Leukocyte Adhesion Molecules Research Articles

Postprandial inflammation and endothelial dysfuction

Postprandial hyperlipidaemia is a common metabolic disturbance in atherosclerosis. During the postprandial phase, chylomicrons and their remnants can penetrate the intact endothelium and cause foam cell formation. These particles are highly atherogenic after modification. People in the Western world are non-fasting for most of the day, which consequently leads to a continuous challenge of the endothelium by atherogenic lipoproteins and their remnants. Furthermore, atherosclerosis is considered a low-grade chronic inflammatory disease. Many studies have shown that the process of atherogenesis in part starts with the interaction between the activated leucocytes and activated endothelium. Postprandial lipoproteins can activate leucocytes in the blood and up-regulate the expression of leucocyte adhesion molecules on the endothelium, facilitating adhesion and migration of inflammatory cells into the subendothelial space. Another inflammatory process associated with postprandial lipaemia is the activation of the complement system. Its central component C3 has been associated with obesity, coronary sclerosis, the metabolic syndrome and fasting and postprandial TAGs (triacylglycerols). Moreover, chylomicrons are the strongest stimulators of adipocyte C3 production via activation of the alternative complement cascade. A postprandial C3 increment has been shown in healthy subjects and in patients with CAD (coronary artery disease) and with FCHL (familial combined hyperlipidaemia). Postprandial lipaemia has been related to TAG and free fatty acid metabolism. All of these mechanisms provide an alternative explanation for the atherogenicity of the postprandial period.

Hypothermic preservation of lung allograft inhibits cytokine-induced chemoattractant-1, endothelial leucocyte adhesion molecule, vascular cell adhesion molecule-1 and intracellular adhesion molecule-1 expression

Organ dysfunction is a major clinical problem after lung transplantation. Prolonged cold ischaemia and reperfusion injury are believed to play a central role in this complication. The influence of cold preservation on subsequent warm reperfusion was studied in an isolated, ventilated and perfused rat lung. Rat lungs were flushed with cold Perfadex-solution and stored at 4 degrees C for different time periods. Thereafter lungs were perfused and ventilated for up to 3 h. Physiological parameters, production of inflammatory mediators and leucocyte infiltration were measured before and after perfusion. Lungs subjected to a cold ischaemia time of up to 6 h showed stable physiological conditions when perfused for 3 h. However, cold-ischaemia time beyond 6 h resulted in profound tissue oedema, thereby impairing ventilation and perfusion. Warm reperfusion and ventilation per se induced a strong inflammatory response, as demonstrated by a significant up-regulation of chemokines and adhesion molecules (cytokine-induced chemoattractant-1, intracellular adhesion molecule and endothelial leucocyte adhesion molecule), accompanied by enhanced leucocyte infiltration. Although the up-regulation of inflammatory mediators was blunted in lungs that were subjected to cold ischaemia, this did not influence leucocyte infiltration. In fact, cold ischaemia time correlated with leucocyte sequestration. Although cold preservation inhibits the expression of inflammatory mediators it does not affect leucocyte sequestration during warm reperfusion. Cold preservation might cause impairment of the endothelial barrier function, as evidenced by tissue oedema and profound leucocyte infiltration.

Successful allogeneic stem cell transplant for leukocyte adhesion deficiency using an adjusted busulfan‐containing regimen

LAD is a rare and fatal congenital disorder in which there is a defect of the leukocyte adhesion molecule (CD18) on neutrophils. Severe LAD results in frequent and potentially fatal infections. Although allogeneic HSCT is the only curative treatment for severe LAD, strategies for HSCT remain to be established since a high engraftment failure rate and severe persistent infection are still seen. We report a four-month-old boy with LAD who was successfully treated with allogeneic HSCT from an HLA-complete matched sibling following a conditioning regimen of pharmacokinetically adjusted individual busulfan doses.

Ellagic acid inhibits IL-1β-induced cell adhesion molecule expression in human umbilical vein endothelial cells

Expression of cell adhesion molecules by endothelium and the attachment of monocytes to endothelium may play a major role in atherosclerosis. Ellagic acid (EA) is a phenolic compound found in fruits and nuts including raspberries, strawberries, grapes and walnuts. Previous studies have indicated that EA possesses antioxidant activity in vitro. In the present study, we investigated the effects of EA on the formation of intracellular reactive oxygen species, the translocation of NFkappaB and expression of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 and endothelial leucocyte adhesion molecule (E-selectin) induced by IL-1beta in human umbilical vein endothelial cells (HUVEC). We found that EA significantly reduced the binding of human monocytic cell line, U937, to IL-1beta-treated HUVEC. The production of reactive oxygen species by IL-1beta was dose-dependently suppressed by EA. Supplementation with increasing doses of EA up to 50 micromol/l was most effective in inhibiting the expression of VCAM-1 and E-selectin. Furthermore, the inhibition of IL-1beta-induced adhesion molecule expression by EA was manifested by the suppression of nuclear translocation of p65 and p50. In conclusion, EA inhibits IL-1beta-induced nuclear translocation of p65 and p50, thereby suppressing the expression of VCAM-1 and E-selectin, resulting in decreased monocyte adhesion. Thus, EA has anti-inflammatory properties and may play an important role in the prevention of atherosclerosis.

Folic acid does not improve surrogate markers of early atherosclerosis in atorvastatin-treated patients

Abstract Homocysteine lowering with folic acid has been shown to be ineffective in reducing vascular events in patients with established cardiovascular disease. However, it may be beneficial in the early stages of atherosclerosis particularly for the population at risk. We have investigated the effect of folic acid administration on homocysteine levels, endothelial function, and leukocyte adhesion molecules in atorvastatin-treated patients. Thirty-nine patients were randomized to folic acid 5 mg daily or no additional treatment. Plasma total homocysteine levels were determined by high-performance liquid chromatography. Biochemical and hematologic tests were performed using routine automated analyzer methods. We examined the expression of l-selectin (CD62L); α -subunits of integrins LFA-1 (CD11a), Mac-1 (CD11b), and VLA-4 (CD49d); and β -subunit of β -2 integrins (CD18) by an immunofluorescence method using single-step staining of whole blood with monoclonal antibodies. The fluorescence was quantified by flow cytometry. Reactivity of the forearm skin microvascular bed to thermal and ischemic stimuli was measured using laser Doppler flowmetry. Postocclusive and thermal reactive hyperemia tests were performed. Statistical analysis used 2-sample t test and paired t test. Homocysteine levels decreased significantly in the folic acid–treated group (11.78 ± 2.7 vs 9.75 ± 1.89 μ mol/L, P μ mol/L). There was no effect of folic acid treatment on leukocyte expression of cell adhesion molecules or microvascular reactivity. The lack of effect of folic acid on microvascular reactivity and leukocyte adhesion molecules supports the evidence against the beneficial effects of folic acid administration in the early stages of atherogenesis.

Tumor necrosis factor α (TNF-α) receptor-II is required for TNF-α–induced leukocyte-endothelial interaction in vivo

AbstractTumor necrosis factor-α (TNF-α) binds to 2 distinct cell-surface receptors: TNF-α receptor-I (TNFR-I: p55) and TNF-α receptor-II (TNFR-II: p75). TNF-α induces leukocyte adhesion molecules on endothelial cells (ECs), which mediate 3 defined steps of the inflammatory response; namely, leukocyte rolling, firm adhesion, and transmigration. In this study, we have investigated the role of p75 in TNF-α–induced leukocyte adhesion molecules using cultured ECs derived from wild-type (WT), p75-null (p75−/−), or p55-null (p55−/−) mice. We observed that p75 was essential for TNF-α–induced E-selectin, vascular cell adhesion molecule 1 (VCAM-1), and intercellular adhesion molecule 1 (ICAM-1) expression. We also investigated the putative role of p75 in inflammation in vivo using an intravital microscopic approach with a mouse cremaster muscle model. TNF-α–stimulated leukocyte rolling, firm adhesion to ECs, and transmigration were dramatically reduced in p75−/− mice. Transplanted WT cremaster in p75−/− mice showed a robust leukocyte rolling and firm adhesion upon TNF-α activation, suggesting that the impairment in EC-leukocyte interaction in p75−/− mice is due to EC dysfunction. These results demonstrate, for the first time, that endothelial p75 is essential for TNF-α–induced leukocyte–endothelial-cell interaction. Our findings may contribute to the identification of novel p75-targeted therapeutic approaches for inflammatory diseases.

Severe malaria in Cameroonian children: correlation between plasma levels of three soluble inducible adhesion molecules and TNF-α

Plasma levels of three soluble inducible adhesion molecules, namely: intercellular adhesion molecule-1 (sICAM-1), vascular cell adhesion molecule-1 (sVCAM-1) and endothelial leucocyte adhesion molecule-1 (sELAM-1) or sE-selectin and the pro-inflammatory cytokine, tumour necrosis factor-alpha (TNF-α) were measured in well-defined clinical groups of children with severe and uncomplicated malaria. The goal of the study was to investigate the role of these molecules in immunopathogenic processes associated with severe malaria in Cameroonian children. Results showed significantly increased plasma concentrations of sICAM-1, sVCAM-1 and sE-selectin in children with severe malaria compared to those with uncomplicated malaria and healthy children ( P < 0.001). TNF-α levels increased significantly in children with severe malaria, approximately 2-folds compared to those with uncomplicated malaria and about 3-folds compared to healthy children ( P < 0.001). More importantly, levels of TNF-α strongly correlated with those of the three adhesion molecules and were significantly associated with increased risk of death ( P = 0.03). In addition, children who died from severe malaria showed higher mean levels of all measured factors compared to those who recovered, with significant differences observed with sICAM-1 ( P < 0.001) and sE-selectin ( P = 0.002). Furthermore, children with severe malarial anemia relative to those without, showed significantly elevated levels of the three soluble molecules; and sICAM-1 was significantly associated with increased risk of severe anemia. Taken together, these results confirm the role of TNF-α and the three adhesion molecules in pathogenic processes associated with severe malaria in children, and suggest an association between sICAM-1 and severe malarial anemia.

Effect of N-Acetylcysteine on Lipopolysaccharide-Induced Uveitis in Rats

In this study we investigated the in vivo effect of N-acetylcysteine (NAC) on lipopolysaccharide (LPS)-induced uveitis in rats. To induce uveitis, LPS (100 microg) was injected into subcutaneous tissue of Wistar rats (170-190 g). NAC was injected intraperitoneally. Intracameral levels of protein, cells, nitrite, tumor necrosis factor (TNF)-alpha, and interleukin (IL)-6 were determined by spectrophotometry, hemocytometry, and enzyme-linked immunosorbent assay. Expression of TNF-alpha, IL-6, endothelial leukocyte adhesion molecule-1 (E-selectin), intercellular adhesion molecule-1 (ICAM-1), and inducible nitric oxide synthase (iNOS) mRNA was examined by real-time polymerase chain reaction. LPS injection elevated intracameral protein and cells, and the elevation was inhibited by NAC. LPS injection induced expression of TNF-alpha, IL-6, E-selectin, and ICAM-1 mRNA in the iris/ciliary body at 3 h, and iNOS mRNA at 6 h. The LPS-induced elevation of the mRNA levels was inhibited by NAC. NAC inhibited LPS-induced intracameral elevation of TNF-alpha, IL-6, and nitrite. NAC decreased LPS-induced uveitis in vivo by reducing the expression of proinflammatory cytokines and adhesion molecules.

Preoperative unstable angina causes venous adaptation to surgical graft injury

Ischemic preconditioning may provide a systemic organ protection, evident as the phenomenon known as remote preconditioning. Unstable angina may be a clinical analogue to ischemic preconditioning. Vein graft harvesting induces inflammation of the graft wall. We hypothesized that preoperative unstable angina preconditions vein grafts and reduces the inflammatory response to graft harvesting. Consecutive patients with stable or unstable angina undergoing open heart surgery (n = 12 in each group) were studied. Saphenous vein biopsies were collected at the start of graft harvesting, and when the last proximal anastomosis to the aorta was finished (average 112 minutes later). Gene expression of inflammatory mediators (tumor necrosis factor alpha, interleukin-1beta (IL-1beta), E-selectin (CD62E), intercellular leukocyte adhesion molecule 1, inducible nitric oxide synthase, endothelin-1) increased after surgical handling (semiquantitative RT-PCR). In vein grafts from unstable patients the increase was attenuated for Il-1beta (p < 0.004) and CD62E (p < 0.001). In stable patients the protein expression of IkappaBalpha and heat shock protein72 was reduced by surgical handling (p < 0.04), but was not influenced in unstable patients (immunoblotting). In vitro relaxation to acetylcholine was enhanced, and contractions to phenylephrine and endothelin-1 were attenuated in veins rings from unstable patients (p < 0.003). In conclusion, surgical handling of vein grafts induces inflammation of the vessel wall. This response was reduced in grafts from patients with unstable angina, indicating a possible systemic preconditioning-like effect of acute coronary syndromes.

Issue Highlights

HomeCirculationVol. 115, No. 3Issue Highlights Free AccessIn BriefPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessIn BriefPDF/EPUBIssue Highlights Originally published23 Jan 2007https://doi.org/10.1161/circ.115.3.287Circulation. 2007;115:287EARLY OUTCOMES OF TRICUSPID VALVE REPLACEMENT IN YOUNG CHILDREN, by Bartlett et al.Few data on the outcome of tricuspid valve replacement in young children are available to guide decisions. Bartlett and colleagues reviewed the results of tricuspid valve replacement in 97 children younger than age 6 years using the database of the Pediatric Cardiac Care Consortium of 45 centers between 1984 and 2002. The primary outcome was survival to discharge. The most frequent cardiac diagnoses were Ebstein’s anomaly (40%), pulmonary atresia (11%), and tetralogy of Fallot (8%). In-hospital mortality was 26% overall and was highest among infants (64%). Valve thrombosis and heart block requiring a pacemaker were common complications. The high morbidity and mortality of tricuspid valve replacement in young children and especially infants suggests that other surgical options should be considered. See p 319.MYOCARDIAL ISCHEMIC MEMORY IMAGING WITH MOLECULAR ECHOCARDIOGRAPHY, by Villanueva et al.Myocardial ischemia that does not result in necrosis may be difficult to diagnose after resolution of the ischemia. Such episodes are associated with endothelial upregulation of leukocyte adhesion molecules. In this issue, Villanueva et al describe the potential of myocardial ischemic memory using contrast echocardiography. Lipid microbubbles were designed to adhere to selectins, and this was tested in a model of inflamed rat cremaster muscle and in a rat model. Twelve rats underwent 15 minutes of left anterior descending coronary artery occlusion and then at 15 minutes and 1 hour following reperfusion, there was greater opacification of the ischemic bed using microbubbles with the selectin ligand. Immunostaining confirmed endothelial P-selectin expression. Although preliminary, the present study raises the potential that this technique may allow the identification of recent myocardial ischemia in patients and facilitate the triage of patients with chest pain. See p 345.PREVALENCE OF LONG-QT SYNDROME GENE VARIANTS IN SUDDEN INFANT DEATH SYNDROME, by Arnestad et al.andCARDIAC SODIUM CHANNEL DYSFUNCTION IN SUDDEN INFANT DEATH SYNDROME, by Wang et al.Sudden infant death syndrome is unexplained, unexpected death in the first year of life and has multifactorial etiologies. One important cause relates to the genes responsible for congenital long-QT syndrome. In companion manuscripts in this issue of Circulation, Arnestad and colleagues report their molecular autopsy findings of genetic screening for 7 known long-QT syndrome—associated genes in 201 Norwegian victims of sudden infant death syndrome. They identified mutations or rare genetic variants in 10% of cases, of which half were in the sodium channel SCN5A gene. Wang and colleagues then performed biophysical in vitro functional experiments on the SCN5A mutations in transiently transfected cells. They found defects in the voltage dependence of inactivation and kinetics, including increased persistent sodium currents, similar to the biophysical changes seen in SCN5A mutations causing long-QT syndrome. Taken together, these investigations conclude that neonatal electrocardiographic screening may identify QT prolongation prior to sudden infant death syndrome, potentially affecting outcome. These studies further our understanding of the relationship between sudden infant death syndrome and genes causing long-QT syndrome. See pp 361 and 368.Visit http://circ.ahajournals.org:Clinician UpdateMetabolic Syndrome. See p e32.Images in Cardiovascular MedicineDouble-Outlet Left Ventricle. See p e36.Serial Images Demonstrating Proximal Extension of an Aortic Intramural Hematoma. See p e38. Download figureDownload PowerPointLost P’s, but Not Yet Forgotten. See p e41.Book ReviewPediatric Prevention of Atherosclerotic Cardiovascular Disease. See p e43.CorrespondenceSee p e45. Previous Back to top Next FiguresReferencesRelatedDetails January 23, 2007Vol 115, Issue 3 Advertisement Article InformationMetrics https://doi.org/10.1161/circ.115.3.287 Originally publishedJanuary 23, 2007 PDF download Advertisement

Myocardial Ischemic Memory Imaging With Molecular Echocardiography

Diagnosing acute coronary syndrome in patients presenting with chest discomfort is a challenge. Because acute myocardial ischemia/reperfusion is associated with endothelial upregulation of leukocyte adhesion molecules, which persist even after ischemia has resolved, we hypothesized that microbubbles designed to adhere to endothelial selectins would permit echocardiographic identification of recently ischemic myocardium. Lipid microbubbles (diameter, 3.3+/-1.7 microm) were synthesized. The selectin ligand sialyl Lewis(x) was conjugated to the microbubble surface (MB(sLex)). Control bubbles (MB(CTL)) bore surface Lewis(x) or sialyl Lewis(c). Intravital microscopy of mouse cremaster muscle was performed after intravenous injection of MB(sLex) (n=11) or MB(CTL) (n=9) with or without prior intrascrotal tumor necrosis factor-alpha. There was greater adhesion of MB(sLex) to inflamed versus noninflamed endothelium (P = 0.0081). Rats (n=12) underwent 15 minutes of anterior descending coronary artery occlusion. After 30 minutes and 1 hour of reperfusion, high-mechanical-index nonlinear echocardiographic imaging was performed in which single frames were acquired at 3.5 and 4 minutes after intravenous injection of MB(sLex) or MB(CTL). Video intensity at 4 minutes was subtracted from that at 3.5 minutes to derive target-specific acoustic signal. MB(sLex) caused greater opacification in postischemic versus nonischemic myocardium at both time points (P < or = 0.002). Immunostaining confirmed endothelial P-selectin expression in the ischemic bed. Echocardiographic identification of recently ischemic myocardium is possible using ultrasound contrast agents targeted to selectins. This may offer a new approach to the more timely and precise diagnosis of acute coronary syndrome in patients presenting with chest pain of uncertain cardiac origin.

Modifying the anti-inflammatory effects of high-density lipoprotein

The anti-inflammatory effects of high-density lipoproteins (HDL) are well documented and include inhibition of low-density lipoprotein (LDL) oxidation, reduction of inflammatory cytokines and vascular leukocyte adhesion molecules, and participation in innate immunity. However, certain conditions, including coronary disease, diabetes mellitus, systemic inflammation, and a diet high in saturated fat, are associated with modification of HDL such that it paradoxically enhances LDL oxidation and/or vascular inflammation. Treatment with statins and/or apolipoprotein A1 mimetic peptides improves HDL's anti-inflammatory functions, and these as well as other medications may represent a novel pathway through which to target atherosclerosis.

Reduction of Ischemia-reperfusion Injury to Skin Flap by Treatment with Monoclonal Antibody to Endothelial Leukocyte Adhesion Molecule-1

Reduction of Ischemia-reperfusion Injury to Skin Flap by Treatment with Monoclonal Antibody to Endothelial Leukocyte Adhesion Molecule-1

Influence of dextran-70 on systemic inflammatory response and myocardial ischaemia-reperfusion following cardiac operations

IntroductionExperimental studies have demonstrated that dextran-70 reduces the leukocyte–endothelium interaction, but clinical evidence is still lacking. Our objective was to justify the anti-inflammatory effect of dextran-70 following cardiac operations.MethodsForty patients undergoing coronary bypass surgery (n = 32) or aortic valve replacement (n = 8) were enrolled in this prospective, randomized, double-blind study. Two groups were formed. In group A (n = 20), dextran-70 infusion was administered at a dose of 7.5 ml/kg before the initiation of cardiopulmonary bypass and at a dose of 12.5 ml/kg after the cessation of cardiopulmonary bypass. Group B served as a control with identical amounts of gelatin infusion (n = 20). The plasma concentration of procalcitonin, C-reactive protein, IL 6, IL 6r, IL 8, IL 10, soluble endothelial leukocyte adhesion molecule-1, soluble intercellular adhesion molecule-1, cardiac troponin-I and various haemodynamic parameters were measured in the perioperative period. Multivariate methods were used for statistical analysis.ResultsIn group A, lower peak (median) plasma levels of procalcitonin (0.2 versus 1.4, p < 0.001), IL 8 (5.6 versus 94.8, p < 0.001), IL 10 (47.2 versus 209.7, p = 0.001), endothelial leukocyte adhesion molecule-1 (88.5 versus 130.6, p = 0.033), intercellular adhesion molecule-1 (806.7 versus 1,375.7, P = 0.001) and troponin-I (0.22 versus 0.66, p = 0.018) were found. There was no significant difference in IL 6, IL-6r and C-reactive protein values between groups. Higher figures of the cardiac index (p = 0.010) along with reduced systemic vascular resistance (p = 0.005) were noted in group A.ConclusionOur investigation demonstrated that the use of dextran-70 reduces the systemic inflammatory response and cardiac troponin-I release following cardiac operation.Trial registration numberISRCTN38289094.

The Expression of the Adhesion Molecules on Interfacial Membrane from the Aseptically Loosened Failed Femoral Stems in Revisional Hip Arthroplasty

Purpose: To clarify the relationship between aseptic loosening of hip arthroplasty and adhesion molecules on interfacial membrane from revisional hip arthroplasty. Materials and Methods: We studied 26 revisional total hip arthroplasties between May 2004 and July 2006, and 15 synovial tissues from hip fractures were selected as the control group. We analyzed the degree of femoral osteolysis by Paprosky's classification. We examined the expression of soluble endothelial leukocyte adhesion molecule-1 (E-selectin), vascular adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) by immunohistochemical staining technique. We compared and analyzed radiologic evaluation and expression of adhesion molecules. Results: Expression of E-selectin was observed in 100%, VCAM-1 in 42.3% and ICAM-1 in 34.6%. Expression of adhesion molecules were increased compared to the control group (p＜0.05). The higher the expression of E-selectin, the higher the degree of osteolysis (p=0.023). Conclusion: These results showed that adhesion molecules are involved in aseptic loosening of hip arthroplasties, and we proposed that E-selectin may strongly engage in the cascade of aseptic loosening in hip arthroplasty.

MDI 301, a non-irritating retinoid, induces changes in human skin that underlie repair

Previous studies have demonstrated that all-trans retinoic acid (RA) increases collagen production and decreases matrix metalloproteinase (MMP) activity in organ-cultured human skin. Decreased MMP activity is associated with up-regulation of tissue inhibitor of metalloproteinase-1 (TIMP-1). These changes are accompanied by a hyperplastic response in the epidermis. Here we show that a synthetic picolinic ester-substituted retinoid (designated as MDI 301) has comparable effects to those of RA in regard to these activities. What makes these findings of interest is that RA also stimulates elaboration of several pro-inflammatory cytokines and up-regulates leukocyte adhesion molecules in organ-cultured skin. MDI 301 does not induce such changes or is much less active. In a past study we showed that while RA was irritating to the skin of topically treated hairless mice, MDI 301 was essentially non-irritating under the same conditions [Varani et al. (2003) Arch. Dermatol Res 295:255-262]. Taken in conjunction with the findings from the past study, the present data suggest that MDI 301 will be similar to RA in capacity to repair damaged skin, but will be effective under conditions that are not irritating. These findings, thus, suggest that retinoid efficacy and clinically relevant irritancy are not inextricably linked. Potential for efficacy under conditions in which irritation is not observed is a strong rationale for further development of MDI 301 as a skin-repair agent.

Epigenetic Regulation of Tumor Endothelial Cell Anergy: Silencing of Intercellular Adhesion Molecule-1 by Histone Modifications

Tumors can escape from immunity by repressing leukocyte adhesion molecule expression on tumor endothelial cells and by rendering endothelial cells unresponsive to inflammatory activation. This endothelial cell anergy is induced by angiogenic growth factors and results in reduced leukocyte-vessel wall interactions, thereby attenuating infiltration of leukocytes into the tumor. This report describes a novel mechanism of endothelial cell anergy regulation. We recently reported that DNA methyltransferase (DNMT) and histone deacetylase (HDAC) inhibitors have angiostatic activity. Here, we studied whether epigenetic mechanisms regulate this angiogenesis-mediated escape from immunity. We found that DNMT inhibitors 5-aza-2'-deoxycytidine and zebularine, as well as HDAC inhibitor trichostatin A, reexpressed intercellular adhesion molecule-1 (ICAM-1) on tumor-conditioned endothelial cells in vitro, resulting in restored leukocyte-endothelial cell adhesion. In addition, treatment with DNMT or HDAC inhibitors in vivo also restored ICAM-1 expression on tumor endothelial cells from two different mouse tumor models. Furthermore, leukocyte-vessel wall interactions in mouse tumors were increased by these compounds, as measured by intravital microscopy, resulting in enhanced leukocyte infiltration. We show that ICAM-1 down-regulation in tumor endothelial cells is associated with ICAM-1 promoter histone H3 deacetylation and loss of histone H3 Lys(4) methylation but not with DNA hypermethylation. In conclusion, our data show that ICAM-1 is epigenetically silenced in tumor endothelial cells by promoter histone modifications, which can be overcome by DNMT and HDAC inhibitors, suggesting a new molecular mechanism based on which novel therapeutic approaches for cancer can be pursued.

Cellular adhesion molecules in chronic urticaria: modulation of serum levels occurs during levocetirizine treatment

Some antihistamines are capable of reducing levels of adhesion molecules in wealing tissues of patients with chronic urticaria (CU). To determine if 6 weeks of therapy with levocetirizine 5 mg once daily would also induce any decrease in serum levels of intercellular adhesion molecule-1, vascular cell adhesion molecule-1, endothelial leucocyte adhesion molecule-1 (ELAM-1) or P-selectin in subjects with CU and chronic autoimmune urticaria. Thirty-six patients with CU (18 with positive and 18 with negative autologous serum skin test) were studied, together with 10 control healthy subjects. All patients received levocetirizine 5 mg daily. Serum soluble cellular adhesion molecule (CAM) levels were determined by immunoenzymatic assay before and after the end of the study period. Disease activity was recorded according to the EAACI/GA(2)LEN/EDF scoring system. After levocetirizine therapy CAM levels decreased in patients with CU, significantly in the cases of ELAM-1 and P-selectin. Patients' clinical scores improved during regular antihistamine therapy. Levocetirizine 5 mg daily demonstrated a broad anti-inflammatory effect in patients with CU. The significant decrease in serum levels of ELAM-1 and P-selectin might reflect the inhibitory activity on neutrophil rolling and extravasation towards inflamed skin.

Vein Graft Harvesting Induces Inflammation and Impairs Vessel Reactivity

Saphenous veins are often used for coronary artery bypass grafting (CABG), but loss of patency is a problem. The surgical procedure may contribute to graft injury. Our aim was to study the impact of surgical handling of saphenous veins on graft inflammation and vascular function. Biopsy samples of saphenous veins were taken from 9 patients undergoing elective CABG at the start of vein harvesting (open technique) and after the last proximal anastomosis was sutured. Messenger RNA was extracted and amplified with semiquantitative reverse transcription polymerase chain reaction. Gene expression of proinflammatory cytokines (tumor necrosis factor-alpha, interleukin-1beta), leukocyte adhesion molecules (E-selectin, intercellular adhesion molecule-1), and vasoactive substances (endothelin-1, inducible and endothelial nitric oxide synthase) was investigated. Translocation of nuclear factor-kappaB (NFkappaB) was evaluated with electrophoretic mobility shift assay. Immunostaining for von Willebrand factor was performed to evaluate loss of endothelium, and in vitro vein reactivity to phenylephrine and endothelin-1 was studied. Gene expression of cytokines and leukocyte adhesion molecules increased after graft harvesting and storage, whereas vasoactive substances did not change. Nuclear translocation of NFkappaB occurred after surgical handling, concurrent with partial loss of endothelium and impaired contractile function. Standard surgical handling of vein grafts induces NFkappaB-driven inflammation in the vessel wall and impairs vascular function. This may potentially contribute to both early and late graft occlusion.

Molecular events during leukocyte diapedesis

The recruitment of leukocytes from the circulation into tissues requires leukocyte migration through the vascular endothelium. The mechanisms by which leukocytes attach and firmly adhere to the endothelial cell surface have been studied in detail. However, much less is known about the last step in this process, the diapedesis of leukocytes through the vascular endothelium. This minireview focuses on the interactions between leukocyte and endothelial cell adhesion molecules that are important during leukocyte extravasation. In the past few years a series of endothelial cell surface and adhesion molecules have been identified that are located at endothelial cell contacts and found to participate in leukocyte diapedesis. These junctional cell adhesion molecules are believed to have an active role in controlling the opening and closure of endothelial cell contacts to allow the passage of leukocytes between adjacent endothelial cells. Alternatively, leukocytes can cross the endothelium at nonjunctional locations, with leukocytes migrating through a single endothelial cell. Further work is clearly needed to understand, in greater detail, the molecular mechanisms that allow leukocytes to cross the endothelium via either the paracellular or the transcellular pathway.