The research in the Herskovits lab is supported by 335400 ERC and R01A/109048 NIH grants.

Remarque: Au cours de toute l&#39; expérience, les cellules macrophagiques sont mises en incubation à 37 ° C dans un CO 2 par air pulsé incubateur à 5% et retirés de l&#39;incubateur seulement pour des manipulations expérimentales, qui sont exécutées dans une enceinte de sécurité biologique de classe II. Travailler avec L. bactéries monocytogenes est en fonction du niveau de sécurité biologique 2 règlements. Préparation et infection bactérienne (Jour 1 et 2) 1. Cellule <ol><li> jour 1 <ol><li> Cellules de semences 2,0 x 10 7 de la moelle osseuse dérivées de macrophages (BMDM) sur une boîte de 145 mm dans 30 ml BMDM + média Pen-Strep (tableau 2). Seed 3 plaques pour chaque souche bactérienne à analyser. Incuber une nuit à 37 ° C dans CO 2 à air forcé incubateur à 5%. </li><li> Lancer une culture bactérienne d&#39;une nuit de type sauvage (WT) L. monocytogenes 10403S souche dans 10 ml de cerveau - coeur (BHI) moyenne, à 30 ° C dans un incubateur standard. tubes Lieu de culture inclinés sans agitation. Remarque:Ces conditions de croissance régulent à la hausse l&#39;expression des gènes de flagelles, ce qui favorise une infection efficace. </li></ol></li><li> Jour 2 <ol><li> Moyen Préchauffer BMDM (sans antibiotiques Pen-Strep) (tableau 2) et du tampon phosphate salin (PBS) à 37 ° C. </li><li> Laver monocouche macrophage deux fois avec 25 ml de pré-chauffé PBS pour éliminer les antibiotiques. Ajouter 30 ml de milieu de BMDM frais. </li><li> Laver 1,5 ml de culture bactérienne pendant une nuit avec du PBS par centrifugation des bactéries à&gt; 14 000 x g pendant 1 minute, élimination du surnageant et remise en suspension des bactéries doucement dans 1,5 ml de PBS par pipetage. Répéter deux fois. </li><li> Infect chaque plaque macrophage avec 0,5 ml d&#39;une culture d&#39;une nuit lavée de type sauvage L. monocytogenes. Si vous utilisez plusieurs plaques, infecter chaque plaque 15 min d&#39;intervalle. Cet intervalle de temps permettra de récolter chaque plaque individuellement à la fin de l&#39;infection. Remarque: La multiplicité d&#39;infection (MOI) est dosé par étalement des dilutions en séries de la culture bactérienne utilisée pour l&#39;infection sur des plaques d&#39;agar BHI et en comptant les unités formant colonie (UFC) après 24 heures d&#39;incubation des plaques à 37 ° C. Utiliser 0,5 ml de WT L. monocytogenes souche résultats 10403S dans une MOI de ~ 100 (100 bactéries CFU par cellule de macrophage). Lors de l&#39;analyse des mutants bactériens défectueux dans la croissance intracellulaire, un MOI plus élevé devrait être envisagée. </li><li> Après 0,5 heures d&#39;incubation à 37 ° C, laver les cellules infectées à deux reprises avec du PBS, pour éliminer les bactéries seules, et ajouter 30 ml de milieu BMDM préchauffé. bactéries attachées seront internaliser pendant 0,5 heure suivante. </li><li> A 1 après l&#39;infection h, ajouter 30 pl de gentamicine (1: 1000 pour atteindre une concentration finale de 50 pg / ml) pour tuer les bactéries extra-cellulaires. </li><li> Assembler l&#39;appareil de filtration en plaçant une tête de filtre sur un flacon collecteur de liquide avec un orifice de sortie de vide. Ensuite, placer un filtre (0,45 pm) sur une tête de filtre, suivie d&#39;une ampoule à cylindre et fixer les différentes parties d&#39;un métal clampe. Préparer l&#39;eau sans RNase glacée. </li><li> À 6 heures après l&#39;infection, les bactéries de la récolte des cellules infectées comme suit. Traiter chaque plaque individuellement. Note: Habituellement, L. monocytogenes complète de 1 log de ​​la croissance pendant 6 heures de l&#39; infection dans les cellules macrophages. incubations plus longues pourraient entraîner une prolifération bactérienne et la mort cellulaire des macrophages, alors que les périodes d&#39;incubation plus courtes pourrait entraîner des charges bactériennes considérablement plus faibles. MOI et le moment de l&#39;infection peuvent être modifiées pour atteindre des conditions optimales. <ol><li> Laver les cellules infectées par le PBS une fois. Ajouter 20 ml d&#39;eau sans RNase glacée pour lyser les cellules macrophages. L&#39;utilisation d&#39;un racleur de cellules, racler les cellules de la plaque rapidement mais soigneusement. </li><li> Recueillir les cellules lysées dans un tube conique de 50 ml. Vortex pendant 30 secondes. Centrifuger à 800 xg pendant 3 min à 4 ° C. </li><li> Passer le surnageant à travers le dispositif de filtre à l&#39;aide d&#39;un système à vide. En utilisant une pince à épiler, rouler le filtre et le transférer à un 15 ml rapidement conile tube cal. Snap-geler les tubes avec les filtres dans de l&#39;azote liquide. </li><li> Assembler l&#39;appareil de filtration avec un nouveau filtre pour l&#39;échantillon suivant, comme décrit dans 1.2.7. </li><li> Conserver les filtres congelés à -80 ° C pour le lendemain. Sinon, passez directement à l&#39;extraction d&#39;acide nucléique. </li></ol></li></ol></li></ol> 2. Nucleic Acids Extraction (Jour 3) Remarque: Effectuez toutes les manipulations avec des solutions de phénol et de chloroforme dans une hotte. <ol><li> Préparer un mélange 1: 1 de phénol acidifiés: le chloroforme, 400 ul de chaque échantillon. Mélanger dans des tubes séparés, puis de retirer la couche aqueuse résultante par aspiration. Ajouter 40 pl de SDS à 10%. </li><li> Décongeler les tubes contenant filtres sur la glace pour les garder froids. A chaque tube contenant un filtre à ajouter 650 ul d&#39;acétate-EDTA (AE) tampon (tableau 2). </li><li> Effectuez les étapes suivantes le plus rapidement possible. <ol><li> Vigoureusement vortex le tube contenant le filtre de sorteque le filtre transporte vers la périphérie du tube et le tampon lave complètement le filtre. Toujours garder le froid du tube en le plaçant de retour sur la glace. Remarque: Il peut être nécessaire de vortex en outre le tube tout inversé pour laver complètement les bactéries hors du filtre. </li><li> Répétez l&#39;opération pour tous les tubes. Il peut être utile de tourner vers le bas de la suspension peu (1 min à 120 xg) à la fin du processus. </li></ol></li><li> Transférer le tampon des bactéries contenant un tube de 1,5 ml contenant du SDS et du phénol / chloroforme mélange (tel que préparé à 2.1). Répétez l&#39;opération pour tous les tubes. Il peut être nécessaire de faire tourner les filtres contenant des tubes (1 min à 120 x g) à nouveau pour obtenir un tampon résiduel du filtre. </li><li> Placer tous les tubes de 1,5 ml dans un dispositif à tourbillon multi-tubes, et vortex à pleine vitesse pendant 10 min. </li><li> Incuber les tubes dans un bloc chauffant à 65 ° C pendant 10 min. Centrifugeuse à vitesse maximale (&gt; 14.000 xg) pendant 5 min. </li><li> Transférer la phase aqueuse (environ 400 pi) de chaque tube à un nouveau tube de 1,5 ml contenant 40 ul d&#39;acétate de sodium 3 M (pH 5,2) et 1,0 ml d&#39;éthanol à 100%. Vortex soigneusement chaque tube. Remarque: Le glycogène peut être ajouté à cette étape pour améliorer la visualisation de la pastille précipitée. </li><li> Incuber les échantillons à -80 ° C pendant 1 heure. Alternativement, incuber les échantillons à -20 ° C pendant la nuit. Ensuite, centrifuger les échantillons à 4 ° C pendant 20 min à vitesse maximale (&gt; 14 000 x g). </li><li> Aspirer avec précaution de l&#39;éthanol (couche supérieure) de chaque tube. Ajouter 500 ul d&#39;éthanol froid à 70% à chaque échantillon et vortexer soigneusement. Centrifuger à 4 ° C pendant 20 min à vitesse maximale (&gt; 1 4000 x g). </li><li> Aspirer délicatement de l&#39;éthanol à partir de chaque tube. Sécher les échantillons pendant environ 2 minutes en utilisant un évaporateur sous vide sans chaleur. Ne pas trop sécher les échantillons. </li><li> Ajouter de l&#39;eau sans RNase 25 pi à chaque échantillon. Incuber à température ambiante pendant 20 min. vortex soigneusement et spin-down. </li><li> Mesurer la concentration en ARN dans les til échantillons à l&#39;aide d&#39;un microvolume spectrophotomètre UV-Vis. Attendez-vous à extraire environ 0,5 à 1 pg d&#39;acides nucléiques par plaque. Note: les répétitions techniques peuvent être combinées à ce stade. </li></ol> 3. Traitement de la DNase <ol><li> Mettre en place la réaction selon le tableau 1 dans un tube de microcentrifugation. Incuber à 37 ° C pendant 45 min. Ajouter 450 l&#39; eau libre de RNase-pi et 500 pi de phénol-chloroforme-IAA mélange (tableau 2), des phases séparées par centrifugation pendant 2 min à vitesse maximale (&gt; 14.000 xg). </li><li> Transférer la couche aqueuse dans un nouveau tube et on ajoute 500 ul de chloroforme-IAA mélange (tableau 2), vortexer et des phases séparées par centrifugation à 2 minutes vitesse maximale (&gt; 14 000 x g). </li><li> Transférer la couche aqueuse dans un nouveau tube et on ajoute 1 ml d&#39;éthanol et 50 ul d&#39;acétate de sodium 3 M (pH 5,2). Vortex. Remarque: Le glycogène peut être ajouté à cette étape pour améliorer la visualisation de la pastille précipitée. </li><li&gt; Incuber pendant 1 heure à -80 ° C. Alternativement, incuber les échantillons à -20 ° C pendant la nuit. Centrifuger à 4 ° C pendant 20 min à vitesse maximale. </li><li> Aspirer délicatement de l&#39;éthanol à partir de chaque tube. Ajouter 500 ul d&#39;éthanol froid à 70% à chaque échantillon et vortexer soigneusement. Centrifugeuse à 4 ° C pendant 20 min à vitesse maximale. Aspirer délicatement de l&#39;éthanol à partir de chaque tube. </li><li> Sécher les échantillons pendant environ 2 minutes en utilisant un évaporateur sous vide sans chaleur. Ne pas trop sécher les échantillons. </li><li> Ajouter 12 ul d&#39;eau sans RNase, incuber pendant 2 min à température ambiante, vortex et spin-down. Les échantillons contiennent l&#39;ARN purifié, les garder sur la glace. En variante, on dissout l&#39; ARN dans RNase H 2 O avec 0,1 mM d&#39; EDTA ou d&#39;un tampon TE (Tris 10 mM, EDTA 1 mM). </li><li> Mesurer la concentration d&#39;ARN en utilisant un microvolume spectrophotomètre UV-Vis. Attendez-vous à ~ 100 ng d&#39;ARN par échantillon (si les répétitions techniques sont combinées). Note: l&#39;ARN extrait selon ce protocole est adapté for analyse de la transcription génique par des techniques multiples. Nous employons habituellement une analyse par RT-qPCR pour étudier L. monocytogenes transcription génique lors de l&#39; infection des cellules macrophages 1-4. </li></ol>

<ol>
	<li>Lobel, 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=The+metabolic+regulator+CodY+links+Listeria+monocytogenes+metabolism+to+virulence+by+directly+activating+the+virulence+regulatory+gene+prfA.">The metabolic regulator CodY links Listeria monocytogenes metabolism to virulence by directly activating the virulence regulatory gene prfA.</a> Mol Microbiol. , (2014).</li><li>Lobel, L., Sigal, N., Borovok, I., Ruppin, E., Herskovits, A. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integrative+genomic+analysis+identifies+isoleucine+and+CodY+as+regulators+of+Listeria+monocytogenes+virulence.">Integrative genomic analysis identifies isoleucine and CodY as regulators of Listeria monocytogenes virulence.</a> PLoS Genet. 8 , e1002887 (2012).</li><li>Kaplan Zeevi, 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=Listeria+monocytogenes+multidrug+resistance+transporters+and+cyclic+di-AMP,+which+contribute+to+type+I+interferon+induction,+play+a+role+in+cell+wall+stress.">Listeria monocytogenes multidrug resistance transporters and cyclic di-AMP, which contribute to type I interferon induction, play a role in cell wall stress.</a> J Bacteriol. 195, 5250-5261 (2013).</li><li>Rabinovich, L., Sigal, N., Borovok, I., Nir-Paz, R., Herskovits, A. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prophage+excision+activates+Listeria+competence+genes+that+promote+phagosomal+escape+and+virulence.">Prophage excision activates Listeria competence genes that promote phagosomal escape and virulence.</a> Cell. 150, 792-802 (2012).</li><li>Swaminathan, B., Gerner-Smidt, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+epidemiology+of+human+listeriosis.">The epidemiology of human listeriosis.</a> Microbes Infect. 9, 1236-1243 (2007).</li><li>Hamon, M., Bierne, H., 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=Listeria+monocytogenes:+a+multifaceted+model.">Listeria monocytogenes: a multifaceted model.</a> Nat Rev Microbiol. 4, 423-434 (2006).</li><li>Dussurget, O., Pizarro-Cerda, J., 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=Molecular+determinants+of+listeria+monocytogenes+virulence.">Molecular determinants of listeria monocytogenes virulence.</a> Ann Rev Microbiol. 58, 587-610 (2004).</li><li>Portnoy, D. A., Auerbuch, V., Glomski, I. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+cell+biology+of+Listeria+monocytogenes+infection:+the+intersection+of+bacterial+pathogenesis+and+cell-mediated+immunity.">The cell biology of Listeria monocytogenes infection: the intersection of bacterial pathogenesis and cell-mediated immunity.</a> J Cell Biol. 158, 409-414 (2002).</li><li>Freitag, N. E., Port, G. C., Miner, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Listeria+monocytogenes+-+from+saprophyte+to+intracellular+pathogen.">Listeria monocytogenes - from saprophyte to intracellular pathogen.</a> Nat Rev Microbiol. 7, 623-628 (2009).</li><li>Graham, J. E., Clark-Curtiss, 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=Identification+of+Mycobacterium+tuberculosis+RNAs+synthesized+in+response+to+phagocytosis+by+human+macrophages+by+selective+capture+of+transcribed+sequences+(SCOTS).">Identification of Mycobacterium tuberculosis RNAs synthesized in response to phagocytosis by human macrophages by selective capture of transcribed sequences (SCOTS).</a> Proc Natl Acad Sci U S A. 96, 11554-11559 (1999).</li><li>Toledo-Arana, 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=The+Listeria+transcriptional+landscape+from+saprophytism+to+virulence.">The Listeria transcriptional landscape from saprophytism to virulence.</a> Nature. 459, 950-956 (2009).</li><li>Schnappinger, 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=Transcriptional+Adaptation+of+Mycobacterium+tuberculosis+within+Macrophages:+Insights+into+the+Phagosomal+Environment.">Transcriptional Adaptation of Mycobacterium tuberculosis within Macrophages: Insights into the Phagosomal Environment.</a> J Exp Med. 198, 693-704 (2003).</li><li>Albrecht, M., Sharma, C. M., Reinhardt, R., Vogel, J., Rudel, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deep+sequencing-based+discovery+of+the+Chlamydia+trachomatis+transcriptome.">Deep sequencing-based discovery of the Chlamydia trachomatis transcriptome.</a> Nucleic Acids Res. 38, 868-877 (2010).</li><li>La, M. V., Raoult, D., Renesto, P. <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+whole+bacterial+pathogen+transcription+within+infected+hosts.">Regulation of whole bacterial pathogen transcription within infected hosts.</a> FEMS Microbiol Rev. 32, 440-460 (2008).</li><li>Westermann, A. J., Gorski, S. A., Vogel, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dual+RNA-seq+of+pathogen+and+host.">Dual RNA-seq of pathogen and host.</a> Nat Rev Microbiol. 10, 618-630 (2012).</li><li>Rienksma, R. 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=Comprehensive+insights+into+transcriptional+adaptation+of+intracellular+mycobacteria+by+microbe-enriched+dual+RNA+sequencing.">Comprehensive insights into transcriptional adaptation of intracellular mycobacteria by microbe-enriched dual RNA sequencing.</a> BMC Genomics. 16, 34 (2015).</li><li>Afonso-Grunz, F., 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=Dual+3'Seq+using+deepSuperSAGE+uncovers+transcriptomes+of+interacting+Salmonella+enterica+Typhimurium+and+human+host+cells.">Dual 3'Seq using deepSuperSAGE uncovers transcriptomes of interacting Salmonella enterica Typhimurium and human host cells.</a> BMC Genomics. 16, 323 (2015).</li><li>Englen, M. D., Valdez, Y. E., Lehnert, N. M., Lehnert, B. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Granulocyte/macrophage+colony-stimulating+factor+is+expressed+and+secreted+in+cultures+of+murine+L929+cells.">Granulocyte/macrophage colony-stimulating factor is expressed and secreted in cultures of murine L929 cells.</a> J Immunol Methods. 184, 281-283 (1995).</li><li>Becavin, 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=Comparison+of+widely+used+Listeria+monocytogenes+strains+EGD,+10403S,+and+EGD-e+highlights+genomic+variations+underlying+differences+in+pathogenicity.">Comparison of widely used Listeria monocytogenes strains EGD, 10403S, and EGD-e highlights genomic variations underlying differences in pathogenicity.</a> MBio. 5, e00969-e900914 (2014).</li><li>Celada, A., Gray, P. W., Rinderknecht, E., Schreiber, 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=Evidence+for+a+gamma-interferon+receptor+that+regulates+macrophage+tumoricidal+activity.">Evidence for a gamma-interferon receptor that regulates macrophage tumoricidal activity.</a> J Exp Med. 160, 55-74 (1984).</li></ol>

The authors have nothing to disclose.

Le protocole décrit ici représente un procédé optimisé pour l&#39; isolement de l&#39; ARN bactérien de L. monocytogenes bactéries en croissance intracellulaire dans les cellules macrophages. Ce protocole est basé sur la lyse différentielle de cellules, et comprend deux grandes étapes d&#39;enrichissement de l&#39;ARN bactérien: macrophage noyaux sédimentation au moyen d&#39;une centrifugation et d&#39;une collecte rapide des bactéries par filtration. Ces étapes sont suivies par un procédé d&#39...

Bactéries pathogènes intracellulaires ─ bactéries causant des maladies infectieuses et capables de croître et de reproduction des cellules à l&#39; intérieur de l&#39; hôte humain ─ sont un problème de santé majeur dans le monde entier 5. Envahir et se répliquer dans une cellule de mammifère, les agents pathogènes intracellulaires ont acquis des mécanismes et des facteurs de virulence sophistiqués. Bien que ces mécanismes sont essentiels à la capacité de provoquer une maladie, nous savons peu de choses sur leur régulation et de la dynamique. Comme les profils d&#39;expression des gènes de bactéries cultivées dans un milieu liquide ne reflètent pas l&#39;environnement réel dans les cellules hôtes, il y a un besoin croissant de transcriptome analyses de bactéries cultivées dans leurs niches intracellulaires. Ces analyses permettront au déchiffrement des adaptations bactériennes spécifiques déclenchées par l&#39;hôte et aidera à identifier de nouvelles cibles pour la conception thérapeutique. L&#39;analyse du transcriptome de bactéries intracellulairement cultivées est très difficile puisque l&#39;ARN mammifère sont plus nombreux que l&#39;ARN bactérien par aumoins dix fois. Dans ce manuscrit, nous décrivons une méthode expérimentale pour isoler l&#39; ARN bactérien de la bactérie Listeria monocytogenes croissance à l&#39; intérieur de cellules macrophages murins. L&#39;ARN extrait peut être utilisé pour étudier des adaptations et des mécanismes intracellulaires de virulence de bactéries pathogènes, par diverses techniques d&#39;analyse de la transcription, tels que la RT-PCR, l&#39;ARN-Seq, puces à ADN et d&#39;autres techniques à base d&#39;hybridation. L. monocytogenes est l&#39;agent causal de la listériose chez l&#39; homme, une maladie avec des manifestations cliniques ciblant principalement les personnes immunodéprimées, les personnes âgées et les femmes enceintes 6. Il est un pathogène intracellulaire facultatif Gram positif qui envahit un large éventail de cellules de mammifères qui ont été utilisés pendant des décennies comme un modèle dans les interactions hôte-pathogène études 7. Lors de l&#39;invasion, il se trouve d&#39;abord dans une vacuole ou le phagosome (dans le cas des cellules phagocytaires), à partir duquel il doit s&#39;échapper en til accueille cytosol des cellules afin de répliquer. On a montré que plusieurs facteurs de virulence à la médiation du processus d&#39;échappement, essentiellement la hémolysine formant des pores, listériolysine O (LLO) et deux autres phospholipases 8. Dans le cytosol , les bactéries utilisent la machinerie de polymérisation de l&#39; actine hôte pour se propulser sur les filaments d&#39;actine au sein de la cellule et de se propager de cellule à cellule (Figure 1). Tous les principaux facteurs de virulence de L. monocytogenes impliqués dans l&#39; invasion, la survie intracellulaire et la réplication, sont activés par le régulateur de transcription maître de virulence, PrfA. 8-10. Dans la dernière décennie, plusieurs études menées par nous et d&#39; autres ont des méthodes d&#39;analyse de transcriptome des bactéries intracellulairement cultivées appliquée avec succès à l&#39; intérieur des cellules hôtes 2,11-15. Deux approches principales sont utilisées pour séparer l&#39;ARN bactérien de l&#39;hôte-ARN qui sont basées sur: 1) l&#39;enrichissement sélectif de l&#39;ARN bactérien et 2) l&#39;isolement de l&#39;ARN par diffelyse cellulaire rentiel. La première approche repose sur l&#39; hybridation soustractive d&#39;extraits d&#39;ARN totaux à des molécules d&#39;ARN de mammifères (par exemple en utilisant des kits disponibles dans le commerce) ou la capture sélective de séquences transcrites bactériennes (Scots) 11. La seconde approche est basée sur la lyse différentielle des bactéries et des cellules hôtes, dans lequel les cellules hôtes sont des cellules bactériennes lysées tandis que restent intactes. Les cellules bactériennes sont ensuite séparés du lysat des cellules hôtes, habituellement par centrifugation, et l&#39;ARN est extrait en utilisant des techniques standard. Le principal problème avec cette approche est que, avec des bactéries intactes, des cellules hôtes sont également des noyaux isolés, ainsi les préparations d&#39;ARN contiennent encore l&#39;ARN mammifère. Une façon de surmonter ce problème est de séparer les bactéries intactes à partir des cellules hôtes noyaux par centrifugation différentielle, bien que cette procédure prend généralement du temps soulevant l&#39;inquiétude des changements dans le profil d&#39;expression génique lors de l&#39;extraction. Dans cet article, nous présentons un ba amélioré et rapidecteria protocole d&#39;extraction d&#39;ARN, qui est basée sur la différence de l&#39;approche de lyse cellulaire. Tout d&#39; abord, L. monocytogenes infectées par les cellules macrophages sont lysés avec de l&#39; eau froide. Ensuite, les noyaux macrophage sont éliminés par une brève centrifugation et bactéries intactes sont rapidement collectées sur les filtres, à partir de laquelle l&#39;ARN est isolé par extraction phénol-SDS à chaud des acides nucléiques bactériens.

<table>
	<tbody>
		<tr>
			<td rowspan="2">Listeria monocytogenes 10403S</td>
			<td rowspan="2"></td>
			<td rowspan="2"></td>
			<td rowspan="2">20</td>
		</tr>
		<tr>
		</tr>
		<tr>
			<td rowspan="2">Bone marrow derived macrophages prepared from C57B/6 female mice</td>
			<td rowspan="2"></td>
			<td rowspan="2"></td>
			<td rowspan="2">21</td>
		</tr>
		<tr>
		</tr>
		<tr>
			<td>H2O, RNAse free</td>
			<td>Thermo Scientific</td>
			<td>10977-015</td>
			<td>DEPC-treated water can be used</td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Gibco</td>
			<td>41965039</td>
			<td></td>
		</tr>
		<tr>
			<td>Glutamine</td>
			<td>Gibco</td>
			<td>25030081</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium pyruvate</td>
			<td>Gibco</td>
			<td>11360-088</td>
			<td></td>
		</tr>
		<tr>
			<td>b-Mercaptoethanol&#160;&#160;</td>
			<td>Gibco</td>
			<td>31350010</td>
			<td></td>
		</tr>
		<tr>
			<td>Pen/Strep</td>
			<td>Gibco</td>
			<td>15140-122</td>
			<td></td>
		</tr>
		<tr>
			<td>Gentamicin</td>
			<td>Sigma-Aldrich</td>
			<td>G1397</td>
			<td></td>
		</tr>
		<tr>
			<td>FBS</td>
			<td>Gibco</td>
			<td>10270106</td>
			<td></td>
		</tr>
		<tr>
			<td>Dulbecco&#8217;s Phosphate Buffered Saline-PBS</td>
			<td>Sigma-Aldrich</td>
			<td>D8537</td>
			<td></td>
		</tr>
		<tr>
			<td>Brain heart infusion (BHI)</td>
			<td>Merckmillipore</td>
			<td>1104930500</td>
			<td></td>
		</tr>
		<tr>
			<td>Phenol saturated pH 4.3</td>
			<td>Fisher</td>
			<td>BP1751I-400</td>
			<td></td>
		</tr>
		<tr>
			<td>Chloroform</td>
			<td>Fisher</td>
			<td>BP1145-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Iso-amyl alcohol</td>
			<td>Sigma-Aldrich</td>
			<td>W205702</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium acetate</td>
			<td>Sigma-Aldrich</td>
			<td>W302406</td>
			<td></td>
		</tr>
		<tr>
			<td>EDTA</td>
			<td>Sigma-Aldrich</td>
			<td>EDS</td>
			<td></td>
		</tr>
		<tr>
			<td>DNaseI</td>
			<td>Fermentas,</td>
			<td>EN0521</td>
			<td></td>
		</tr>
		<tr>
			<td>SDS 10%</td>
			<td>Sigma-Aldrich</td>
			<td>L4522</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol absolute</td>
			<td>Merck Millipore</td>
			<td>1070174000</td>
			<td></td>
		</tr>
		<tr>
			<td>37&#176;C, 5% CO2 forced-air incubator</td>
			<td>Thermo Scientific</td>
			<td>Model 3111</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell scrapers</td>
			<td>Nunc</td>
			<td>179693</td>
			<td></td>
		</tr>
		<tr>
			<td>Kontes glass holder for 45 mm filters</td>
			<td>Fisher</td>
			<td>K953755-0045</td>
			<td></td>
		</tr>
		<tr>
			<td>MF-Millipore filters 45 mm, 0.45 &#181;m</td>
			<td>Merck Millipore</td>
			<td>HAWP04700</td>
			<td></td>
		</tr>
		<tr>
			<td>SpeedVac system</td>
			<td>Thermo Scientific</td>
			<td>SPD131DDA</td>
			<td></td>
		</tr>
		<tr>
			<td>Vortex-Genie 2</td>
			<td>Scientific Industries</td>
			<td>Model G560E</td>
			<td></td>
		</tr>
		<tr>
			<td>NanoDrop</td>
			<td>Thermo Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>145 mm cell culture dishes</td>
			<td>Greiner</td>
			<td>639 160</td>
			<td></td>
		</tr>
		<tr>
			<td>1.7 ml tubes, RNase-free</td>
			<td>Axygen</td>
			<td>MCT-175-C</td>
			<td></td>
		</tr>
		<tr>
			<td>30&#176;C incubator</td>
			<td>Thermo Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>65 &#176;C heat block</td>
			<td>Thermo Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>4 &#176;C table centrifuge</td>
			<td>Eppendorf</td>
			<td>5417R</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile pipettes, 25 ml</td>
			<td>Greiner</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Falcon tubes, 50 ml</td>
			<td>Greiner</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Liquid nitrogen</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

rna purification from intracellularly grown listeria monocytogenes in macrophage cells

Analysis of the transcriptome of bacterial pathogens during mammalian infection is a valuable tool for studying genes and factors that mediate infection. However, isolating bacterial RNA from infected cells or tissues is a challenging task, since mammalian RNA mostly dominates the lysates of infected cells. Here we describe an optimized method for RNA isolation of Listeria monocytogenes bacteria growing within bone marrow derived macrophage cells. Upon infection, cells are mildly lysed and rapidly filtered to discard most of the host proteins and RNA, while retaining intact bacteria. Next, bacterial RNA is isolated using hot phenol-SDS extraction followed by DNase treatment. The extracted RNA is suitable for gene transcription analysis by multiple techniques. This method is successfully employed in our studies of Listeria monocytogenes gene regulation during infection of macrophage cells 1-4. The protocol can be easily modified to study other bacterial pathogens and cell types.

Le système de modèle est représenté sur la figure 1 et comprend des cellules macrophages infectés par L. monocytogenes, des bactéries qui se répliquent dans le cytoplasme des macrophages. La figure 2 représente le schéma expérimental. La figure 3 représente des résultats typiques d&#39; une telle analyse par RT-qPCR des gènes de virulence pendant WT L. monocytogenes croissance dans les macrophages par rappo...

Watch this Scientific Journal Video about RNA Purification from Intracellularly Grown Listeria monocytogenes in Macrophage Cells at JoVE.com

RNA Purification from Intracellularly Grown Listeria monocytogenes in Macrophage Cells

Here we describe a method for bacterial RNA isolation from Listeria monocytogenes bacteria growing inside murine macrophages. This technique can be used with other intracellular pathogens and mammalian host cells.

ARN Purification de Intracellulairement Grown<em&gt; Listeria monocytogenes</em&gt; Dans les cellules macrophages

Analysis of the transcriptome of bacterial pathogens during mammalian infection is a valuable tool for studying genes and factors that mediate infection. ...

rna-purification-from-intracellularly-grown-listeria-monocytogenes

Research

JoVE Journal

Immunology and Infection

RNA Purification from Intracellularly Grown Listeria monocytogenes in Macrophage Cells

9.1K vues.  Tel Aviv University. Here we describe a method for bacterial RNA isolation from Listeria monocytogenes bacteria growing inside murine macrophages. This technique can be used with other intracellular pathogens and mammalian host cells.

Vidéo: RNA Purification from Intracellularly Grown Listeria monocytogenes in Macrophage Cells

Co-culture Models of Pseudomonas aeruginosa Biofilms Grown on Live Human Airway Cells

Bacterial biofilms have been associated with a number of different human diseases, but biofilm development has generally been studied on non-living surfaces. In this paper, we describe protocols for forming Pseudomonas aeruginosa biofilms on human airway epithelial cells (CFBE cells) grown in culture. In the first method (termed the Static Co-culture Biofilm Model), P. aeruginosa is incubated with CFBE cells grown as confluent monolayers on standard tissue culture plates. Although the bacterium is quite toxic to epithelial cells, the addition of arginine delays the destruction of the monolayer long enough for biofilms to form on the CFBE cells. The second method (termed the Flow Cell Co-culture Biofilm Model), involves adaptation of a biofilm flow cell apparatus, which is often used in biofilm research, to accommodate a glass coverslip supporting a confluent monolayer of CFBE cells. This monolayer is inoculated with P. aeruginosa and a peristaltic pump then flows fresh medium across the cells. In both systems, bacterial biofilms form within 6-8 hours after inoculation. Visualization of the biofilm is enhanced by the use of P. aeruginosa strains constitutively expressing green fluorescent protein (GFP). The Static and Flow Cell Co-culture Biofilm assays are model systems for early P. aeruginosa infection of the Cystic Fibrosis (CF) lung, and these techniques allow different aspects of P. aeruginosa biofilm formation and virulence to be studied, including biofilm cytotoxicity, measurement of biofilm CFU, and staining and visualizing the biofilm.

Co-culture Models of Pseudomonas aeruginosa Biofilms Grown on Live Human Airway Cells

This paper describes different methods of growing Pseudomonas aeruginosa biofilms on cultured human airway epithelial cells. These protocols can be adapted to study different aspects of biofilm formation, including visualization of the biofilm, staining of the biofilm, measuring the colony forming units (CFU) of the biofilm, and studying biofilm cytotoxicity.

Co-culture des modèles Pseudomonas aeruginosa Les biofilms Cultivé sur le Live cellules des voies respiratoires de l&#39;homme

Bacterial biofilms have been associated with a number of different human diseases, but biofilm development has generally been studied on non-living ...

Recherche

Immunologie et infection

Measuring Bacterial Load and Immune Responses in Mice Infected with Listeria monocytogenes

Listeria monocytogenes (Listeria) is a Gram-positive facultative intracellular pathogen1. Mouse studies typically employ intravenous injection of Listeria, which results in systemic infection2. After injection, Listeria quickly disseminates to the spleen and liver due to uptake by CD8&alpha;+ dendritic cells and Kupffer cells3,4. Once phagocytosed, various bacterial proteins enable Listeria to escape the phagosome, survive within the cytosol, and infect neighboring cells5. During the first three days of infection, different innate immune cells (e.g. monocytes, neutrophils, NK cells, dendritic cells) mediate bactericidal mechanisms that minimize Listeria proliferation. CD8+ T cells are subsequently recruited and responsible for the eventual clearance of Listeria from the host, typically within 10 days of infection6.
Successful clearance of Listeria from infected mice depends on the appropriate onset of host immune responses6	. There is a broad range of sensitivities amongst inbred mouse strains7,8. Generally, mice with increased susceptibility to Listeria infection are less able to control bacterial proliferation, demonstrating increased bacterial load and/or delayed clearance compared to resistant mice. Genetic studies, including linkage analyses and knockout mouse strains, have identified various genes for which sequence variation affects host responses to Listeria infection6,8-14. Determination and comparison of infection kinetics between different mouse strains is therefore an important method for identifying host genetic factors that contribute to immune responses against Listeria. Comparison of host responses to different Listeria strains is also an effective way to identify bacterial virulence factors that may serve as potential targets for antibiotic therapy or vaccine design.
We describe here a straightforward method for measuring bacterial load (colony forming units [CFU] per tissue) and preparing single-cell suspensions of the liver and spleen for FACS analysis of immune responses in Listeria-infected mice. This method is particularly useful for initial characterization of Listeria infection in novel mouse strains, as well as comparison of immune responses between different mouse strains infected with Listeria. We use the Listeria monocytogenes EGD strain15 that, when cultured on blood agar, exhibits a characteristic halo zone around each colony due to &beta;-hemolysis1 (Figure 1). Bacterial load and immune responses can be determined at any time-point after infection by culturing tissue homogenate on blood agar plates and preparing tissue cell suspensions for FACS analysis using the protocols described below. We would note that individuals who are immunocompromised or pregnant should not handle Listeria, and the relevant institutional biosafety committee and animal facility management should be consulted before work commences.

Measuring Bacterial Load and Immune Responses in Mice Infected with Listeria monocytogenes

Listeria monocytogenes is a model organism for studying immune responses and genetic susceptibility to intracellular bacteria in mice. This method enables one to measure bacterial load and generate single-cell suspensions of the liver and spleen from mice for FACS analysis to determine changes in immune cells due to Listeria infection.

Mesure de la charge bactérienne et les réponses immunitaires chez des souris infectées avec des Listeria monocytogenes</em

Listeria monocytogenes (Listeria) is a Gram-positive facultative intracellular pathogen1. Mouse studies typically employ intravenous injection of ...

Affinity Purification of Influenza Virus Ribonucleoprotein Complexes from the Chromatin of Infected Cells

Like all negative-strand RNA viruses, the genome of influenza viruses is packaged in the form of viral ribonucleoprotein complexes (vRNP), in which the single-stranded genome is encapsidated by the nucleoprotein (NP), and associated with the trimeric polymerase complex consisting of the PA, PB1, and PB2 subunits. However, in contrast to most RNA viruses, influenza viruses perform viral RNA synthesis in the nuclei of infected cells. Interestingly, viral mRNA synthesis uses cellular pre-mRNAs as primers, and it has been proposed that this process takes place on chromatin1. Interactions between the viral polymerase and the host RNA polymerase II, as well as between NP and host nucleosomes have also been characterized1,2.
Recently, the generation of recombinant influenza viruses encoding a One-Strep-Tag genetically fused to the C-terminus of the PB2 subunit of the viral polymerase (rWSN-PB2-Strep3) has been described. These recombinant viruses allow the purification of PB2-containing complexes, including vRNPs, from infected cells. To obtain purified vRNPs, cell cultures are infected, and vRNPs are affinity purified from lysates derived from these cells. However, the lysis procedures used to date have been based on one-step detergent lysis, which, despite the presence of a general nuclease, often extract chromatin-bound material only inefficiently. 
Our preliminary work suggested that a large portion of nuclear vRNPs were not extracted during traditional cell lysis, and therefore could not be affinity purified. To increase this extraction efficiency, and to separate chromatin-bound from non-chromatin-bound nuclear vRNPs, we adapted a step-wise subcellular extraction protocol to influenza virus-infected cells. Briefly, this procedure first separates the nuclei from the cell and then extracts soluble nuclear proteins (here termed the "nucleoplasmic" fraction). The remaining insoluble nuclear material is then digested with Benzonase, an unspecific DNA/RNA nuclease, followed by two salt extraction steps: first using 150 mM NaCl (termed "ch150"), then 500 mM NaCl ("ch500") (Fig. 1). These salt extraction steps were chosen based on our observation that 500 mM NaCl was sufficient to solubilize over 85% of nuclear vRNPs yet still allow binding of tagged vRNPs to the affinity matrix.
After subcellular fractionation of infected cells, it is possible to affinity purify PB2-tagged vRNPs from each individual fraction and analyze their protein and RNA components using Western Blot and primer extension, respectively. Recently, we utilized this method to discover that vRNP export complexes form during late points after infection on the chromatin fraction extracted with 500 mM NaCl (ch500)3.

Influenza viruses replicate their RNA genome in association with host-cell chromatin. Here, we present a method to purify intact viral ribonucleoprotein complexes from the chromatin of infected cells. Purified viral complexes can be analyzed by both Western blot and primer extension of protein and RNA content, respectively.

Purification par affinité des complexes virus de la grippe ribonucléoprotéiques de la chromatine des cellules infectées

Like all negative-strand RNA viruses, the genome of influenza viruses is packaged in the form of viral ribonucleoprotein complexes (vRNP), in which the ...

Purification of Pathogen Vacuoles from Legionella-infected Phagocytes

The opportunistic pathogen Legionella pneumophila is an amoeba-resistant bacterium, which also replicates in alveolar macrophages thus causing the severe pneumonia "Legionnaires' disease"1. In protozoan and mammalian phagocytes, L. pneumophila employs a conserved mechanism to form a specific, replication-permissive compartment, the "Legionella-containing vacuole" (LCV). LCV formation requires the bacterial Icm/Dot type IV secretion system (T4SS), which translocates as many as 275 "effector" proteins into host cells. The effectors manipulate host proteins as well as lipids and communicate with secretory, endosomal and mitochondrial organelles2-4.
The formation of LCVs represents a complex, robust and redundant process, which is difficult to grasp in a reductionist manner. An integrative approach is required to comprehensively understand LCV formation, including a global analysis of pathogen-host factor interactions and their temporal and spatial dynamics. As a first step towards this goal, intact LCVs are purified and analyzed by proteomics and lipidomics.
The composition and formation of pathogen-containing vacuoles has been investigated by proteomic analysis using liquid chromatography or 2-D gel electrophoresis coupled to mass-spectrometry. Vacuoles isolated from either the social soil amoeba Dictyostelium discoideum or mammalian phagocytes harboured Leishmania5, Listeria6, Mycobacterium7, Rhodococcus8, Salmonella9 or Legionella spp.10. However, the purification protocols employed in these studies are time-consuming and tedious, as they require e.g. electron microscopy to analyse LCV morphology, integrity and purity. Additionally, these protocols do not exploit specific features of the pathogen vacuole for enrichment.
The method presented here overcomes these limitations by employing D. discoideum producing a fluorescent LCV marker and by targeting the bacterial effector protein SidC, which selectively anchors to the LCV membrane by binding to phosphatidylinositol 4-phosphate (PtdIns(4)P)3,11 . LCVs are enriched in a first step by immuno-magnetic separation using an affinity-purified primary antibody against SidC and a secondary antibody coupled to magnetic beads, followed in a second step by a classical Histodenz density gradient centrifugation12,13 (Fig. 1).
A proteome study of isolated LCVs from D. discoideum revealed more than 560 host cell proteins, including proteins associated with phagocytic vesicles, mitochondria, ER and Golgi, as well as several GTPases, which have not been implicated in LCV formation before13. LCVs enriched and purified with the protocol outlined here can be further analyzed by microscopy (immunofluorescence, electron microscopy), biochemical methods (Western blot) and proteomic or lipidomic approaches.

Purification of Pathogen Vacuoles from Legionella-infected Phagocytes

This article describes a method for the isolation and purification of intact Legionella-containing vacuoles (LCVs) from amoeba and macrophages. The two-step protocol comprises LCV enrichment by immuno-magnetic separation using an antibody against a bacterial LCV marker and further purification by density gradient centrifugation.

Purification de vacuoles agent pathogène à partir<em&gt; Legionella</em&gt; Infectées par les phagocytes

The opportunistic pathogen Legionella pneumophila is an amoeba-resistant bacterium, which also replicates in alveolar macrophages thus causing the severe ...

Oral Transmission of Listeria monocytogenes in Mice via Ingestion of Contaminated Food

L. monocytogenes are facultative intracellular bacterial pathogens that cause food borne infections in humans. Very little is known about the gastrointestinal phase of listeriosis due to the lack of a small animal model that closely mimics human disease. This paper describes a novel mouse model for oral transmission of L. monocytogenes. Using this model, mice fed L. monocytogenes-contaminated bread have a discrete phase of gastrointestinal infection, followed by varying degrees of systemic spread in susceptible (BALB/c/By/J) or resistant (C57BL/6) mouse strains. During the later stages of the infection, dissemination to the gall bladder and brain is observed. The food borne model of listeriosis is highly reproducible, does not require specialized skills, and can be used with a wide variety of bacterial isolates and laboratory mouse strains. As such, it is the ideal model to study both virulence strategies used by L. monocytogenes to promote intestinal colonization, as well as the host response to invasive food borne bacterial infection.

Oral Transmission of Listeria monocytogenes in Mice via Ingestion of Contaminated Food

This paper describes a novel method for oral infection of mice using Listeria monocytogenes-contaminated food. The protocol can readily be adapted for use with other food borne bacterial pathogens.

La transmission orale de<em&gt; Listeria monocytogenes</em&gt; Chez la souris par l&#39;ingestion d&#39;aliments contaminés

L. monocytogenes are facultative intracellular bacterial pathogens that cause food borne infections in humans. Very little is known about the ...

Bone Marrow-derived Macrophage Production

Macrophages are critical components of the innate and adaptive immune responses, and they are the first line of defense against foreign invaders because of their powerful microbicidal activities. Macrophages are widely distributed throughout the body and are present in the lymphoid organs, liver, lungs, gastrointestinal tract, central nervous system, bone, and skin. Because of their repartition, they participate in a wide range of physiological and pathological processes. Macrophages are highly versatile cells that are able to recognize microenvironmental alterations and to maintain tissue homeostasis. Numerous pathogens have evolved mechanisms to use macrophages as Trojan horses to survive, replicate in, and infect both humans and animals and to propagate throughout the body. The recent explosion of interest in evolutionary, genetic, and biochemical aspects of host-pathogen interactions has renewed scientific attention regarding macrophages. Here, we describe a procedure to isolate and cultivate macrophages from murine bone marrow that will provide large numbers of macrophages for studying host-pathogen interactions as well as other processes.

Macrophages have long been recognized as a critical component of the innate and adaptive immune responses. The recent explosion of knowledge pertaining to evolutionary, genetic, and biochemical aspects of the interaction between macrophages and microbes has renewed scientific attention to macrophages. This article describes a method to differentiate macrophages from mouse bone marrow.

Dérivées de moelle osseuse Macrophages production

Macrophages are critical components of the innate and adaptive immune responses, and they are the first line of defense against foreign invaders because ...

Imaging InlC Secretion to Investigate Cellular Infection by the Bacterial Pathogen Listeria monocytogenes

Bacterial intracellular pathogens can be conceived as molecular tools to dissect cellular signaling cascades due to their capacity to exquisitely manipulate and subvert cell functions which are required for the infection of host target tissues. Among these bacterial pathogens, Listeria monocytogenes is a Gram positive microorganism that has been used as a paradigm for intracellular parasitism in the characterization of cellular immune responses, and which has played instrumental roles in the discovery of molecular pathways controlling cytoskeletal and membrane trafficking dynamics. In this article, we describe a robust microscopical assay for the detection of late cellular infection stages of L. monocytogenes based on the fluorescent labeling of InlC, a secreted bacterial protein which accumulates in the cytoplasm of infected cells; this assay can be coupled to automated high-throughput small interfering RNA screens in order to characterize cellular signaling pathways involved in the up- or down-regulation of infection.

Imaging InlC Secretion to Investigate Cellular Infection by the Bacterial Pathogen Listeria monocytogenes

Listeria monocytogenes is a Gram positive bacterial pathogen frequently used as a major model for the study of intracellular parasitism. Imaging late L. monocytogenes infection stages within the context of small-interfering RNA screens allows for the global study of cellular pathways required for bacterial infection of target host cells.

Imagerie RICL sécrétion d&#39;enquêter sur l&#39;infection cellulaire par le pathogène bactérien<em&gt; Listeria monocytogenes</em

Bacterial intracellular  pathogens can be conceived as molecular tools to dissect cellular signaling  cascades due to their capacity to exquisitely ...

Isolation, Identification, and Purification of Murine Thymic Epithelial Cells

The thymus is a vital organ for T lymphocyte development. Of thymic stromal cells, thymic epithelial cells (TECs) are particularly crucial at multiple stages of T cell development: T cell commitment, positive selection and negative selection. However, the function of TECs in the thymus remains incompletely understood. In the article, we provide a method to isolate TEC subsets from fresh mouse thymus using a combination of mechanical disruption and enzymatic digestion. The method allows thymic stromal cells and thymocytes to be efficiently released from cell-cell and cell-extracellular matrix connections and to form a single-cell suspension. Using the isolated cells, multiparameter flow cytometry can be applied to identification and characterization of TECs and dendritic cells. Because TECs are a rare cell population in the thymus, we also describe an effective way to enrich and purify TECs by depleting thymocytes, the most abundant cell type in the thymus. Following the enrichment, cell sorting time can be decreased so that loss of cell viability can be minimized during purification of TECs. Purified cells are suitable for various downstream analyses like Real Time-PCR, Western blot and gene expression profiling. The protocol will promote research of TEC function and as well as the development of in vitro T cell reconstitution.

Here we describe an efficient method for isolation, identification, and purification of mouse thymic epithelial cells (TECs). The protocol can be utilized for studies of thymus function for normal T cell development, thymus dysfunction, and T cell reconstitution.

Isolement, identification et la purification de cellules murines thymique épithéliales

The thymus is a vital organ for T lymphocyte development. Of thymic stromal cells, thymic epithelial cells (TECs) are particularly crucial at multiple ...

Assessing Bacterial Invasion of Cardiac Cells in Culture and Heart Colonization in Infected Mice Using Listeria monocytogenes

Listeria monocytogenes is a Gram-positive facultative intracellular pathogen that is capable of causing serious invasive infections in immunocompromised patients, the elderly, and pregnant women. The most common manifestations of listeriosis in humans include meningitis, encephalitis, and fetal abortion. A significant but much less documented sequelae of invasive L. monocytogenes infection involves the heart. The death rate from cardiac illness can be up to 35% despite treatment, however very little is known regarding L. monocytogenes colonization of cardiac tissue and its resultant pathologies. In addition, it has recently become apparent that subpopulations of L. monocytogenes have an enhanced capacity to invade and grow within cardiac tissue. This protocol describes in detail in vitro and in vivo methods that can be used for assessing cardiotropism of L. monocytogenes isolates. Methods are presented for the infection of H9c2 rat cardiac myoblasts in tissue culture as well as for the determination of bacterial colonization of the hearts of infected mice. These methods are useful not only for identifying strains with the potential to colonize cardiac tissue in infected animals, but may also facilitate the identification of bacterial gene products that serve to enhance cardiac cell invasion and/or drive changes in heart pathology. These methods also provide for the direct comparison of cardiotropism between multiple L. monocytogenes strains.

Assessing Bacterial Invasion of Cardiac Cells in Culture and Heart Colonization in Infected Mice Using Listeria monocytogenes

Listeria monocytogenes causes fetal infections in pregnant women and meningitis in susceptible populations. Subpopulations of bacteria can colonize cardiac tissue, causing myocarditis in patients and laboratory animals. Here we present a protocol that describes how to assess L. monocytogenes cardiac cell invasion in vitro and cardiac colonization in infected animals.

Évaluation de l’invasion bactérienne des cellules cardiaques en culture et colonisation cardiaque chez des souris infectées à l’aide de Listeria monocytogenes

Listeria monocytogenes is a Gram-positive facultative intracellular pathogen that is capable of causing serious invasive infections in immunocompromised ...

Experimental Infection with Listeria monocytogenes as a Model for Studying Host Interferon-&#947; Responses

L. monocytogenes is a gram-positive bacterium that is a cause of food borne disease in humans. Experimental infection of mice with this pathogen has been highly informative on the role of innate and adaptive immune cells and specific cytokines in host immunity against intracellular pathogens. Production of IFN-&#947; by innate cells during sublethal infection with L. monocytogenes is important for activating macrophages and early control of the pathogen1-3. In addition, IFN-&#947; production by adaptive memory lymphocytes is important for priming the activation of innate cells upon reinfection4. The L. monocytogenes infection model thus serves as a great tool for investigating whether new therapies that are designed to increase IFN-&#947; production have an impact on IFN-&#947; responses in vivo and have productive biological effects such as increasing bacterial clearance or improving mouse survival from infection. Described here is a basic protocol for how to conduct intraperitoneal infections of C57BL/6J mice with the EGD strain of L. monocytogenes and to measure IFN-&#947; production by NK cells, NKT cells, and adaptive lymphocytes by flow cytometry. In addition, procedures are described to: (1) grow and prepare the bacteria for inoculation, (2) measure bacterial load in the spleen and liver, and (3) measure animal survival to endpoints. Representative data are also provided to illustrate how this infection model can be used to test the effect of specific agents on IFN-&#947; responses to L. monocytogenes and survival of mice from this infection.

This protocol describes how to inoculate C57BL/6J mice with the EGD strain of Listeria monocytogenes (L. monocytogenes) and to measure interferon-&#947; (IFN-&#947;) responses by natural killer (NK) cells, natural killer T (NKT) cells, and adaptive T lymphocytes post-infection. This protocol also describes how to conduct survival studies in mice after infection with a modified LD50 dose of the pathogen.

Infection expérimentale avec<em&gt; Listeria monocytogenes</em&gt; En tant que modèle pour l&#39;étude de l&#39;hôte Réponses Interféron-y

L. monocytogenes is a gram-positive bacterium that is a cause of food borne disease in humans. Experimental infection of mice with this pathogen has been ...

ARN Purification de Intracellulairement Grown

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Co-culture des modèles Pseudomonas aeruginosa Les biofilms Cultivé sur le Live cellules des voies respiratoires de l'homme

Mesure de la charge bactérienne et les réponses immunitaires chez des souris infectées avec des Listeria monocytogenes

Purification par affinité des complexes virus de la grippe ribonucléoprotéiques de la chromatine des cellules infectées

Purification de vacuoles agent pathogène à partir

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