrophils (ED50 = 0.002 U/ml) and expression of ICAM-1 by isolated myocytes. IL-6 neutralizing antibody markedly reduced the ability of reperfusion lymph to stimulate adhesion and ICAM-1 expression, and estimates of levels of IL-6 in reperfusion lymph ranged from 0.035 to 0.14 U/ml. These results indicate that cytokines capable of promoting neutrophil-myocyte adhesion occur in extracellular fluid during reperfusion of ischemic myocardium, and that one of these cytokines is IL-6. Neutrophil-myocyte adhesion may be of pathogenic significance because it may enhance the cytotoxic activity of the neutrophil.

Animals↗

Neutrophil induced oxidative injury of cardiac myocytes. A compartmented system requiring CD11b/CD18-ICAM-1 adherence.

We have previously shown that cytokines and postischemic cardiac lymph induce expression of intercellular adhesion molecule-1 (ICAM-1, CD54) on canine adult cardiac myocytes. ICAM-1 expression allows adherence of activated neutrophils to myocytes that is blocked by anti-CD18 mAb, R15.7, or anti-ICAM-1 mAb, CL18/6. Interleukin 1, tumor necrosis factor-alpha, or interleukin 6-stimulated cardiac myocytes were loaded with 2',7'-dichlorofluorescin, and oxidation to the fluorescent dichlorofluorescein was monitored. Fluorescence and neutrophil/myocyte adherence followed the same time course, and both were blocked by monoclonal antibodies to CD18, CD11b, and ICAM-1, but mAb R7.1, recognizing a functional epitope on CD11a, was not inhibitory. The iron chelator, desferroxamine, and the hydroxyl radical scavenger, dimethylthiourea, did not inhibit neutrophil adherence, but completely inhibited fluorescence. In contrast, the extracellular oxygen radical scavengers superoxide dismutase and catalase, and the extracellular iron chelator, starch-immobilized desferroxamine, did not affect either fluorescence or adherence. Under the experimental conditions used, no superoxide production could be detected in the extracellular medium. Fluorescence microscopy demonstrated that fluorescence began within 5 min after neutrophil adherence to an individual myocyte, and myocyte contracture followed rapidly. Fluorescent intensity was highest initially at the site of myocyte-neutrophil adherence. When only neutrophils were loaded with 2',7'-dichlorofluorescein, fluorescence was observed only in those neutrophils adhering to the cardiac myocytes. Thus, adherence dependent on Mac-1 (CD11b/CD18) and ICAM-1 (CD54) activates the neutrophil respiratory burst resulting in a highly compartmented iron-dependent myocyte oxidative injury.

Animals↗

Recruitment of CD11b/CD18 to the neutrophil surface and adherence-dependent cell locomotion.

Chemotactic stimulation of neutrophils results in translocation of CD11b/CD18 (Mac-1) from intracellular storage pools to the cell surface. Though results from several laboratories indicate that the newly arrived surface Mac-1 is not involved in the adherence induced by the initial stimulus, the present study addresses the hypothesis that this Mac-1 plays a role in subsequent adherence-dependent functions. The response of human neutrophils to changing concentrations of a chemotactic stimulus was evaluated by determining the amount of newly arrived surface Mac-1, and Mac-1-dependent adhesion and locomotion. Small step-wise increases in the concentration of f-Met-Leu-Phe (FMLP) resulted in proportional stepwise increases in surface Mac-1 that plateaued within 2-4 min. This newly arrived Mac-1 supported adhesion to protein-coated surfaces only when the cells were exposed to an additional increase in the FMLP stimulus level. Adherence-dependent cellular locomotion was evaluated in chambers that allowed rapid changes in the stimulus concentration. Repeated small increments in the stimulus level at 200-s intervals resulted in significantly longer migration paths than a single-step increase in the stimulus. The results support the hypothesis that small increments in the chemotactic stimulus bring Mac-1 to the cell surface, and this newly mobilized Mac-1 is available for adherence-dependent locomotion with subsequent increases in the concentration of the stimulus.

Adult↗

Insoluble immune complex-stimulated neutrophil leukotriene B4 production is dependent on Fc gamma RII and Fc gamma RIII and independent of pertussis toxin-sensitive signal transduction pathways.

Leukotriene B4 (LTB4) release initiated by interaction of immune complexes (ICs) with Fc gamma RII and Fc gamma RIII receptors on human neutrophils was studied using well-defined complexes. Immune complexes consisting of polyclonal rabbit antibody to human albumin were prepared at equivalence (insoluble complex) and at five times antigen excess (soluble complex). Incubation of human neutrophils with soluble and insoluble ICs led to the synthesis of LTB4 from endogenous arachidonic acid (AA). LTB4 release induced by ICs was markedly inhibited by monoclonal antibodies against either Fc gamma RII or Fc gamma RIII receptor. Treatment of neutrophils with pertussis toxin significantly inhibited the release of LTB4 induced by soluble ICs. However pertussis toxin treatment minimally inhibited the LTB4 release induced by insoluble ICs. Crosslinking of either Fc gamma RII and Fc gamma RIII receptors on neutrophil surfaces induced LTB4 release. This is the first experimental observation showing that both Fc gamma RII and Fc gamma RIII directly induce neutrophil LTB4 metabolism in the absence of exogenous AA. These studies also suggest the involvement of novel pertussis toxin insensitive signal transduction pathways in insoluble ICs stimulation of neutrophils.

Antigen-Antibody Complex↗

Adhesion molecules in experimental phacoanaphylactic endophthalmitis.

Intraocular accumulation of inflammatory neutrophils is an important feature of experimental phacoanaphylactic endophthalmitis (EPE). Increasing evidence suggests that localization of neutrophils to the site of inflammation requires the participation of neutrophil and endothelial adhesion molecules. These studies were undertaken to determine if blocking of adhesion molecules on neutrophils (CD18) or endothelium (ELAM-1) could attenuate EPE in Lewis rats. Treatment of experimental animals with anti-CD18 or anti-ELAM-1 significantly suppressed intraocular neutrophil accumulation, retinal hemorrhage, and vasculitis, and attenuated retinal edema formation by 48% and 70%, respectively. These observations demonstrate that antibodies directed against adhesion molecules on the neutrophil (CD18) or the vascular endothelial cell (ELAM-1) exhibit potent anti-inflammatory effects, resulting in a striking amelioration of injury in EPE in rats.

Animals↗

Monoclonal antibodies to leukocyte integrins CD11a/CD18 and CD11b/CD18 or intercellular adhesion molecule-1 inhibit chemoattractant-stimulated neutrophil transendothelial migration in vitro.

Intercellular adhesion molecule-1 (ICAM-1) is present on the endothelium and binds to one or more members of the CD11/CD18 family of leukocyte surface integrins. To assess the role of these molecules in mediating chemotaxis of neutrophils across the endothelium, an in vitro model consisting of monolayers of human umbilical vein endothelial cells (HUVEC) grown on amniotic connective tissue was used. Neutrophils placed on the apical sides of these cultures migrated across the endothelium in response to chemoattractants added basally. Monoclonal antibodies (MoAbs) to CD11a, CD11b, and CD18 on the neutrophils inhibited this migration by 52% +/- 11%, 29% +/- 19%, and 90% +/- 7%, respectively. An MoAb to ICAM-1 inhibited transendothelial chemotaxis of the leukocytes by 55% +/- 16%. Inhibition was mediated by binding of the MoAb to ICAM-1 on the HUVEC, rather than by any direct effect of the antibody on the neutrophils. When used in combination, MoAbs to CD11a and to CD11b inhibited migration in a nearly additive fashion. A similar additive effect was observed when MoAbs to CD11b and to ICAM-1 were used together. In contrast, MoAbs to CD11a and to ICAM-1 produced no more inhibition when used in combination than when added singly. These results show that ICAM-1, CD11a/CD18, and CD11b/CD18 all participate in controlling migration of neutrophils across endothelial monolayers in response to chemotactic agents.

Amnion↗

Canine neutrophil margination mediated by lectin adhesion molecule-1 in vitro.

The contributions of the canine neutrophil lectin adhesion molecule-1 (LECAM-1) (canine homologue of the murine MEL-14 Ag) in neutrophil-endothelial cell adhesion and transendothelial migration were studied using anti-LECAM-1 mAb, CL2/6, and SL1 under static conditions and at wall shear stresses of up to 1.85 dynes/cm2 (dpc). Both mAb were found to inhibit attachment of neutrophils to cytokine-stimulated canine jugular vein endothelium. The inhibitory effects of the anti-LECAM-1 mAb were more evident at a wall shear stress of 1.85 dpc (greater than 50%) than at 0.23 dpc or under static conditions (approximately 30%). In contrast the anti-CD18 mAb, R15.7, exhibited higher inhibitory ability at the lower shear stress and under static conditions with marginal inhibition of adhesion at 1.85 dpc. Anti-LECAM-1 and anti-CD18 mAb showed additive inhibitory effects at the lower wall shear stress and under static conditions. Chemotactic stimulation of the neutrophils caused rapid down-regulation of LECAM-1 from the neutrophil surface and reduced adhesion by 60% at a wall shear stress of 1.85 dpc. This inhibition was not additive to anti-LECAM-1 mAb. Pretreatment with CL2/6 or SL1 did not affect trans-endothelial migration of adherent neutrophils under any experimental conditions tested. Anti-CD18 mAb, however, blocked transendothelial migration by 98% and 56% under static condition and at a wall shear stress of 0.23 dpc, respectively. The results in this report indicate that canine LECAM-1 is involved in the initial adhesion of unstimulated neutrophils to cytokine-stimulated endothelial cells under flow, but in contrast to CD18-integrins, plays no role in the transendothelial migration.

Animals↗

Antibodies against human neutrophil LECAM-1 (LAM-1/Leu-8/DREG-56 antigen) and endothelial cell ELAM-1 inhibit a common CD18-independent adhesion pathway in vitro.

Neutrophil adhesion to interleukin-1 (IL-1)-stimulated human umbilical vein endothelial cells (HUVEC) involves the CD18 family of leukocyte integrins (lymphocyte function-associated antigen-1 [LFA-1], Mac-1, and p150,95) and LECAM-1 (DREG-56/LEU-8/LAM-1 antigen) on neutrophils and intercellular adhesion molecule-1 (ICAM-1) and endothelial leukocyte adhesion molecule-1 (ELAM-1) on the endothelium. In this study, we compare CD18-independent adhesion pathways mediated by neutrophil LECAM-1 and endothelial ELAM-1 and find that these two pathways overlap in a variety of assays: (1) anti-LECAM-1 and anti-ELAM-1 monoclonal antibody (MoAb) inhibit neutrophil binding to HUVEC, and the inhibitory effect is not additive; (2) anti-LECAM-1 MoAb, like anti-ELAM-1 MoAb, inhibits neutrophil binding to HUVEC stimulated for 3 hours with IL-1, but not to HUVEC stimulated for 8 hours, by which time ELAM-1 expression is downregulated; (3) anti-ELAM-1 MoAb has no effect on transendothelial migration, a CD18-dependent, LECAM-1-independent neutrophil function. Interestingly, anti-ELAM MoAb has a reduced but significant inhibitory effect on the adhesion of activated neutrophils that have shed their cell-surface LECAM-1. We also show that neutrophil binding to ELAM-1-transfected L cells is inhibited not only by anti-ELAM-1 but also by anti-LECAM-1 MoAb. These results suggest that LECAM-1 and ELAM-1 can operate in the same adhesion pathway, possibly as a receptor-counterreceptor pair. LECAM-1 and ELAM-1 are likely to interact with other ligands as well, perhaps through carbohydrate determinants that modify more than one glycoprotein.

Animals↗

Diminished lectin-, epidermal growth factor-, complement binding domain-cell adhesion molecule-1 on neonatal neutrophils underlies their impaired CD18-independent adhesion to endothelial cells in vitro.

To define further the molecular basis for abnormal interactions of cord blood or neonatal neutrophils with endothelial cells in vitro, we studied neutrophil adhesion and migration under experimental conditions specifically designed to evaluate CD18-independent mechanisms. Unstimulated cord blood neutrophils of healthy term neonates demonstrated significantly diminished adhesion to IL-1-stimulated endothelial cell monolayers under conditions of shear stress (congruent to 1.85 dynes/cm2); overall levels of migration by neonatal cells were also significantly diminished, although the adherent subpopulation of these cells migrated relatively normally. A mAb (DREG-56) against the human homologue of the murine MEL-14 antigen (termed lectin-, epidermal growth factor-, complement binding domain-cell adhesion molecule-1 (LECAM-1), a member of the LEC-CAM family of adhesion molecules) markedly inhibited adhesion of healthy adult but not cord blood neutrophils. In additional assessments of endothelial cell adhesion or migration in the absence of shear forces, cord blood neutrophils demonstrated significantly diminished values compared to adult controls. Moreover, mAb DREG-56 significantly diminished adhesion of healthy adult but not cord blood suspensions in the presence or absence of the anti-CD18 mAb R15.7. Immunofluorescence assessments of unstimulated cord blood neutrophils or neutrophils of neonates 12 to 48 h of age showed dramatically diminished levels of surface LECAM-1 compared to adult neutrophils. Chemotactic stimuli (FMLP, 10 nM, 15 min) consistently "down-regulated" surface LECAM-1 on adult neutrophils to levels approximately 10% of unstimulated suspensions and comparable to those of most unstimulated neonatal suspensions. Moreover, FMLP stimuli elicited little or no down-regulation of LECAM-1 on neonatal cells. In comparative studies, endothelial cell adhesion of unstimulated cord blood or adult control neutrophils (assessed under conditions of flow) was directly related to levels of neutrophil surface LECAM-1. Although FMLP stimulation significantly diminished both adhesion and LECAM-1 surface levels of adult control cells, the adhesion and LECAM-1 expression observed with cord blood cells were not significantly influenced by this stimulus. The mechanisms underlying diminished LECAM-1 expression and LECAM-1-dependent adhesion of neonatal neutrophils and the physiologic significance of these abnormalities deserve investigation.

Adult↗

Thick filter neutrophil chemotaxis performed in the absence of albumin.

Migration through a filter is a technique widely used for the study of cell chemotaxis. Since the original description of the technique by Boyden in 1962 (J. Exp. Med. 115, 453) using neutrophils and thick filters prepared from cellulose nitrate, albumin has been required in the incubation medium to support chemotaxis. However, the binding to albumin of compounds affecting chemotaxis can reduce their free concentration. We developed two procedures for studying neutrophil chemotaxis under reduced or albumin-free conditions. In one, cellulose nitrate filters were pretreated with albumin by a novel procedure and chemotaxis was carried out in albumin-free medium. As tested with the chemoattractant LTB4 and human neutrophils, the procedure resulted in full chemotaxis, measured by the number of cells crossing the filter, with an EC50 of 0.43 nM for LTB4. The LTB4-receptor antagonist LY 223982 inhibited the chemotactic action of LTB4 with a Ki of 62 nM in the albumin-pretreated filter system, thus showing 58 times greater potency than in medium containing 0.5% albumin. The second procedure makes use, for the first time, of a relatively new filter (Hydrophilic Durapore). This filter has the same dimensions and pore rating of the cellulose nitrate filter but did not require pretreatment with albumin to support chemotaxis in the albumin-free medium. LTB4 stimulated neutrophil chemotaxis across this filter with an EC50 of 0.29 nM. LY 223982 had a Ki of 11 nM, thus exhibiting a potency even greater than in the albumin-pretreated cellulose nitrate filter system. fMLP and C5a also stimulated chemotaxis in the absence of albumin. These results suggest that albumin is not obligatory for neutrophil chemotaxis through thick filters. The role of albumin in the chemotaxis assay using cellulose nitrate filters may be to counteract the adherence of cells or chemotactic agents to the filters.

Albumins↗

ELAM-1 is an adhesion molecule for skin-homing T cells.

Endothelial cell leukocyte adhesion molecule-1 (ELAM-1) has been described as an inducible endothelial cell-adhesion molecule for neutrophils, and is believed to have a key role in the extravasation of these cells at sites of acute inflammation. Here we report that ELAM-1-transfected COS cells also bind a unique skin-associated subset of circulating memory T cells defined by the expression of the cutaneous lymphocyte-associated antigen. T cells expressing this antigen bind at least as well as neutrophils to expressed ELAM-1, whereas other lymphocytes in the peripheral blood bind poorly, or not at all. Immunohistological survey of chronically inflamed tissue specimens revealed that vascular expression of ELAM-1 occurs at cutaneous sites in preference to noncutaneous sites. We conclude that at sites of chronic inflammation, ELAM-1 may function as a skin vascular addressin, a tissue-selective endothelial cell-adhesion molecule for skin-homing memory T lymphocytes.

Animals↗

The peripheral lymph node homing receptor, LECAM-1, is involved in CD18-independent adhesion of human neutrophils to endothelium.

The binding of polymorphonuclear granulocytes (PMN) to activated vascular endothelium is a crucial step in the recruitment of PMN to an inflammatory site. Studies employing cytokine-activated endothelium in culture have shown that PMN binding involves the CD18 family of leukocyte integrins, but also CD18-independent adhesion mechanism(s) on PMN that have not been defined. We unify here two previously disparate approaches to study cell adhesion events between endothelial cells and leukocytes. We show that antibodies to human LECAM-1, the peripheral lymph node homing receptor that is also expressed on PMN, partially inhibit the adhesion of human PMN not only to HEV in frozen sections of lymph node tissue, but also to cytokine-activated human umbilical vein endothelium in vitro. Inhibition with anti-LECAM-1 antibodies and anti-CD18 antibodies is additive. Furthermore, the anti-LECAM-1 antibodies inhibit the adhesion of CD18-deficient PMN to cytokine activated human endothelial cells. These findings indicate that LECAM-1 and CD18-mediated binding mechanisms are independent, and act coordinately or sequentially to mediate PMN attachment to cytokine activated endothelium.

CD18 Antigens↗

PMN adhesion and extravasation as a paradigm for tumor cell dissemination.

Current evidence indicates that the localization and extravasation of neutrophils is a complex process involving several adhesion molecules with apparently distinct functions, and a highly coordinated and dynamic interplay between the neutrophil and the endothelial cell that is influenced by the shear forces present at the interface between these two cell types. Chemotactic stimulation of the neutrophil not only induces directed locomotion but markedly alters the surface expression and functions of the neutrophil adhesion molecules, having both an upregulating and downregulating influence. Cytokines such as interleukin 1 induce the synthesis and surface expression of endothelial adhesion molecules such as ICAM-1 and ELAM-1, and stimuli such as thrombin and histamine induce the rapid mobilization to the endothelial surface of another adhesion molecule, GMP-140. Transendothelial migration of neutrophils in most settings both in vitro and in vivo appears to require CD18 integrins on the neutrophil and ICAM-1 on the endothelial cells. This is most clearly demonstrated by the genetic deficiency of CD18 in humans, dogs and cattle, where neutrophil extravasation at most inflammatory sites is almost completely absent. Though the coordinated functions of the various neutrophil and endothelial adhesion molecules are highly efficient in promoting neutrophil extravasation, there has been relatively little investigation of their utilization in tumor cell dissemination. Recent results indicate that such studies may prove fruitful. For example, some adenocarcinoma cell lines express the complex carbohydrate (sialyl Lewis x) recently shown to be a ligand for ELAM-1.

Animals↗

Alternative splicing is an efficient mechanism for the generation of protein diversity: contractile protein genes as a model system.

Alternative splicing has emerged in recent years as a widespread device for regulating gene expression and generating protein diversity. Its analysis has provided some mechanistic understanding of this form of gene regulation and, in addition, has provided new insights into some fundamental aspects of splicing. This mode of regulation is particularly prevalent in muscle cells, where genes such as troponin T are able to generate up to 64 different isoforms from a single transcriptional unit. Alternative splicing has the potential to raise the coding capacity of the small multigene families that code for the contractile proteins so that several million structurally different sarcomeres can be generated. The mammalian alpha-tropomyosin gene has proved particularly useful for the analysis of the mechanisms involved in this type of regulation. In particular, the mutually exclusive splicing of exons 2 and 3 has provided answers about the processes involved in the three main regulatory steps: (a) establishment of mutually exclusive behavior; (b) the elements involved in setting up the default pattern of splicing, and (c) the switch from the default to the regulated splicing pattern in some cell types.

Animals↗

Production of an antibody to arterial fatty acid-binding protein (FABP) using a synthetic peptide as the antigen.

1. A procedure is described for the preparation of an antibody to arterial FABP using a synthetic peptide as an antigen. In order to locate a highly conserved region located on the outer surface of FABP, computer analysis of primary and secondary structures of several proteins from the FABP family was undertaken and a 24 amino acid sequence beginning at the fifth position from the N-terminus of rat heart FABP was chosen. 2. The synthetic peptide consisted of eight replications of the 24 amino acid sequence individually attached to the alpha and epsilon amino groups of each terminal lysine on an octalysine branched peptide. 3. Antibody to the synthetic antigen was raised in New Zealand rabbits. Western analysis was conducted and detection was accomplished by using goat-anti-rabbit second antibody conjugated to alkaline phosphatase. 4. The antibody produced from the previously described peptide, recognized purified rat heart FABP and demonstrated a high positive correlation (r = 0.96) when known concentrations of purified hFABP were plotted against densitometric measurement of the bands. 5. Additionally, the antibody recognized FABP from the 104,000 g supernates of rat atrial and arterial tissue fractionated by a Sephadex G-75 column. 6. Therefore, the antibody produced from this particular protocol employing a synthetic peptide can be utilized qualitatively and quantitatively in the analysis of the heart and arterial FABP content.

Amino Acid Sequence↗