The authors would like to thank Prof. Hartwig Wolburg for performing the electron microscopy.

1. Prepare Cell Culture Filter Inserts for Seeding HIBCPP Cells in an Inverted Model System
<ol>
	<li>Pre-warm DMEM/ F12 (Ham) supplemented with 5 &#181;g/ml insulin, 100 U/ml penicillin, 100 &#181;g/ml streptomycin and 10% fetal calf serum (FCS).</li>
	<li>Use sterile forceps to place 0.33 cm&#178; growth area cell culture filter inserts with a pore size of 3 &#181;m upside down into a 12-well plate (Figure 1E).</li>
	<li>Fill medium into the lower compartment of the cell culture filter insert (about ...

<ol>
	<li>Abott, N. J., Patabendige, A. A. K., Dolman, D. E. M., Yusof, S. R., Begley, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structure+and+function+of+the+blood-brain+barrier.">Structure and function of the blood-brain barrier.</a> Neurobiol Dis. 37, 13-25 (2009).</li><li>Wolburg, H., Paulus, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Choroid+plexus:+biology+and+pathology.">Choroid plexus: biology and pathology.</a> Acta Neuropathol. 119, 75-88 (2010).</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> Semin Imunopathol. 31, 497-511 (2009).</li><li>Ishiwata, I., Ishiwata, C., Ishiwata, E., Sato, Y., Kiguchi, K., Tachibana, T., 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=Establishment+and+characterization+of+a+human+malignant+choroid+plexus+papilloma+cell+line+(HIBCPP).">Establishment and characterization of a human malignant choroid plexus papilloma cell line (HIBCPP).</a> Hum Cell. 18, 67-72 (2005).</li><li>Schwerk, C., Papandreou, T., Schuhmann, D., Nickol, L., Borkowski, J., Steinmann, U., 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=Polar+invasion+and+translocation+of+Neisseria+meningitidis+and+Streptococcus+suis+in+anovel+human+model+of+the+blood-cerebrospinal+fluid+barrier.">Polar invasion and translocation of Neisseria meningitidis and Streptococcus suis in anovel human model of the blood-cerebrospinal fluid barrier.</a> PloS One. 7, e30069 (2012).</li><li>Bernd, A., Ott, M., Ishikawa, H., Schroten, H., Schwerk, C., Fricker, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+efflux+transport+proteins+of+the+human+choroid+plecus+papilloma+cell+line+HIBCPP,+a+functional+in+vitro+model+of+the+blood-cerebrospinal+fluid+barrier.">Characterization of efflux transport proteins of the human choroid plecus papilloma cell line HIBCPP, a functional in vitro model of the blood-cerebrospinal fluid barrier.</a> Pharm Res. , (2014).</li><li>Gr&#252;ndler, T., Quednau, N., Stump, C., Orian-Rousseau, V., Ishikawa, H., Wolburg, 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=The+surface+proteins+InlA+and+InlB+are+interdependently+required+for+polar+basolateral+invasion+by+Listeria+monocytogenes+in+a+human+model+of+the+blood-cerebrospinal+fluid+barrier.">The surface proteins InlA and InlB are interdependently required for polar basolateral invasion by Listeria monocytogenes in a human model of the blood-cerebrospinal fluid barrier.</a> Microbes Infect. 15, 291-301 (2013).</li><li>Schwerk, C., Tenenbaum, T., Kwang, S. K., Schroten, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+choroid+plexus+-+a+multi-role+player+during+infectious+diseases+of+the+CNS.">The choroid plexus - a multi-role player during infectious diseases of the CNS.</a> Front Cell Neurosci. 9, 80 (2015).</li><li>Pron, B., Taha, M. K., Rambaud, C., Fournet, J. C., Pattey, N., Monnet, J. P., 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=Interaction+of+Neisseria+meningtidis+with+the+components+of+the+blood-brain+barrier+correlates+with+increased+expression+of+PilC.">Interaction of Neisseria meningtidis with the components of the blood-brain barrier correlates with increased expression of PilC.</a> J Infect Dis. 176, 1285-1292 (1997).</li><li>Guarner, J., Greer, P. W., Whitney, A., Shieh, W. J., Fischer, M., White, E. H., Carlone, G. 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=Pathogenesis+and+diagnosis+of+human+meningococcal+disease+using+immunohistochemical+and+PCR+assays+assays.">Pathogenesis and diagnosis of human meningococcal disease using immunohistochemical and PCR assays assays.</a> Am J Clin Pathol. 122, 754-764 (2004).</li><li>Pizarro-Cerda, J., Kuhbacher, A., Cossart, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Entry+of+Listeria+monocytogenes+in+mammalian+epithelial+cells:+an+updated+view.">Entry of Listeria monocytogenes in mammalian epithelial cells: an updated view.</a> Cold Spring Harb Perspect Med. 2, (2012).</li><li>Beutler, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microbe+sensing,+positive+feedback+loops+and+the+pathogenesis+of+inflammatory+diseases.">Microbe sensing, positive feedback loops and the pathogenesis of inflammatory diseases.</a> Immunol. Rev. 227, 248-263 (2009).</li><li>Wilson, E. H., Weninger, W., Hunter, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trafficking+of+immune+cells+in+the+central+nervous+system.">Trafficking of immune cells in the central nervous system.</a> J Clin Invest. 120, 1368-1379 (2010).</li><li>Meeker, R. B., Williams, K., Killebrew, D. A., Hudson, L. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+trafficking+through+the+choroid+plexus.">Cell trafficking through the choroid plexus.</a> Cell Adh Migr. 6, 390-396 (2012).</li><li>Borkowski, J., Li, L., Steinmann, U., Quednau, N., Stump-Guthier, C., Weiss, 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=Neisseria+meningitidis+elicits+a+pro-inflammatory+response+involving+I+kappa+B+zeta+in+a+human+blood-cerebrospinal+fluid+barrier+model.">Neisseria meningitidis elicits a pro-inflammatory response involving I kappa B zeta in a human blood-cerebrospinal fluid barrier model.</a> J Neuroinflammation. 11, 163 (2014).</li><li>Steinmann, U., Borkowski, J., Wolburg, H., Schroppel, B., Findeisen, P., Weiss, 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=Transmigration+of+polymorphnuclear+neutrophils+and+monocytes+through+the+human+blood-cerebrospinal+fluid+barrier+after+bacterial+infection+in+vitro.">Transmigration of polymorphnuclear neutrophils and monocytes through the human blood-cerebrospinal fluid barrier after bacterial infection in vitro.</a> J Neuroinflammation. 10, 30 (2013).</li><li>McGuiness, B. T., Clarke, I. N., Lambden, P. R., Barlow, A. K., Poolman, J. T., Heckels, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Point+mutation+in+meningococcal+por+A+gene+associated+with+increased+endemic+disease.">Point mutation in meningococcal por A gene associated with increased endemic disease.</a> Lancet. 337, 514-517 (1991).</li><li>Ram, S., Cox, A. D., Wright, J. C., Vogel, U., Getzlaff, S., Boden, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neisserial+lipopolysaccharide+is+a+target+for+complement+component+C4b.+inner+core+phosphoethanolamine+residues+define+C4b+linkage+specificity.">Neisserial lipopolysaccharide is a target for complement component C4b. inner core phosphoethanolamine residues define C4b linkage specificity.</a> J Biol Chem. 278, 50853-50862 (2003).</li><li>Claus, H., Maiden, M. C., Maag, R., Frosch, M., Vogel, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Many+carried+meningococci+lack+the+genes+required+for+capsule+synthesis+and+transport.">Many carried meningococci lack the genes required for capsule synthesis and transport.</a> Microbiology. 148, 1813-1819 (2002).</li><li>Claus, H., Maiden, M. C., Wilson, D. J., Mccarthy, N. D., Jolley, K. A., Urwin, R., 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=Genetic+analysis+of+meningococci+carried+by+children+and+young+adults.">Genetic analysis of meningococci carried by children and young adults.</a> J Infect Dis. 191, 1263-1271 (2005).</li><li>Tenenbaum, T., Papandreou, T., Gellrich, D., Friedrichs, U., Seibt, A., Adam, R., 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=Polar+bacterial+invasion+and+translocation+of+Streptococcus+suis+across+the+blood-cerebrospinal+fluid+barrier+in+vitro.">Polar bacterial invasion and translocation of Streptococcus suis across the blood-cerebrospinal fluid barrier in vitro.</a> Cell Microbiol. 11, 323-336 (2009).</li><li>Laflamme, N., Echchannaoui, H., Landmann, R., Rivest, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cooperation+between+toll-like+receptor+2+and+4+in+the+brain+of+mice+challenged+with+cell+wall+components+derived+from+gram-negative+and+gram-positive+bacteria.">Cooperation between toll-like receptor 2 and 4 in the brain of mice challenged with cell wall components derived from gram-negative and gram-positive bacteria.</a> Eur J Immunol. 33, 1127-1138 (2003).</li><li>Laflamme, S., Rivest, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toll-like+receptor+4:+the+missing+link+of+the+cerebral+innate+immune+response+triggered+by+circulating+gram-negative+bacterial+cell+wall+components.">Toll-like receptor 4: the missing link of the cerebral innate immune response triggered by circulating gram-negative bacterial cell wall components.</a> FASEB J. 15, 155-163 (2001).</li><li>Zughaier, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neisseria+meningitidis+capsular+polysaccharides+indice+inflammatory+responses+via+TLR2+and+TLR4-MD-2.">Neisseria meningitidis capsular polysaccharides indice inflammatory responses via TLR2 and TLR4-MD-2.</a> J Leukoc Biol. 89, 469-480 (2011).</li><li>Yamamoto, M., Yamazaki, S., Uematsu, S., Sato, S., Hemmi, M., Hoshino, K., 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=Regulation+of+Toll/IL-1-receptor+-mediated+gene+expression+by+the+inducible+nuclear+protein+IkappaBzeta.">Regulation of Toll/IL-1-receptor -mediated gene expression by the inducible nuclear protein IkappaBzeta.</a> Nature. 430, 218-222 (2004).</li><li>Lorenz, J., Zahlten, J., Pollok, I., Lippmann, J., Scharf, S., N'Guessan, P. 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=Legionella+pheumophila-induced+IkappaBzeta-dependent+expression+of+interleukin-6+in+lung+epithelium.">Legionella pheumophila-induced IkappaBzeta-dependent expression of interleukin-6 in lung epithelium.</a> Eur Respir J. 37, 648-657 (2011).</li><li>Jaerve, A., Muller, H. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemokines+in+CNS+injury+and+repair.">Chemokines in CNS injury and repair.</a> Cell Tissue Res. 349, 229-248 (2012).</li><li>Schneider, H., Weber, C. E., Schoeller, J., Steinmann, U., Borkowski, J., Ishikawa, 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=Chemotaxis+of+T-cells+after+infection+of+human+choroid+plexus+papilloma+cells+with+Echovirus+30+in+an+in+vitro+model+of+the+blood-cerebrospinal+fluid+barrier.">Chemotaxis of T-cells after infection of human choroid plexus papilloma cells with Echovirus 30 in an in vitro model of the blood-cerebrospinal fluid barrier.</a> Virus Res. 170, 66-74 (2012).</li><li>Chodobski, A., Szmydynger-Chodobska, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Choroid+plexus:+Target+for+polypeptides+and+site+of+their+synthesis.">Choroid plexus: Target for polypeptides and site of their synthesis.</a> Microsc. Res. Tech. 52, 65-82 (2001).</li><li>Dickson, P. 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The authors have nothing to disclose.

The epithelial cells of the CP form the BCSFB that separates the CSF from the blood2,3. We recently established the HIBCPP cell line as a functional human model of the BCSFB. The cells display important barrier functions of the BCSFB in vitro, including the development of a high membrane potential, a low permeability for macromolecules, as well as the presence of continuous strands of TJs5. The TJ proteins contribute to an apical/basolateral polarity of the cells. The polarity is of high im...

The blood-cerebrospinal fluid barrier (BCSFB) is one of the three barrier sites between the blood and the brain1. Its morphological correlate are the epithelial cells of the choroid plexus (CP)2,3, an endothelial-epithelial convolute, which is strongly vascularized and located in the ventricles of the brain. The CP serves to produce the cerebrospinal fluid (CSF) as well as to separate the latter from the blood. In order to achieve barrier function, the CP epithelial cells show a low pinocytotic activity, express specific transporters, and are densely connected by a continuous network of tight junctions (TJs)2,3.
Human choroid plexus papilloma (HIBCPP) cells, derived from a malignant choroid plexus papilloma of a Japanese woman4, were used to construct a functional in vitro model of the BCSFB. HIBCPP cells show a couple of characteristics of a functional BCSFB as the formation of TJ strands, the development of a high transepithelial membrane potential that can be determined as transepithelial electrical resistance (TEER), and minor permeabilities for macromolecules. Moreover, HIBCPP cells express characteristic transporters, which may serve to regulate the ionic microenvironment, and show apical/basolateral polarity5,6,7.
The BCSFB has been shown to function as an entry site for pathogens (bacteria, viruses, and fungi) into the central nervous system (CNS)8. The invasion of pathogens, including Neisseria meningitidis (N. meningitidis), a Gram-negative bacterium, can cause severe diseases like meningitis. Evidence that it overcomes the protective epithelial barrier of the CP is supported by histopathological observations in patients with meningococcal disease exhibiting increased amounts of meningococci in the vessels and CP epithelial cells9,10. To gain entry into host cells bacteria often hijack endocytotic mechanisms, which are mediated or triggered by specific surface receptors located on the host cells. Since interactions of pathogens with these receptors can be species specific11, animal models can only be consulted to a restricted extent. The HIBCPP cell line provides the opportunity to study the invasion process as well as the underlying molecular mechanisms in a human model system. Employing cell culture inserts enables us to analyze interactions of pathogens with host cells from two distinct cell sides. Many bacteria, including N. meningitidis, are strongly subject to the impact of gravity during infection assays. For optimal interaction of pathogens with the HIBCPP cells during the assays, the bacteria are initially added into the upper compartment of the cell culture filter insert system. To enable infection from the apical or the basolateral cell side, respectively, two variations of the in vitro system have been established: In the standard system HIBCPP cells are seeded into the upper compartment of the filter insert, mimicking the situation when microorganisms are located on the CSF-side and get into contact with the apical side of the cells (Figure 1A, C). In contrast, using the HIBCPP cells in an inverted cell culture filter insert system reflects the conditions when bacteria have entered the blood stream. Microorganisms disseminate in the blood and encounter CP epithelial cells from the basolateral side (Figure 1B, D). Noteworthy, in this model system it has been shown that bacteria invade HIBCPP cells in a polar fashion specifically from the basolateral cell side5,7.
Subsequently to infection of the CP, the invaded pathogens can be recognized by the innate immune system through ligation to pattern-recognition receptors (PRRs). Well-described members of the PRRs belong to the Toll-like receptor (TLR) family. TLRs can bind to characteristic structures of infectious microorganisms, which are termed pathogen-associated molecular patterns (PAMPs). Ligation of the receptors leads to activation of host cell signaling cascades that trigger expression of cytokines and chemokines12, which in turn stimulate transmigration of immune cells across the BCSFB13,14. It has been shown that HIBCPP cells express several TLRs at mRNA level and that infection with N. meningitidis results in secretion of several cytokines and chemokines, including CXCL1-3, IL6, IL8 and TNF&#945;15,16.
Here, we describe cultivation and infection of the human cell line HIBCPP in an inverted cell culture insert system that mimics the BCSFB. This model system enables to study interactions of pathogens with the in vivo relevant basolateral cell side as well as the subsequent cellular response.

<table border="0" cellpadding="0" cellspacing="0" width="573">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">0.25% Trypsin-EDTA</td>
			<td style="width:71px;">Gibco</td>
			<td style="width:119px;">25200-056</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">4&#180;,6 diamidino-2-phenylindole (DAPI)</td>
			<td>Life Technologies</td>
			<td>D1306</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">12-well plates</td>
			<td>Starlab</td>
			<td>CC7682-7512</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">24-well plates</td>
			<td>Starlab</td>
			<td>CC7682-7524</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Anti Neisseria meningitidis &#945;-OMP</td>
			<td></td>
			<td></td>
			<td>This antibody was a gift from Drs. H. Claus and U. Vogel (University of W&#252;rzburg, Germany)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Alexa Fluor 488 (chicken anti rabbit)</td>
			<td>Invitrogen</td>
			<td>A21441</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Alexa Fluor 594 (chicken anti rabbit)</td>
			<td>Invitrogen</td>
			<td>A21442</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Alexa Fluor 660 Phalloidin</td>
			<td>Invitrogen</td>
			<td>A22285</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Bovine serum albumine (BSA)</td>
			<td>Calbiochem</td>
			<td>12659</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Chocolate agar plates</td>
			<td>Biomerieux</td>
			<td>43109</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cytochalasin D</td>
			<td>Sigma</td>
			<td>C8273</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DMEM/F12 + L-Glut + 15 mM HEPES</td>
			<td>Gibco</td>
			<td>31330-095</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DMEM/F12 + L-Glut + 15 mM HEPES w/o Phenolred</td>
			<td>Gibco</td>
			<td>11039-047</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dimethyl sulfoxide</td>
			<td>Sigma</td>
			<td>D2650</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fetal calf serum (FCS)</td>
			<td>Life Technologies</td>
			<td>10270106</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">FITC-Inulin</td>
			<td>Sigma</td>
			<td>F3272</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Insulin</td>
			<td>Sigma</td>
			<td>19278</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MgCl2</td>
			<td>Sigma</td>
			<td>2393</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NaHCO3</td>
			<td>Sigma</td>
			<td>55761</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">PBS + Mg +Ca</td>
			<td>Gibco</td>
			<td>14040-174</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Penicillin/Streptomycin</td>
			<td>MP Biomedicals</td>
			<td>1670049</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Polyvitex</td>
			<td>Biomerieux</td>
			<td>55651</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Proteose peptone</td>
			<td>BD</td>
			<td>211684</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Serum-free medium</td>
			<td>Gibco</td>
			<td>10902-096</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Thincert cell culture inserts for 24-well plates, pore size 3 &#181;m</td>
			<td>Greiner</td>
			<td>662630</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tissue culture flask 75 cm&#178; red cap sterile</td>
			<td>Greiner</td>
			<td>658175</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Triton X-100</td>
			<td>Sigma</td>
			<td>T8787</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Volt-Ohm Meter Millicell-ERS2 with MERSSTX01 electrode</td>
			<td>Millipore</td>
			<td>MERSSTX00</td>
			<td></td>
		</tr>
	</tbody>
</table>

a choroid plexus epithelial cell-based model of the human blood-cerebrospinal fluid barrier to study bacterial infection from the basolateral side

The epithelial cells of the choroid plexus (CP), located in the ventricular system of the brain, form the blood-cerebrospinal fluid barrier (BCSFB). The BCSFB functions in separating the cerebrospinal fluid (CSF) from the blood and restricting the molecular exchange to a minimum extent. An in vitro model of the BCSFB is based on cells derived from a human choroid plexus papilloma (HIBCPP). HIBCPP cells display typical barrier functions including formation of tight junctions (TJs), development of a transepithelial electrical resistance (TEER), as well as minor permeabilities for macromolecules. There are several pathogens that can enter the central nervous system (CNS) via the BCSFB and subsequently cause severe disease like meningitis. One of these pathogens is Neisseria meningitidis (N. meningitidis), a human-specific bacterium. Employing the HIBCPP cells in an inverted cell culture filter insert system enables to study interactions of pathogens with cells of the BCSFB from the basolateral cell side, which is relevant in vivo. In this article, we describe seeding and culturing of HIBCPP cells on cell culture inserts. Further, infection of the cells with N. meningitidis along with analysis of invaded and adhered bacteria via double immunofluorescence is demonstrated. As the cells of the CP are also involved in other diseases, including neurodegenerative disorders like Alzheimer`s disease and Multiple Sclerosis, as well as during the brain metastasis of tumor cells, the model system can also be applied in other fields of research. It provides the potential to decipher molecular mechanisms and to identify novel therapeutic targets.

Here we describe culturing and infection of HIBCPP cells in an inverted cell culture insert system. This model allows us to study invasion mechanisms and the underlying molecular signaling pathways from the basolateral cell side, reproducing a physiological situation of bacteria disseminating and entering epithelial cells via the blood stream (Figure 1).
The HIBCPP cells display certain barrier functions, which ...

Watch this Scientific Journal Video about A Choroid Plexus Epithelial Cell-based Model of the Human Blood-Cerebrospinal Fluid Barrier to Study Bacterial Infection from the Basolateral Side at JoVE.com

A Choroid Plexus Epithelial Cell-based Model of the Human Blood-Cerebrospinal Fluid Barrier to Study Bacterial Infection from the Basolateral Side

The epithelial cells of the choroid plexus (CP) form the blood-cerebrospinal fluid barrier (BCSFB). An in vitro model of the BCSFB employs human choroid plexus papilloma (HIBCPP) cells. This article describes culturing and basolateral infection of HIBCPP cells using a cell culture filter insert system.

The epithelial cells of the choroid plexus (CP), located in the ventricular system of the brain, form the blood-cerebrospinal fluid barrier (BCSFB). The ...

The overall goal of this method is to generate a choroid plexus epithelial cell-based model of the human blood-cerebrospinal fluid barrier. Enabling the study of bacterial infections from the basal-lateral side. This method can help to answer key questions about infectious diseases of the Central Nervous System, such as which processes are involved during bacterial interactions with the choroid plexus epithelium.The main advantage of this technique is that it allows analysis of the interactions of pathogens with the basal lateral black side of epithelial cells. This method can also be applied to other studies such as, to the investigation of the transmigration of the immune cells and tumor cells across the choroid plexus epithelium. I first had the idea for using the human chorcoid plexus papilloma, or HIBCCP cells for this method when I read the 2005 manuscript by Shibata et.al.describing the cell line. Begin by using sterile forceps to place 0.33 centimeters squared growth area cell culture filter inserts, with three micron size pores upside down into individual wells of a twelve well plate. Then, with a serological pipette, flood the well with about three milliliters of the pre-warmed medium, aspirating any extra solution, until the lower compartment is just filled.Next, add 100 micrometers of 37 degree subculture medium supplemented with ten percent FCS on top of the filter. When adding the medium it is very important to avoid the generation of air bubbles, since the bubbles will prevent the cells from being fed sufficiently. When the medium has been added to all of the inserts, cover the plate and transfer the inserts to a 37 degree Celsius five percent CO2 incubator.Now, wash a flask of HIBCPP cells with ten milliliters of PVS, two times with swirling. After the second wash, add three milliliters of 0.25 percent tripsyn EDTA to the cells and swirl the flask. Then, incubate the cells for about twenty minutes.At the end of the incubation, confirm that the cells have lifted from the bottom of the flask and display a round shape. The cells do not detach completely from each other and are often found in agglomerates. Re-suspend the culture with 17 milliliters of medium to stop the reaction and transfer the suspension to a 50 milliliter tube.Then, spin down the cells, and re-suspend the pellet in an appropriate volume of medium for counting. Next, dilute the cells to a one times ten to the sixth cells per milliliter concentration, and invert the tube to evenly distribute the cells. Then, add 80 micro liters of cells to the top of each filter insert.When all of the inserts have been seeded, cover the plate, and return it to the incubator for overnight culture. The next day, add one milliliter of medium to each well of a 24 well plate. Then, using forceps, lift each insert and discard the medium inside, placing the inserts right side up in individual wells of the 24 well plate.When the filter inserts are flipped from the 12 well plate into the 24 well plate, be careful not to touch the filter membrane with the cells growing on top. Fill the inserts with 0.5 milliliters of fresh medium, and return the plate to the incubator. Transfer the inserts into a new 24 well plate with fresh medium every two days, thereby replacing the medium in the upper compartment.To measure the trans-epithelial electrical resistance, or TEER of the cells, first immerse the electrode tips of an epithelial tissue volt-ohm meter into 80 percent ethanol. After 15 minutes, remove the electrode from the ethanol to allow the electrode to dry. Then, place the tips into an aliquot of subculture medium for another 15 minutes.When the electrode has equilibrated, position the longer arm so that it touches the bottom of the lower compartment of one well of the cell culture plate, and the shorter arm so that it reaches into the filter insert compartment. Measure the resistance values of the cell culture filter inserts in medium without cells to obtain the blank values. Then, measure the TEER of each of the seeded inserts.After measuring, place the electrode back into 80 percent ethanol for 15 minutes, followed by storage in a dry tube. When the TEER values of the HIBCPP seeded inserts exceed 70 ohms per centimeter squared, renew the medium using fresh culture medium supplemented with five micro grams per milliliter of insulin and one percent FCS, and return the plate to the cell culturing incubator overnight. To determine the paracellular permeability of the insert cultures, add 50 micro grams per milliliter of freshly prepared FITC-inulin in fresh serum low culture medium to the upper filter compartment of each insert, and return the cells to the incubator.When the cultures have reached a TEER of around 500 ohms per centimeter squared, infect the cells with a bacterial suspension of interest at a multiplicity of infection of ten, and return the cells to the incubator for the appropriate culture period. Then, wash the cells three times by transferring the filter into a new well with one milliliter of serum-free medium. Each time, place the medium in the filter compartment with 500 micro liters of the same medium, finally, determine the concentration of inulin that passed from the filter compartment through the cell layer after the bacterial infection by collecting medium samples from the lower well of each cell culture filter insert, and measuring all the samples in a micro plate reader against ten one and two FITC-inulin standard dilutions.HIBCCP cells exhibit specific barrier functions that enable them to restrict their molecular exchanges to a modest degree. For example, immunofluorescent analyses of the type-junction associated with the protein, ZO-1, Occludin, and Claudin-1, reveal an uninterrupted signal at the sites of cell to cell contact. Illustrating the interconnectedness of the cells by continuous strands of tight junctions.When cultured under the appropriate conditions, HIBCPP cells display a high membrane potential, that reaches up to about 500 ohms per centimeter squared without treatment, maintaining the typical barrier functions of the blood-cerebrospinal fluid barrier, Like the formation of a membrane potential, as well as a low-permeability for macro molecules. As increasing concentrations of DMSO are applied, however, the TEER values decrease in a dose-dependent manner, with a similar significant drop in the TEER value observed after Cytochalasin D treatment. More, the addition of two volume percent DMSO, or Cytochalasin D, results in a corresponding significant permeability increase for FITC-inulin flux.Further, the bacterial infection of the HIBCCP cells results in a significant invasion of the cell layer by two pathogenic bacterial strains. MC58, and its capsule-deficient mutant. Whereas only a minor invasion is observed for the apathogenic alpha 14 strain.While attempting this procedure, it's important to remember not to touch the filter membrane after seeding the cells as the intact HIBCCP layer will be disrupted by the contact. Following this procedure, other methods like vitro transmigration assays can be performed to answer additional questions about the mechanisms of immune and tumor cell migration across choroid plexus epithelial cells. After its development, this technique paved the way for researchers in the field pharmacology to explore the transfer of substrates across the choroid plexus epithelium in vitro.After watching this video, you should have a good understanding of how to prepare a HIBCCP cell-based model of the blood-cerebrospinal fluid barrier for basal lateral infection with pathogens. Don't forget that working with human pathogens can be extremely hazardous and that precautions such as working under an appropriate safety hood should always be taken while performing this procedure.

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14.0K Views.  Heidelberg University. The overall goal of this method is to generate a choroid plexus epithelial cell-based model of the human blood-cerebrospinal fluid barrier. Enabling the study of bacterial infections from the basal-lateral side. This method can help to answer key questions about infectious diseases of the Central Nervous System, such as which processes are involved during bacterial interactions with the choroid plexus epithelium.The main advantage of this technique is that it allows analysis of the int...

Video: A Choroid Plexus Epithelial Cell-based Model of the Human Blood-Cerebrospinal Fluid Barrier to Study Bacterial Infection from the Basolateral Side