Expression Of Cell Surface Adhesion Molecules Research Articles

(325) A Descriptive Analysis of Digital Resources for Educating Sickle Cell Patients About Priapism

Abstract Introduction Men with sickle cell disease (SCD, HbSS or HbSC hemoglobinopathy) are at increased risk of priapism via increased cell surface adhesion molecule expression and blunted vasodilatory responses to nitric oxide. Previous studies have suggested that priapism knowledge is poor among men with SCD; however, studies have yet to characterize public-facing priapism educational resources. Objective To describe key features of online educational resources targeted to priapism patients with SCD in the US. Methods In March 2023, we searched the following keywords and terms using the Google search engine and search features within Facebook, YouTube, and TikTok: “painful erection”, “priapism”, “priapism patient education”, “priapism for patients”, and “priapism sickle cell patient”. Searches were performed via a computer located in Manhattan, New York and in the English language only. Results Google search results differed considerably when searching “painful erection” versus “priapism” and are depicted in Table 1: the former directed users to telehealth commercial websites while the latter directed users to websites hosted by healthcare and professional organizations and medical reference sites which primarily discussed etiology and need for prompt diagnosis of the condition. YouTube search results overwhelmingly focus on discussion of diagnosis, pathophysiology, and management of priapism, and most of these appear designed for a medical or medically-literate audience; however, when querying for “priapism sickle cell patient”, users are directed to patient testimonial or documentary style videos. The results of a Facebook pages search seemed intended for student education and associated with low quality media material. An equivalent search performed on Tik Tok yields videos with noticeably different characteristics, namely: starring and created by “younger” urologists and hematologists, depicting a diverse cohort of providers and patients, written/spoken in Spanish and Portuguese, informal dialogue, increased use of Q&A format. Compared to YouTube videos, TikTok posts were more recent, received more views, and were associated with more comments. Conclusions Our exploratory search for priapism educational resources revealed differences in content, tone, and format between online sites and mobile platforms. Based on view and comment statistics, it appears as though mobile platforms such as TikTok have an increasing role in disseminating knowledge about priapism. However, it remains unclear as to whether individual modalities are well-suited to deliver information in a specific disease phase (e.g. preventative, acute, or chronic). Importantly, the impact of word-of-mouth and private provider-to-patient interactions cannot be estimated by this methodology. Disclosure No.

Antithrombin-III mitigates thrombin-mediated endothelial cell contraction and sickle red blood cell adhesion in microscale flow.

SummaryIndividuals with sickle cell disease (SCD) have persistently elevated thrombin generation that results in a state of systemic hypercoagulability. Antithrombin‐III (ATIII), an endogenous serine protease inhibitor, inhibits several enzymes in the coagulation cascade, including thrombin. Here, we utilize a biomimetic microfluidic device to model the morphology and adhesive properties of endothelial cells (ECs) activated by thrombin and examine the efficacy of ATIII in mitigating the adhesion of SCD patient‐derived red blood cells (RBCs) and EC retraction. Microfluidic devices were fabricated, seeded with ECs, and incubated under physiological shear stress. Cells were then activated with thrombin with or without an ATIII pretreatment. Blood samples from subjects with normal haemoglobin (HbAA) and subjects with homozygous SCD (HbSS) were used to examine RBC adhesion to ECs. Endothelial cell surface adhesion molecule expression and confluency in response to thrombin and ATIII treatments were also evaluated. We found that ATIII pretreatment of ECs reduced HbSS RBC adhesion to thrombin‐activated endothelium. Furthermore, ATIII mitigated cellular contraction and reduced surface expression of von Willebrand factor and vascular cell adhesion molecule‐1 (VCAM‐1) mediated by thrombin. Our findings suggest that, by attenuating thrombin‐mediated EC damage and RBC adhesion to endothelium, ATIII may alleviate the thromboinflammatory manifestations of SCD.

Influence of hydroxychloroquine blood levels on adhesion molecules associated with endothelial dysfunction in patients with systemic lupus erythematosus

BackgroundPatients with SLE have an endothelial dysfunction (ED), which is considered the earliest marker of cardiovascular (CV) disease. Endothelial cell activation induced by proinflammatory cytokines is defined by the endothelial...

Redox Control of Integrin-Mediated Hepatic Inflammation in Systemic Autoimmunity.

Significance: Systemic autoimmunity affects 3%-5% of the population worldwide. Systemic lupus erythematosus (SLE) is a prototypical form of such condition, which affects 20-150 of 100,000 people globally. Liver dysfunction, defined by increased immune cell infiltration into the hepatic parenchyma, is an understudied manifestation that affects up to 20% of SLE patients. Autoimmunity in SLE involves proinflammatory lineage specification in the immune system that occurs with oxidative stress and profound changes in cellular metabolism. As the primary metabolic organ of the body, the liver is uniquely capable to encounter oxidative stress through first-pass derivatization and filtering of waste products. Recent Advances: The traffic of immune cells from their development through recirculation in the liver is guided by cell adhesion molecules (CAMs) and integrins, cell surface proteins that tightly anchor cells together. The surface expression of CAMs and integrins is regulated via endocytic traffic that is sensitive to oxidative stress. Reactive oxygen species (ROS) that elicit oxidative stress in the liver may originate from the mitochondria, the cytosol, or the cell membrane. Critical Issues: While hepatic ROS production is a source of vulnerability, it also modulates the development and function of the immune system. In turn, the liver employs antioxidant defense mechanisms to protect itself from damage that can be harnessed to serve as therapeutic mechanisms against autoimmunity, inflammation, and development of hepatocellular carcinoma. Future Directions: This review is aimed at delineating redox control of integrin signaling in the liver and checkpoints of regulatory impact that can be targeted for treatment of inflammation in systemic autoimmunity. Antioxid. Redox Signal. 36, 367-388.

Nitro-oleic acid inhibits vascular endothelial inflammatory responses and the endothelial-mesenchymal transition

BackgroundInflammatory-mediated pathological processes in the endothelium arise as a consequence of the dysregulation of vascular homeostasis. Of particular importance are mediators produced by stimulated monocytes/macrophages inducing activation of endothelial cells (ECs). This is manifested by excessive soluble pro-inflammatory mediator production and cell surface adhesion molecule expression. Nitro-fatty acids are endogenous products of metabolic and inflammatory reactions that display immuno-regulatory potential and may represent a novel therapeutic strategy to treat inflammatory diseases. The purpose of our study was to characterize the effects of nitro-oleic acid (OA-NO2) on inflammatory responses and the endothelial-mesenchymal transition (EndMT) in ECs that is a consequence of the altered healing phase of the immune response. MethodsThe effect of OA-NO2 on inflammatory responses and EndMT was determined in murine macrophages and murine and human ECs using Western blotting, ELISA, immunostaining, and functional assays. ResultsOA-NO2 limited the activation of macrophages and ECs by reducing pro-inflammatory cytokine production and adhesion molecule expression through its modulation of STAT, MAPK and NF-κB-regulated signaling. OA-NO2 also decreased transforming growth factor-β-stimulated EndMT and pro-fibrotic phenotype of ECs. These effects are related to the downregulation of Smad2/3. ConclusionsThe study shows the pleiotropic effect of OA-NO2 on regulating EC-macrophage interactions during the immune response and suggests a role for OA-NO2 in the regulation of vascular endothelial immune and fibrotic responses arising during chronic inflammation. General significanceThese findings propose the OA-NO2 may be useful as a novel therapeutic agent for treatment of cardiovascular disorders associated with dysregulation of the endothelial immune response.

Endothelial protein kinase MAP4K4 promotes vascular inflammation and atherosclerosis.

Signalling pathways that control endothelial cell (EC) permeability, leukocyte adhesion and inflammation are pivotal for atherosclerosis initiation and progression. Here we demonstrate that the Sterile-20-like mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4), which has been implicated in inflammation, is abundantly expressed in ECs and in atherosclerotic plaques from mice and humans. On the basis of endothelial-specific MAP4K4 gene silencing and gene ablation experiments in Apoe−/− mice, we show that MAP4K4 in ECs markedly promotes Western diet-induced aortic macrophage accumulation and atherosclerotic plaque development. Treatment of Apoe−/− and Ldlr−/− mice with a selective small-molecule MAP4K4 inhibitor also markedly reduces atherosclerotic lesion area. MAP4K4 silencing in cultured ECs attenuates cell surface adhesion molecule expression while reducing nuclear localization and activity of NFκB, which is critical for promoting EC activation and atherosclerosis. Taken together, these results reveal that MAP4K4 is a key signalling node that promotes immune cell recruitment in atherosclerosis.

Cytoskeletal regulatory gene expression and migratory properties of B-cell progenitors are affected by the ETV6-RUNX1 rearrangement.

Although the ETV6-RUNX1 fusion is a frequent initiating event in childhood leukemia, its role in leukemogenesis is only partly understood. The main impact of the fusion itself is to generate and sustain a clone of clinically silent preleukemic B-cell progenitors (BCP). Additional oncogenic hits, occurring even several years later, are required for overt disease. The understanding of the features and interactions of ETV6-RUNX1-positive cells during this "latency" period may explain how these silent cells can persist and whether they could be prone to additional genetic changes. In this study, two in vitro murine models were used to investigate whether ETV6-RUNX1 alters the cellular adhesion and migration properties of BCP. ETV6-RUNX1-expressing cells showed a significant defect in the chemotactic response to CXCL12, caused by a block in CXCR4 signaling, as demonstrated by inhibition of CXCL12-associated calcium flux and lack of ERK phosphorylation. Moreover, the induction of ETV6-RUNX1 caused changes in the expression of cell-surface adhesion molecules. The expression of genes regulating the cytoskeleton was also affected, resulting in a block of CDC42 signaling. The abnormalities described here could alter the interaction of ETV6-RUNX1 preleukemic BCP with the microenvironment and contribute to the pathogenesis of the disease. Alterations in the expression of cytoskeletal regulatory genes and migration properties of BCP represent early events in the evolution of the disease, from the preleukemic phase to the clinical onset, and suggest new strategies for effective eradication of leukemia.

Trophoblast deportation: just a waste disposal system or antigen sharing?

Trophoblast deportation, the removal of trophoblastic debris from the placenta via the maternal blood, was first described over 100 years ago. Deported trophoblastic debris ranges in size from nano-meter scale subcellular particles to large multinucleated syncytial knots. Whether trophoblast deportation has any biological significance remains unclear. However, the (semi) allogeneic fetus must induce maternal tolerance to paternally inherited placental antigens. We propose that the clearance of deported trophoblasts may be a mechanism by which the maternal immune system is maintained in a state of tolerance towards paternal antigens. Using an in vitro model, we have shown that when syncytial knots are shed by an apoptosis-like programmed cell death process, then phagocytosed by macrophages, the macrophages produce a tolerogenic response. However, necrotic syncytial knots, when phagocytosed, appear to be immunostimulatory. We have also shown that endothelial cells are likely to be involved in the clearance of syncytial knots from the pulmonary vessels. Phagocytosis of apoptotic syncytial knots by endothelial cells is silent while phagocytosis of necrotic syncytial knots leads to endothelial cell activation characterised by increased endothelial cell-surface adhesion molecule expression and secretion of IL-6 and TGFβ1. All of these molecules may interact with the maternal immune system to exacerbate any adverse maternal response. We propose that in normal pregnancy clearance of apoptotic syncytial knots is important to maintain maternal immune tolerance to the fetus and that in abnormal pregnancies, especially preeclampsia, clearance of necrotic syncytial knots may contribute to the pathogenesis of that condition.

Inflammatory Cell Tissue Extravasation Pathways Can Be Regulated by Adherent Stem Cells by Inhibiting Selectin Ligand and Adhesion Receptor Expression On T Cells and Activated Endothelium.

Abstract 3631Poster Board III-567MultiStem is an adult bone marrow derived stem cell product with immune-modulatory activity that falls within a class of adherent stem cell platforms emerging as modalities for allogeneic therapy for modulation of GVHD. Despite initial preclinical and clinical success there remains significant need for mechanistic understanding of stromal cell interaction with inflammatory cells, particularly relating to biodistribution and the microenvironments encountered after intravenous administration. Successful GVHD treatment or prophylaxis regimens will likely by optimized by a better appreciation of adherent stem cell interactions with GVHD initiating T cells in the tissue microenvironment or in secondary lymphoid tissues. In this study we evaluated interactions of MultiStem with activated peripheral blood cells as well as activated endothelial cells using in vitro co-culture systems that permit cross-talk via soluble factors. In co-culture experiments with activated T cells we observed that MultiStem strongly inhibits gene expression of Fut7, the enzyme responsible for expression of Lewis antigen (CD15s). The resultant lack of CD15s expression on the cell surface of activated T cells was shown to result in their reduced ability to bind to endothelium activated with TNFa, relative to T cells activated in the absence of MultiStem. Furthermore, we found that co-culture of MultiStem with endothelial cells prevents upregulation of E-selectin, V-CAM, and to a lesser degree, I-CAM, to the cell surface of endothelial cells upon activation with TNF-α or interleukin-1α. Inhibition of E-selectin expression by co-culture with MultiStem was not caused by increased cleavage of E-selectin from the cell surface. Instead, MultiStem modulates cell surface induction through decreasing transcription of V-CAM, E-selectin and ICAM. This reduction in cell surface adhesion molecule expression results in decreased neutrophil binding to endothelial cells compared with untreated controls. This activity does not appear to be common to all bone marrow derived adherent stem cells as mesenchymal stem cells (MSC) are unable to modulate V-CAM, E-selectin or I-CAM cell surface upregulation upon activation with TNF-α. These results suggest MSC and MultiStem have distinct secretion profiles. These novel observations indicate that, in addition to immunomodulation activity, MultiStem has unique potential to deter GVHD by impacting various arms of the extravasation process of GVHD pathology causing inflammatory cells. Disclosures:Van't Hof:Athersys: Employment, Equity Ownership. Raber:Athersys: Employment, Equity Ownership. Woda:Athersys: Employment, Equity Ownership. Lehman:Athersysa: Employment, Equity Ownership. Cutrone:Athersys: Employment. Ting:Athersys: Employment, Equity Ownership. Deans:Athersys: Employment, Equity Ownership.

Adhesion Molecules in Cerebral Ischemia and Atherosclerosis

Adhesion molecules are integral membrane proteins that have cytoplasmic, transmembrane and extracellular domains. Dozens of different adhesion molecules have been identified, but, adhesion molecules are conventionally divided into four main groups, each of which has a different function: 1. The selectins, 2. The immunglobulin gene superfamily, 3. The integrins and 4. The cadherins. Under normal conditions, there is little or no cell-surface expression of adhesion molecules. Various inflammatory processes induce their expressions, such as atherosclerosis and cerebral ischemia, with the upregulations mediated by cytokines. Normally, vascular endothelial cells have low adhesiveness for leukocytes; however, when stimulated they express adhesion molecules at their surfaces responsible for adhesion and activation of leukocytes as a precondition for transendothelial migration of leukocytes. The effect of anti-adhesion molecule strategies in focal cerebral and spinal cord ischemia showed a beneficial effect in models in which transient focal ischemia was followed by reperfusion, but not in models of permanent ischemia. In addition anti-inflammatory agents could have reduced expression and shedding of adhesion molecules as a result of its antiinflammatory properties.Atherosclerosis, cerebral ischemia, adhesion molecules.

Circulating Adhesion Molecules and Purine Nucleotides During Kidney Allograft Reperfusion

The impairment of organ function due to ischemia-reperfusion injury is still an important problem in solid organ transplantation. Numerous experimental and clinical studies of native organs have shown that ischemia-reperfusion constitutes an acute inflammatory process involving cell surface adhesion molecule expression. These markers are crucial for the recruitment and infiltration of effector cells into the postischemic tissue. Purines released by the postischemic tissue as the products of the degradation of high-energy nucleotides can be regarded as markers of disturbed energy metabolism. The aim of this study was to examine the correlation between circulating adhesion molecules and purine metabolites in graft renal vein plasma during 49 cases of kidney reperfusion. E-selectin, ICAM-1, and VCAM-1 concentrations correlated positively with hypoxanthine concentrations during reperfusion, whereas the concentrations of ICAM-1 correlated negatively with xanthine concentrations. The results of the present study suggested that the concentrations of adhesion molecules in the renal vein during reperfusion correlated with purine metabolites, reflecting metabolic changes in renal tissue.

Ventilation during Cardiopulmonary Bypass: Impact on Neutrophil Activation and Pulmonary Sequestration

Background: Cardiopulmonary bypass (CPB) is associated with neutrophil activation, pulmonary sequestration, and release of inflammatory mediators leading to pulmonary dysfunction. We investigate the effect of continuous ventilation during cardiopulmonary bypass on neutrophil activation and pulmonary sequestration. Methods: Forty-six patients undergoing coronary artery bypass grafting with cardiopulmonary bypass were prospectively randomized to continuous ventilation and nonventilation groups. Blood samples were collected, and bronchoalveolar lavage (BAL) was performed following induction of anesthesia and at 4 hr after aortic declamping. Differential white cell count was measured, and flow cytometry to determine cell count numbers and quantify CD45 and CD11b leukocyte cell surface adhesion molecule expression was performed on the blood and BAL samples. Results: Twenty-three patients were randomized to standard nonventilated CPB and 23 patients to ventilation throughout CPB. Significant increases in blood and BAL neutrophil numbers were detected at 4 hr following aortic declamping in both groups (Blood: NV p <. 0001, V p <. 0001; BAL: NV p =. 017, V p =. 0007). No significant inter-group differences in BAL and blood neutrophil numbers were found. Significantly higher blood neutrophil CD11b mean fluorescent intensity levels were present 4 hr following declamping compared with baseline in both groups (NV Blood, p =. 021; V Blood p <. 0001). No significant inter- or intragroup differences in BAL neutrophil CD11b mean fluorescent intensity levels were found. There was no death or major complication. Conclusions: Cardiopulmonary bypass during coronary artery bypass grafting is associated with increased neutrophil pulmonary sequestration, and blood neutrophil CD11b activation. Continuous ventilation during cardiopulmonary bypass does not significantly reduce neutrophil pulmonary sequestration or activation.

Inhibition of Tumor Necrosis Factor α–Stimulated Monocyte Adhesion to Human Aortic Endothelial Cells by AMP-Activated Protein Kinase

Proatherosclerotic adhesion of leukocytes to the endothelium is attenuated by NO. As AMP-activated protein kinase (AMPK) regulates endothelial NO synthesis, we investigated the modulation of adhesion to cultured human aortic endothelial cells (HAECs) by AMPK. HAECs incubated with the AMPK activator, AICAR, or expressing constitutively active AMPK demonstrated reduced TNFalpha-stimulated adhesion of promonocytic U-937 cells. Rapid inhibition of TNFalpha-stimulated U-937 cell adhesion by AICAR was NO-dependent, associated with unaltered cell surface adhesion molecule expression, and reduced MCP-1 secretion by HAECs. In contrast, inhibition of TNFalpha-stimulated U-937 cell adhesion by prolonged AMPK activation was NO-independent and associated with reduced cell surface adhesion molecule expression. AMPK activation in HAECs inhibits TNFalpha-stimulated leukocyte adhesion by a rapid NO-dependent mechanism associated with reduced MCP-1 secretion and a late NO-independent mechanism whereby adhesion molecule expression, in particular E-selectin, is suppressed.

P264

Renewed interest in post-injury resuscitation with hypertonic saline is due to its immunomodulatory effects. Hypertonicity reduces proinflammatory chemokine production, cell surface adhesion molecule expression, and markers of lung injury. The Tumor Necrosis Factor alpha (TNα) induced Nuclear Factor kappa B (NF-κB) pathway is a primary mediator of these proinflammatory processes. We therefore hypothesized that hypertonicity inhibits TNFα-induced phosphorylation of Inhibitor of kappa B (IκB) and activation of NF-κB.

Murine Lewis Lung Carcinoma-Derived Endothelium Expresses Markers of Endothelial Activation and Requires Tumor-Specific Extracellular Matrix In Vitro

The purpose of the study was to identify characteristics specific to tumor-derived endothelium that may be important in tumor biology, or for the development of targeted therapeutics or imaging agents. Normal C57BI/6 murine heart or lung endothelium, or C57BI/6 murine Lewis lung carcinoma tumor-derived endothelium was isolated from excised tissues using specific antibodies. The endothelium was cultured using either native fibronectin, or the oncofetal form of fibronectin. Cell surface adhesion molecule expression was analyzed by flow cytometry, and the cellular distribution of specific molecules was examined using indirect immunofluorescence staining. Oncofetal fibronectin was critical for maintaining the phenotype of tumor-derived endothelium, which demonstrated an elongated morphology in vitro, with few cell-cell contacts. They expressed high levels of CD31, CD102, and vascular endothelial cadherin, and constitutively expressed CD62E, CD54, and CD106, indicating an “activated” phenotype. Moreover, they expressed significantly greater levels of Sca-1 and Flk-1 than normal murine endothelium. Cellular distribution of CD31, β-catenin, and CD106 in tumor-derived endothelium was not continuous at cell borders, as observed in cultures of murine heart endothelium. In conclusion, Lewis lung carcinoma-derived tumor endothelium exhibits a specific phenotype in vitro, distinct from normal endothelium, and could be used as an in vitro tool for developing targeted agents.

An in vitro model for grafting of hematopoietic stem cells predicts bone marrow reconstitution of myeloablative mice.

Homing and engraftment of hematopoietic stem cells (HSCs) to bone marrow (BM) is a complex process that primarily depends on the cell-surface expression of adhesion molecules on stem and stromal cells. Here we report an in vitro model for homing of stem cells on pre-established stromal layer; the stroma-adhered cells were found to engraft, multiply, and differentiate in BM of age-matched mice. In vitro study revealed that initially the adhesion of BM cells on irradiated stroma was increased with time, and it attained a peak at 2 h of contacts. During that time, 44.1 +/- 6.5% (n = 8) cells were adhered, and this value was maintained up to 6 x 10(6) cells. The adhered cell fraction was enriched by 3.9-, 2.5-, and 1.7-fold Sca-1, colony forming cell (CFC), and cobblestone area forming cells (CAFC), respectively, as compared to the fresh BM cells. These adhered cells homed to BM with an engraftment efficiency of 11.8 +/- 2.5% (n = 6). The homed cells reconstituted BM of myeloablative mice by self-renewing and differentiating into myeloid cells. Overall, a simple in vitro model system has been described to study homing and grafting of HSCs that can be deployed to any possible experimental conditions to investigate the interactions between stromal and stem cells.

Endothelial expression of intercellular adhesion molecule 1 and vascular cell adhesion molecule 1 is suppressed by postbypass plasma containing increased soluble intercellular adhesion molecule 1 and vascular cell adhesion molecule 1

Objective: Endothelial cell dysfunction has been implicated in the inflammatory response to cardiopulmonary bypass, and the upregulation of endothelial cell expression of adhesion molecules might promote leukocyte extravasation in vivo. Soluble endothelial cell adhesion molecules are increased after bypass. The aim of this study was to investigate the relationship between endothelial cell-surface expression of adhesion molecules and their concentration in plasma after coronary artery bypass grafting. Methods: Ten patients undergoing coronary artery bypass with cardiopulmonary bypass had 5 plasma samples taken at defined intervals before, during, and after cardiopulmonary bypass. Plasma was incubated with human umbilical vein endothelial cell monolayers, and expression of E-selectin, intercellular adhesion molecule 1, and vascular cell adhesion molecule 1 on the surface of human umbilical vein endothelial cell monolayers was measured by means of enzyme-linked immunosorbent assay. Plasma soluble adhesion molecules, C-reactive protein, interleukin 8, interleukin 10, transforming growth factor β1, and neutrophil counts were determined for each patient. Results: Markers typical of acute inflammation (ie, interleukin 8, neutrophils, and C-reactive protein) were all increased after bypass. Soluble plasma intercellular and vascular cell adhesion molecule 1 (but not E-selectin) were increased after bypass. However, endothelial cell expression of vascular cell adhesion molecule 1 and intercellular adhesion molecule 1 (but not E-selectin) were significantly decreased by exposure to postbypass plasma. Additionally, postbypass plasma inhibited interleukin 1β-stimulated endothelial cell expression of vascular cell and intercellular adhesion molecule 1. Interleukin 10 and transforming growth factor β1, both of which are known to inhibit endothelial cell adhesion molecule expression, were respectively increased 10-fold and 3-fold (P <.05) after bypass. Conclusions: Despite containing increased soluble intercellular and vascular cell adhesion molecule 1, postbypass plasma inhibits endothelial cell expression of intercellular and vascular cell adhesion molecule 1. Upregulated vascular expression of adhesion molecules might not be essential for endothelial activation after bypass.J Thorac Cardiovasc Surg 2002;124:758-67

Tocotrienol is the most effective vitamin E for reducing endothelial expression of adhesion molecules and adhesion to monocytes

α-Tocopherol and its esterified derivatives have been shown to be effective in reducing monocytic-endothelial cell adhesion. However, the effect of α-tocotrienol (α-T3) has not been characterized. In the present study, using human umbilical vein endothelial cells (HUVEC) as the model system, we examined the relative inhibitory effects of α-T3 and other vitamin E derivatives on cell surface adhesion molecule expression under TNF-α stimulation. Using enzyme-linked immunosorbent assay, we demonstrated that α-T3 markedly inhibited the surface expression of vascular cell adhesion molecule-1 in TNF-α activated HUVEC in a dose- and time-dependent manner. The optimal inhibition was observed at 25 μmol/l α-T3 within 24 h (77±5%) without cytotoxicity. In addition, the surface expression of intercellular adhesion molecule-1 and E-selectin were also reduced by 40±7 and 42±5%, respectively. In order to further evaluate the effects of α-T3 on the vascular endothelium, we investigated the ability of monocytes to adhere to endothelial cells. Interestingly, a 63±3% decrease in monocytic cell adherence was observed. Compared to α-tocopherol and α-tocopheryl succinate, α-T3 displayed a more profound inhibitory effect on adhesion molecule expression and monocytic cell adherence. This inhibitory action by α-T3 on TNF-α-induced monocyte adhesion was shown to be NF-κB dependent and was interestingly reversed with co-incubation with farnesol and geranylgeraniol, suggesting a role for prenylated proteins in the regulation of adhesion molecule expression. In summary, the above results suggest that α-T3 is a potent and effective agent in the reduction of cellular adhesion molecule expression and monocytic cell adherence.

Immunopathogenesis of the antiphospholipid antibody syndrome: an update.

The primary antiphospholipid antibody syndrome is characterized clinically by the presence of venous and arterial thrombosis, recurrent fetal loss, and thrombocytopenia. The presence of antiphospholipid antibodies is a central serologic finding in primary antiphospholipid antibody syndrome, and plays a critical role in diagnosis. Contrary to initial reports, it is now widely accepted that these autoantibodies are directed predominantly against two antigens: phospholipid-binding plasma protein beta2-glycoprotein I and prothrombin. The mechanism by which antiphospholipid antibodies cause disease is under vigorous investigation. It is hypothesized that antiphospholipid antibodies induce a procoagulant state by binding to antigens on endothelial cells and trophoblast cell surfaces. Indeed, beta2-glycoprotein I appears to function as a cofactor that facilitates this interaction. The resulting endothelial cell activation is associated with cell-surface expression of adhesion molecules that lead to monocyte adhesion - the first steps in thrombosis. Although the precise mechanism that mediates endothelial cell-platelet interaction have not been fully elucidated, platelet binding to the endothelium appears to be the next phase in thrombosis. Thus, the antiphospholipid antibody may be a triggering or activating factor in placental spiral artery thrombosis and subsequent placental infarction. More recently, a role for annexin V has emerged. Studies suggest that thrombosis in the antiphospholipid syndrome may be due to disruption of the annexin shield by antiphospholipid (and cofactor) antibodies, which results in the increased exposure of trophoblasts and endothelial cells to thrombogenic phospholipids.

NF- κ B Independent Suppression of Endothelial Vascular Cell Adhesion Molecule-1 and Intercellular Adhesion Molecule-1 Gene Expression by Inhibition of Flavin Binding Proteins and Superoxide Production

Oxidation-reduction (redox) coupled mechanisms play an important role in the regulation of cell surface adhesion molecule expression. In endothelial cells membrane-bound NADH/NADPH oxidase is a significant source of intracellular superoxide (O2−) production. We explored the role of flavin containing proteins such as NADH/NADPH oxidase in the induction of vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) gene expression in human aortic endothelial cells (HAECs) and human dermal microvascular endothelial cells (HMECs). Treatment of HAECs by tumor necrosis factor- α (TNF- α, 100 U/ml) for 1 h induced a 31% increase in O2−production within 5 min as determined by lucigenin chemiluminescence analysis of whole cells (n=4, P<0.05). Pretreatment with the NADH/NADPH oxidase inhibitor diphenylene iodonium (DPI, 40μ m) for 1 h inhibited O2−production. DPI also inhibited TNF and LPS-induced VCAM-1 and ICAM-1 cell surface expression and TNF- α, LPS, or IL-1 β induced VCAM-1 and ICAM-1 mRNA accumulation. However, DPI did not inhibit TNF- α -induced activation of nuclear NF- κ B-like binding activity in HAECs and HMECs. Furthermore, DPI did not inhibit TNF- α induced transactivation of NF- κ B-driven VCAM-1 and HIV-LTR promoter gene constructs in transiently transfected HMECs. These data suggest that flavin binding proteins such as NADH/NADPH oxidase can regulate VCAM-1 gene expression independent of NF- κ B. Furthermore, intracellular O2−generation is not necessary for NF- κ B activation or for transactivation of NF-κ B driven promoters.