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PubMed1995

Constitutive overexpression of the L-selectin gene in fresh leukemic cells of adult T-cell leukemia that can be transactivated by human T-cell lymphotropic virus type 1 Tax.

L-selectin is an adhesion molecule of the selectin family that mediates the initial step of leukocyte adhesion to vascular endothelium. Upon cellular activation, expression of the L-selectin gene is downregulated at both the protein and mRNA levels. To understand the mechanism of leukemic cell infiltration into organs, we studied the expression and regulation of L-selectin mRNA in fresh leukemic cells of adult T-cell leukemia (ATL) patients and investigated the response of the L-selectin promoter to human T-cell lymphotropic virus type 1 (HTLV-1) Tax, which is a viral transcriptional transactivator. Flow cytometry showed that L-selectin was expressed on fresh ATL cells along with other activation antigens. Northern blot analysis showed that ATL cells overexpressed that L-selectin mRNA and that the level was aberrantly upregulated after PMA stimulation. Studies using in situ hybridization showed expression of the L-selectin mRNA in the infiltrating leukemic cells in the liver of two ATL patients. Intravenous injection of a rat T-cell line that overexpresses L-selectin showed increased organ infiltration. The induction of Tax expression in JPX9 cells resulted in about a twofold increase in the mRNA expression levels compared with the basal level. Chloramphenicol acetyltransferase (CAT) assay after transient cotransfection showed about a fivefold transactivation of the L-selectin promoter by Tax. The serum level of the shed form of L-selectin was significantly increased in ATL patients (mean +/- SD, 4,215.4 +/- 4,111 ng/mL) compared with those of asymptomatic carriers and healthy blood donors (mean +/- SD, 1,148.0 +/- 269.0 ng/mL and 991.9 +/- 224 ng/mL, respectively). These results indicated that ATL cells constitutively overexpress the L-selectin gene that can be transactivated by HTLV-1 Tax. The overexpression of L-selectin, as well as of inflammatory cytokines, by ATL cells may provide a basis for ATL cells to attach the vascular endothelium, leading to transmigration and organ infitration.

Adult↗
PubMed1997

The origin of P-selectin as a circulating plasma protein.

P-selectin is a 140 kD protein found in the alpha-granules of platelets and the Weibel-Palade bodies of endothelial cells. On cell activation it is expressed on the cell surface and also secreted into plasma. Whether the circulating soluble P-selectin (sP-selectin) originates from platelets, endothelial cells, or both, is not known. We studied the level of sP-selectin in diseases with different platelet counts, with or without evidence of endothelial cell activation. Endothelial cell activation was confirmed by the detection of sE-selectin and ED1-fibronectin. A significant positive correlation between platelet count and sP-selectin concentration was observed in healthy controls, and in patients with thrombocytopenia due to bone marrow aplasia, or with thrombocytosis (r = 0.85; n = 47; p < 0.001). In patients with idiopathic thrombocytopenic purpura (ITP) the sP-selectin concentration was 110 +/- 39 ng/ml (n = 10), compared to 122 +/- 38 ng/ml in healthy controls (n = 26). However, their mean platelet count was lower (58 x 10(9)/l versus 241 x 10(9)/l in the control group). Accordingly, the levels of sP-selectin expressed per platelet increased to significantly higher levels (2.0 +/- 1.2 versus 0.6 +/- 0.2 fg/platelet in the control group; p < 0.0001). This suggests increased platelet turnover in patients with ITP. High levels of sP-selectin were found in patients with sepsis (398 +/- 203 ng/ml; n = 15) and with thrombotic thrombocytopenic purpura (TTP; 436 +/- 162 ng/ml; n = 12). Compared with patients with ITP, the concentration of sP-selectin per platelet was higher in patients with sepsis (4.8 +/- 4.3 fg/platelet; p < 0.005) or TTP (17.1 +/- 9.5 fg/platelet; p < 0.001). Endothelial cells are very likely to be the source in these patients and the presence of endothelial cell activation was confirmed by increased levels of circulating E-selectin and ED1-fibronectin. This study suggests that platelets are the major source of circulating sP-selectin in healthy individuals. Endothelial cell activation is associated with an increased sP-selectin concentration per platelet.

Adult↗
PubMed1997

Synergy between L-selectin signaling and chemotactic activation during neutrophil adhesion and transmigration.

L-selectin enables capture and rolling of neutrophils on inflamed endothelium. This may facilitate the binding of agonists such as IL-8 and platelet-activating factor (PAF), which signal CD18-mediated firm adhesion and transmigration. Recent studies demonstrate that L-selectin can mediate transmembrane signaling. However, the functional effects of costimulation through agonist and L-selectin require further study. Here, we quantify cell adhesion, motility, and transmigration in response to co-activation through L-selectin and agonist. The surface expression of CD11b/CD18 increased and L-selectin decreased in proportion to the extent of L-selectin cross-linking. A flow cytometric assay was used to measure CD11b/CD18-dependent adhesion to fluorescent beads adsorbed with albumin. Neutrophil adhesion was detected within seconds of adding PAF (20 pM), IL-8 (50 pM), or cross-linking L-selectin. Costimulation through agonist and L-selectin potentiated by up to threefold the rate and extent of bead capture. Stimulation through L-selectin induced membrane ruffling, whereas PAF or IL-8 induced bipolar shape change. L-selectin cross-linking sustained the transient shape change induced by low concentrations (10-50 pM) of agonist. Chemokinesis stimulated by IL-8 was inhibited in the presence of cross-linking L-selectin. This was attributed to enhanced cell spreading following costimulation. Migration across HUVEC monolayers stimulated with IL-1 was also potentiated in the presence of L-selectin cross-linking. We propose that cross-linking of L-selectin and binding of agonist receptors may act synergistically to amplify neutrophil activation and emigration in the inflamed vasculature.

Cell Adhesion↗
PubMed1998

Relationship between cleaved L-selectin levels and the outcome of acute myeloid leukemia.

High plasma levels of the shed form of L-selectin (sL-selectin) are frequently detectable in acute myeloid leukemia (AML). sL-selectin can inhibit blast cell adhesion to vascular endothelium and may thereby influence the phenotype of AML. In this study, we have investigated the relationship between sL-selectin levels and clinical presentation or disease outcome in 100 patients with AML. Fifty-eight patients were found to have sL-selectin levels >/=3.12 microgram/mL (>/=3 SD above the mean of healthy controls: "increased"). Patients with extramedullary disease such as lymphadenopathies, splenomegaly, hepatomegaly, and/or muco-cutaneous infiltration had significantly increased sL-selectin levels (P < .001). sL-selectin levels were significantly heterogeneous in the French-American-British subtypes (P = .0003). Patients with "normal" sL-selectin levels had higher probability of achieving complete remission (CR) than with "increased" levels: 81% versus 64%, respectively (P = .06). When adjusting for clinically relevant covariates predictive for CR (sex, age, Auer rods), "normal" sL-selectin levels were significantly associated with CR (odds ratio, 3.08; 95% confidence interval [CI], 1.10 to 8.58; P = .03). Moreover, patients with "increased" sL-selectin levels (>/=3.12 microgram/mL) had shorter event-free survival (EFS) (median 7.3 v 12 months, P = .008) and overall survival (median 1 v 2.05 years, P = .03) than patients with sL-selectin <3.12 microgram/mL. Multivariate statistical analysis (adjusted for age and presence of Auer rods) indicated that sL-selectin was an independent prognostic factor for EFS (hazard ratio [HR], 1.96; 95% CI, 1.21 to 3.17, P = .006) and overall survival (HR, 1.80; 95% CI, 1.09 to 2.98; P = .02). Thus, plasma sL-selectin may be a useful prognostic marker in the evaluation of AML at diagnosis.

Acute Disease↗
PubMed2002

Therapeutic effect of sulphated hyaluronic acid, a potential selectin-blocking agent, on experimental progressive mesangial proliferative glomerulonephritis.

The initial event in the process of leukocyte infiltration is characterized by leukocyte rolling on the surface of the endothelium, which is mediated by selectins. P- and L-selectin bind to the sulphated sugar chains of their natural ligands, including sulphated glycolipids such as sulphatide. Recently, it has been demonstrated that sulphated glycolipids and sulphated oligosaccharides interfere with selectin binding pathways. This study synthesized sulphated hyaluronic acid (SHA), which is a potential selectin-blocking agent, and examined its therapeutic effect on the experimental progressive mesangial proliferative glomerulonephritis induced by anti-Thy-1 monoclonal antibody (1-22-3 MAb) after unilateral nephrectomy. The selectin-inhibitory effect of SHA in vitro was confirmed. SHA inhibited the binding of P- and L-selectin to sulphatide, which is a glycolipid ligand for P- and L-selectin, at a concentration of 1.5 micro g/ml and 100 micro g/ml. Immunohistochemical examination showed that P-selectin was up-regulated in the glomeruli in the 1-22-3 MAb nephritis model, while the ligands for L-selectin were not detected in the glomerular tufts. A single administration of SHA ameliorated proteinuria and glomerular leukocyte infiltration in 24 h after the injection of anti-Thy-1 MAb. Anti-P-selectin MAb, but not anti-L-selectin MAb, inhibited proteinuria and glomerular leukocyte infiltration. To examine further the therapeutic effect of SHA on chronic glomerulonephritis, SHA was administered daily from day 3 to day 14 in this model. Proteinuria and glomerular leukocyte infiltration were significantly diminished in SHA-treated rats on day 14. These results suggest that SHA ameliorated rat progressive mesangial proliferative glomerulonephritis by inhibiting P-selectin-dependent leukocyte infiltration in glomeruli. Sulphated oligosaccharides may be beneficial for the therapy of mesangial proliferative glomerulonephritis.

Animals↗
PubMed1997

TNF-alpha induces selectin-mediated leukocyte rolling in mouse cremaster muscle arterioles.

Leukocyte rolling is commonly restricted to venules and mediated by selectins expressed both on leukocytes (L-selectin) and the vascular endothelium (P- and E-selectin). We show here that 2- to 3-h tumor necrosis factor-alpha (TNF-alpha) stimulation of the mouse cremaster muscle induces rolling in arterioles (diameters 30-70 microm; wall shear rates 225-1,770 s(-1)). Weak P-selectin expression was detected on arteriolar endothelium of TNF-alpha-stimulated cremaster muscles. No rolling was observed in arterioles smaller than 30 microm (wall shear rates 1,500-3,250 s(-1)). The arteriolar rolling flux fraction in wild-type mice averaged approximately 5% and rolling was blocked by the P-selectin monoclonal antibody (MAb) RB40.34. Rolling in L- and E-selectin-deficient mice was similar to that in wild-type mice and was also blocked by the MAb RB40.34. Rolling was completely absent in arterioles of P-selectin-deficient mice. The average rolling velocity in arterioles of wild-type and L-selectin-deficient mice was approximately 50 microm/s but increased to approximately 110 microm/s in E-selectin-deficient mice and after injection of the blocking E-selectin MAb 9A9 in wild-type mice. We conclude that TNF-alpha treatment induces P-selectin-dependent rolling in arterioles that requires E-selectin for rolling at normal velocities.

Animals↗
PubMed2005

Differential metastasis inhibition by clinically relevant levels of heparins--correlation with selectin inhibition, not antithrombotic activity.

PURPOSE: Unfractionated heparin reduces metastasis in many murine models. Multiple mechanisms are proposed, particularly anticoagulation and/or inhibition of P-selectin and L-selectin. However, the doses used are not clinically tolerable and other heparins are now commonly used. We studied metastasis inhibition by clinically relevant levels of various heparins and investigated the structural basis for selectin inhibition differences. EXPERIMENTAL DESIGN: Five clinically approved heparins were evaluated for inhibition of P-selectin and L-selectin binding to carcinoma cells. Pharmacokinetic studies determined optimal dosing for clinically relevant anticoagulant levels in mice. Experimental metastasis assays using carcinoma and melanoma cells investigated effects of a single injection of various heparins. Heparins were compared for structural relationships to selectin inhibition. RESULTS: One (Tinzaparin) of three low molecular weight heparins showed increased selectin inhibitory activity, and the synthetic pentasaccharide, Fondaparinux, showed none when normalized to anticoagulant activity. Experimental metastasis models showed attenuation with unfractionated heparin and Tinzaparin, but not Fondaparinux, at clinically relevant anticoagulation levels. Tinzaparin has a small population of high molecular weight fragments not present in other low molecular weight heparins, enriched for selectin inhibitory activity. CONCLUSIONS: Heparin can attenuate metastasis at clinically relevant doses, likely by inhibiting selectins. Equivalent anticoagulation alone with Fondaparinux is ineffective. Clinically approved heparins have differing abilities to inhibit selectins, likely explained by size distribution. It should be possible to size fractionate heparins and inhibit selectins at concentrations that do not have a large effect on coagulation. Caution is also raised about the current preference for smaller heparins. Despite equivalent anticoagulation, hitherto unsuspected benefits of selectin inhibition in various clinical circumstances may be unwittingly discarded.

Animals↗
PubMed2002

Sialyltransferase specificity in selectin ligand formation.

Selectin ligands are glycan structures that participate in leukocyte trafficking and inflammation. At least 6 ST3Gal sialyltransferases (I-VI) have been identified that may contribute to selectin ligand formation. However, it is not known which of these sialyltransferases are involved in vivo and whether they may differentially regulate selectin function. We have produced and characterized mice genetically deficient in ST3Gal-I, ST3Gal-II, ST3Gal-III, and ST3Gal-IV. Unlike mice bearing severe defects in selectin ligand formation, there was no finding of leukocytosis with these single ST3Gal deficiencies. Among neutrophils, only ST3Gal-IV was found to play a role in the synthesis of selectin ligands. In vitro rolling of marrow-derived neutrophils on E- or P-selectins presented by Chinese hamster ovary cells was reduced in the absence of ST3Gal-IV. However, in a tumor necrosis factor alpha (TNF-alpha)-induced inflammation model in vivo, no defect among P-selectin ligands was observed. Nevertheless, the number of leukocytes rolling on postcapillary venules in an E-selectin-dependent manner was decreased while E-selectin-dependent rolling velocity was increased. We propose that multiple ST3Gal sialyltransferases contribute to selectin ligand formation, as none of these ST3Gal deficiencies recapitulated the degree of E- and P-selectin ligand deficit observed on neuraminidase treatment of intact neutrophils. Our findings indicate a high degree of functional specificity among sialyltransferases and a substantial role for ST3Gal-IV in selectin ligand formation.

Animals↗
PubMed2001

Soluble forms of P-, E- and L-selectin in children with Kawasaki disease.

Kawasaki disease (KD) is an acute, self-limiting systemic vasculitis syndrome of unknown origin, that mainly affects small and medium-sized arteries, particularly the coronary artery, which affects primarily infants and young children. Cell adhesion molecules play important roles in the inflammatory process. The aims of this study were to investigate the pathophysiological role of cell adhesion molecules in KD, and to look for the evidence of direct relationship between the plasma levels of soluble cell adhesion molecules and the incidence of coronary artery lesion (CAL). The 52 patients with KD, Group A patients who were clinical responders of initial intravenous immunoglobulin (IVIG) treatment (n = 30), Group B patients who did not respond to the initial IVIG treatment (n = 22), were studied. The circulating E-selectin (105.6 +/- 12.6 ng/ml) in the acute phase of KD, while the peak plasma P-selectin level (238.4 +/- 26.8 ng/ml) occurred in the subacute phase of illness (p < 0.05, respectively). Plasma L-selectin levels (1557.3 +/- 44.3 ng/ml) during the convalescent phase tend to higher than in the acute and in the convalescent phases (p = NS). The analysis of paired samples in Group A patients before (E-selectin: 131.2 +/- 9.8 ng/ml, P-selectin: 216.6 +/- 13.4 ng/ml) and 48 hour after (E-selectin: 98.9 +/- 9.2 ng/ml, P-selectin: 153.9 +/- 34.1 ng/ml) IVIG administration revealed significantly lower values of E- and P-selectins, however, no significant differences in those in Group B patients. There were also no significant differences in the values of L-selectins between the 2 groups. Before IVIG treatment, the plasma levels of E- (225.1 +/- 46.1 ng/ml) and P-selectin (259.4 +/- 76.2 ng/ml) of patients with CAL (n = 11) were significantly higher than those of patients (n = 41) without CAL (p < 0.05, respectively). Plasma L-selectin levels (1596.9 +/- 385.0 ng/ml) in patients with CAL tended to be lower than those in patients without CAL (p = NS). E- and P-selectin may have potential as predictors of CAL in patients with KD.

Child↗
PubMed1995

Oxidized low-density lipoprotein induces the expression of P-selectin (GMP140/PADGEM/CD62) on human endothelial cells.

It is now well established that monocytes adhere to endothelial cells activated by oxidized low-density lipoproteins (LDL). However, the adhesive receptors on endothelial cells involved in binding monocytes, following an insult by oxidized LDL, remains to be elucidated. In this study we have looked at the effect of native or oxidized LDL on the expression of P-selectin. Native LDL (N-LDL) was oxidized by incubation with either endothelial cells (EC-LDL) or copper (Cu-LDL), or in culture medium as a control (C-LDL). Expression of P-selectin was assayed with an anti-P-selectin (CD62) monoclonal antibody (LYP20). Results show that EC-LDL and Cu-LDL, but not N-LDL or C-LDL, induce the expression of P-selectin by human umbilical-vein endothelial cells (HUVECs). Induction of P-selectin by low concentrations (20 micrograms/ml) of LDL is directly related to the state of oxidation of the LDL particles. In addition, high concentrations (100 micrograms/ml) of N-LDL also activate HUVECs by inducing P-selectin expression. This expression was sustained for a period of over 1 h on LDL-activated endothelial cells, in contrast with thrombin- or histamine-activated endothelial cells, whose P-selectin levels fall within 15-20 min after induction. E-selectin, in contrast with P-selectin, could not be induced by endothelial cells treated with low or high concentrations of oxidized LDL. Results in this study show that P-selectin expressed by oxidized-LDL-treated endothelial cells are involved in mediating the adhesion of a monocytic cell line (U937) or monocytes in peripheral-blood mononuclear cells. An anti-P-selectin monoclonal antibody (LYP20) inhibited the binding of U937 cells and monocytes. These results strongly suggest that P-selectin is involved in the early stages of atherogenesis.

Cell Adhesion↗
PubMed2002

P-selectin-dependent macrophage migration into the tubulointerstitium in unilateral ureteral obstruction.

BACKGROUND: Interstitial infiltration of macrophages (Mø) is one of the main causal factors for the tubulointerstitial injury. However, precise mechanisms of Mø infiltration into tubulointerstitium have not been fully explored. The purposes of this study were to assess the role of selectins in the acute infiltration of Mø in rats with unilateral ureteral obstruction (UUO) and to evaluate the role of vasa recta, that is, whether they facilitate massive influx of Mø into the interstitium by functioning as specialized vessels. METHODS: To evaluate the role of selectins in Mø infiltration into tubulointerstitium, the expression of selectins and L-selectin ligands was examined by immunohistochemistry and immunoelectron microscopy. The functional role of P-selectin in vasa recta was studied by Stamper-Woodruff assay, in vivo p-Mø migration assay and in vivo blocking experiments with the monoclonal antibody (mAb) ARP2-4. RESULTS: Selective expression of P-selectin was detected in vasa recta as early as one hour after UUO, and the expression increased thereafter for 96 hours. In contrast, endothelial expression of L-selectin ligands and E-selectin were not detectable. In the Stamper-Woodruff assay on kidney sections of rats with UUO, the adhesion of isolated rat peritoneal Mø (p-Mø) to vasa recta was significantly inhibited by the mAb ARP2-4 (P-selectin blocker; P < 0.01), but not by mAb ARE-5 (E-selectin blocker) or rLECIg (rat L-selectin chimeric protein). In the in vivo transfer experiments with fluorescein-labeled p-Mø into rats 48 hours after UUO, labeled p-Mø had accumulated around vasa recta at three minutes and had infiltrated predominantly into the outer medulla at 180 minutes. The number of labeled p-Mø was reduced when the rats were pretreated with ARP2-4 (P < 0.01). Finally, ARP2-4 (10 mg/kg), injected 15 minutes before UUO, reduced the number of infiltrated Mø (P < 0.01). CONCLUSION: The results suggest that vasa recta, which express P-selectin, contribute to massive infiltration of Mø into the interstitium by functioning as specialized post-capillary venules.

Animals↗
PubMed1996

Interleukin 4 or oncostatin M induces a prolonged increase in P-selectin mRNA and protein in human endothelial cells.

During acute inflammation, P-selectin is transiently mobilized from Weibel-Palade bodies to the surface of histamine-activated endothelial cells, where it mediates rolling adhesion of neutrophils under hydrodynamic flow. During chronic or allergic inflammation, sustained expression of P-selectin on the endothelial cell surface has been observed. We found that the cytokines interleukin 4 (IL-4) or oncostatin M (OSM) induced a five- to ninefold increase in P-selectin messenger RNA (mRNA) in human umbilical vein endothelial cells (HUVEC) that persisted as long as 72 h. IL-4 elevated P-selectin mRNA by increasing its transcription rate rather than by prolonging its already long half-life. Stimulation of P-selectin transcription by IL-4 or OSM required new protein synthesis and tyrosine phosphorylation of cellular proteins. Tumor necrosis factor alpha, IL-1 beta, lipopolysaccharide, or IL-3 did not increase P-selectin mRNA in HUVEC, and did not augment the IL-4-induced increase in P-selectin transcripts. IL-4 or OSM increased P-selectin protein on the cell surface as well as in Weibel-Palade bodies. Under flow conditions, neutrophils rolled on P-selectin expressed by IL-4-treated HUVEC, and even more neutrophils rolled on P-selectin after IL-4-treated HUVEC were stimulated with histamine. These data demonstrate that IL-4 or OSM stimulates endothelial cells to synthesize more P-selectin over prolonged periods. The increased expression of P-selectin may facilitate the emigration of leukocytes into sites of chronic or allergic inflammation.

Animals↗
PubMed2006

Ischemia-induced angiogenesis: role of inflammatory response mediated by P-selectin.

P-selectin is a 140-kDa glycoprotein expressed on endothelial cells and platelets. P-selectin mediates the tethering and rolling of leukocytes along the endothelium, an early step of leukocyte extravasation. Although inflammation is a requisite process for ischemia-induced angiogenesis, little is known regarding the role of P-selectin in angiogenesis in the setting of tissue ischemia. We examined whether ischemia-induced angiogenesis is altered in P-selectin knockout (P-selectin(-/-)) mice. Angiogenesis was evaluated in a surgically induced hind-limb ischemia model using laser Doppler blood flowmetry (LDBF) and histological capillary density (CD). After left hind-limb ischemia, the ischemic/normal limb LDBF ratio was persistently lower in P-selectin(-/-) mice compared with wild-type (WT) mice. CD was also significantly lower in P-selectin(-/-) mice than in WT mice on Postoperative Day 14. Fewer numbers of total CD45+ inflammatory leukocytes infiltrated into the ischemic tissues in P-selectin(-/-) mice than in WT mice, and immunohistochemical analysis revealed the number of infiltrated leukocytes expressing vascular endothelial growth factor was also decreased in P-selectin(-/-) mice. P-selectin mRNA expression was augmented after hind-limb ischemia in WT mice. In conclusion, P-selectin may play an important role in ischemia-induced angiogenesis by promoting early inflammatory mononuclear cell infiltration. P-selectin would become one possible target molecule for modulating inflammatory angiogenesis.

Animals↗
PubMed2005

Role of selectins in the intestinal epithelial migration of eosinophils.

Understanding the mechanisms by which eosinophils migrate into and across the intestinal epithelium can provide alternative therapeutic targets for conditions characterized by eosinophilic cryptitis and crypt abscesses. Eosinophil migration is dependent on adhesion molecules such as selectins. Human eosinophils express L-selectin and P-selectin counterligand P-selectin glycoprotein ligand-1 (PSGL-1). The tetrasaccharide sialyl Lewis(x) (sLe(x)) binds to all three selectins, so compounds that mimic sLe(x), such as TBC1269, are potential antagonists. We hypothesized that eosinophils migrate from the basolateral to the apical surface of intestinal epithelium through the orchestrated effects of selectins. TBC1269 was added to fluorescently labeled HL-60 clone 15 eosinophils as well as human blood eosinophils, in incremental amounts. Subsequently, blocking antibodies toward L-selectin and PSGL-1 were used in a similar manner. HL-60 eosinophils were allowed to migrate into T-84 monolayers. The number of migrated HL-60 cells was calculated by comparing fluorescence with known cell densities. HL-60 and human eosinophils that were undergoing migration were significantly lower in the presence of TBC1269. This effect was concentration dependent, and near complete inhibition of migration was seen at a TBC1269 concentration of 10 mg/mL. In addition, HL-60 eosinophil migration was significantly lower in the presence of the blocking antibodies to PSGL-1 and L-selectin (39.2 and 51.6% inhibition, respectively). Simultaneous blocking of PSGL-1 and L-selectin resulted in inhibition of 76.0% of the migration. The results of this study suggest a major role for selectins in the intestinal epithelial migration of differentiated eosinophils. sLe(x), L-selectin, and the P-selectin counterligand PSGL-1 can be potential therapeutic targets.

Cell Adhesion↗
PubMed1999

Expression of functional selectin ligands on Th cells is differentially regulated by IL-12 and IL-4.

Immune responses may be qualitatively distinct depending on whether Th1 or Th2 cells predominate at the site of Ag exposure. T cell subset-specific expression of ligands for vascular selectins may underlie the distinct patterns of recruitment of Th1 or Th2 cells to peripheral inflammatory sites. Here we examine the regulation of selectin ligand expression during murine T helper cell differentiation. Large numbers of Th1 cells interacted with E- and P-selectin under defined flow conditions, while few Th2 and no naive T cells interacted. Th1 cells also expressed more fucosyltransferase VII mRNA than naive or Th2 cells. IL-12 induced expression of P-selectin ligands on Ag-activated naive T cells, even in the presence of IL-4, and on established Th2 cells restimulated in the presence of IL-12 and IFN-gamma. In contrast, Ag stimulation alone induced only E-selectin ligand. Interestingly, restimulation of established Th2 cells in the presence of IL-12 and IFN-gamma induced expression of P-selectin ligands but not E-selectin ligands; IFN-gamma alone did not enhance expression of either selectin ligand. In summary, functional P- and E-selectin ligands are expressed on most Th1 cells, few Th2 cells, but not naive T cells. Furthermore, selectin ligand expression is regulated by the cytokine milieu during T cell differentiation. IL-12 induces P-selectin ligand, while IL-4 plays a dominant role in down-regulating E-selectin ligand.

Animals↗
PubMed2007

Periprocedural soluble P- and E-selectin levels fail as predictors of clinical restenosis in patients treated with elective coronary stenting.

An increasing amount of basic scientific data indicates that adhesion molecules may be involved in the pathogenesis of vessel re-narrowing in patients undergoing coronary angioplasty. Furthermore, inflammation is suggested to be a pivotal mechanism linking atherosclerosis and restenosis. The aim of this study was to assess if periprocedural evaluation of soluble P-selectin (sP-selectin) and E-selectin (sE-selectin) possesses any additive value in the restenosis prediction to C-reactive protein (CRP) measurement. One hundred and nine stable angina patients were consecutively enrolled into the prospective cohort study. All participants were treated with single vessel coronary bare metal stenting. sP-selectin, sE-selectin and CRP were measured in peripheral venous blood samples collected before and 6, 24 h and 1 month after the procedure. Clinical follow-up visits were held 7 days(*), 1(*), 3, 6(*), and 12 months ((*)with an exercise test) after stenting. Any symptoms of restenosis were verified angiographically. Clinical restenosis occurred in 18 subjects. Concentrations of sP-selectin and sE-selectin did not differ between patients with and without clinical restenosis at any measuring point. In the latter group a decrease in sP-selectin and sE-selectin levels was observed 6 h after stenting. These findings when considered in all of the investigated subjects had no impact on the subsequent incidence of restenosis. An inflammatory response assessed as an increase in CRP level with the peak values at 24 h was noted in the whole population. However, it was significantly more pronounced in the restenosis group. Application of the Cox's proportional hazard model revealed a high CRP level 24 h after stenting and the history of coronary angioplasty concerning a nontarget lesion to be the only independent predictors of clinical restenosis. To conclude, the periprocedural evaluation of sP-selectin and sE-selectin in peripheral venous blood in patients undergoing elective coronary stenting provides no prognostic information in terms of clinical restenosis prediction, and the magnitude of the systemic inflammatory response triggered by coronary angioplasty assessed as an increase in CRP level and the history of coronary angioplasty concerning nontarget stenosis remain independent predictors of lesion re-narrowing.

Aged↗
PubMed1993

L- and E-selectin can recognize the same naturally occurring ligands on high endothelial venules.

The selectin family of cell adhesion molecules consists of three members, E-selectin (ELAM-1), L-selectin (LECAM-1), and P-selectin (CD62, GMP140, or PADGEM), which are all involved in binding of leukocytes to endothelial cells. All members have structural similarities and they can all bind to a common carbohydrate epitope, sialyl Lewis X in in vitro assays. To study cross-reactivity of the selectins in more detail we used Ig chimeras of murine and human L- and human E-selectin. All three chimeras bound to the natural ligands of L-selectin on specialized high endothelial venules in both human and murine lymphoid organs as determined by immunohistochemistry and were able to precipitate 50- and 90-kDa sulfated ligands from organ cultures of murine peripheral and mesenteric lymph nodes. This recognition was calcium dependent and inhibitable by mAb specific for the lectin domain of the respective selectin. L- and E-selectin binding to high endothelial venules and to the sulfated ligands was inhibitable by the carbohydrates, fucoidan and sialyl Lewis X, respectively. Although immunoprecipitations showed that both murine and human L-selectin could recognize the sulfated ligands from high endothelial venules more efficiently than human E-selectin at the concentrations used, both L- and E-selectin chimeras could inhibit in vivo lymphocyte trafficking into peripheral lymph nodes equally well.

Animals↗
PubMed1996

The cytoplasmic domains of E- and P-selectin do not constitutively interact with alpha-actinin and are not essential for leukocyte adhesion.

The selectins are a family of carbohydrate-binding adhesion molecules involved in the regulation of leukocyte migration. Although there is strong homology between different selectins in their extracellular regions, there is none in the cytoplasmic tails, suggesting selectin-specific functions for these domains. Our previous work showed that the cytoplasmic tail of L-selectin interacts with the actin cytoskeleton via alpha-actinin and vinculin, and that truncation of the cytoplasmic tail of L-selectin blocked both association with alpha-actinin and vinculin and leukocyte adhesion. In the present study, the effects of truncation of the cytoplasmic tails of E- or P-selectin on cell adhesion and cell surface expression were examined, and possible interactions between alpha-actinin and the E- and P-selectin cytoplasmic tails were assessed. In contrast to previous observations demonstrating a requirement for the L-selectin cytoplasmic tail, truncation of the E- or P-selectin cytoplasmic domains had no effect on cell adhesion, or on cell surface expression, when assessed in transiently transfected COS cells. This lack of effect on cell surface expression and adhesion was also observed when transfections were performed with lower amounts of cDNA, which led to submaximal levels of expression. In addition, no interaction between alpha-actinin and the cytoplasmic tails of either E- or P-selectin could be detected under conditions in which binding of alpha-actinin to the L-selectin cytoplasmic tail could be readily demonstrated. Therefore, interactions between the cytoplasmic tail of E- or P-selectin and alpha-actinin or other cytoskeletal proteins are not necessary for leukocyte adhesion per se, but may facilitate downstream biologic events.

Actinin↗