E- and P-Selectin Are Not Required for the Development of Experimental Autoimmune Encephalomyelitis in C57BL/6 and SJL Mice 1 Axinia Do ¨ring,* Martin Wild, † Dietmar Vestweber, † Urban Deutsch,* and Britta Engelhardt 2 * In multiple sclerosis and in its animal model experimental autoimmune encephalomyelitis (EAE), inflammatory cells migrate across the endothelial blood-brain barrier (BBB) and gain access to the CNS. It is well-established that  4 integrins are actively involved in leukocyte recruitment across the BBB during EAE. In contrast, the role of endothelial E- and P-selectin in this process has been a controversial issue. In this study, we demonstrate that P-selectin protein can be detected in meningeal blood vessel endothelial cells in healthy SJL and C57BL/6 mice and on rare parenchymal CNS blood vessels in C57BL/6, but not SJL, mice. During EAE, expression of P-selectin but not E-selectin was found up-regulated on inflamed CNS microvessels surrounded by inflammatory infiltrates irrespective of their meningeal or parenchymal localization with a more prominent immunostaining detected in C57BL/6 as compared with SJL mice. P-selectin immunostaining could be localized to CNS endothelial cells and to CD41-positive platelets adhering to the vessel wall. Despite the presence of P-selectin in wild-type mice, E/P-selectin-deficient SJL and C57BL/6 mice developed clinical EAE indistinguishable from wild-type mice. Absence of E- and P-selectin did neither influence the activation of myelin-specific T cells nor the composition of the cellular infiltrates in the CNS during EAE. Finally, endothelial-specific tetracycline-inducible expression of E-selectin at the BBB in transgenic C57BL/6 mice did not alter the de- velopment of EAE. Thus, E- and P-selectin are not required for leukocyte recruitment across the BBB and the development of EAE in C57BL/6 and in SJL mice. The Journal of Immunology, 2007, 179: 8470 – 8479. I n multiple sclerosis (MS), 3 and in its animal model, experi- mental autoimmune encephalomyelitis (EAE), circulating immune cells gain access to the CNS and cause inflamma- tion, blood-brain barrier (BBB) breakdown, and demyelination, which all set the stage for the development of the clinical mani- festations of this disabling disease. EAE is a T cell-mediated au- toimmune disease, which can be induced either by immunization with myelin Ags or by the transfer of encephalitogenic T cells in susceptible rodent strains including mice. In the SJL mouse, EAE can be transferred by proteolipid protein (PLP)-specific CD4 + T cells, and in the C57BL/6 mouse by myelin oligodendrocyte glycoprotein (MOG)-specific CD4 + T cells into naive syngeneic recipients, respectively. Interaction of circulating immunocompe- tent cells with the BBB endothelium is thus a critical step in the pathogenesis of CNS inflammation. The recruitment of specific leukocyte subsets from the blood- stream into distinct tissues is mediated by the sequential interac- tion of different adhesion and signaling molecules on leukocytes and the endothelial cells lining the vessel wall (reviewed by Ref. 1). The multistep interaction starts with an initial transient contact of the circulating leukocyte with the vascular endothelium, medi- ated by adhesion molecules of the selectin family and their respec- tive carbohydrate ligands, or by  4 integrins. After the initial tether, the leukocyte rolls along the vascular wall with greatly re- duced velocity. The rolling leukocyte can then bind chemotactic factors from the family of chemokines presented on the endothelial surface. Chemokines bind to serpentine receptors on the leukocyte surface delivering a G protein-mediated inside-out signal to inte- grins present on the leukocyte surface, thereby enhancing their avidity. Only integrins with increased avidity are able to mediate the firm adhesion of the leukocytes to the vascular endothelium by binding to their endothelial ligands of the Ig superfamily. This ultimately leads to diapedesis of the leukocyte. We and others have demonstrated that T cell recruitment across the BBB during EAE is unique due to the predominant involve- ment of  4 integrins. After the seminal study by Yednock et al. (2) demonstrating that Abs blocking  4 integrin inhibit EAE by block- ing T cell interaction with the BBB, numerous following studies confirmed and extended the predominant involvement of  4 inte- grin/VCAM-1 in inflammatory cell recruitment into the CNS in different EAE models in a number of species (3–6). Using intra- vital microscopy, we have demonstrated that the recruitment of encephalitogenic T cell blasts across the spinal cord white matter microvasculature in healthy mice depends on  4 integrin-mediated initial capture and G protein-dependent arrest (7). In inflamed pial venules of mice suffering from EAE,  4 integrins contribute to rolling and mediate G protein-dependent arrest of endogenous leu- kocytes (8, 9) or encephalitogenic T cells (10). Thus,  4 integrins can mediate both the initial low-affinity interaction of circulating leukocytes with the CNS microvasculature and the subsequent G protein-dependent arrest requiring high-affinity binding of  4 in- tegrins. In humans, predominant involvement of  4 integrins in *Theodor Kocher Institute, University of Bern, Bern, Switzerland; and † Max Planck Institute for Molecular Biomedicine, Mu ¨nster, Germany Received for publication June 12, 2007. Accepted for publication October 3, 2007. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. 1 This work was supported by a grant of the Swiss National Foundation (3100A0_118390) to B.E. 2 Address correspondence and reprint requests to Dr. Britta Engelhardt, Theodor Kocher Institute, University of Bern, Freiestrasse 1, CH-3012 Bern, Switzerland. E-mail address: bengel@tki.unibe.ch 3 Abbreviations used in this paper: MS, multiple sclerosis; EAE, experimental auto- immune encephalomyelitis; BBB, blood-brain barrier; PLP, proteolipid protein; MOG, myelin oligodendrocyte glycoprotein; PSGL, P-selectin glycoprotein ligand; p.i., postimmunization; TET, tetracycline; vWF, von Willebrand factor. Copyright © 2007 by The American Association of Immunologists, Inc. 0022-1767/07/$2.00 The Journal of Immunology www.jimmunol.org