We gratefully acknowledge Lydia Sorokin, who has shared her original in situ zymography protocol10 with us.&#160;

All studies were conducted under the guidelines according to the Swiss legislation on the protection of animals and were approved by the Veterinary Office of the Canton of Bern, Switzerland (permission numbers: BE 31/17 and BE 77/18).
1. Housing of C57BL/6 mice in specific pathogen free (SPF) conditions
<ol>
	<li>House mice in individual ventilated cages with a 12/12 h light-dark cycle. Provide food and water ad libidum.&#160;To supervise microbiological quality of the mice, the experimental...

<ol>
	<li>Tietz, S., Engelhardt, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Brain+barriers:+Crosstalk+between+complex+tight+junctions+and+adherens+junctions.">Brain barriers: Crosstalk between complex tight junctions and adherens junctions.</a> Journal of Cell Biology. 209, 493-506 (2015).</li><li>Wu, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endothelial+basement+membrane+laminin+alpha5+selectively+inhibits+T+lymphocyte+extravasation+into+the+brain.">Endothelial basement membrane laminin alpha5 selectively inhibits T lymphocyte extravasation into the brain.</a> Nature Medicine. 15, 519-527 (2009).</li><li>Hannocks, M. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+characterization+of+perivascular+drainage+pathways+in+the+murine+brain.">Molecular characterization of perivascular drainage pathways in the murine brain.</a> Journal of Cerebral Blood Flow &amp; Metabolism. 38, 669-686 (2018).</li><li>Kermode, A. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Breakdown+of+the+blood-brain+barrier+precedes+symptoms+and+other+MRI+signs+of+new+lesions+in+multiple+sclerosis.+Pathogenetic+and+clinical+implications.">Breakdown of the blood-brain barrier precedes symptoms and other MRI signs of new lesions in multiple sclerosis. Pathogenetic and clinical implications.</a> Brain. 113 (Pt 5), 1477-1489 (1990).</li><li>Tommasin, S., Gianni, C., De Giglio, L., Pantano, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuroimaging+techniques+to+assess+inflammation+in+Multiple+Sclerosis.">Neuroimaging techniques to assess inflammation in Multiple Sclerosis.</a> Neuroscience. , (2017).</li><li>Lopes Pinheiro, M. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immune+cell+trafficking+across+the+barriers+of+the+central+nervous+system+in+multiple+sclerosis+and+stroke.">Immune cell trafficking across the barriers of the central nervous system in multiple sclerosis and stroke.</a> Biochimica Biophysica Acta. 1862, 461-471 (2016).</li><li>Bartholomaus, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effector+T+cell+interactions+with+meningeal+vascular+structures+in+nascent+autoimmune+CNS+lesions.">Effector T cell interactions with meningeal vascular structures in nascent autoimmune CNS lesions.</a> Nature. 462, 94-98 (2009).</li><li>Kyratsous, N. I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualizing+context-dependent+calcium+signaling+in+encephalitogenic+T+cells+in+vivo+by+two-photon+microscopy.">Visualizing context-dependent calcium signaling in encephalitogenic T cells in vivo by two-photon microscopy.</a> Proceedings of the National Academy of Sciences of the United States of America. 114, E6381-E6389 (2017).</li><li>Lodygin, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+combination+of+fluorescent+NFAT+and+H2B+sensors+uncovers+dynamics+of+T+cell+activation+in+real+time+during+CNS+autoimmunity.">A combination of fluorescent NFAT and H2B sensors uncovers dynamics of T cell activation in real time during CNS autoimmunity.</a> Nature Medicine. 19, 784-790 (2013).</li><li>Agrawal, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dystroglycan+is+selectively+cleaved+at+the+parenchymal+basement+membrane+at+sites+of+leukocyte+extravasation+in+experimental+autoimmune+encephalomyelitis.">Dystroglycan is selectively cleaved at the parenchymal basement membrane at sites of leukocyte extravasation in experimental autoimmune encephalomyelitis.</a> Journal of Experimental Medicine. 203, 1007-1019 (2006).</li><li>Song, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Focal+MMP-2+and+MMP-9+activity+at+the+blood-brain+barrier+promotes+chemokine-induced+leukocyte+migration.">Focal MMP-2 and MMP-9 activity at the blood-brain barrier promotes chemokine-induced leukocyte migration.</a> Cell Reports. 10, 1040-1054 (2015).</li><li>Tietz, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lack+of+junctional+adhesion+molecule+(JAM)-B+ameliorates+experimental+autoimmune+encephalomyelitis.">Lack of junctional adhesion molecule (JAM)-B ameliorates experimental autoimmune encephalomyelitis.</a> Brain, Behavior, and Immunity. 73, 3-20 (2018).</li><li>Mähler Convenor, M., Berard, M., Feinstein, R., Gallagher, A., Illgen-Wilcke, B., Pritchett-Corning, K., Raspa, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=FELASA+recommendations+for+the+health+monitoring+of+mouse,+rat,+hamster,+guinea+pig+and+rabbit+colonies+in+breeding+and+experimental+units.">FELASA recommendations for the health monitoring of mouse, rat, hamster, guinea pig and rabbit colonies in breeding and experimental units.</a> Lab Anim. 48 (3), 178-192 (2014).</li><li>Bittner, S., Afzali, A. M., Wiendl, H., Meuth, S. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myelin+oligodendrocyte+glycoprotein+(MOG35-55)+induced+experimental+autoimmune+encephalomyelitis+(EAE)+in+C57BL/6+mice.">Myelin oligodendrocyte glycoprotein (MOG35-55) induced experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice.</a> Journal of Visual Experiments. , (2014).</li><li>Tietz, S. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Refined+clinical+scoring+in+comparative+EAE+studies+does+not+enhance+the+chance+to+observe+statistically+significant+differences.">Refined clinical scoring in comparative EAE studies does not enhance the chance to observe statistically significant differences.</a> European Journal of Immunology. 46, 2481-2483 (2016).</li><li>Mendel, I., Kerlero de Rosbo, N., Ben-Nun, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+myelin+oligodendrocyte+glycoprotein+peptide+induces+typical+chronic+experimental+autoimmune+encephalomyelitis+in+H-2b+mice:+fine+specificity+and+T+cell+receptor+V+beta+expression+of+encephalitogenic+T+cells.">A myelin oligodendrocyte glycoprotein peptide induces typical chronic experimental autoimmune encephalomyelitis in H-2b mice: fine specificity and T cell receptor V beta expression of encephalitogenic T cells.</a> European Journal of Immunology. 25, 1951-1959 (1995).</li><li>Miller, S. D., Karpus, W. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+autoimmune+encephalomyelitis+in+the+mouse.">Experimental autoimmune encephalomyelitis in the mouse.</a> Current Protocols in Immunology. 15, (2007).</li><li>Sobel, R. A., Tuohy, V. K., Lu, Z. J., Laursen, R. A., Lees, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+experimental+allergic+encephalomyelitis+in+SJL/J+mice+induced+by+a+synthetic+peptide+of+myelin+proteolipid+protein.">Acute experimental allergic encephalomyelitis in SJL/J mice induced by a synthetic peptide of myelin proteolipid protein.</a> Journal of Neuropathology &amp; Experimental Neurology. 49, 468-479 (1990).</li><li>Westarp, M. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=T+lymphocyte+line-mediated+experimental+allergic+encephalomyelitis--a+pharmacologic+model+for+testing+of+immunosuppressive+agents+for+the+treatment+of+autoimmune+central+nervous+system+disease.">T lymphocyte line-mediated experimental allergic encephalomyelitis--a pharmacologic model for testing of immunosuppressive agents for the treatment of autoimmune central nervous system disease.</a> Journal of Pharmacology and Experimental Therapeutics. 242, 614-620 (1987).</li><li>Klotz, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=B7-H1+shapes+T-cell-mediated+brain+endothelial+cell+dysfunction+and+regional+encephalitogenicity+in+spontaneous+CNS+autoimmunity.">B7-H1 shapes T-cell-mediated brain endothelial cell dysfunction and regional encephalitogenicity in spontaneous CNS autoimmunity.</a> Proceedings of the National Academy of Sciences of the United States of America. 113, E6182-E6191 (2016).</li><li>Tietz, S. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MK2+and+Fas+receptor+contribute+to+the+severity+of+CNS+demyelination.">MK2 and Fas receptor contribute to the severity of CNS demyelination.</a> PLoS One. 9, e100363 (2014).</li><li>Coisne, C., Mao, W., Engelhardt, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cutting+edge:+Natalizumab+blocks+adhesion+but+not+initial+contact+of+human+T+cells+to+the+blood-brain+barrier+in+vivo+in+an+animal+model+of+multiple+sclerosis.">Cutting edge: Natalizumab blocks adhesion but not initial contact of human T cells to the blood-brain barrier in vivo in an animal model of multiple sclerosis.</a> Journal of Immunology. 182, 5909-5913 (2009).</li><li>Korner, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Critical+points+of+tumor+necrosis+factor+action+in+central+nervous+system+autoimmune+inflammation+defined+by+gene+targeting.">Critical points of tumor necrosis factor action in central nervous system autoimmune inflammation defined by gene targeting.</a> Journal of Experimental Medicine. 186, 1585-1590 (1997).</li><li>Krueger, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blood-brain+barrier+breakdown+involves+four+distinct+stages+of+vascular+damage+in+various+models+of+experimental+focal+cerebral+ischemia.">Blood-brain barrier breakdown involves four distinct stages of vascular damage in various models of experimental focal cerebral ischemia.</a> Journal of Cerebral Blood Flow &amp; Metabolism. 35, 292-303 (2015).</li><li>Hawkins, B. T., Egleton, R. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescence+imaging+of+blood-brain+barrier+disruption.">Fluorescence imaging of blood-brain barrier disruption.</a> Journal of Neuroscience Methods. 151, 262-267 (2006).</li><li>Graesser, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Altered+vascular+permeability+and+early+onset+of+experimental+autoimmune+encephalomyelitis+in+PECAM-1-deficient+mice.">Altered vascular permeability and early onset of experimental autoimmune encephalomyelitis in PECAM-1-deficient mice.</a> Journal of Clinical Investigation. 109, 383-392 (2002).</li><li>Engelhardt, B., Sorokin, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+blood-brain+and+the+blood-cerebrospinal+fluid+barriers:+function+and+dysfunction.">The blood-brain and the blood-cerebrospinal fluid barriers: function and dysfunction.</a> Seminars in Immunopathology. 31, 497-511 (2009).</li><li>Owens, T., Bechmann, I., Engelhardt, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perivascular+spaces+and+the+two+steps+to+neuroinflammation.">Perivascular spaces and the two steps to neuroinflammation.</a> Journal of Neuropathology &amp; Experimental Neurology. 67, 1113-1121 (2008).</li><li>Sixt, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endothelial+cell+laminin+isoforms,+laminins+8+and+10,+play+decisive+roles+in+T+cell+recruitment+across+the+blood-brain+barrier+in+experimental+autoimmune+encephalomyelitis.">Endothelial cell laminin isoforms, laminins 8 and 10, play decisive roles in T cell recruitment across the blood-brain barrier in experimental autoimmune encephalomyelitis.</a> Journal of Cell Biology. 153, 933-946 (2001).</li><li>Grewal, I. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CD62L+is+required+on+effector+cells+for+local+interactions+in+the+CNS+to+cause+myelin+damage+in+experimental+allergic+encephalomyelitis.">CD62L is required on effector cells for local interactions in the CNS to cause myelin damage in experimental allergic encephalomyelitis.</a> Immunity. 14, 291-302 (2001).</li></ol>

No conflicts of interest declared.

Here, we present a protocol to induce and monitor EAE in female C57BL/6 mice. Females are preferentially chosen, and there is a incidence of women : men of 3:1 in MS. To assess the severity of EAE, we made use of a 3-point scoring sheet. EAE severity is generally scored with respect to the severity of motor dysfunctions. Mice with advanced stages of EAE, i.e. exhibiting a score above 2 should be sacrificed to avoid unnecessary suffering of the animals. Thus, it is recommended to score the mice at close intervals e.g. twi...

The central nervous system (CNS) coordinates all body and mental functions in vertebrates, and CNS homeostasis is essential for a proper communication of neurons. CNS homeostasis is warranted by the neurovascular unit (NVU), which protects the CNS from the changing milieu of the blood stream. The NVU is composed of CNS microvascular endothelial cells, which are biochemically unique and establish the blood-brain barrier (BBB) in continuous crosstalk with pericytes, astrocytes, neurons, and extracellular matrix (ECM) components, establishing two distinct basement membranes1. The endothelial basement membrane that ensheathes the abluminal aspect of the BBB endothelial cells harbors a high number of pericytes and is composed of laminin &#945;4 and laminin &#945;5, in addition to other ECM proteins2. In contrast, the parenchymal basement membrane consists of laminin &#945;1 and laminin &#945;2 and is embraced by astrocytic end-feet. The parenchymal basement membrane together with the astrocyte end-feet composes the glia limitans that segregates the CNS neuronal network from the cerebrospinal fluid filled perivascular or subarachnoid spaces3. Due to the unique architecture of the NVU, immune cell trafficking into the CNS is distinct from that into peripheral tissues as it requires a two-step process with the immune cells, first breaching the endothelial BBB and subsequently the glia limitans in order to reach the CNS parenchyma.&#160;
Multiple sclerosis (MS) is a common neuroinflammatory disease of the CNS, in which a large number of circulating immune cells enter the CNS and cause neuroinflammation, demyelination, and focal loss of BBB integrity4. Loss of BBB integrity is an early hallmark of MS, as indicated by the presence of gadolinium contrast enhancing lesions in the CNS as visualized by magnetic resonance imaging (MRI)5. Leukocyte extravasation into the CNS occurs at the level of postcapillary venules; however, the precise mechanisms involved in immune cell diapedesis across the BBB basement membrane and subsequently the glial barrier remain to be explored. Experimental autoimmune encephalomyelitis (EAE) serves as an animal model for MS and has significantly contributed to our current knowledge about MS pathogenesis. For instance, using the EAE model it has been discovered that leukocyte extravasation occurs in a multistep process, including an initial capture and rolling step mediated by selectins and mucin-like molecules such as P-selectin glycoprotein ligand (PSGL)-1, followed by integrin-dependent firm arrest and crawling of T cells on BBB endothelial cells to permissive sides for diapedesis6.&#160;
Once T cells have crossed the endothelial BBB and the endothelial basement membrane, they need to encounter their cognate antigen on macrophages or dendritic cells strategically localized in the leptomeningeal or perivascular spaces. This interaction induces focal production of pro-inflammatory mediators that trigger the subsequent mechanisms required for CNS tissue invasion of immune cells via the glia limitans7,8,9. Focal activation of matrix-metalloproteinases (MMP) -2 and MMP-9 alters chemokine activation and induces degradation of extracellular matrix receptors on astrocyte end-feet, which is a prerequisite for immune cell migration across the glia limitans into the CNS parenchyma and to induce the onset of clinical symptoms of EAE10,11.&#160;
Combining detection of CNS infiltrating immune cell with BBB leakage and gelatinase activity in CNS tissue sections provides valuable information about the functional integrity of the endothelial and glial barrier in the context of neuroinflammation. For instance, we recently investigated the constitutive loss of the endothelial tight junction molecule junctional adhesion molecule (JAM)-B in immune cell trafficking into the CNS in the context of EAE. Compared to healthy wild-type C57BL/6 mice, healthy JAM-B-deficient littermates showed no impairment of BBB integrity as shown by in vivo permeability assessment using endogenous as well as exogenous tracers12. In the context of EAE, JAM-B-deficient C57BL/6 mice showed ameliorated disease symptoms, which was associated with inflammatory cell trapping in the leptomeningeal and perivascular spaces12. To examine this phenomenon we applied in situ zymography, allowing identification of gelatinase activity in order to test if lack of gelatinase activity in JAM-B-deficient mice may be responsible for the reduced numbers of immune cells able to breach the glia limitans12.&#160;&#160;
Given the availability of different genetically modified mouse models lacking, e.g., different BBB tight junction molecules that might cause changes in BBB function, methodologies for investigating BBB integrity are important. In addition, newly developed drugs could impact on NVU barriers. Here we show how to induce EAE in C57BL/6 mice by active immunization with the myelin oligodendrocyte glycoprotein (MOG)-peptide aa35-55 in complete Freund&#8217;s adjuvants. We then explain how to localize immune cell infiltration across the endothelial and glial barriers of the NVU and how to study in vivo endothelial and glial barrier integrity by in situ detection of exogenous tracers and gelatinase activity, respectively.&#160;&#160;

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr >
			<td >AMCA anti-rabbit antibody</td>
			<td >Jackson ImmunoResearch</td>
			<td >111-156-045</td>
			<td >Store at 4 &#176;C; protect from light</td>
		</tr>
		<tr >
			<td >Anti-CD45 Antibody (30F11)</td>
			<td >Pharmingen</td>
			<td >07-1401</td>
			<td >Store at 4 &#176;C</td>
		</tr>
		<tr >
			<td >Anti-Laminin Antibody</td>
			<td >DAKO</td>
			<td >Z0097</td>
			<td >Store at 4 &#176;C</td>
		</tr>
		<tr >
			<td >Breeding food</td>
			<td >e.g. PROVIMI KLIBA SA</td>
			<td >3336</td>
			<td ></td>
		</tr>
			<tr >
			<td >Individually ventilated cages, Blue line Type II or III</td>
			<td >e.g. Tecniplast	</td>
			<td >1145T, 1285L</td>
			<td ></td>
		</tr>	
		<tr >
			<td >BSA fraction V</td>
			<td >Applichem</td>
			<td >A1391</td>
			<td >Store at 4 &#176;C</td>
		</tr>
		<tr >
			<td >Cold gelatine</td>
			<td >Sigma-Aldrich</td>
			<td >G 9391</td>
			<td ></td>
		</tr>
		<tr >
			<td >Coplin jar + rack</td>
			<td >e.g. Carl Roth GmbH + Co. KG</td>
			<td >H554.1; H552.1</td>
			<td ></td>
		</tr>
		<tr >
			<td >Cy3 anti-rat antibody</td>
			<td >Jackson ImmunoResearch</td>
			<td >111-156-144</td>
			<td >Store at 4 &#176;C; protect from light</td>
		</tr>
		<tr >
			<td >Cover slips 24 x 40 mm # 1</td>
			<td >e.g. Thermo Scientific</td>
			<td >85-0186-00</td>
			<td></td>
		</tr>
		<tr >
			<td >Dextran Alexa Fluor 488 (10,000 MW)</td>
			<td >e.g. Molecular probes</td>
			<td >D22910</td>
			<td >Store at -20 &#176;C; protect from light</td>
		</tr>
		<tr >
			<td >Dextran Texas Red (3000 MW)</td>
			<td >Invitrogen</td>
			<td >D3328</td>
			<td >Store at -20 &#176;C; protect from light</td>
		</tr>
		<tr >
			<td >EnzChek Gelatinase/Collagenase Assay Kit&#160;</td>
			<td >Thermo Fisher Scientific; EnzCheck</td>
			<td >E12055</td>
			<td >Store at -20 &#176;C; protect form light</td>
		</tr>
		<tr >
			<td >Female C57BL/6J mice (8-12 weeks)</td>
			<td >e.g. Janvier Labs</td>
			<td ></td>
			<td >Females, 8-12 weeks</td>
		</tr>
		<tr >
			<td >Freezing box for histology slides</td>
			<td >e.g. Carl Roth GmbH + Co. KG</td>
			<td >2285.1</td>
			<td ></td>
		</tr>
		<tr >
			<td >18G x 1&#189;&#8217;&#8217; (1.2mm x 40mm) injection needle</td>
			<td >e.g. BD, BD Microlance 3</td>
			<td >304622</td>
			<td ></td>
		</tr>
		<tr >
			<td >27G x &#190;&#8217;&#8217; &#8211; Nr. 20 (0.4mm x 19mm) injection needle</td>
			<td >e.g. BD, BD Microlance 3</td>
			<td >302200</td>
			<td ></td>
		</tr>
		<tr >
			<td >30G x &#189;&#8217;&#8217; (0.3 mm x 13 mm) injection needle</td>
			<td >e.g. BD, BD Microlance 3</td>
			<td >304000</td>
			<td ></td>
		</tr>
		<tr >
			<td >Incomplete Freund&#8217;s adjuvant (IFA)</td>
			<td >e.g. Santa Cruz Biotechnology</td>
			<td >sc-24648</td>
			<td >Store at 4&#176;C</td>
		</tr>
		<tr >
			<td >Maintenance food</td>
			<td >e.g. PROVIMI KLIBA SA</td>
			<td >3436</td>
			<td ></td>
		</tr>
		<tr >
			<td >MOGaa35-55 peptide</td>
			<td >e.g. GenScript</td>
			<td ></td>
			<td >Store at -80 &#176;C</td>
		</tr>
		<tr >
			<td >microscope slides (Superfrost Plus )</td>
			<td >Thermo Scientific</td>
			<td >J1800AMNZ</td>
			<td ></td>
		</tr>
		<tr >
			<td >Mycobacterium tuberculosis H37RA</td>
			<td >e.g. BD</td>
			<td >231141</td>
			<td >Store at 4 &#176;C&#160;</td>
		</tr>
		<tr >
			<td >NaCl 0.9 %</td>
			<td >B. Braun</td>
			<td >3535789</td>
			<td ></td>
		</tr>
		<tr >
			<td >O.C.T. compound (Tissue-Tek )</td>
			<td >Sakura</td>
			<td >4583</td>
			<td ></td>
		</tr>
		<tr >
			<td >Omnican 50 30G x &#189;&#8217;&#8217;</td>
			<td >B. Braun</td>
			<td >9151125S</td>
			<td></td>
		</tr>
		<tr >
			<td >Paraformaldehyde</td>
			<td >Merck</td>
			<td >30525-89-4</td>
			<td ></td>
		</tr>
		<tr >
			<td >Pertussis toxin</td>
			<td >e.g. List biological laboratories, Inc.</td>
			<td >180</td>
			<td >Store at 4 &#176;C</td>
		</tr>
		<tr >
			<td >poly(vinyl alcohole) (Mowiol 4-88)</td>
			<td >Sigma-Aldrich</td>
			<td >81381</td>
			<td ></td>
		</tr>
		<tr >
			<td >Protease Inhibitor EDTA free (Roche)</td>
			<td >Sigma-Aldrich</td>
			<td >4693132001</td>
			<td >Store at 4 &#176;C</td>
		</tr>
		<tr >
			<td >repelling pen e.g. DAKO Pen</td>
			<td >e.g. DAKO</td>
			<td >S2002</td>
			<td ></td>
		</tr>
		<tr >
			<td >sealing film e.g. Parafilm M</td>
			<td >e.g Sigma-Aldrich</td>
			<td >P7793</td>
			<td ></td>
		</tr>
		<tr >
			<td >Silica gel</td>
			<td >e.g. Carl Roth GmbH + Co. KG</td>
			<td >9351.1</td>
			<td ></td>
		</tr>
		<tr >
			<td >Stitch scissor</td>
			<td >F.S.T</td>
			<td >15012-12</td>
			<td ></td>
		</tr>
		<tr >
			<td >syringe 1 ml</td>
			<td >e.g. PRIMO</td>
			<td >62.1002</td>
			<td ></td>
		</tr>
		<tr >
			<td >syringe 10 ml</td>
			<td >e.g. CODAN Medical ApS</td>
			<td >2022-05</td>
			<td ></td>
		</tr>
		<tr >
			<td >vaporizer system Univentor 400</td>
			<td >UNO.BV</td>
			<td ></td>
			<td></td>
		</tr>
	</tbody>
</table>

visualizing impairment of the endothelial and glial barriers of the neurovascular unit during experimental autoimmune encephalomyelitis in vivo

The neurovascular unit (NVU) is composed of microvascular endothelial cells forming the blood-brain barrier (BBB), an endothelial basement membrane with embedded pericytes, and the glia limitans composed by the parenchymal basement membrane and astrocytic end-feed embracing the abluminal aspect of central nervous system (CNS) microvessels. In addition to maintaining CNS homeostasis the NVU controls immune cell trafficking into the CNS. During immunosurveillance of the CNS low numbers of activated lymphocytes can cross the endothelial barrier without causing BBB dysfunction or clinical disease. In contrast, during neuroinflammation such as in multiple sclerosis or its animal model experimental autoimmune encephalomyelitis (EAE) a large number of immune cells can cross the BBB and subsequently the glia limitans eventually reaching the CNS parenchyma leading to clinical disease. 
Immune cell migration into the CNS parenchyma is thus a two-step process that involves a sequential migration across the endothelial and glial barrier of the NVU employing distinct molecular mechanisms. If following their passage across the endothelial barrier, T cells encounter their cognate antigen on perivascular antigen-presenting cells their local reactivation will initiate subsequent mechanisms leading to the focal activation of gelatinases, which will enable the T cells to cross the glial barrier and enter the CNS parenchyma. Thus, assessing both, BBB permeability and MMP activity in spatial correlation to immune cell accumulation in the CNS during EAE allows to specify loss of integrity of the endothelial and glial barriers of the NVU. 
We here show how to induce EAE in C57BL/6 mice by active immunization and how to subsequently analyze BBB permeability in vivo using a combination of exogenous fluorescent tracers. We further show, how to visualize and localize gelatinase activity in EAE brains by in situ zymogaphy coupled to immunofluorescent stainings of BBB basement membranes and CD45+ invading immune cells.

Assessment of the clinical course of EAE in C57BL/6 mice should result in a disease curve as depicted in Figure 2A and changes in the mouse body weight as presented in Figure 2B. C57BL/6 mice immunized with MOGaa35-55 usually start to develop disease symptoms around day 10-12 after active immunization (Figure 1A). Typically, immunized mice show a transient drop of body weight the day after the injection of the emulsion and the first...

Watch this Scientific Journal Video about Visualizing Impairment of the Endothelial and Glial Barriers of the Neurovascular Unit during Experimental Autoimmune Encephalomyelitis In Vivo at JoVE.com

Visualizing Impairment of the Endothelial and Glial Barriers of the Neurovascular Unit during Experimental Autoimmune Encephalomyelitis In Vivo

Here, we present protocols to investigate impairment of the neurovascular unit during experimental autoimmune encephalomyelitis in vivo. We specifically address how to determine blood-brain barrier permeability and gelatinase activity involved in leukocyte migration across the glia limitans.&#160;

The neurovascular unit (NVU) is composed of microvascular endothelial cells forming the blood-brain barrier (BBB), an endothelial basement membrane with ...

The methods presented here allow us to study the molecular mechanisms of immune cell migration across the brain barriers in experimental autoimmune encephalomyelitis, an animal model for multiple sclerosis. By investigating blood-brain barrier permeability and matrix-metalloprotease activity at the same time in spatial correlation to immune cell infiltration in brain tissue sections, we can precisely associate these neuroinflammatory events to the clinical signs of EAE. Professional handling of diseased mice needs in-depth training, as well as the correct scoring of the clinical signs of EAE.Thus, the visual demonstration is beneficial. Begin this procedure with anesthetization of C57-Black/6 mice that have been housed in specific-pathogen-free conditions as described in the text protocol. Fix the anesthetized mouse in one hand, and inject 30 microliters of MOG peptide and complete Freund's adjuvant emulsion subcutaneously into each of the hind leg flanks, in close proximity to the inguinal lymph nodes.Now, place the mouse on its belly, and inject 20 microliters of the MOG-peptide emulsion into the soft fatty tissue on both the left and right at the tail root. Also, inject a little droplet of the emulsion into the neck of the mouse. Inject 100 microliters of pertussis toxin solution intraperitoneally into the mouse.Hold the head of the mouse below the body center to avoid injection into the intestine. Replace the maintenance diet to the breeding diet in order to provide the mice with food of higher energy content before and during the expected clinical disease. Repeat the pertussis toxin injection 48 hours after the first treatment.Check the health status of EAE mice every morning by taking a look inside the cages. Score EAE mice every afternoon. Take every individual mouse included in the EAE experiment out of the cage, and check whether the tail has tonus.Move the tail upward with a finger. A healthy mouse will keep its tail up. If clinical EAE has started, the tail tonus will be lower, visible by a gradual drop of the tail.Eventually, the mouse will not be able to lift its tail at all. Place every individual mouse included in the EAE experiment on the clean bench to observe and document the walking behavior. See the text for scoring criteria for the assessment of disease severity, which is the EAE score.Assess and document the weight of every mouse included in the experiment. For preparing dextran stock solutions, dissolve 10 milligrams of three-kilodalton Dextran Texas Red in 500 microliters of 0.9%sodium chloride solution and five milligrams of 10-kilodalton Dextran Alexa Fluor 488 in 250 microliters of 0.9%sodium chloride solution. For the dextran working solution, just before injection, pipette 55 microliters of 10-kilodalton Dextran Alexa Fluor 488 stock solution onto a piece of sealing film.Then, add 55 microliters of three-kilodalton Dextran Texas Red stock solution. Mix and collect 100 microliters into a disposable fine syringe. Next, place an anesthetized mouse in the lateral position on the table.Intravenously inject 100 microliters of fluorescent tracers into the mouse before the mouse wakes up. Let the tracer circulate for 15 minutes before performing perfusion of mice as detailed in the text protocol. Fill a flat dewar container with crushed dry ice, and add 2-methylbutane until the liquid reaches about one centimeter above the dry ice pack.Cover with a loose lid, such as an ice bucket cover. After clipping off the head of the perfused mouse with sharp scissors, remove the skin and ears using a smaller set of scissors. Carefully dissect the skullcap by cutting from the foramen magnum towards the front at the left and the right side, to allow upfolding of the skullcap over the brain.Then, carefully lift out the intact brain from the base of the skull while severing the optical nerves using a flat metal spatula. Place the brain on aluminum foil. Cut the brain in three pieces by placing two coronal cuts.The three pieces represent the frontal brain, middle brain, and cerebellum with brain stem. Fill a Cryomold to the first quarter with optimum-temperature cutting matrix. Then, place the brain slices into the Cryomold, with the anterior side of each brain piece facing downwards.Cover the tissue completely with matrix. Place the Cryomold with the tissue in a horizontal orientation into the 2-methylbutane bath. Ensure that the tissue freezes from the bottom to the top within one minute by avoiding dipping the entire tissue block into the bath.Transfer the frozen tissue to minus 80 degrees Celsius for storage. See the text protocol for preparation of the frozen tissue sections. Retrieve six-micron, non-fixed brain tissue sections that had been prepared from EAE mice.In a fume hood, thaw the sections inside the plastic freezing box containing silica gel in the lid to avoid retention of water in the tissue. Separate two tissue sections on one slide by drawing lines with a water-repelling pen. Centrifuge reaction solutions for five minutes at 13, 300 times g at room temperature, and pre-warm to 37 degrees Celsius using a water bath.Then, rehydrate the tissue sections for five minutes at 37 degrees Celsius using 1X reaction buffer. After five minutes, pour off the 1X reaction buffer. Add reaction solution on the tissue sections, and incubate for four hours at 37 degrees Celsius.Then, wash the slides five times in double-distilled water. Now, fix the sections for five minutes with ice-cold methanol at minus 20 degrees Celsius before washing them once with PBS at room temperature. Add 1%BSA in PBS to the section, and incubate for 20 minutes at room temperature.Then, discard the buffer from the section by flipping the slide on a tissue. Add primary antibody cocktail to the section, and incubate for one hour at room temperature. After washing the sections twice with PBS, add secondary antibody cocktail, and incubate for one hour at room temperature.Then, wash the sections twice with PBS, and mount the slides with embedding solution. After letting the mounted sections dry overnight at room temperature, analyze stained tissue sections using a fluorescent microscope. The EAE disease severity increases until the peak of the disease, which can be expected between days 16 and 20 after EAE induction.At the peak of clinical EAE, mice also showed the lowest body weight, which increases in correlation to the amelioration of EAE in the remission phase of the disease. Shown here is a representative picture of the choroid plexus and the adjacent brain parenchyma of a C57-Black/6 mouse suffering from EAE. The mouse was intravenously injected 15 minutes before sacrificing.Tracers readily diffuse across the fenestrated microvessels into the stoma of the choroid plexus, while the blood-brain barrier does not allow the diffusion of circulating tracers into the brain parenchyma, which is thus devoid of any fluorescent signal. These images show representative leaky blood vessels in the cerebellum of a C57-Black/6 mouse suffering from EAE. Arrowheads indicate tracers diffused across the brain microvessels into the CNS parenchyma, suggesting that the blood-brain barrier function is impaired in these vessels.In the CNS parenchyma, green and red fluorescent signal is visible outside of the blood vessel walls. Correct subcutaneous placement of the MOG-CFA emulsion is essential to mount the appropriate immune response leading to EAE. Intraperitoneal and intramuscular injection should be avoided.Prepare CFA under a fume hood to avoid inhalation of the attenuated Mycobacterium. Also, avoid one's self-injection with the MOG-CFA emulsion, as this may cause condyloma or even lead to EAE in individuals that are genetically predisposed. Brain-infiltrating immune cells can be isolated from the CNS of mice suffering from EAE to quantify infiltrating immune cell subsets during neuroinflammation by flow cytometry.Assessing the integrity of the endothelial and the glial brain barriers can be translated to the analysis of genetically modified mouse models or to models of other neurological disorders.

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Research

JoVE Journal

Immunology and Infection

7.5K visualizações.  University of Bern. Os métodos aqui apresentados permitem estudar os mecanismos moleculares da migração de células imunes através das barreiras cerebrais em encefalomielite autoimune experimental, um modelo animal para esclerose múltipla. Ao investigar a permeabilidade da barreira hematoencefálica e a atividade de desoproteporase matricial ao mesmo tempo em correlação espacial com a infiltração de células imunes em seções de tecido cerebral, podemos associar precisamente esses eventos neuroinflamat...