Expression Of Adhesion Receptors Research Articles

Self-recognition of the endothelium enables regulatory T-cell trafficking and defines the kinetics of immune regulation

Localization of CD4+CD25+Foxp3+ regulatory T (Treg) cells to lymphoid and non-lymphoid tissue is instrumental for the effective control of immune responses. Compared with conventional T cells, Treg cells constitute a minute fraction of the T-cell repertoire. Despite this numeric disadvantage, Tregs efficiently migrate to sites of immune responses reaching an optimal number for the regulation of T effector (Teff) cells. The array and levels of adhesion and chemokine receptor expression by Tregs do not explain their powerful migratory capacity. Here we show that recognition of self-antigens expressed by endothelial cells in target tissue is instrumental for efficient Treg recruitment in vivo. This event relies upon IFN-γ-mediated induction of MHC-class-II molecule expression by the endothelium and requires optimal PI3K p110δ activation by the T-cell receptor. We also show that, once in the tissue, Tregs inhibit Teff recruitment, further enabling a Teff:Treg ratio optimal for regulation.

Human eosinophil adhesion and receptor expression.

Eosinophils migrate from the bone marrow in response to cytokines and chemokines which induce the expression and activation of adhesion receptors. In understanding the recruitment of eosinophils, protocols to identify eosinophil adhesion and receptor expression have been identified. In this summary, the eosinophil peroxidase and fluorescent labeling assays are described as measurements of indirect and direct eosinophil adhesion, respectively. Additional protocols that identify eosinophil receptor expression via immunofluorescent microscopy and flow cytometry are also described.

On-chip phenotypic analysis of inflammatory monocytes in atherogenesis and myocardial infarction

Monocyte recruitment to inflamed arterial endothelium initiates plaque formation and drives progression of atherosclerosis. Three distinct monocyte subsets are detected in circulation (CD14(++)CD16(-), CD14(++)CD16(+), and CD14(+)CD16(++)), and each may play distinct roles during atherogenesis and myocardial infarction. We studied a range of subjects that included otherwise healthy patients with elevated serum triglyceride levels to patients presenting with acute myocardial infarction. Our objective was to correlate an individual's risk with the activation state of each monocyte subset as a function of changes in adhesion receptor expression using flow cytometric quantitation of integrins and l-selectin membrane expression. A microfluidic-based laboratory-on-a-chip was developed to quantify the adhesion efficiency of monocytes sheared in whole blood on vascular cell adhesion molecule-1, while characterizing adhesion receptor expression and topography on captured monocytes. CD14(++)CD16(+) monocytes adhered with sevenfold higher efficiency than other subsets, and in patients with myocardial infarction the capture efficiency of this subset was double that for healthy subjects. In patients with hypertriglyceridemia, this increase in monocyte adhesion was attributable to CD14(++)CD16(+) uptake of triglyceride-rich lipoproteins and subsequent signaling via a Phospholipase C-dependent mechanism to increase CD11c expression, very late antigen-4 function, and integrin coclustering within focal adhesive sites on vascular cell adhesion molecule-1. In summary, we introduce a unique laboratory-on-a-chip method for quantifying the activation state of monocyte subsets. These experiments reveal that CD11c/CD18 is an inducible integrin whose expression correlates with a monocyte inflammatory state in subjects at risk for atherogenesis and in patients with myocardial infarction.

Altered adhesion receptor expression impairs recruitment of aged T cell to the nasal mucosa in response to influenza virus infection. (P5085)

Abstract Influenza viruses cause significant annual illness and death in the elderly with recurrent seasonal epidemics and sporadic devastating pandemics. CD8 T cells are crucial for resolving influenza virus infection, can protect from divergent viruses, and are highly correlated with protection in the elderly. Due to its anatomical location, the nasal-associated lymphoid tissue (NALT) is crucial for the induction of the immune response, yet little is known regarding the requirements for optimal immunity at this mucosal site. We demonstrated that the number of antiviral CD8 T cells in the NALT was reduced in the aged. Phenotypic analyses of nasal T cells revealed that the carbohydrate-dependent rolling receptors L-Selectin, P-Selectin glycoprotein ligand-1, and CD44 were differentially expressed on aged T cells. We addressed the hypothesis that the reprogramming of adhesion receptor expression in the aged functionally impacts the migration of virus-specific CD8 T cells to the infected nasal mucosa. We demonstrated that rolling receptors, especially L-Selectin, were crucial for CD8 T cell recruitment to the NALT. Thus, the differential adhesion receptor expression profile on aged CD8 T cells may provide a mechanism that contributes to defective mucosal immunity in the elderly and our provides crucial information for novel strategies for improved nasal vaccines.

Ultra-violet irradiation and riboflavin treatment blocks capping of cellular adhesion molecules and abrogates immunogenicity of antigen presenting cells (P1388)

Abstract UV light has known immunomodulatory activity and is used in clinical situations such as for psoriasis. Mirasol treatment, a pathogen reduction technology based on ultra-violet light irradiation in the presence of riboflavin (UV+R), suppresses the ability of treated WBCs to stimulate proliferation of allogeneic T cells in vitro. Prior work showed that surface expression of adhesion molecules was down-regulated after UV+R treatment. We now show that, UV+ R treatment also decreased capping of the intercellular adhesion molecules (ICAMs)-1, -2, -3 and lymphocyte function-associated antigen (LFA)-3. UV+R treated U937 antigen presenting cells (APCs) induce decreased cell-cell conjugation with PBMCs 25% (p = 0.003) and show a 66% (p = 0.0005) reduction in stimulating T cell proliferation in a mixed lymphocyte reaction compared to untreated or gamma-irradiated U937 APCs. Additionally, UV+R treated U937 APCs failed to induce expression of the early T cell activation marker CD69 and also have decreased membrane viscosity when compared to untreated APCs. Diminished surface expression and perturbation of adhesion receptors within the U937 APCs plasma membrane down-regulates T cell stimulation and proliferation in vitro by lowering the surface expression of adhesion receptors needed for cell-cell conjugation and by perturbation of the ability to mobilize and aggregate adhesion receptors to form a cap, a critical component needed for T cell activation.

Disruption of dystroglycan–laminin interactions modulates water uptake by astrocytes

Cerebral edema is a serious complication of ischemic brain injury. Cerebral edema includes accumulation of extracellular fluid due to leakage of the brain’s microvessel permeability barrier, and swelling of astrocytes as they absorb water from the extracellular space. Expression of matrix adhesion receptors in brain microvessels decreases in ischemic stroke; this contributes to increased microvessel permeability and detachment of astrocytes from the extracellular matrix (ECM). Since loss of the astrocyte adhesion receptor dystroglycan has been associated with disrupted polarization of ion and water channels, we hypothesized that adhesion of astrocytes to the ECM contributes to regulation of water uptake, and that disruption of matrix adhesion impairs the ability of astrocytes to direct water transport. To test this hypothesis, the capacity of astrocytes to take up water was measured using a fluorescence self-quenching assay under both oxygen/glucose deprivation (OGD) and direct antibody-mediated blockade of α-dystroglycan. Both conditions decreased the rate of water uptake. Moreover, inhibiting proteolytic cleavage of dystroglycan that occurs in OGD abrogated the effect of OGD, but not direct blockade of α-dystroglycan, indicating that interfering with dystroglycan-matrix binding itself affects water uptake. Activation of extracellular signal-related kinase (ERK) by OGD was dependent on α-dystroglycan binding, and inhibition of ERK activity with U0126 abrogated the loss of water uptake following OGD. These studies demonstrate for the first time that water uptake in astrocytes is regulated by dystroglycan-dependent signaling associated with matrix adhesion. This presents a novel potential approach to the treatment of cerebral edema.

Integrin alpha2 beta1 modulates MMP-1expression in Tuberculosis

Event Abstract Back to Event Integrin alpha2 beta1 modulates MMP-1expression in Tuberculosis Sara Brilha1*, Joanna C. Porter2, Heather I. Zecchini3 and Jon S. Friedland1 1 Imperial College London, Department of Infectious Diseases and Immunity, United Kingdom 2 University College London, Centre for Inflammation and Tissue Repair, United Kingdom 3 Cancer Research UK Cambridge Research Institute, Light Microscopy Facility, United Kingdom In tuberculosis (TB) Matrix Metalloproteinase-1 (MMP-1), a collagenase, has a major role in tissue destruction and cavitation (1). MMP-1 secretion is amplified by networks such as those between monocytes and respiratory epithelial cells (2). Cell adhesion to the extracellular matrix is mediated by integrins, which can coordinate rapid responses to airway injuries (3). We hypothesised that adhesion to collagen I modulates MMP-1 secretion in primary Human Bronchial Epithelial cells (NHBEs) in TB. NHBEs were stimulated with conditioned medium from Mtb-infected monocytes (CoMtb) or control medium, in the presence or absence of coated or free human collagen I. Integrin engagement was studied by neutralising anti-integrin alpha2 and alpha3 antibodies (mAbs), confocal microscopy and laser scanning cytometry. MMP-1 gene expression and secretion was measured by ELISA, Luminex, real-time PCR and functional DQ collagenase assay. CoMtb stimulated NHBEs, adherent to 100μg/ml coated collagen decreased MMP-1 secretion from 1647±65pg/mL to 1127±91pg/mL (32%). In contrast, free collagen upregulated MMP-1 by 23%. Gene expression data was consistent with secretion. Collagenolytic activity was 3-fold higher in absence of collagen than with coated collagen and 5-fold higher in the presence free collagen (p<0.05). MMP-1 suppression with coated collagen was abolished by 2mM EDTA (p>0.05). Adhesion to coated anti-alpha2 mAbs reduced MMP-1 secretion by 30% (p<0.01). Confocal microscopy showed integrin alpha2 beta1 polarization on coated collagen while free collagen I caused integrin alpha2 beta1 microclustering. In summary, MMP-1 activity, gene expression and secretion is regulated by collagen-cell interactions and integrins are potentially crucial in the control of inflammatory tissue destruction in TB. References 1- Elkington, P., T. Shiomi, R. Breen, R. K. Nuttall, C. A. Ugarte-Gil, N. F. Walker, L. Saraiva, B. Pedersen, F. Mauri, M. Lipman, D. R. Edwards, B. D. Robertson, J. D'Armiento, and J. S. Friedland. 2011. MMP-1 drives immunopathology in human tuberculosis and transgenic mice. J Clin Invest 121:1827-1833. 2-Elkington, P. T., J. E. Emerson, L. D. Lopez-Pascua, C. M. O'Kane, D. E. Horncastle, J. J. Boyle, and J. S. Friedland. 2005. Mycobacterium tuberculosis up-regulates matrix metalloproteinase-1 secretion from human airway epithelial cells via a p38 MAPK switch. J Immunol 175:5333-5340. 3-Pilewski, J. M., J. D. Latoche, S. M. Arcasoy, and S. M. Albelda. 1997. Expression of integrin cell adhesion receptors during human airway epithelial repair in vivo. Am J Physiol 273:L256-263. Keywords: Matrix Metalloproteinases, Epithelial Cells, Extracellular Matrix, Integrins, Tuberculosis Conference: 15th International Congress of Immunology (ICI), Milan, Italy, 22 Aug - 27 Aug, 2013. Presentation Type: Abstract Topic: Host-pathogen interactions Citation: Brilha S, Porter JC, Zecchini HI and Friedland JS (2013). Integrin alpha2 beta1 modulates MMP-1expression in Tuberculosis. Front. Immunol. Conference Abstract: 15th International Congress of Immunology (ICI). doi: 10.3389/conf.fimmu.2013.02.00105 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 10 Mar 2013; Published Online: 22 Aug 2013. * Correspondence: Miss. Sara Brilha, Imperial College London, Department of Infectious Diseases and Immunity, London, United Kingdom, s.brilha110@imperial.ac.uk Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Sara Brilha Joanna C Porter Heather I Zecchini Jon S Friedland Google Sara Brilha Joanna C Porter Heather I Zecchini Jon S Friedland Google Scholar Sara Brilha Joanna C Porter Heather I Zecchini Jon S Friedland PubMed Sara Brilha Joanna C Porter Heather I Zecchini Jon S Friedland Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

MiR-223 is dispensable for platelet production and function in mice

MicroRNAs (miRNAs) are key physiological regulators in multiple cell types. Here, we assessed platelet production and function in mice deficient in miR-223, one of the most abundantly expressed miRNAs in platelets and megakaryocytes. We found platelet number, size, life-span as well as surface expression of platelet adhesion receptors to be unchanged in miR-223-deficient mice. Likewise, loss of miR-223 did not affect platelet activation, adhesion and aggregation and also had no effect on bleeding times. Moreover, miR-223 null megakaryocytes developed normally and were capable to form pro-platelets. However, we detected a transient delay in the recovery of platelet numbers following antibody-induced platelet depletion in miR-223-deficient animals. This delay was not observed after transplantation of bone marrow from miR-223-deficient animals into wild-type recipients, indicating a non-cell-autonomous role of miR-223 for thrombopoiesis. Overall, our data indicate a surprisingly modest role of miR-223 in platelet production, while the function of platelets does not seem to depend on miR-223.

Burn-injury affects gut-associated lymphoid tissues derived CD4+ T cells

After scald burn-injury, the intestinal immune system responds to maintain immune balance. In this regard CD4+T cells in Gut-Associated Lymphoid Tissues (GALT), like mesenteric lymph nodes (MLN) and Peyer's patches (PP) respond to avoid immune suppression following major injury such as burn. Therefore, we hypothesized that the gut CD4+T cells become dysfunctional and turn the immune homeostasis towards depression of CD4+ T cell-mediated adaptive immune responses. In the current study we show down regulation of mucosal CD4+ T cell proliferation, IL-2 production and cell surface marker expression of mucosal CD4+ T cells moving towards suppressive-type. Acute burn-injury lead to up-regulation of regulatory marker (CD25+), down regulation of adhesion (CD62L, CD11a) and homing receptor (CD49d) expression, and up-regulation of negative co-stimulatory (CTLA-4) molecule. Moreover, CD4+CD25+ T cells of intestinal origin showed resistance to spontaneous as well as induced apoptosis that may contribute to suppression of effector CD4+ T cells. Furthermore, gut CD4+CD25+ T cells obtained from burn-injured animals were able to down-regulate naïve CD4+ T cell proliferation following adoptive transfer of burn-injured CD4+CD25+ T cells into sham control animals, without any significant effect on cell surface activation markers. Together, these data demonstrate that the intestinal CD4+ T cells evolve a strategy to promote suppressive CD4+ T cell effector responses, as evidenced by enhanced CD4+CD25+ T cells, up-regulated CTLA-4 expression, reduced IL-2 production, tendency towards diminished apoptosis of suppressive CD4+ T cells, and thus lose their natural ability to regulate immune homeostasis following acute burn-injury and prevent immune paralysis.

The Nitrone S-PBN Reduces Human Monocyte and Lymphocyte Adhesion on Porcine Endothelial Cells

Introduction: In solid organ xenotransplantation the first interactions between the recipient immune system and the graft occur at the endothelium. Reactive oxygen species activate the endothelium, leading to modulation of endothelial phenotype and permeability. This process may be inhibited by free radical scavengers, such as the low toxic nitrone S-PBN (2-sulfophenyl-N-tertbutyl-nitrone). We previously showed that S-PBN significantly prolongs 15-deoxyspergualin-induced survival of mouse heart xenografts in rats. To study the mechanism by which S-PBN interferes with the early recipient immune responses to a graft, we established an in vitro model to study the influence of S-PBN on human peripheral blood mononuclear cell (PBMC) activation and adhesion on porcine endothelial cells (pEC). Methods: Human PBMC or pEC derived from Gala1,3Gal-KO minipigs were preincubated with S-PBN and cocultured in adhesion assays under shear stress for 20 min. Adhesion of T, B, and NK cells and monocytes was quantified by cell counting and staining for cell-lineage markers of adherent PBMC by flow cytometry. Cells were analyzed for the expression of adhesion and activation markers after S-PBN preincubation and after the adhesion assay. Influence of S-PBN on chemotactic activity in PBMC induced by pEC-derived soluble factors was analyzed in chemotaxis assays. Toxic effects of S-PBN on pEC and PBMC were analyzed by ECIS, microscopy, and propidium iodide staining. Results: Preincubation of human PBMC, but not pEC, with S-PBN decreased the PBMC adhesion in a dose-response dependent manner. Significant reduction of monocyte and T-cell adhesion was induced by 0.2 mM S-PBN or more and of NK and B cells at 1 mM S-PBN or more. The most pronounced inhibition of adhesion was detected in the monocyte population, reaching 30%, 44%, and 60% with 0.2, 1, and 5 mM S-PBN, respectively. S-PBN treatment induced a significant downregulation of the adhesion receptor L-selectin (CD62L) on PBMC but had no significant effect on the adhesion receptor expression on pEC. Further, induction of chemotactic activity in PBMC by pEC-derived soluble factors was reduced by S-PBN. No toxic effect of S-PBN on PBMC or pEC was detected at concentrations up to 25 mM, whereas 125 mM S-PBN was toxic for pEC. Conclusion: Non-toxic doses of S-PBN significantly reduce the adhesion of human PBMC on pEC, with the most pronounced effect on the monocyte subpopulation. The reduction may in part be due to a decreased adhesion receptor expression and inhibition of activation in PBMC. Thus, S-PBN may inhibit xenograft infiltration by attenuating human leukocyte interactions with the porcine endothelium.

Erythrocytes Induce Proinflammatory Endothelial Activation in Hypoxia

Although exposure to ambient hypoxia is known to cause proinflammatory vascular responses, the mechanisms initiating these responses are not understood. We tested the hypothesis that in systemic hypoxia, erythrocyte-derived H(2)O(2) induces proinflammatory gene transcription in vascular endothelium. We exposed mice or isolated, perfused murine lungs to 4 hours of hypoxia (8% O(2)). Leukocyte counts increased in the bronchoalveolar lavage. The expression of leukocyte adhesion receptors, reactive oxygen species, and protein tyrosine phosphorylation increased in freshly recovered lung endothelial cells (FLECs). These effects were inhibited by extracellular catalase and by the removal of erythrocytes, indicating that the responses were attributable to erythrocyte-derived H(2)O(2). Concomitant nuclear translocation of the p65 subunit of NF-κB and hypoxia-inducible factor-1α stabilization in FLECs occurred only in the presence of erythrocytes. Hemoglobin binding to the erythrocyte membrane protein, band 3, induced the release of H(2)O(2) from erythrocytes and the p65 translocation in FLECs. These data indicate for the first time, to our knowledge, that erythrocytes are responsible for endothelial transcriptional responses in hypoxia.

Novel Antiplatelet Activity of Protocatechuic Acid through the Inhibition of High Shear Stress-Induced Platelet Aggregation

Bleeding is the most common and serious adverse effect of currently available antiplatelet drugs. Many efforts are being made to develop novel antithrombotic agents without bleeding risks. Shear stress-induced platelet aggregation (SIPA), which occurs under abnormally high shear stress, plays a crucial role in the development of arterial thrombotic diseases. Here, we demonstrate that protocatechuic acid (PCA), a bioactive phytochemical from Lonicera (honeysuckle) flowers, selectively and potently inhibits high shear (>10,000 s(-1))-induced platelet aggregation. In isolated human platelets, PCA decreased SIPA and attenuated accompanying platelet activation, including intracellular calcium mobilization, granule secretion, and adhesion receptor expression. The anti-SIPA effect of PCA was mediated through blockade of von Willebrand factor binding to activated glycoprotein Ib, a primary and initial event for the accomplishment of SIPA. Conspicuously, PCA did not inhibit platelet aggregation induced by other endogenous agonists like collagen, thrombin, or ADP that are important in both pathological thrombosis and normal hemostasis. Antithrombotic effects of PCA were confirmed in vivo in a rat arterial thrombosis model, where PCA significantly delayed the arterial occlusion induced by FeCl(3). Of particular note, PCA did not increase bleeding times in a rat tail transection model, whereas conventional antiplatelet drugs, aspirin, and clopidogrel substantially prolonged it. Collectively, these results suggest that PCA may be a novel antiplatelet agent that can prevent thrombosis without increasing bleeding risks.

Soluble Human IL-1 Receptor Type 2 Inhibits Ectopic Endometrial Tissue Implantation and Growth: Identification of a Novel Potential Target for Endometriosis Treatment

Endometriosis is often associated with a chronic pelvic immuno-inflammatory process, which is closely related to disease pathogenesis and major symptoms. Our studies led to the detection of a marked imbalance between IL-1 and its natural inhibitor IL-1 receptor type 2 (IL1R2) in women with endometriosis. This points to a deficiency in the local control of IL-1 that, in view of the cytokine's elevated levels and potent proinflammatory, angiogenic, and growth-promoting effects, may contribute to endometriosis development. Using an in vivo model in which human endometrial tissue was inoculated into nude mice and left to establish before any further treatment, our data showed that sIL1R2 interferes with the capability of endometrial tissue to invade, grow, disseminate, and stimulate angiogenesis into the host tissue. sIL1R2 significantly down-regulated the expression of major cell adhesion receptors (αv and β3 integrins), matrix metalloproteinases (MMP-2 and -9), and vascular endothelial cell growth factor. Interestingly, treatment with sILR2 (5 μg/kg) led to a concomitant upregulation of matrix metalloproteinases natural inhibitors (TIMP1 and TIMP2) and down-regulation of BclII, a potent anti-apoptotic protein. This creates an imbalance between pro- and anti-proteolytic and apoptotic factors and may further contribute to IL1R2 growth-inhibitory effects. This study provides evidence that sIL1R2 alters ectopic endometrial tissue growth, remodeling, and survival in vivo and may represent an interesting potential therapeutic tool.

The platelet activating factor receptor: a new anti-infective target in respiratory disease?

There is increasing evidence that vulnerability to pneumococcal pneumonia is mediated by the expression of adhesion receptors for bacteria on lower airway cells. A key bacterial adhesion receptor is the...

New insights into the mechanisms of venous thrombosis

Venous thrombosis is a leading cause of morbidity and mortality in industrialized countries, especially in the elderly. Many risk factors have been identified for venous thrombosis that alter blood flow, activate the endothelium, and increase blood coagulation. However, the precise mechanisms that trigger clotting in large veins have not been fully elucidated. The most common site for initiation of the thrombus appears to be the valve pocket sinus, due to its tendency to become hypoxic. Activation of endothelial cells by hypoxia or possibly inflammatory stimuli would lead to surface expression of adhesion receptors that facilitate the binding of circulating leukocytes and microvesicles. Subsequent activation of the leukocytes induces expression of the potent procoagulant protein tissue factor that triggers thrombosis. Understanding the mechanisms of venous thrombosis may lead to the development of new treatments.

Favourable outcome in Sickle cell stroke with use of nitric oxide

Introduction Stroke in Sickle cell Disease (SCD) is common, frequently recurrent, peaks in late childhood and can cause profound neurological deficits. The mechanism is thought to involve abnormal adherence of sickled cells to the vascular endothelium and as a result of haemolysis stimulating endothelial cell activation, hypercoaguability and alterations in vasomotor tone. Nitric Oxide is a free radical and potent vasodilator which can decrease platelet activation, adhesion receptor expression on the vascular endothelium and vascular smooth muscle proliferation, affecting ischemia-reperfusion injury, modulating endothelial proliferation, and regulating inflammation. Case History We present a 12 year old girl with SS disease on a transfusion programme (Hbs Conclusion This case report presents additional anecdotal evidence that NO therapy has a potential role in management of SS related stroke and justifies additional trials to evaluate its potential role Discussion Inhaled nitric oxide could be beneficial in treatment of stroke in sickle cell disease, by increasing nitric oxide bioavailability, improving blood flow and oxygenation by preventing erythrocyte, platelet, and leukocyte adhesion to the vascular endothelium. Our case demonstrated a dramatic clinical and radiological recovery following the nitric oxide administration and therefore more studies are needed to research its usefulness in comparison with conventional management like exchange transfusion. Abbreviations SS: Sickle cell anaemia; EDAS: Encephalo-duro-arterio-synangiosis

Abstract 3353: Nodal signaling mediates the aggressive, tumorigenic phenotype in breast cancer cells

Abstract The embryonic morphogen Nodal is a potent inducer of EMT and critical mediator of stem cell pluripotency in the developing embryo, but is not expressed in normal adult tissues. Intriguingly, our lab has recently shown that Nodal, a TGF-beta family member, is in fact secreted by melanoma and breast cancer cells and that Nodal expression positively correlates with tumor grade in human patient samples. Our current studies demonstrate a positive role for Nodal in regulating breast cancer cell renewal and aggressiveness. Specifically, short hairpin (shRNA) knockdown of Nodal expression in human breast cancer cell lines diminishes proliferation, invasion and clonogenicity of these cell lines in vitro and dramatically curtails tumor formation in a mouse xenograft model. Additionally, our data suggest that these effects may be caused, in part, by alterations in the expression of adhesion receptors known to function in tumor engraftment and metastasis. Taken together, our data suggest that Nodal signaling may facilitate the acquisition of self-renewal and migratory capabilities in breast cancer cells and represent a novel therapeutic target for disrupting these processes in breast cancer cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3353. doi:1538-7445.AM2012-3353

Engineered cell homing

AbstractOne of the greatest challenges in cell therapy is to minimally invasively deliver a large quantity of viable cells to a tissue of interest with high engraftment efficiency. Low and inefficient homing of systemically delivered mesenchymal stem cells (MSCs), for example, is thought to be a major limitation of existing MSC-based therapeutic approaches, caused predominantly by inadequate expression of cell surface adhesion receptors. Using a platform approach that preserves the MSC phenotype and does not require genetic manipulation, we modified the surface of MSCs with a nanometer-scale polymer construct containing sialyl Lewisx (sLex) that is found on the surface of leukocytes and mediates cell rolling within inflamed tissue. The sLex engineered MSCs exhibited a robust rolling response on inflamed endothelium in vivo and homed to inflamed tissue with higher efficiency compared with native MSCs. The modular approach described herein offers a simple method to potentially target any cell type to specific tissues via the circulation.

Amplification of P. falciparum Cytoadherence through Induction of a Pro-Adhesive State in Host Endothelium

This study examined the ability of P.falciparum-infected erythrocytes (IE) to induce a pro-adhesive environment in the host endothelium during malaria infection, prior to the systemic cytokine activation seen in the later phase of disease. Previous work had shown increases in receptor levels but had not measured to actual impact on IE binding. Using a co-culture system with a range of endothelial cells (EC) and IE with different cytoadherent properties, we have characterised the specific expression of adhesion receptors and subsequent IE binding by FACS and adhesion assays. We have also examined the specific signalling pathways induced during co-culture that are potentially involved in the induction of receptor expression. The results confirmed that ICAM-1 is up-regulated, albeit at much lower levels than seen with TNF activation, in response to co-culture with infected erythrocytes in all three tissue endothelial cell types tested but that up-regulation of VCAM-1 is tissue-dependent. This small increase in the levels of EC receptors correlated with large changes in IE adhesion ability. Co-culture with either RBC or IE increased the potential of subsequent adhesion indicating priming/modulation effects on EC which make them more susceptible to adhesion and thereby the recruitment of IE. Trypsin surface digestion of IE and the use of a Pfsbp1-knockout (ko) parasite line abrogated the up-regulation of ICAM-1 and reduced IE binding to EC suggesting that PfEMP-1 and other molecules exported to the IE surface via the PfSBP1 pathway are major mediators of this phenotype. This was also supported by the higher induction of EC adhesion receptors by adherent IE compared to isogenic, non-adherent lines.

Antioxidant properties of pioglitazone limit nicotinamide adenine dinucleotide phosphate hydrogen oxidase and augment superoxide dismutase activity in cardiac allotransplantation

Many non-immunologic factors contribute to the development of cardiac allograft vasculopathy (CAV), chief among them being ischemia-reperfusion injury associated with oxidative stress. We hypothesized that pioglitazone, a peroxisome proliferator-activated receptor (PPAR)-γ agonist, could attenuate graft oxidant stress in cardiac transplantation. Experiments were performed using a murine heterotopic cardiac allotransplantation model. Pioglitazone was administered to recipients once daily, beginning 1 day before transplantation. At 4 hours after transplantation, pioglitazone significantly reduced the expression of endothelial cell adhesion receptors and infiltration of polymorphonuclear leukocytes (PMNs). The anti-oxidant balance in pioglitazone-treated cardiac allografts was significantly bolstered by reduced nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) oxidase (Nox1 and p22(phox) sub-units) activity and preservation of manganese superoxide dismutase (SOD) activity, resulting in the mitigation of oxidative damage at the level of lipids, proteins, and DNA. At 7 days after transplantation, PPAR-γ was significantly up-regulated by pioglitazone, but nuclear factor-κB and inducible nitric oxide synthase were significantly down-regulated. A concomitant reduction of inflammatory cytokines and chemokines and graft leukosequestration was noted. Pioglitazone consequently prolonged cardiac allograft survival and attenuated CAV development. In vitro experiments demonstrated that pioglitazone decreased transendothelial PMN migration, NADPH oxidase activity, and loss of SOD activity in PMNs and endothelial cells. Pioglitazone can suppress the oxidative stress and damage and can stimulate antioxidant capacity in cardiac allografts after transplantation. Mitigation of graft oxidant stress could be an important mechanism through which pioglitazone confers benefit after cardiac transplantation.