- Email: [email protected]
β-catenin signaling reduces vascularization, barrier breakdown and tumor growth in a mouse glioma model
332
Abstracts
SESSION 11 Blood brain -barrier L.11.1 Molecular mechanisms of immune cell migration across the blood–brain barrier Britta Engelhardt Theodor Kocher Institute, University of Bern, CH-3012 Bern, Switzerland E-mail address: [email protected] Central nervous system (CNS) homeostasis is a prerequisite for proper electrical activity of neuronal cells. Therefore the endothelial blood–brain barrier (BBB) and the epithelial blood–cerebrospinal fluid barrier (BCSFB) tightly seal off the CNS from the continuously changing milieu within the blood stream. In spite of these barriers the CNS is, however, subject to immune surveillance and immune mediated diseases. We have shown that in experimental autoimmune encephalomyelitis (EAE) different sets of memory/effector T cells can cross the non-inflamed BBB or BCSFB using specific molecular keys and gain access to the cerebrospinal fluid (CSF) drained ventricular, subarachnoidal and perivascular spaces. When these pioneer T cells encounter their specific antigen on antigen presenting cells strategically localized immediately behind the brain barriers, reactivation of the T cells will trigger a local inflammatory response leading to the stimulation of the BBB. The activated BBB will then provide novel traffic signals allowing for the entry of large numbers of circulating inflammatory cells into the perivascular spaces and finally across the glia limitans into the CNS parenchyma where they cause tissue injury. doi:10.1016/j.vph.2011.08.077
L.11.2 Endothelial Wnt/β-catenin signaling reduces vascularization, barrier breakdown and tumor growth in a mouse glioma model Marco Reisa, Cathrin J. Czupallaa, Nicole Zieglera, Kavi Devraja, Sascha Seidela, Rosario Heckb, Sonja Thoma, Jadranka Macasa, Ernesto Bockampb, Stefanie Dimmelerc, Karl H. Platea, Stefan Liebnera a Institute of Neurology (Edinger-Institute), Johann Wolfgang Goethe-University Frankfurt Medical School, Heinrich-Hoffmann-Straβe 7, 60528 Frankfurt, Germany b Medical Center of the Johannes Gutenberg-University Mainz, III, Division of Experimental and Translational Oncology, Obere Zahlbacher Str. 63, 55131 Mainz, Germany c Institute for Cardiovascular Regeneration, Johann Wolfgang Goethe-University Frankfurt Medical School, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany E-mail address: [email protected] (S. Liebner) Endothelial Wnt/β-catenin signaling is necessary for developmental angiogenesis of the central nervous system and differentiation of the blood–brain barrier (BBB), but it seems to be inoperable in the adult. In particular, its relevance for vascularization and barrier alterations in brain glioma is largely unknown. To investigate the effect of Wnt/β-catenin signaling for brain tumor angiogenesis, we generated mouse GL261 glioma cell lines expressing either Wnt1 or the Wnt signaling inhibitor dickkopf-1 (Dkk1) in a doxycycline-dependent manner. We show that in subcutaneous and intracranial glioma, endothelial β-catenin stabilization by Wnt1 resulted in a more quiescent vessel phenotype and induced the attachment of mural cells. Accordingly, tumor vessels of Wnt1 expressing glioma were less permeable and showed distinct junctional staining of the tight junction marker claudin-3. Conversely, Dkk1 increased vessel density and promoted tumor growth. Wnt1 activated the Dll4/Notch pathway
in tumor endothelia, inhibiting an angiogenic and favoring a quiescent endothelial phenotype. Currently, we investigate in detail the additional, even more complex effects of the Wnt/ β-catenin pathway in endothelial cell biology. In conclusion, physiological levels of Wnt/β-catenin signaling promote angiogenesis, whereas sustained and reinforced signaling leads to inhibition of angiogenesis and vessel stabilization, which might proof to be a valuable therapeutic target for anti-angiogenic cancer therapy. doi:10.1016/j.vph.2011.08.078
L.11.3 Basement membranes of the blood vessel wall and their contribution to structural and functional vascular integrity Lydia Sorokin Physiological Chemistry and Pathobiochemistry; Münster University, Münster, Germany E-mail address: [email protected] Basement membrane (BM) composition varies with both blood vessel and with tissue type. Of all BM components, the laminin family shows the greatest variability and represents the biological active component of BMs, interacting with a wide repertoire of integrin and non-integrin receptors to control functions such as vessel integrity and permeability. I will focus on central nervous system (CNS) microvessels, which have a unique composition of cellular and extracellular matrix layers that collectively constitute the blood–brain barrier. In addition to the endothelial cell monolayer and its underlying BM, cerebral microvessels are ensheathed by astrocyte endfeet and leptomeningeal cells, which contribute to a second BM, the so-called parenchymal BM as it delineates the border to the brain parenchyma. At the level of capillaries these two BMs fuse to form a single structure, which shares characteristics of both endothelial and parenchymal BMs. While considerable information is available on the cellular constitutents of the CNS microvessels and their contribution to the BBB, little is known about the BM layers. Our work has shown that endothelial and parenchymal BMs of CNS vessels are structurally and functionally distinct, and has highlighted their importance in the restricted permeability characteristic of the CNS microvessels. In particular, laminin isoforms are heterogeneously localized along the length of CNS microvessels and play an important role in defining sites of high and low penetrability by infiltrating cells, such as extravasating leukocytes during inflammation.1 Data will be presented on the biochemical differences of BMs of CNS microvessels, and how vascular laminins provide cues that determine mechanisms of leukocyte penetration of CNS postcapillary venules.1 1. Wu, C., F. Ivars, P. Anderson, R. Hallmann, D. Vestweber, P. Nilsson, H. Robenek, K. Tryggvason, J. Song, E. Korpos, K. Loser, S. Beissert, E. Georges-Labouesse, & L.M. Sorokin. 2009. Nat Med. 15, 519–27.
doi:10.1016/j.vph.2011.08.079
O.11.1 Defective vascular integrity upon KRIT1/ICAP-1 complex loss in CCM correlates with aberrant beta 1 integrin-dependent extracellular matrix remodeling Eva Faurobert, Claire Rome, Gwénola Boulday, Justyna Lisowska, Sandra Manet, Marilyne Malbouyres, KeramidasMichelle Kéramidas, Daniel Bouvard, Elisabeth Tournier-Lasserve, Florence Ruggiero, Jean-Luc Coll, Corinne Albiges-Rizo
Abstracts
SESSION 11 Blood brain -barrier L.11.1 Molecular mechanisms of immune cell migration across the blood–brain barrier Britta Engelhardt Theodor Kocher Institute, University of Bern, CH-3012 Bern, Switzerland E-mail address: [email protected] Central nervous system (CNS) homeostasis is a prerequisite for proper electrical activity of neuronal cells. Therefore the endothelial blood–brain barrier (BBB) and the epithelial blood–cerebrospinal fluid barrier (BCSFB) tightly seal off the CNS from the continuously changing milieu within the blood stream. In spite of these barriers the CNS is, however, subject to immune surveillance and immune mediated diseases. We have shown that in experimental autoimmune encephalomyelitis (EAE) different sets of memory/effector T cells can cross the non-inflamed BBB or BCSFB using specific molecular keys and gain access to the cerebrospinal fluid (CSF) drained ventricular, subarachnoidal and perivascular spaces. When these pioneer T cells encounter their specific antigen on antigen presenting cells strategically localized immediately behind the brain barriers, reactivation of the T cells will trigger a local inflammatory response leading to the stimulation of the BBB. The activated BBB will then provide novel traffic signals allowing for the entry of large numbers of circulating inflammatory cells into the perivascular spaces and finally across the glia limitans into the CNS parenchyma where they cause tissue injury. doi:10.1016/j.vph.2011.08.077
L.11.2 Endothelial Wnt/β-catenin signaling reduces vascularization, barrier breakdown and tumor growth in a mouse glioma model Marco Reisa, Cathrin J. Czupallaa, Nicole Zieglera, Kavi Devraja, Sascha Seidela, Rosario Heckb, Sonja Thoma, Jadranka Macasa, Ernesto Bockampb, Stefanie Dimmelerc, Karl H. Platea, Stefan Liebnera a Institute of Neurology (Edinger-Institute), Johann Wolfgang Goethe-University Frankfurt Medical School, Heinrich-Hoffmann-Straβe 7, 60528 Frankfurt, Germany b Medical Center of the Johannes Gutenberg-University Mainz, III, Division of Experimental and Translational Oncology, Obere Zahlbacher Str. 63, 55131 Mainz, Germany c Institute for Cardiovascular Regeneration, Johann Wolfgang Goethe-University Frankfurt Medical School, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany E-mail address: [email protected] (S. Liebner) Endothelial Wnt/β-catenin signaling is necessary for developmental angiogenesis of the central nervous system and differentiation of the blood–brain barrier (BBB), but it seems to be inoperable in the adult. In particular, its relevance for vascularization and barrier alterations in brain glioma is largely unknown. To investigate the effect of Wnt/β-catenin signaling for brain tumor angiogenesis, we generated mouse GL261 glioma cell lines expressing either Wnt1 or the Wnt signaling inhibitor dickkopf-1 (Dkk1) in a doxycycline-dependent manner. We show that in subcutaneous and intracranial glioma, endothelial β-catenin stabilization by Wnt1 resulted in a more quiescent vessel phenotype and induced the attachment of mural cells. Accordingly, tumor vessels of Wnt1 expressing glioma were less permeable and showed distinct junctional staining of the tight junction marker claudin-3. Conversely, Dkk1 increased vessel density and promoted tumor growth. Wnt1 activated the Dll4/Notch pathway
in tumor endothelia, inhibiting an angiogenic and favoring a quiescent endothelial phenotype. Currently, we investigate in detail the additional, even more complex effects of the Wnt/ β-catenin pathway in endothelial cell biology. In conclusion, physiological levels of Wnt/β-catenin signaling promote angiogenesis, whereas sustained and reinforced signaling leads to inhibition of angiogenesis and vessel stabilization, which might proof to be a valuable therapeutic target for anti-angiogenic cancer therapy. doi:10.1016/j.vph.2011.08.078
L.11.3 Basement membranes of the blood vessel wall and their contribution to structural and functional vascular integrity Lydia Sorokin Physiological Chemistry and Pathobiochemistry; Münster University, Münster, Germany E-mail address: [email protected] Basement membrane (BM) composition varies with both blood vessel and with tissue type. Of all BM components, the laminin family shows the greatest variability and represents the biological active component of BMs, interacting with a wide repertoire of integrin and non-integrin receptors to control functions such as vessel integrity and permeability. I will focus on central nervous system (CNS) microvessels, which have a unique composition of cellular and extracellular matrix layers that collectively constitute the blood–brain barrier. In addition to the endothelial cell monolayer and its underlying BM, cerebral microvessels are ensheathed by astrocyte endfeet and leptomeningeal cells, which contribute to a second BM, the so-called parenchymal BM as it delineates the border to the brain parenchyma. At the level of capillaries these two BMs fuse to form a single structure, which shares characteristics of both endothelial and parenchymal BMs. While considerable information is available on the cellular constitutents of the CNS microvessels and their contribution to the BBB, little is known about the BM layers. Our work has shown that endothelial and parenchymal BMs of CNS vessels are structurally and functionally distinct, and has highlighted their importance in the restricted permeability characteristic of the CNS microvessels. In particular, laminin isoforms are heterogeneously localized along the length of CNS microvessels and play an important role in defining sites of high and low penetrability by infiltrating cells, such as extravasating leukocytes during inflammation.1 Data will be presented on the biochemical differences of BMs of CNS microvessels, and how vascular laminins provide cues that determine mechanisms of leukocyte penetration of CNS postcapillary venules.1 1. Wu, C., F. Ivars, P. Anderson, R. Hallmann, D. Vestweber, P. Nilsson, H. Robenek, K. Tryggvason, J. Song, E. Korpos, K. Loser, S. Beissert, E. Georges-Labouesse, & L.M. Sorokin. 2009. Nat Med. 15, 519–27.
doi:10.1016/j.vph.2011.08.079
O.11.1 Defective vascular integrity upon KRIT1/ICAP-1 complex loss in CCM correlates with aberrant beta 1 integrin-dependent extracellular matrix remodeling Eva Faurobert, Claire Rome, Gwénola Boulday, Justyna Lisowska, Sandra Manet, Marilyne Malbouyres, KeramidasMichelle Kéramidas, Daniel Bouvard, Elisabeth Tournier-Lasserve, Florence Ruggiero, Jean-Luc Coll, Corinne Albiges-Rizo