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P-selectin
Kinds of P-selectin Terms modified by P-selectin Selected AbstractsNew Nonhydrolyzable Mimetics of Sialyl Lewis X and Their Binding Affinity to P-SelectinHELVETICA CHIMICA ACTA, Issue 5 2004Frédéric Carrel Wittig olefination of (2S,3R,5S,6R)-5-(acetyloxy)-tetrahydro-6-[(methoxymethoxy)methyl]-3-(phenylthio)- 2H -pyran-2-acetaldehyde ((+)- 10) with {2-[(2S,3R,4R,5R,6S)-tetrahydro-3,4,5-tris(methoxymethoxy)-6-methyl- 2H -pyran-2-yl]ethyl}triphenylphosphonium iodide ((,)- 11) gave a (Z)-alkene derivative (+)- 12 that was converted into (,R,2R,3S,4R,5R,6S)-tetrahydro- ,,3-dihydroxy-2-(hydroxymethyl)-5-(phenylthio)-6-{(2Z)-4-[(2S,3S,4R,5S,6S)-tetrahydro-3,4,5-trihydroxy-6-methyl-2H -pyran-2-yl]but-2-enyl}2H -pyran-4-acetic acid (8), (,R,2R,3S,4R,6S)-tetrahydro- ,,3-dihydroxy-2-(hydroxymethyl)-6-{4-[(2S,3S,4R,5S,6S)-tetrahydro-3,4,5-trihydroxy-6-methyl-2H -pyran-2-yl]butyl}-2H -pyran-4-acetic acid (9), and simpler analogues without the hydroxyacetic side chain such as (2S,3S,4R,5S,6S)-tetrahydro-6-methyl-2-{(2Z)-4-[(2S,3R,5S,6R)-tetrahydro-5-hydroxy-6-(hydroxymethyl)-3-(phenylthio)-2H -pyran-2-yl]but-2-enyl}-2H -pyran-3,4,5-triol (30), (2S,3S,4R,5S,6S)-tetrahydro-6-methyl-2-{[(2S,5S,6R)-tetrah dro-5-hydroxy-6-(hydroxymethyl)-2H -pyran-2-yl]butyl}-2H -pyran-3,4,5- triol ((,)- 41) and (2S,3S,4R,5S,6S)-tetrahydro-6-methyl-2-{(2Z/E))-4-[(2R,5S,6R)-tetrahydro-5-hydroxy-6-(hydroxymethyl)-2H -pyran-2-yl]but-2-enyl}-2H -pyran-3,4,5-triol (43). The key intermediates (+)- 10 and (,)- 11 were derived from isolevoglucosenone and from L -fucose, respectively. The following IC50 values were measured in a ELISA test for the affinities of sialyl Lewis x tetrasaccharide, 8, 9, 30, (,)- 41, and 43 toward P-selectin: 0.7, 2.5,2.8, 7.3,8.0, 5.3,5.9, 5.0,5.2, and 3.4,4.1,mM, respectively. [source] The effects of maximal treadmill graded exercise testing on haemorheological, haemodynamic and flow cytometry platelet markers in patients with systolic or diastolic heart failureEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 3 2008I. Chung ABSTRACT Background, Acute exercise has been associated with activation of thrombosis, and this risk may be accentuated in patients with heart failure. Given the relation of platelets to atherothrombosis, we tested the hypothesis that acute exercise would adversely affect platelet indices and platelet activation markers in patients with systolic and diastolic heart failure. Materials and methods, We studied 20 patients with systolic heart failure (17 men, 3 women; mean age 64 ± 10 years, all with ejection fraction (EF) , 40%) and 20 patients with diastolic heart failure (14 men, 6 women; mean age 64 ± 8 years, mean EF = 66%) who were exercised to maximal intensity, who were compared to 13 healthy controls (6 men, 7 women; mean age 60 ± 4 years, mean EF = 73%). We measured platelet indices (platelet volume, mass and component) and platelet activation markers (platelet-bound CD62P%G, CD63%G and CD40L%G using flow cytometry, as well as plasma sCD40L and soluble P-selectin (sP-sel) levels). Results, Baseline Mean Platelet Volume (MPV), sP-sel, CD40L%G and CD63%G levels were significantly higher in patients with systolic and diastolic heart failure, when compared with controls. The mean exercise duration and VO2 peak in patients with systolic and diastolic heart failure were not significantly different, but lower than that seen in healthy controls. Following exercise, mean haematocrit, CD62P%G, and CD63%G significantly increased in all three subject groups (all P < 0·05). The proportional change in CD62P%G and CD63%G were not significantly different between healthy controls and heart failure patients (P > 0·05). Conclusion, Acute maximal graded exercise increases platelet activation markers, with no disproportionate differences between heart failure patients and healthy controls, despite the former group having a lower exercise tolerance and VO2 peak. [source] Genetic influence in antithrombotic actions of atorvastatin in hypercholesterolaemiaEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 1 2008L. Puccetti ABSTRACT Background, Recent data indicate that statins could offer coronary artery disease (CAD) benefit even by mechanisms beyond lipid lowering. Genetic influence has been shown for some antithrombotic actions of statins via oxidized-low-density lipoprotein cholesterol (ox-LDL) receptors and nitric oxide synthase (NOS) activity modulation. The present study was designed to evaluate the influence of ox-LDL lectin-like receptor-1 (LOX-1) and NOS polymorphisms in the incidence of cardiovascular events in pure hypercholesterolaemic subjects during statin treatment. Materials and methods, A prospective 4-year study involving 1039 event-free subjects (643 males, 396 females) treated with atorvastatin (10,40 mg day,1) to reach the appropriate Adult Treatment Panel-III LDL target of 3·36 mmol L,1. Enrolled subjects were evaluated every 6 months or at a clinical event. LOX-1 3,UTR/T-C and NOS G894T polymorphisms were detected by allelic discrimination assays (polymerase chain reaction), lipid profile by enzymatic-colorimetric method, ox-LDL by enzyme linked immunosorbent assay, platelet activation by P-selectin (P-sel) expression (FACScan), NOS activity (by intracellular citrullin recovery) and homocysteine (high performance liquid chromatography), C-reactive protein (CRP) by sensitive nephelometric technique. Results, LOX-1 3,UTR/T showed the strongest association with events in the whole cohort with respect to each other variable including LDL reduction and NOS G894T (OR 4·90, 95% CI 3·19,6·98, P < 0·00001). Smoking influenced events in LDL-targeted subjects (P < 0·0001). Ox-LDL and P-sel were better indicators than LDL or other variables according to 3,UTR/C genotype regardless of the magnitude of LDL reduction (OR 4·21, 95% CI 2·29,6·70 P < 0·0001). Conclusions, LOX-1 polymorphisms could influence statin effectiveness in CAD prevention by induction of sensitivity to antithrombotic mechanisms such as antiplatelet activity. [source] Prognostic value of interleukin-6, plasma viscosity, fibrinogen, von Willebrand factor, tissue factor and vascular endothelial growth factor levels in congestive heart failureEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 11 2003B. S. P. Chin Abstract Background, Congestive heart failure (CHF) carries a poor prognosis with a high mortality rate, frequent hospitalizations and increased risk of thrombotic complications such as stroke. Cytokines may contribute to the progression and prothrombotic state of CHF, including the pro-inflammatory interleukin-6 (IL-6) and the pro-angiogenic vascular endothelial growth factor (VEGF), both of which are raised in CHF. The procoagulant properties of both cytokines may be mediated via tissue factor (TF), a potent clotting activator. We hypothesized that plasma levels of these markers, as well as levels of plasma viscosity, fibrinogen, soluble P-selectin and von Willebrand factor (markers of abnormal rheology, clotting, platelet activation, and endothelial damage, respectively) will be useful in predicting morbidity and mortality in chronic stable CHF. Methods and results, One hundred and twenty consecutive out-patients with chronic stable CHF (92 males; mean [SD] age 64 [11] years, mean [SD] left ventricular ejection fraction of 29 [6]%) were recruited and followed for 2 years during which 42 patients reached a clinical end-point of all-cause mortality and cardiovascular hospitalizations, including stroke and myocardial infarction. Plasma IL-6 (P = 0·003) and TF (P = 0·013) levels, but not other research indices, were higher in those who suffered events compared with those without events. Predictors of end-points were high (, median) TF (P = 0·011), and IL-6 (P = 0·023) levels, as well as the lowest quartile of a left ventricular ejection fraction (P = 0·007). A strong correlation was present between TF and IL-6 levels (r = 0·59; P < 0·0001) and with VEGF levels (r = 0·43; P < 0·0001). Conclusion, IL-6 and TF are predictors of poor prognosis in chronic CHF, raising the hypothesis that IL-6 may contribute to the progression and thrombotic complications of CHF via its actions on TF expression. Although VEGF did not independently predict outcome in chronic CHF, the possibility arises that it may act with IL-6 to induce TF expression. [source] The use of platelet density and volume measurements to estimate the severity of pre-eclampsiaEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 12 2000P. Järemo This study evaluated whether it is possible to estimate the severity of pre-eclampsia through in vitro measurements of platelet and granulocyte parameters. Eighteen pre-eclamptic women in the third-trimester of pregnancy and 11 women in the third-trimester of normal pregnancies were included in the study. Three to 12 months after delivery, 15 patients with pre-eclampsia and all the subjects with normal pregnancies were re-examined. Before delivery, peak platelet density was determined using a specially designed apparatus. Before and 3,12 months after delivery the following were measured: platelet counts, mean platelet volume and neutrophil and monocyte counts. Furthermore, circulating P-selectin, interleukin-6 and myeloperoxidase were determined to estimate platelet, monocyte and granulocyte activities, respectively. Compared to their results after delivery, pre-eclamptic females demonstrated lower platelet counts (P < 0·001) and raised mean platelet volumes (P < 0·01). Both pre-eclamptic women (P < 0·01) and normal pregnancies (P < 0·05) demonstrated elevated soluble P-selectin at pregnancy. Then pre-eclamptic women had advanced neutrophil counts (P < 0·01) but normal pregnancies showed a similar phenomenon (P < 0·001). Interleukin-6 remained normal during pregnancy. Plasma myeloperoxidase levels were lower both in pre-eclampsia (P < 0·05) and in normal pregnancies (P < 0·001). In pre-eclampsia elevated blood pressure was related to higher mean platelet volumes (P < 0·05). Furthermore, a group of pre-eclamptic females whose platelets had disturbed density distribution displayed elevated mean platelet volumes (P < 0·01). The present work demonstrates considerable platelet alterations in pre-eclampsia. We failed to show granulocyte involvement in the pathogenesis of the disease. Severe pre-eclampsia is related to elevated mean platelet volumes. The latter parameter is associated with disturbed density distribution. It appears possible to estimate disease severity from measurements of platelet density and volume. [source] A 4-trifluoromethyl derivative of salicylate, triflusal, stimulates nitric oxide production by human neutrophils: role in platelet functionEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 9 2000De Miguel Background The thrombotic process is a multicellular phenomenon in which not only platelets but also neutrophils are involved. Recent in vitro studies performed in our laboratory have demonstrated that triflusal, a 4-trifluoromethyl derivative of salicylate, reduced platelet aggregation not only by inhibiting thromboxane A2 production but also by stimulating nitric oxide (NO) generation by neutrophils. The aim of the present study was to evaluate whether oral treatment of healthy volunteers with triflusal could modify the ability of their neutrophils to produce NO and to test the role of the NO released by neutrophils in the modulation of ADP-induced platelet aggregation and ,-granule secretion. Methods The study was performed in 12 healthy volunteers who were orally treated with triflusal (600 mg day,1) for 5 days. Flow cytometric detection of platelet surface expression of P-selectin was used as a measure of the ability of platelets to release the contents of their ,-granules. Results After treatment with triflusal, there was an increase in NO production by neutrophils and an increase in endothelial nitric oxide synthase (eNOS) protein expression in neutrophils. A potentiation of the inhibition of platelet aggregation by neutrophils was reversed by incubating neutrophils with both an l -arginine antagonist, NG -nitro- l -arginine methyl ester ( l -NAME) and an NO scavenger, 2-(4-carboxyphenyl)-4,4,5,5 tetramethylimidazoline 1-oxyl 3-oxide (C-PTIO). A slight decrease in P-selectin surface expression on platelets was found which was not modified by the presence of neutrophils and therefore by the neutrophil-derived NO. Exogenous NO released by sodium nitroprusside dose-dependently inhibited both ADP-stimulated ,-granule secretion and platelet aggregation. Therefore, platelet aggregation showed a greater sensitivity to be inhibited by exogenous NO than P-selectin expression. Conclusion Oral treatment of healthy volunteers with triflusal stimulated NO production and eNOS protein expression in their neutrophils. After triflusal treatment, the neutrophils demonstrated a higher ability to prevent ADP-induced platelet aggregation. However, the neutrophils and the endogenous NO generated by them failed to modify P-selectin expression in ADP-activated platelets. [source] Increased circulating platelet,leukocyte aggregates in myeloproliferative disorders is correlated to previous thrombosis, platelet activation and platelet countEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 3 2001Morten Krogh Jensen Abstract: Platelet,leukocyte adhesion may occur as a consequence of platelet activation and possibly plays a key role in the deposition of activated platelets and fibrin in the thrombotic plug. The aim of the present study was to assess by whole blood flow cytometry the presence of circulating platelet,leukocyte aggregates (PLA) and the platelet,leukocyte response to platelet agonist stimulation (ADP and TRAP) in 50 patients with chronic myeloproliferative disorders (MPD) and 30 controls. PLA were identified as platelet,granulocyte/monocyte aggregates (PGMA), platelet,monocyte aggregates (PMA) and defined as the percentage of leukocytes coexpressing the platelet-specific marker glycoprotein Ib. Compared to controls the mean percentage of PGMA and PMA was increased in unstimulated whole blood from patients with MPD (7.98 vs. 1.76%; p<0.001 and 12.34 vs. 3.2%; p<0.001, respectively). The percentage of PGMA was correlated to the platelet count (r=0.46; p<0.001), percentage of P-selectin (r=0.69; p<0.001) and thrombospondin (r=0.58; p<0.001) positive platelets and platelet expression of GPIV (r=0.33; p=0.02). The mean percentage of PGMA and PMA was significantly increased in ADP-stimulated whole blood of patients (57.14 vs. 47.92%; p=0.009 and 54.91 vs. 45.89%; p<0.001, respectively). Compared to patients without a history of thrombosis, patients having experienced microvascular disturbances or a thrombotic event had a higher mean percentage of PGMA and PMA in non-stimulated whole blood (10.07 vs. 6.34%; p=0.025 and 14.81 vs. 10.48%; p=0.021, respectively) and a higher percentage of PGMA in ADP stimulated whole blood (64.32 vs. 51.50%; p<0.01). These data document an increased frequency of PLA in non-stimulated whole blood in MPD associated with a previous history of thrombosis or microvascular disturbances. [source] C-Disaccharides as Probes for Carbohydrate Recognition , Investigation of the Conformational Requirements for Binding of Disaccharide Mimetics of Sialyl Lewis XEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2007Richard W. Denton Abstract A set of C-disaccharide analogs was designed to probe the recognition of a known O-disaccharide mimetic of sialyl Lewis X, to P-selectin. The synthesis of the C-glycosides centered on the de novo construction of the galactose residue via an oxocarbenium ion/enol ether cyclization. Conformational analysis was performed by a combination of NMR spectroscopy and molecular mechanics (MM) and molecular dynamics (MD) calculations. The inhibition of P-selectin binding was evaluated in a P-selectin Biacore assay. At 12 mM, the O-glycoside showed 48,% inhibition of binding, while the C-glycoside analogs exhibited between 25,31,% inhibition. This data is discussed within the context of the active conformation of sLex and the conformational behavior of these ligands. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Transfection of the c- erbB2/neu gene upregulates the expression of sialyl Lewis X, ,1,3-fucosyltransferase VII, and metastatic potential in a human hepatocarcinoma cell lineFEBS JOURNAL, Issue 12 2001Fei Liu The pCMV4 plasmid containing the cancer-promoting gene, c- erbB2/neu, was cotransfected into the human hepatocarcinoma cell line 7721 with the pcDNA3 vector, which contains the ,neo' selectable marker. Several clones showing stable expression of c- erbB2/neu were established and characterized by determination of c- erbB2/neu mRNA and its encoded protein p185. Expression of Lewis antigens and ,1,3-fucosyltransferases and the biological behavior of 7721 cells after c- erbB2/neu transfection were studied using mock cells transfected with the vectors pCMV4 and pcDNA3 as controls. SLex expression on the surface of mock cells was high, whereas expression of SDLex, Lex and SLea was absent or negligible. This is compatible with the abundant expression of ,1,3-fucosyltransferase VII, very low expression of ,fucosyltransferase III/VI, and almost absent expression of ,1,3-fucosyltransferase IV in the mock cells. After transfection of c- erbB2/neu, expression of SLex and ,1,3-fucosyltransferase VII were simultaneously elevated, but that of ,fucosyltransferase III/VI was not altered. The expression of both SLex and ,1,3-fucosyltransferase VII correlated positively with the expression of c- erbB2/neu in different clones, being highest in clone 13, medium in clone 6, and lowest in clone 7. In addition, the adhesion of 7721 cells to human umbilical vein endothelial cells (HUVECs) or P-selectin, as well as cell migration and invasion, were increased in c- erbB2/neu -transfected cells. These increases also correlated positively with the expression intensities of c- erbB2/neu, SLex and ,1,3-fucosyltransferase VII in the different clones, whereas cell adhesion to fibronectin correlated negatively with these variables. mAbs to SLex (KM93) and SDLex (FH6) significantly and slightly, respectively, abolished cell adhesion to HUVECs or P-selectin and cell migration and invasion. mAbs to SDLex and SLea did not suppress cell adhesion to HUVECs nor inhibit cell migration and invasion. Transfection of ,1,3-fucosyltransferase VII cDNA into 7721 cells showed similar results to transfection of c- erbB2/neu, and the increased adhesion to HUVECs, cell migration, and invasion were also inhibited significantly by KM93 and slightly by FH6. These results indicate that expression of ,1,3-fucosyltransferase VII and its specific product, SLex, and their capacity for cell adhesion, migration and invasion are closely related. Therefore, the c- erbB2/neu gene is proposed to be a metastasis-promoting gene, and its effects are at least partially mediated by the increased expression of ,1,3-fucosyltransferase VII and SLex. [source] L-selectin and E-selectin expressed on monocytes mediating Ehrlichia chaffeensis attachment onto host cellsFEMS MICROBIOLOGY LETTERS, Issue 2 2003Jian-zhi Zhang Abstract Ehrlichia chaffeensis, the agent of human monocytic ehrlichiosis, is an obligatory intracellular bacterium that exhibits monocytic host cell tropism. Ehrlichiae must enter the host cell, and then establish infection. The tropism of E. chaffeensis for monocytes suggests that the cell contains some specific surface components that mediate E. chaffeensis attachment and entry into host cells. In this study, host cell surface components that play a role in ehrlichial attachment were identified using a human monocyte/macrophage cell line, THP-1. E. chaffeensis attachment to THP-1 cells was partially blocked in the presence of antibodies to E-selectin and L-selectin, but not by antibodies to P-selectin, integrin ,m, integrin ,x, or normal mouse IgG as determined by real time polymerase chain reaction. Conversely, in HeLa cells that do not exhibit surface expression of E-selectin and L-selectin, antibodies to these cell surface proteins did not inhibit E. chaffeensis attachment. These findings indicate that E-selectin and L-selectin are cell surface proteins that might act as co-receptors and contribute to E. chaffeensis attachment and entry into THP-1. [source] Effects of Helicobacter pylori Eradication on Platelet Activation and Disease Recurrence in Patients with Acute Coronary SyndromesHELICOBACTER, Issue 6 2004J. Ignasi Elizalde ABSTRACT Background., Platelet activation is consistently observed in animal models of Helicobacter pylori infection and could help to explain the alleged epidemiological association between H. pylori and coronary heart disease. Materials and Methods., Ninety-two patients with recent acute coronary syndromes were enrolled. Helicobacter pylori -positive patients were randomized to receive a 7-day course of omeprazole, amoxycillin and metronidazole or placebos. Two months later, H. pylori status was reassessed and baseline parameters, including soluble P-selectin and platelet surface expression of CD62P, CD63 and CD41, were measured again. Patients were followed-up for 1 year or until death or readmission. Results., No baseline differences were observed between H. pylori -positive and -negative cases. Among H. pylori -positive patients, 18 received placebo and 31 received active medication resulting in eradication in 21 cases. No differences were observed in inflammatory parameters or platelet activation markers between patients with persistent or resolved H. pylori infection. However, coronary events recurred at 6 and 12 months, respectively, in 35% and 55% of patients with persisting H. pylori infection compared with 10% and 25% of patients in whom H. pylori was either absent or eradicated (p = .01). Only final H. pylori status [RR 3.07 (95% CI 1.35,98)] and number of coronary risk factors [RR 2.58 (95% CI 1.51,4.41)] were independent predictors of recurrence. Conclusions., Infection with H. pylori does not induce significant platelet activation in patients treated for coronary disease. Helicobacter pylori -infected patients, however, may have an increased risk of recurrence of coronary events. [source] New Nonhydrolyzable Mimetics of Sialyl Lewis X and Their Binding Affinity to P-SelectinHELVETICA CHIMICA ACTA, Issue 5 2004Frédéric Carrel Wittig olefination of (2S,3R,5S,6R)-5-(acetyloxy)-tetrahydro-6-[(methoxymethoxy)methyl]-3-(phenylthio)- 2H -pyran-2-acetaldehyde ((+)- 10) with {2-[(2S,3R,4R,5R,6S)-tetrahydro-3,4,5-tris(methoxymethoxy)-6-methyl- 2H -pyran-2-yl]ethyl}triphenylphosphonium iodide ((,)- 11) gave a (Z)-alkene derivative (+)- 12 that was converted into (,R,2R,3S,4R,5R,6S)-tetrahydro- ,,3-dihydroxy-2-(hydroxymethyl)-5-(phenylthio)-6-{(2Z)-4-[(2S,3S,4R,5S,6S)-tetrahydro-3,4,5-trihydroxy-6-methyl-2H -pyran-2-yl]but-2-enyl}2H -pyran-4-acetic acid (8), (,R,2R,3S,4R,6S)-tetrahydro- ,,3-dihydroxy-2-(hydroxymethyl)-6-{4-[(2S,3S,4R,5S,6S)-tetrahydro-3,4,5-trihydroxy-6-methyl-2H -pyran-2-yl]butyl}-2H -pyran-4-acetic acid (9), and simpler analogues without the hydroxyacetic side chain such as (2S,3S,4R,5S,6S)-tetrahydro-6-methyl-2-{(2Z)-4-[(2S,3R,5S,6R)-tetrahydro-5-hydroxy-6-(hydroxymethyl)-3-(phenylthio)-2H -pyran-2-yl]but-2-enyl}-2H -pyran-3,4,5-triol (30), (2S,3S,4R,5S,6S)-tetrahydro-6-methyl-2-{[(2S,5S,6R)-tetrah dro-5-hydroxy-6-(hydroxymethyl)-2H -pyran-2-yl]butyl}-2H -pyran-3,4,5- triol ((,)- 41) and (2S,3S,4R,5S,6S)-tetrahydro-6-methyl-2-{(2Z/E))-4-[(2R,5S,6R)-tetrahydro-5-hydroxy-6-(hydroxymethyl)-2H -pyran-2-yl]but-2-enyl}-2H -pyran-3,4,5-triol (43). The key intermediates (+)- 10 and (,)- 11 were derived from isolevoglucosenone and from L -fucose, respectively. The following IC50 values were measured in a ELISA test for the affinities of sialyl Lewis x tetrasaccharide, 8, 9, 30, (,)- 41, and 43 toward P-selectin: 0.7, 2.5,2.8, 7.3,8.0, 5.3,5.9, 5.0,5.2, and 3.4,4.1,mM, respectively. [source] Biliverdin therapy protects rat livers from ischemia and reperfusion injuryHEPATOLOGY, Issue 6 2004Constantino Fondevila Heme oxygenase (HO-1) provides a cellular defense mechanism during oxidative stress and catalyzes the rate-limiting step in heme metabolism that produces biliverdin (BV). The role of BV and its potential use in preventing ischemia/reperfusion injury (IRI) had never been studied. This study was designed to explore putative cytoprotective functions of BV during hepatic IRI in rat liver models of ex vivo perfusion and orthotopic liver transplantation (OLT) after prolonged periods of cold ischemia. In an ex vivo hepatic IRI model, adjunctive BV improved portal venous blood flow, increased bile production, and decreased hepatocellular damage. These findings were correlated with amelioration of histological features of IRI, as assessed by Suzuki's criteria. Following cold ischemia and syngeneic OLT, BV therapy extended animal survival from 50% in untreated controls to 90% to 100%. This effect correlated with improved liver function and preserved hepatic architecture. Additionally, BV adjuvant after OLT decreased endothelial expression of cellular adhesion molecules (P-selectin and intracellular adhesion molecule 1), and decreased the extent of infiltration by neutrophils and inflammatory macrophages. BV also inhibited expression of inducible nitric oxide synthase and proinflammatory cytokines (interleukin 1,, tumor necrosis factor ,, and interleukin 6) in OLTs. Finally, BV therapy promoted an increased expression of antiapoptotic molecules independently of HO-1 expression, consistent with BV being an important mediator through which HO-1 prevents cell death. In conclusion, this study documents and dissects potent cytoprotective effects of BV in well-established rat models of hepatic IRI. Our results provide the rationale for a novel therapeutic approach using BV to maximize the function and thus the availability of donor organs. (HEPATOLOGY 2004;40:1333,1341.) [source] Expression of VCAM-1, ICAM-1, E- and P-selectin and tumour-associated macrophages in renal cell carcinomaHISTOPATHOLOGY, Issue 1 2000B Hemmerlein Aims Neoangiogenesis is accompanied by an increase in endothelial surface, which can support infiltration by immune cells depending on adhesion molecule expression. Therefore, the expression of cell adhesion molecules on microvessels and epithelial cells was analysed in renal cell carcinomas as compared to tumour-free tissue. Methods and results PECAM-1, CD34, ICAM-1, VCAM-1, VLA-4, P- and E-selectin, the macrophage antigens Ki-M1P and Mac-1, and lymphocyte function antigen LFA-1 were identified immunohistochemically. VCAM-1, ICAM-1, and E-selectin were equally or less expressed, whereas P-selectin was increased on microvessels in tumour tissue. The density of VCAM-1-positive tumour microvessels correlated positively with an advanced tumour stage and E- and P-selectin-positive tumour microvessels with the amount of associated macrophages. The expression of ICAM-1 and VCAM-1 on neoplastic epithelia correlated with an increased density of macrophages and a minor degree of tumour differentiation. Conclusions The positive correlation of macrophage infiltration and expression of cell adhesion molecules on tumour microvessels and epithelia with minor tumour differentiation and an advanced stage indicates that adhesion molecule expression is not associated with an effective antitumour function of macrophages [source] Effect of tourniquet pressure and intra-individual variability on plasma fibrinogen, platelet P-selectin and monocyte tissue factorINTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY, Issue 6 2000J. L. Ritchie Small differences in levels of certain haemostatic components may be clinically significant. It is important therefore to eliminate potential sources of confounding variability. This study investigated the effect of removing tourniquet pressure prior to sample collection on plasma fibrinogen levels, platelet P-selectin and monocyte tissue factor expression. Blood was collected from the right arm under maintained tourniquet pressure and from the left arm following the release of pressure once the vein was sufficiently inflated for insertion of a needle. Whole blood was labelled within one hour of venepuncture to allow analysis of platelet P-selectin and monocyte tissue factor by flow cytometry. Plasma fibrinogen levels were analysed in samples stored at ,70 °C, for all individuals at the end of the study using a method based on the Clauss technique. Intra-individual variability for each of the components was assessed by collecting samples under tourniquet pressure from four individuals on the same day on three consecutive weeks. Intra-individual variations were greater than assay CVs for all three components. There were no significant differences between the two tourniquet methods of collection for fibrinogen, P-selectin or tissue factor. In conclusion, there is no reason not to use a tourniquet during collection of blood for analysis of plasma fibrinogen, platelet P-selectin or monocyte tissue factor. [source] Expression of VCAM-1, ICAM-1, E-selectin, and P-selectin on endothelium in situ in patients with erythroderma, mycosis fungoides and atopic dermatitisJOURNAL OF CUTANEOUS PATHOLOGY, Issue 9 2000Vigfús Sigurdsson Background: Erythroderma may result from different causes. At present it is unclear whether the patho-mechanisms that lead to these different types of erythroderma are identical or different. Adhesion molecules and their ligands play a major role in endothelial-leukocyte interactions, which affect the binding, transmigration and infiltration of lymphocytes and mononuclear cells during inflammation, injury, or immunological stimulation. The aim of this study was to investigate the adhesion molecule expression on endothelial cells in erythroderma in situ. Methods: Snap-frozen skin biopsy specimens from 23 patients with erythroderma were studied. Eight had idiopathic erythroderma, 5 erythrodermic atopic dermatitis, 4 Sézary syndrome and 6 had erythroderma from miscellaneous causes. As a control we studied skin specimens from 10 patients with mycosis fungoides, 5 patients with atopic dermatitis and 5 healthy non-atopic volunteers. To determine adhesion molecule expression on endothelial cells in situ, sections were immuno-histochemically double stained with biotinylated Ulex Europaeus agglutinin 1 as a pan-endothelial cell marker, and for the adhesion molecules VCAM-1, ICAM-1, E-, and P-selectin. All double- and single-stained blood vessels in the dermis were counted. Results: Mean endothelial expression in erythroderma was as follows: VCAM-1 51.4%, ICAM-1 70.1%, E-selectin 43.5%, and P-selectin 52.6%. There was no statistical difference between different groups of erythroderma. Mean expression of all adhesion molecules tested, was in Sézary syndrome higher than in mycosis fungoides albeit not significant. In erythrodermic atopic dermatitis only VCAM-1 expression was significantly higher than in lesional skin of atopic dermatitis. No differences were observed in expression of the other three adhesion molecules. Conclusions: There is no difference regarding adhesion molecule expression on endothelial cells between different types of erythroderma. [source] Intracoronary enalaprilat during angioplasty for acute myocardial infarction: alleviation of postischaemic neurohumoral and inflammatory stress?JOURNAL OF INTERNAL MEDICINE, Issue 2 2007U. Schaefer Abstract. Aims., Reperfusion after myocardial ischaemia is associated with a distinct ischaemia/reperfusion injury. Since ACE-inhibition, beyond its influence on cardiac angiotensin II formation and kinin metabolism, has been shown to be cardioprotective by decreasing leucocyte adhesion and endothelin-1 (ET-1) release, we investigated the effects of intracoronary (i.c.) enalaprilat during primary angioplasty in acute myocardial infarction. Methods and Results., Twenty-two patients were randomized to receive i.c. enalaprilat (50 ,g) or placebo immediately after reopening of the infarct-related artery (IRA). Plasma concentrations of soluble L-selectin, P-selectin, intercellular adhesion molecule-1 (sICAM-1), vascular cell adhesion molecule-1 (sVCAM-1), ET-1 and nitric oxide metabolite concentrations (NO(x)) were measured in pulmonary arterial blood. Coronary blood flow was assessed using corrected thrombolysis in myocardial infarction (TIMI) frame counts (CTFC). During reperfusion, there was a significant increase in sL-selectin, sP-selectin and ET-1 in the placebo group, which was greatly diminished by enalaprilat. Levels of sVCAM-1 and sICAM-1 were not affected in either group. CTFC in the placebo group remained higher than normal in both the IRA and nonculprit vessels, whereas myocardial blood flow improved with enalaprilat. Conclusion., Enalaprilat as adjunct to primary angioplasty might be a protective approach to prevent leucocyte adhesion and the release of ET-1, thereby improving coronary blood flow. [source] Changes in serum concentrations of tumor necrosis factor , and adhesion molecules in normal pregnant women and those with pregnancy-induced hypertensionJOURNAL OF OBSTETRICS AND GYNAECOLOGY RESEARCH (ELECTRONIC), Issue 6 2003Keiichi Matsubara Abstract Aim:, To study whether serum tumor necrosis factor , gene (TNF,) and adhesion molecule levels are indicators of the onset of pregnancy-induced hypertension (PIH), we compared levels of these molecules between normal pregnant women and PIH patients from the first to the third trimester. Methods:, We serially measured serum concentrations of TNF,, soluble intercellular adhesion molecule-1 (sICAM-1), soluble E-selectin (sE-selectin), soluble vascular cell adhesion molecule-1 (sVCAM-1) and soluble P-selectin (sP-selectin) using enzyme immunoassay kits in 10 normal pregnant women and 10 pregnant women who developed PIH late in gestation. Results:, Serum TNF,, sICAM-1 and sE-selectin levels in PIH affected women were significantly higher from the first trimester compared with those in normal pregnancy. sVCAM-1 and sP-selectin levels were not significantly changed. Conclusion:, Serum TNF,, sE-selectin and sICAM-1 levels might be effective indicators of the onset of PIH. [source] Platelet functions beyond hemostasisJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 11 2009S. S. SMYTH Summary., Although their central role is in the prevention of bleeding, platelets probably contribute to diverse processes that extend beyond hemostasis and thrombosis. For example, platelets can recruit leukocytes and progenitor cells to sites of vascular injury and inflammation; they release proinflammatory and anti-inflammatory and angiogenic factors and microparticles into the circulation; and they spur thrombin generation. Data from animal models suggest that these functions may contribute to atherosclerosis, sepsis, hepatitis, vascular restenosis, acute lung injury, and transplant rejection. This article represents an integrated summary of presentations given at the Fourth Annual Platelet Colloquium in January 2009. The process of and factors mediating platelet,platelet and platelet,leukocyte interactions in inflammatory and immune responses are discussed, with the roles of P-selectin, chemokines and Src family kinases being highlighted. Also discussed are specific disorders characterized by local or systemic platelet activation, including coronary artery restenosis after percutaneous intervention, alloantibody-mediated transplant rejection, wound healing, and heparin-induced thrombocytopenia. [source] Elevated platelet and leukocyte response to oral bacteria in periodontitisJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 1 2009E. A. NICU Summary.,Background:,Periodontitis is associated with an increased risk for cardiovascular diseases (CVD), but the underlying mechanisms are poorly understood. Recently, we showed that platelets from periodontitis patients are more activated than those from controls. Objective:,Given the regularly occurring bacteremic episodes in periodontitis patients, we hypothesized that platelets and/or leukocytes from periodontitis patients are more sensitive to stimulation by oral bacteria, in particular the known periodontal pathogens, than platelets from control subjects. Methods:,Three-color flow cytometry analysis was performed to quantify activation of platelets (P-selectin, PAC-1, CD63) and leukocytes (CD11b) in whole blood from patients with periodontitis (n = 19) and controls (n = 18), with and without stimulation by oral bacteria. Phagocytosis was assessed by using green-fluorescent protein (GFP)-expressing Aggregatibacter actinomycetemcomitans (Aa). Results:,Neutrophils and monocytes were activated by all species of oral bacteria tested, but no differences were observed between patients and controls. In response to several species of oral bacteria, platelets from periodontitis patients showed, compared with controls, increased exposure of P-selectin (P = 0.027) and increased formation of platelet-monocyte complexes (P = 0.040). Platelet-leukocyte complexes bound and/or phagocytosed more GFP- Aa than platelet-free leukocytes (for neutrophils and monocytes, in both patients and controls, P < 0.001). Conclusions:,In periodontitis, increased platelet response to oral bacteria is paralleled by increased formation of platelet-leukocyte complexes with elevated capacity for bacterial clearance. We speculate that activated platelets and leukocytes might contribute to increased atherothrombotic activity. [source] Formation of platelet strings and microthrombi in the presence of ADAMTS-13 inhibitor does not require P-selectin or ,3 integrinJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 3 2007A. K. CHAUHAN Summary. Background:,Ultra-large von Willebrand factor (ULVWF) and the receptor P-selectin are released from endothelial Weibel,Palade bodies during injury or inflammation. VWF mediates platelet adhesion and P-selectin promotes leukocyte rolling. ADAMTS-13 limits the duration of platelet adhesion by cleaving the ULVWF. In the absence of ADAMTS-13, long VWF filaments decorated with platelets form. Recent in vitro studies suggested that P-selectin might anchor these platelet strings to endothelium, but whether the same mechanism exists in vivo remains to be elucidated. Methods:,We address the role of P-selectin and ,3 integrin in platelet string formation in vivo using intravital microscopy by infusing inhibitory ADAMTS-13 antibody in P-selectin-/- and ,3 -deficient mice and activating the endothelium by injecting histamine. Results:,We show that inhibition of ADAMTS-13 combined with endothelial activation leads to similar extents of platelet string formation in wild-type, P-selectin- and integrin ,3 -deficient mice. Further, in venules the platelet strings can coalesce into VWF-platelet aggregates. This process utilizes neither the platelet ,3 integrin nor P-selectin. We also show in vitro that platelets can act as a bridge between the VWF fibers and that VWF can self-associate even in areas devoid of platelets. Conclusions:,The formation or retention of the platelet strings does not require P-selectin or the endothelial VWF receptor ,v,3. Furthermore, in the presence of low ADAMTS-13 activity, VWF-dependent and ,IIb,3 -independent platelet clustering occurs in veins, as has been shown at high arterial shear rates. Our study further supports the importance of regulation of VWF multimer size upon secretion from Weibel,Palade bodies. [source] Two subpopulations of thrombin-activated platelets differ in their binding of the components of the intrinsic factor X-activating complexJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 11 2005M. A. PANTELEEV Summary., Binding of fluorescein-labeled coagulation factors IXa, VIII, X, and allophycocyanin-labeled annexin V to thrombin-activated platelets was studied using flow cytometry. Upon activation, two platelet subpopulations were detected, which differed by 1,2 orders of magnitude in the binding of the coagulation factors and by 2,3 orders of magnitude in the binding of annexin V. The percentage of the high-binding platelets increased dose dependently of thrombin concentration. At 100 nm of thrombin, platelets with elevated binding capability constituted ,4% of total platelets and were responsible for the binding of ,50% of the total bound factor. Binding of factors to the high-binding subpopulation was calcium-dependent and specific as evidenced by experiments in the presence of excess unlabeled factor. The percentage of the high-binding platelets was not affected by echistatin, a potent aggregation inhibitor, confirming that the high-binding platelets were not platelet aggregates. Despite the difference in the coagulation factors binding, the subpopulations were indistinguishable by the expression of general platelet marker CD42b and activation markers PAC1 (an epitope of glycoprotein IIb/IIIa) and CD62P (P-selectin). Dual-labeling binding studies involving coagulation factors (IXa, VIII, or X) and annexin V demonstrated that the high-binding platelet subpopulation was identical for all coagulation factors and for annexin V. The high-binding subpopulation had lower mean forward and side scatters compared with the low-binding subpopulation (,80% and ,60%, respectively). In its turn, the high-binding subpopulation was not homogeneous and included two subpopulations with different scatter values. We conclude that activation by thrombin induces the formation of two distinct subpopulations of platelets different in their binding of the components of the intrinsic fX-activating complex, which may have certain physiological or pathological significance. [source] Factor VIIa-mediated tenase function on activated platelets under flowJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 8 2004M. S. Goel Summary.,Background: Tissue factor (TF) and/or active factor (F)VIIa may be stored inside resting platelets. Objectives: The objective of this study was to examine if platelets, following activation of GPVI, could support tenase and prothrombinase activity without any exogenously added tissue factor. Methods: Thrombin (IIa) formation on gel-filtered platelets with added factors or the clotting of platelet-free plasma (PFP) or platelet-rich plasma (PRP) supplemented with corn trypsin inhibitor (CTI) (to inhibit factor XIIa) was studied in well plate assays with a fluorogenic thrombin substrate or in flow assays by fibrin visualization. Results: Pretreatment of convulxin (CVX)-stimulated, fibrinogen-adherent, gel-filtered platelets with anti-TF, anti-FVII/VIIa, or 1 nm PPACK [inhibitor of FVIIa, factor XIa and factor (F)IIa] delayed fibrin deposition on platelets perfused with PFP/CTI at 62.5 s,1. Anti-TF or anti-FVII/VIIa also attenuated thrombin generation in plate assays using recalcified PRP/CTI treated with CVX. Anti-TF or anti-FVII/VIIa (but not inhibited factor IXa) delayed the burst in thrombin production by gel-filtered platelets suspended in prothrombin and CVX by 14 min and 40 min, respectively. Anti-FVII/VIIa completely eliminated thrombin generation on fibrinogen-adherent, gel-filtered platelets pretreated with 10 µm PPACK and 10 µm EGR-CK [inhibitor of factor (F)Xa], rinsed, and then supplemented with CVX, prothrombin, and FX. Addition of anionic phospholipid to PFP/CTI or to a mixture of prothrombin, FX, and recVIIa was not sufficient to generate detectable tenase activity. Lastly, isolated, unactivated neutrophils suspended in FX, FII and recVIIa supported a very low level of thrombin generation sensitive to antagonism of P-selectin, CD18, and TF. Conclusions: Activated platelets supported tenase and prothrombinase activity by elevating the function or level of FVIIa and exposing active FVIIa or FVIIa-cofactor(s), distinct from anionic lipid, that may be, in part, TF. [source] A novel flow cytometric analysis for platelet activation on immobilized von Willebrand factor or fibrillar collagenJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 2 2003S. Kao Summary., Under flow conditions, platelets adhere singly or in small aggregates on von Willebrand factor (VWF)-coated surfaces, but form large aggregates on immobilized fibrillar collagen. We developed a novel flow cytometric analysis to study the mechanisms underlying these distinct platelet deposition patterns. Flow cytometry was used to measure platelet activation after platelet adherence onto microspheres coated with either VWF or collagen fibrils. Two representative indices were calculated to quantify activated GpIIb,IIIa and P-selectin expression on adherent platelets. The signaling pathways responsible for platelet activation after interacting with fibrillar collagen were elucidated using various inhibitors. An in vitro endothelial cell wound model was also used to study the roles of VWF and fibrillar collagen in platelet deposition onto subendothelial matrixes. The adherent platelets on fibrillar collagen express more activated GpIIb,IIIa and P-selectin than those on VWF. Activation of GpIIb,IIIa and expression of P-selectin after platelet interaction with collagen occur via different intracellular signaling pathways; however, Ca2+ released from intracellular pools is common to both phenomena. Platelets were deposited singly or formed small aggregates on the endothelial cell wounded area, and this deposition pattern was dependent on VWF molecules secreted by endothelial cells and the absence of subendothelial collagen fibrils. As less activated GpIIb,IIIa and P-selectin are expressed after platelets interact with immobilized VWF alone, subsequent flowing platelet recruitment is minimal. Collagen fibrils, however, can activate adherent platelets sufficiently to promote the formation of large platelet aggregates. [source] P-selectin mediates leukocyte rolling in concanavalin-A-induced hepatitisLIVER INTERNATIONAL, Issue 5 2005Sandra March Abstract: Concanavalin- A (Con-A)-induced hepatitis is an experimental model of human autoimmune hepatitis characterized by leukocyte activation and infiltration of the liver. The aim of the present study was to evaluate the role of P-selectin on leukocyte,endothelial interactions within the hepatic microvasculature in response to Con-A. Methods: The study was performed in P-selectin-deficient mice and wild-type mice pretreated with anti-P-selectin blocking monoclonal antibody (mAb) or vehicle. After 2 h of Con-A (20 mg/kg i.v.) or PBS administration, leukocyte rolling and adhesion and the index of sinusoidal perfusion were evaluated using the intravital microscopy technique in the liver. Apoptosis was determined by flow cytometry analysis of caspase-3 activity assayed on freshly isolated hepatocytes. Results: Con-A induced a significant increase in leukocyte rolling, mainly located at the central venule (2.1±0.4 vs 0.6±0.2 cells/min in wild-type mice treated with vehicle) and less marked, but still significant, in portal venules. This was associated with a significant increase in leukocyte adhesion. In P-selectin-deficient mice treated with Con-A, leukocyte rolling in portal and central venules was markedly reduced. However, leukocyte adhesion was only partially attenuated. A few sinusoids were perfused in wild-type mice treated with Con-A (26%). The percentage of perfused sinusoids was significantly higher in P-selectin-deficient mice (45%; P<0.05 vs wild-type). Similar effects were noted after the simultaneous injection of Con-A and anti-P-selecting mAb in wild-type mice. After Con-A treatment, apoptosis was markedly reduced in isolated hepatocytes of P-selectin-deficent mice (37±7% vs 75±5% in wild type). Conclusion: The results of this intravital microscopy study clearly demonstrate that P-selectin is involved in the initial leukocyte rolling that leads to the development of Con-A-induced liver injury. [source] Inhibition of platelet activation by 5-aminosalicylic acid in inflammatory bowel diseaseALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 9 2000Carty Background: Platelets play an important role in inflammation and are activated in inflammatory bowel disease. Micro-vascular thrombosis in the gut wall leading to intestinal micro-infarction may be a pathogenic feature of Crohn's disease. 5-Aminosalicylic acid is an effective treatment for patients with inflammatory bowel disease. Aims: To assess the effects of 5-aminosalicylic acid on platelet activation, when taken orally and in vitro by patients with inflammatory bowel disease. Methods: Spontaneous and thrombin-induced platelet activation were studied using fluorescent antibodies to the activated platelet surface glycoprotein P-selectin and flow cytometry. Results: Baseline platelet activation in inflammatory bowel disease was significantly greater than that in controls (P=0.0003). Independent of diagnosis or disease activity, spontaneous ex-vivo platelet activation was 50% lower in patients with inflammatory bowel disease taking 5-aminosalicylic acid orally than in those not on such treatment (P < 0.05). In vitro, 5-aminosalicylic acid significantly reduced both spontaneous (P < 0.03 for ,1 ,M 5-aminosalicylic acid) and thrombin-induced platelet activation (P < 0.02 for , 1 ,M 5-aminosalicylic acid). Conclusions: 5-Aminosalicylic acid given either orally or in vitro inhibits platelet activation. If this effect reflects an in vivo action in the gut, it could contribute to the beneficial actions of 5-aminosalicylic acid in inflammatory bowel disease. [source] Leukocyte Adhesion in Capillary-Sized, P-Selectin-Coated MicropipettesMICROCIRCULATION, Issue 2 2008Prithu Sundd ABSTRACT Objective: Leukocyte retention in lung capillaries is observed in normal physiology and following a bacterial infection. It has been hypothesized that cells either become mechanically trapped or adhere to capillary endothelial cells via adhesion molecules. We propose that retention involves both mechanical and adhesive forces and that the biochemical adhesive force is modulated by mechanical forces that alter the area of contact between leukocytes and endothelium. Methods: To probe this hypothesis, an adhesion assay has been developed in which individual HL-60 cells were aspirated into micropipettes pre-coated with P-selectin. Following aspiration, cells were exposed to physiological pressure differences. Results: Little adhesion was seen in micropipettes coated with BSA, whereas significant adhesion was observed in micropipettes coated with P-selectin. The frequency of cell arrest on P-selectin in the micropipette was much greater than on P-selectin in a parallel plate flow chamber even though the disruptive force in the micropipette assay exceeds that in the parallel plate flow chamber. These results demonstrate that receptor,ligand interactions can enhance adhesion in a capillary geometry and that differences in capillary geometry vs. venule geometry can significantly influence the adhesive phenotype. Conclusions: Taken together, these observations support the hypothesis that an interplay between mechanical and biochemical adhesive forces can play a major role in retention. [source] Differential Roles of CD36, ICAM-1, and P-selectin in Plasmodium falciparum Cytoadherence In VivoMICROCIRCULATION, Issue 6 2007Bryan G. Yipp ABSTRACT Cytoadherence of Plasmodium falciparum -infected red blood cells (IRBCs) on human microvascular endothelium is mediated by synergistic adhesive interactions with different adhesion molecules in vitro. Here, the authors used a unique human/severe combined immunodeficient (SCID) mouse chimeric model to directly visualize IRBC,endothelial interactions in an intact human microvasculature in vivo. Stimulation of human skin grafts with 100 ng TNF-, for 4 h led to a dramatic reduction in the distance rolled by IRBCs before arrest, so that the majority of IRBCs adhered directly to the endothelium with a 1.8-fold increase in the number of adherent cells. The decrease in rolling distance and increase in adhesion could be reversed by anti-ICAM-1. More importantly, the effect of TNF-, could be seen only in the presence of CD36. A further increase in adhesion by 4.9-fold was observed after 24 h of TNF-, stimulation. The increase could be reversed by anti-ICAM-1, but not anti-VCAM-1. In histamine-stimulated grafts, the rolling flux fraction and adhesion increased by 2.8- and 1.6-fold, respectively. The increases were attributable to P-selectin as an inhibitory anti-P-selectin antibody abrogated both the increased rolling flux fraction and firm adhesion. These findings indicate that in addition to CD36, ICAM-1, and P-selectin are major contributors to the dynamic process of IRBC adhesion by different mechanisms in vivo. [source] Role of Platelets in Hypercholesterolemia-Induced Leukocyte Recruitment and Arteriolar DysfunctionMICROCIRCULATION, Issue 5 2006KAREN Y. STOKES ABSTRACT Objective: To define the contribution of platelets, specifically platelet-associated P-selectin, to the altered venular and arteriolar responses induced by hypercholesterolemia. Methods: Leukocyte and platelet recruitment in cremasteric venules, and endothelium-dependent relaxation (EDR) in arterioles were determined using intravital videomicroscopy. Wild-type (WT) mice were placed on a normal or high cholesterol diet. Hypercholesterolemic mice were treated with blocking antibodies against either P-selectin or PSGL-1, or were depleted of neutrophils (ANS) or platelets (APS). Bone marrow chimeras (P-selectin deficiency in platelets, but not in endothelial cells) were produced by transplanting bone marrow from P-selectin,/, into WT mice (P-sel,/,, WT). Results: Hypercholesterolemia (HC) elicited the recruitment of adherent platelets and leukocytes in venules and an impaired EDR in arterioles. The exaggerated cell adhesion responses were absent in hypercholesterolemic mice treated with ANS, anti-P-selectin or anti-PSGL-1 antibodies and in P-sel,/,, WT chimeras. The hypercholesterolemia-induced impairment of arteriolar EDR was significantly blunted in mice rendered either neutropenic or thrombocytopenic, and in P-sel,/,, WT chimeras. Conclusions: The findings indicate that platelet-associated P-selectin contributes to the recruitment of leukocytes and platelets in venules of hypercholesterolemic mice and that the P-selectin-mediated adhesive interactions also contribute to the impaired arteriolar function induced by hypercholesterolemia. [source] Interactions of Platelets with Subendothelium and EndotheliumMICROCIRCULATION, Issue 3 2005JUNMEI CHEN PhD ABSTRACT In this review, the authors summarize how platelets interact with subendothelium when the vessel wall is damaged or with intact endothelium in the inflammatory state. When subendothelium is exposed to rapidly flowing blood upon vessel damage, platelets adhere rapidly to the exposed surface, decelerate, and aggregate to arrest bleeding. Under high shear stress, such as is found in the microcirculation, the interaction between subendothelial von Willebrand factor (VWF) and its platelet receptor, glycoprotein (GP) Ib-IX-V, is required to slow down platelets and allow the platelet collagen receptors ,2,1 and GP VI to bind to collagen. GP VI and ,2,1 play important roles to activate platelets in the early stage and work with GP Ib-IX-V to fully activate platelets to form thrombi. GP Ib-IX-V and GP VI employ similar signaling pathways for platelet activation and the signals from both receptors are down-modulated by PECAM-1 (platelet,endothelial,cell adhesion molecule 1) to prevent unnecessary platelet activation under high shear. During inflammatory states, intact endothelial cells release VWF and P-selectin from their Weibel-Palade bodies. Both molecules are ligands for GP Ib-IX-V. The newly released VWF is larger and stickier than the form normally found in plasma and binds platelets spontaneously. Normally, VWF is processed by proteolysis by the plasma metalloprotease ADAMTS-13. Failure of this processing results in the microvascular thrombotic disorder thrombotic thrombocytopenic purpura. In this review, the authors also use available crystal structures of platelet receptors and ligands to explain the details of their interactions. [source] | ||||||||||||||||||||||||||||||||||||||||