PSGL‐1 and E/P‐selectins are essential for T‐cell rolling in inflamed CNS microvessels but dispensable for initiation of EAE

Abstract

T-cell migration across the blood-brain barrier is a crucial step in the pathogenesis of EAE, an animal model for MS. Live cell imaging studies demonstrated that P-selectin glycoprotein ligand-1 (PSGL-1) and its endothelial ligands E-and P-selectin mediate the initial rolling of T cells in brain vessels during EAE. As functional absence of PSGL-1 or E/P-selectins does not result in ameliorated EAE, we speculated that T-cell entry into the spinal cord is independent of PSGL-1 and E/P-selectin. Performing intravital microscopy, we observed the interaction of WT or PSGL-1 −/− proteolipid protein-specific T cells in inflamed spinal cord microvessels of WT or E/P-selectin −/− SJL/J mice during EAE. T-cell rolling but not T-cell capture was completely abrogated in the absence of either PSGL-1 or E-and P-selectin, resulting in a significantly reduced number of T cells able to firmly adhere in the inflamed spinal cord microvessels, but did not lead to reduced T-cell invasion into the CNS parenchyma. Thus, PSGL-1 interaction with E/P-selectin is essential for T-cell rolling in inflamed spinal cord microvessels during EAE. Taken together with previous observations, our findings show that T-cell rolling is not required for successful T-cell entry into the CNS and initiation of EAE.Keywords: Blood-brain barrier r Experimental autoimmune encephalomyelitis r P-selectin r P-selectin glycoprotein ligand-1 r T-cell rolling Additional supporting information may be found in the online version of this article at the publisher's web-site IntroductionIn MS, and in its animal model, EAE, neuro-Ag-specific CD4 + (where CD is cluster of differentiation) T cells breach the bloodbrain barrier (BBB) and gain access to the CNS, where they cause inflammation, demyelination, and BBB breakdown leading to the clinical manifestation of these diseases. T-cell migration across the BBB is a multi-step process mediated by the sequential interaction of different adhesion and/or signaling molecules on the T cells and Correspondence: Prof. Britta Engelhardt e-mail: bengel@tki.unibe.ch the highly specialized endothelium of the BBB [1]. The discovery that α4β1-integrin plays a critical role in T-cell trafficking across the BBB during EAE has led to the development of a humanized monoclonal anti-α4-integrin Ab (natalizumab) for the treatment of MS [2].In vivo live cell imaging studies have provided direct evidence that the multistep extravasation of encephalitogenic T cells across the spinal cord microvasculature during initiation of EAE is unique [3]. Initiation of T-cell interaction with the spinal cord microvascular endothelium takes place in the absence of rolling and is rather mediated by α4-integrin-mediated G-protein-independent capture and subsequent G-protein-dependent arrest of the T cells in spinal cord microvessels [3]. Once neuroinflammation iswww.eji-journal.eu 2288 Karthik Sathiyanadan et al. Eur. J. Immunol. 2014. 44: 2287-2294 ongoing, it is mostly T-cell rolling with a few alternative capture events also detected, which characterize th...

A Novel Cervical Spinal Cord Window Preparation Allows for Two-Photon Imaging of T-Cell Interactions with the Cervical Spinal Cord Microvasculature during Experimental Autoimmune Encephalomyelitis

“…During EAE, BBB leakiness is a pathophysiological hallmark why using soluble plasma tracers might not be feasible. In this case, injection of a fluorescently labeled anti-endothelial antibody, e.g., anti-endoglin antibody as outlined above (step 20.2 of the procedures) that does not interfere with T-cell interaction with the BBB is the method of choice (8, 9). …”

“…One of these studies demonstrated that once neuroinflammation is established, T-cell interaction with the cervical spinal cord microvasculature is initiated by rolling. Interaction of PSGL-1 and its endothelial ligands E- and P-selectin was found to be essential for T-cell rolling in this vascular bed (9). In addition, this methodology has allowed to demonstrate that natalizumab, which is a humanized anti-α4 integrin antibody used for the treatment of relapsing-remitting MS, inhibits the firm adhesion but not the initial rolling or capture of human T cells within inflamed spinal cord microvessels during EAE in mice (10).…”

“…Real-time epifluorescence IVM is the preferred methodology to study rapid T-cell interactions with the vascular wall like T-cell rolling, which occurs at an average speed of 5–6 µm/s in superficial brain microvessels (4) and at about 18 µm/s in cervical spinal cord microvessels (9). Slower T-cell interactions with the BBB, e.g., post-arrest intravascular T-cell crawling at reported speeds of 5–15 μm/min or T-cell diapedesis across the BBB, which was reported to occur at minutes to hours after T-cell arrest (8, 11, 12) cannot be imaged by real-time epifluorescence IVM due to phototoxic effects.…”

Vascular, glial, and lymphatic immune gateways of the central nervous system

“…Live cell-imaging studies have shown that the extravasation of circulating T cells across the inflamed BBB (activated by pro-inflammatory cytokines with high expression of ICAM-1, VCAM-1, and de-novo expression of P-selectin and other adhesion molecules) is mediated by a multi-step cascade starting with P-selectin glycoprotein-1 (PSGL-1)-mediated T cell rolling on endothelial P-selectin [116] (Fig. 6).…”

Ly6Chigh Monocytes Control Cerebral Toxoplasmosis

“…The dependence on PSGL-1 for lymphocyte migration is well established (56,57,(79)(80)(81)(82). However, to date, the function of PSGL-1 in monocyte recruitment has not been sufficiently addressed.…”