Ces travaux ont été soutenus financièrement par les NIH (1 R01 AI095338-01A1).

Les auteurs déclarent qu’ils n’ont pas d’intérêts financiers concurrents.

La migration des neutrophiles à travers les surfaces épithéliales muqueuses est une caractéristique commune dans la pathologie de la maladie après une infection par des agents pathogènes bactériens3. La méthodologie décrite ici offre une approche rapide et simple pour isoler expérimentalement cet événement discret en utilisant un système d’analyse de coculture in vitro dérivé de cellules humaines qui modélise une caractéristique du processus inflammatoire déclenché par des infecti...

Les surfaces muqueuses servent de barrières physiques et immunologiques offrant une protection contre les menaces externes omniprésentes dans l’environnement1,2. Cette barrière épithéliale protectrice peut être compromise lorsque des organismes pathogènes envahissent2. Dans le cas d’un agent pathogène bactérien, cette rencontre provoque souvent un processus inflammatoire en activant le système immunitaire inné et en déclenchant une mobilisation rapide des granulocytes premiers répondants appelés neutrophiles2-4. Les agents chimiotactiques facilitant le recrutement des neutrophiles sont produits en partie par les cellules épithéliales muqueuses cherchant à débarrasser l’hôte de l’agent pathogène incriminé2-4. Infiltration excessive ou non résolue de neutrophiles de la surface épithéliale muqueuse peut provoquer une pathologie importante1,5. Il s’agit d’une conséquence des lésions tissulaires non spécifiques causées par l’arsenal neutrophile antibactérien5-7. Dans de tels cas, la capacité bactérienne de clairance des neutrophiles est éclipsée par la destruction du tissu de centre serveur pendant une insulte infectieuse.  La perturbation de la fonction protectrice de la barrière épithéliale peut entraîner une exposition accrue des tissus sous-jacents à des micro-organismes et/ou à des toxines, exacerbant davantage la pathologie de la maladie8,9. Ces conséquences peuvent être observées dans plusieurs systèmes d’organes, y compris le poumon et le tube digestif1,5. En outre, les conditions inflammatoires non infectieuses telles que les épisodes sévères d’asthme, la maladie pulmonaire obstructive chronique (MPOC), le syndrome de détresse respiratoire aiguë (SDRA) et la maladie inflammatoire de l’intestin (MII) sont marquées par la rupture pathologique de la barrière épithéliale muqueuse par une réponse neutrophile excessive4,5,10-12.
Le processus complexe de recrutement des neutrophiles suivant une infection muqueuse implique plusieurs étapes compartimentées1,5,13,14. Tout d’abord, les neutrophiles doivent s’écarter de la circulation via une série d’interactions de cellule à cellule qui facilitent la migration trans-endothéliale1,13. Les neutrophiles naviguent ensuite dans l’espace interstitiel existant contenant la matrice extracellulaire1,14. Pour atteindre la lumière de la muqueuse infectée, les neutrophiles doivent alors migrer à travers la barrière épithéliale1,4,5. Ce phénomène complexe en plusieurs étapes est souvent étudié dans son ensemble à l’aide de modèles animaux in vivo d’infection15. De tels modèles sont utiles pour établir la nécessité de facteurs spécifiques, tels que les chimiokines, les molécules d’adhésion ou les voies de signalisation qui participent au processus global, mais sont largement inadéquats pour résoudre les contributions moléculaires critiques pour chaque étape compartimentée distincte16. Les systèmes in vitro coculturels modélisant la migration trans-endothéliale, trans-matricielle ou trans-épithéliale des neutrophiles ont été particulièrement utiles à cet égard1,14,16,17.
Un système robuste de dosage de coculture a été développé dans le but de déchiffrer les mécanismes responsables de la migration transépithéliale des neutrophiles en réponse à l’infection pathogène18-22. Ce modèle consiste à infecter la surface apicale des couches de cellules épithéliales humaines polarisées avec un agent pathogène bactérien suivie de l’application de neutrophiles humains fraîchement isolés sur la surface basolatérale18-22. Les neutrophiles migrent à travers la barrière épithéliale en réponse aux produits chimiotactiques épithéliaux-dérivés sécrétés après l’infection pathogène18,21-23. Ce système modèle a été utilisé en utilisant des cultures épithéliales intestinales et pulmonaires exposées à des agents pathogènes bactériens spécifiques aux tissus appropriés et a dévoilé de nouveaux mécanismes moléculaires probablement importants pour le processus de recrutement des neutrophiles lors de l’infection muqueuse3,8,19,24-28. La force de ce modèle de coculture in vitro est qu’une approche réductionniste permet au chercheur de manipuler expérimentalement l’agent pathogène, la barrière épithéliale et/ou le neutrophile dans un système bien contrôlé, hautement reproductible et assez peu coûteux. Les informations recueillies à partir de cette approche peuvent être efficacement exploitées pour effectuer une analyse ciblée des événements compartimentés lors du recrutement des neutrophiles à l’aide de modèles d’infection in vivo 22,29,30.
Cet article démontre les étapes multiples nécessaires pour que l’établissement réussi de ce modèle reproductible explore la migration trans-épithéliale induite par neutrophile par microbe pathogène. Des barrières épithéliales de poumon infectées avec l’agent pathogène Pseudomonas aeruginosa sont présentées dans cet article ; cependant, d’autres épithéliums tissulaires et agents pathogènes peuvent être substitués avec des modifications mineures. L’ensemencement et la culture des couches polarisées de cellules épithéliales de poumon sur les filtres perméables enrobés de collagène inversés sont détaillés ci-dessous, de même que la croissance de l’aeruginosa pathogène de P. et l’isolement des neutrophiles du sang total. Comment ces composants sont combinés pour observer la migration trans-épithéliale induite par le microbe pathogène de neutrophile est présentée avec les contrôles positifs et négatifs appropriés pour établir une analyse reproductible. La polyvalence de cette approche pour examiner de divers aspects de la migration trans-épithéliale induite par neutrophile par microbe pathogène est discutée concernant des études spécifiques dans la littérature.

<table border="0" cellpadding="0" cellspacing="0" width="1470">
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	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">NCl-H292 cells</td>
			<td style="width:147px;">ATCC</td>
			<td style="width:137px;">CRL-1848</td>
			<td style="width:667px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">RPMI-1640 medium</td>
			<td style="width:147px;">ATCC</td>
			<td style="width:137px;">30-2001</td>
			<td style="width:667px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Pseudomonas aeruginosa PAO1</td>
			<td style="width:147px;">ATCC</td>
			<td style="width:137px;">#47085</td>
			<td style="width:667px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Escherichia coli MC1000</td>
			<td style="width:147px;">ATCC</td>
			<td style="width:137px;">#39531</td>
			<td style="width:667px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">D-PBS (1x) liquid</td>
			<td style="width:147px;">Invitrogen</td>
			<td style="width:137px;">14190-144</td>
			<td style="width:667px;">without calcium and magnesium</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Heat Inactivated Fetal bovine serum</td>
			<td style="width:147px;">Invitrogen</td>
			<td style="width:137px;">10082-147</td>
			<td style="width:667px;">10% added to culture medium</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Penicillin-Streptomycin</td>
			<td style="width:147px;">Invitrogen</td>
			<td style="width:137px;">15140-122</td>
			<td style="width:667px;">100x: 10,000 units of penicillin and 10,000 &#181;g of streptomycin per ml.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Trypsin-EDTA (0.05%)</td>
			<td style="width:147px;">Invitrogen</td>
			<td style="width:137px;">25300-062</td>
			<td style="width:667px;">50 ml aliquots are stored frozen at -20 &#186;C.&#160; Aliquot in use can be stored at 4 &#186;C short-term.&#160;&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Hank&#39;s Balanced Salt Solution - HBSS(-)</td>
			<td style="width:147px;">Invitrogen</td>
			<td style="width:137px;">14175-079</td>
			<td style="width:667px;">Sterile, without calcium and magnesium</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Trypan Blue Solution</td>
			<td style="width:147px;">Invitrogen</td>
			<td style="width:137px;">15250-061.</td>
			<td style="width:667px;">Stock = 0.4%</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Collagen, Rat Tail</td>
			<td style="width:147px;">Invitrogen</td>
			<td style="width:137px;">A10483-01</td>
			<td style="width:667px;">Can also be isolated in the laboratory directly from the tails of rats using standard protocols</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Citric acid</td>
			<td style="width:147px;">Sigma-Aldrich&#160;</td>
			<td style="width:137px;">C1909-500G</td>
			<td style="width:667px;">Component of 1 M citrate buffer and acid citrate dextrose (ACD) solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Sodium Citrate</td>
			<td style="width:147px;">Sigma-Aldrich&#160;</td>
			<td style="width:137px;">S4641-500G</td>
			<td style="width:667px;">Component of 1 M citrate buffer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Dextrose anhydrous</td>
			<td style="width:147px;">Sigma-Aldrich&#160;</td>
			<td style="width:137px;">D8066-250G</td>
			<td style="width:667px;">Component of acid citrate dextrose (ACD) solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Ammonium Chloride</td>
			<td style="width:147px;">Sigma-Aldrich&#160;</td>
			<td style="width:137px;">213330-500G</td>
			<td style="width:667px;">Component of red blood cell (RBC) lysis buffer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Sodium bicarbonate</td>
			<td style="width:147px;">Sigma-Aldrich&#160;</td>
			<td style="width:137px;">S6014-500G</td>
			<td style="width:667px;">Component of red blood cell (RBC) lysis buffer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">EDTA</td>
			<td style="width:147px;">Sigma-Aldrich&#160;</td>
			<td style="width:137px;">ED-100G</td>
			<td style="width:667px;">Component of red blood cell (RBC) lysis buffer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">HBSS(+) powder</td>
			<td style="width:147px;">Sigma-Aldrich&#160;</td>
			<td style="width:137px;">H1387-10L</td>
			<td style="width:667px;">Key component of HBSS+</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">HEPES</td>
			<td style="width:147px;">Sigma-Aldrich&#160;</td>
			<td style="width:137px;">H3375-500G</td>
			<td style="width:667px;">Component of HBSS+</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Sigmacote</td>
			<td style="width:147px;">Sigma-Aldrich&#160;</td>
			<td style="width:137px;">SL2-25ML</td>
			<td style="width:667px;">Follow vendor instructions to coat glass pipette tips</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Triton X-100</td>
			<td style="width:147px;">Sigma-Aldrich&#160;</td>
			<td style="width:137px;">T-9284</td>
			<td style="width:667px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">2,2&#39;-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS)</td>
			<td style="width:147px;">Sigma-Aldrich&#160;</td>
			<td style="width:137px;">A9941-50TAB</td>
			<td style="width:667px;">Key component of ABTS substrate solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">30% Hydrogen Peroxide Solution</td>
			<td style="width:147px;">Sigma-Aldrich&#160;</td>
			<td style="width:137px;">H1009-100ML</td>
			<td style="width:667px;">Component of ABTS substrate solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">N-Formyl-Met-Leu-Phe (fMLP or fMLF)</td>
			<td style="width:147px;">Sigma-Aldrich&#160;</td>
			<td style="width:137px;">F-3506</td>
			<td style="width:667px;">A Stock solution of 10 mM in DMSO should be prepared and aliquots stored at -20 &#186;C.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Gelatin Type B</td>
			<td style="width:147px;">Fisher Scientific</td>
			<td style="width:137px;">M-12026</td>
			<td style="width:667px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Pseudomonas isolation agar&#160;</td>
			<td style="width:147px;">Fisher Scientific</td>
			<td style="width:137px;">DF0927-17-1</td>
			<td style="width:667px;">Follow manufacturer&#8217;s instructions to make PIA plates</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Ficoll-Paque PLUS&#160;</td>
			<td style="width:147px;">Fisher Scientific</td>
			<td style="width:137px;">45-001-749</td>
			<td style="width:667px;">Optional, can improve neutrophil purity</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;"></td>
			<td style="width:147px;"></td>
			<td style="width:137px;"></td>
			<td style="width:667px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;"></td>
			<td style="width:147px;"></td>
			<td style="width:137px;"></td>
			<td style="width:667px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;"></td>
			<td style="width:147px;"></td>
			<td style="width:137px;"></td>
			<td style="width:667px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;"></td>
			<td style="width:147px;"></td>
			<td style="width:137px;"></td>
			<td style="width:667px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;"></td>
			<td style="width:147px;"></td>
			<td style="width:137px;"></td>
			<td style="width:667px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Name of Material / Equipment</td>
			<td style="width:147px;">Company</td>
			<td style="width:137px;">Catalog Number</td>
			<td style="width:667px;">Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">24-well migration plate</td>
			<td style="width:147px;">Corning Incorporated</td>
			<td style="width:137px;">#3524</td>
			<td style="width:667px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">24-well wash plate</td>
			<td style="width:147px;">Falcon</td>
			<td style="width:137px;">35-1147</td>
			<td style="width:667px;">Can be reused if soaked in 70% ethanol and washed thoroughly prior to reuse</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">96-well plate</td>
			<td style="width:147px;">Fisher Scientific</td>
			<td style="width:137px;">#12565501</td>
			<td style="width:667px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:520px;">Transwell Permeable Supports&#160;</td>
			<td style="width:147px;">Corning Incorporated</td>
			<td style="width:137px;">#3415</td>
			<td style="width:667px;">Polycarbonate; Diameter: 6.5 mm; Growth area: 0.33 cm2; Dish style: 24-well plate; Pore size: 3.0 &#181;m</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Petri dish</td>
			<td style="width:147px;">Falcon</td>
			<td style="width:137px;">35-1013</td>
			<td style="width:667px;">Each Petri dish holds 24 inverted 0.33 cm2 Transwells.&#160;&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">500 ml 0.2 &#956;m filter / flask</td>
			<td style="width:147px;">Fisher Scientific</td>
			<td style="width:137px;">09-740-25A</td>
			<td style="width:667px;">To sterilize acid citrate dextrose (ACD) solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">5-3/4 in glass Pasteur pipette</td>
			<td style="width:147px;">Fisher Scientific</td>
			<td style="width:137px;">13-678-20A</td>
			<td style="width:667px;">Coat tips with Sigmacote prior to use</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Hemostat</td>
			<td style="width:147px;">Fisher Scientific</td>
			<td style="width:137px;">13-812-14</td>
			<td style="width:667px;">Curved, Serrated</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Invertoskop Inverted Microscope</td>
			<td style="width:147px;">Zeiss</td>
			<td style="width:137px;">#342222</td>
			<td style="width:667px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:520px;">Versa-Max Microplate Reader</td>
			<td style="width:147px;">Molecular Devices</td>
			<td style="width:137px;">#432789</td>
			<td style="width:667px;"></td>
		</tr>
	</tbody>
</table>

in vitro coculture assay to assess pathogen induced neutrophil trans-epithelial migration

Les surfaces muqueuses servent de barrières protectrices contre les organismes pathogènes. Les réponses immunitaires innées sont activées lors de la détection de l’agent pathogène conduisant à l’infiltration de tissus avec des cellules inflammatoires migratrices, principalement des neutrophiles. Ce processus a le potentiel d’être destructeur pour les tissus s’il est excessif ou maintenu dans un état non résolu.  Des modèles in vitro cocultured peuvent être utilisés pour étudier les mécanismes moléculaires uniques impliqués dans la migration trans-épithéliale induite par l’agent pathogène de neutrophile. Ce type de modèle offre une polyvalence dans la conception expérimentale avec possibilité de manipulation contrôlée de l’agent pathogène, de la barrière épithéliale ou des neutrophiles. L’infection pathogène de la surface apicale des monocouches épithéliales polarisées cultivées sur des filtres perméables de transwell incite basolateral physiologiquement approprié à la migration trans-épithéliale apicale des neutrophiles appliquées à la surface basolateral. Le modèle in vitro décrit ici démontre les étapes multiples nécessaires pour démontrer la migration de neutrophile à travers une monocouche épithéliale polarisée de poumon qui a été infectée par le pathogène P. aeruginosa (PAO1). L’ensemencement et la culture des transwells perméables avec les cellules épithéliales dérivées humaines de poumon est décrit, avec l’isolement des neutrophiles du sang humain total et la culture de PAO1 et de K12 E. coli non pathogène (MC1000).  Le processus émigrationnel et l’analyse quantitative des neutrophiles migrés avec succès qui ont été mobilisés en réponse à l’infection pathogène sont montrés avec des données représentatives, y compris des contrôles positifs et négatifs. Ce système de modèle in vitro peut être manipulé et appliqué à d’autres surfaces muqueuses. Les réponses inflammatoires qui impliquent l’infiltration excessive de neutrophile peuvent être destructives aux tissus de centre serveur et peuvent se produire en l’absence des infections pathogènes. Une meilleure compréhension des mécanismes moléculaires qui favorisent la migration transépithéliale des neutrophiles par la manipulation expérimentale du système d’analyse de coculture in vitro décrit ici a un potentiel significatif d’identifier de nouvelles cibles thérapeutiques pour une gamme de maladies infectieuses et inflammatoires muqueuses.

Plusieurs études ont démontré que les couches épithéliales infectées par des agents pathogènes facilitent la migration transépithéliale des neutrophiles3,8,19,24-28,31,32. Ceci se produit par l’intermédiaire d’une induction pathogène-spécifique d’un gradient chimiotactique cellule-dérivé de cellules épithéliales de neutrophile3,23. Par exemple, P. aeruginosa pathogène interagissant avec la surface apicale des cellules épithéliales pulmonaires provoque la migration d...

Watch this Scientific Journal Video about In vitro Coculture Assay to Assess Pathogen Induced Neutrophil Trans-epithelial Migration at JoVE.com

In vitro Coculture Assay to Assess Pathogen Induced Neutrophil Trans-epithelial Migration

La migration trans-épithéliale de neutrophile en réponse à l’infection bactérienne muqueuse contribue aux dommages épithéliaux et à la maladie clinique. Un modèle in vitro a été développé qui combine l’agent pathogène, les neutrophiles humains, et les couches humaines polarisées de cellules épithéliales cultivées sur des filtres de transwell pour faciliter des investigations vers démêler les mécanismes moléculaires orchestrant ce phénomène.

In vitro Essai de coculture pour évaluer la migration transépithéliale des neutrophiles induite par l’agent pathogène

Mucosal surfaces serve as protective barriers against pathogenic organisms.&#160;Innate immune responses are activated upon sensing pathogen leading to ...

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JoVE Journal

Immunology and Infection

In vitro Coculture Assay to Assess Pathogen Induced Neutrophil Trans-epithelial Migration

17.4K vues.  Harvard Medical School. La migration trans-épithéliale de neutrophile en réponse à l’infection bactérienne muqueuse contribue aux dommages épithéliaux et à la maladie clinique. Un modèle in vitro a été développé qui combine l’agent pathogène, les neutrophiles humains, et les couches humaines polarisées de cellules épithéliales cultivées sur des filtres de transwell pour faciliter des investigations vers démêler les mécanismes moléculaires orchestrant ce phéno...

Vidéo: In vitro Coculture Assay to Assess Pathogen Induced Neutrophil Trans-epithelial Migration

Assay for Pathogen-Associated Molecular Pattern (PAMP)-Triggered Immunity (PTI) in Plants

To perceive potential pathogens in their environment, plants use pattern recognition receptors (PRRs) present on their plasma membranes. PRRs recognize conserved microbial features called pathogen-associated molecular patterns (PAMPs) and this detection leads to PAMP-triggered immunity (PTI), which effectively prevents colonization of plant tissues by non-pathogens1,2. The most well studied system in PTI is the FLS2-dependent pathway3. FLS2 recognizes the PAMP flg22 that is a component of bacterial flagellin. 
Successful pathogens possess virulence factors or effectors that can suppress PTI and allow the pathogen to cause disease1. Some plants in turn possess resistance genes that detect effectors or their activity, which leads to effector-triggered immunity (ETI)2.
We describe a cell death-based assay for PTI modified from Oh and Collmer4. The assay was standardized in N. benthamiana, which is being used increasingly as a model system for the study of plant-pathogen interactions5. PTI is induced by infiltration of a non-pathogenic bacterial strain into leaves. Seven hours later, a bacterial strain that either causes disease or which activates ETI is infiltrated into an area overlapping the original infiltration zone. PTI induced by the first infiltration is able to delay or prevent the appearance of cell death due to the second challenge infiltration. Conversely, the appearance of cell death in the overlapping area of inoculation indicates a breakdown of PTI. 
Four different combinations of inducers of PTI and challenge inoculations were standardized (Table 1). The assay was tested on non-silenced N. benthamiana plants that served as the control and plants silenced for FLS2 that were predicted to be compromised in their ability to develop PTI.

Assay for Pathogen-Associated Molecular Pattern PAMP-Triggered Immunity PTI in Plants

A cell death-based assay for PTI in Nicotiana benthamiana plants is described.

Dosage pour Pathogen-Associated Molecular Motif (PAMP)-Triggered Immunité (PTI) chez les plantes

To perceive potential pathogens in their environment, plants use pattern recognition receptors (PRRs) present on their plasma membranes. PRRs recognize ...

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Immunologie et infection

Human T Lymphocyte Isolation, Culture and Analysis of Migration In Vitro

The migration of T lymphocytes involves the adhesive interaction of cell surface integrins with ligands expressed on other cells or with extracellular matrix proteins. The precise spatiotemporal activation of integrins from a low affinity state to a high affinity state at the cell leading edge is important for T lymphocyte migration 1. Likewise, retraction of the cell trailing edge, or uropod, is a necessary step in maintaining persistent integrin-dependent T lymphocyte motility 2. Many therapeutic approaches to autoimmune or inflammatory diseases target integrins as a means to inhibit the excessive recruitment and migration of leukocytes 3. To study the molecular events that regulate human T lymphocyte migration, we have utilized an in vitro system to analyze cell migration on a two-dimensional substrate that mimics the environment that a T lymphocyte encounters during recruitment from the vasculature. T lymphocytes are first isolated from human donors and are then stimulated and cultured for seven to ten days. During the assay, T lymphocytes are allowed to adhere and migrate on a substrate coated with intercellular adhesion molecule-1 (ICAM-1), a ligand for integrin LFA-1, and stromal cell-derived factor-1 (SDF-1). Our data show that T lymphocytes exhibit a migratory velocity of ~15 &mu;m/min. T lymphocyte migration can be inhibited by integrin blockade 1 or by inhibitors of the cellular actomyosin machinery that regulates cell migration 2.

Human T Lymphocyte Isolation, Culture and Analysis of Migration In Vitro

T lymphocyte migration occurs during homing to lymphoid organs, exit from the vasculature, and entering into peripheral tissues. Here, we describe a protocol that can be used to analyze T lymphocyte migration in vitro.

Human T isolement des lymphocytes, de la Culture et de l&#39;analyse des migrations In Vitro</em

The migration of T lymphocytes involves the adhesive interaction of cell surface integrins with ligands expressed on other cells or with extracellular ...

Tracking Neutrophil Intraluminal Crawling, Transendothelial Migration and Chemotaxis in Tissue by Intravital Video Microscopy

The recruitment of circulating leukocytes from blood stream to the inflamed tissue is a crucial and complex process of inflammation1,2. In the postcapillary venules of inflamed tissue, leukocytes initially tether and roll on the luminal surface of venular wall. Rolling leukocytes arrest on endothelium and undergo firm adhesion in response to chemokine or other chemoattractants on the venular surface. Many adherent leukocytes relocate from the initial site of adhesion to the junctional extravasation site in endothelium, a process termed intraluminal crawling3. Following crawling, leukocytes move across endothelium (transmigration) and migrate in extravascular tissue toward the source of chemoattractant (chemotaxis)4. Intravital microscopy is a powerful tool for visualizing leukocyte-endothelial cell interactions in vivo and revealing cellular and molecular mechanisms of leukocyte recruitment2,5. In this report, we provide a comprehensive description of using brightfield intravital microscopy to visualize and determine the detailed processes of neutrophil recruitment in mouse cremaster muscle in response to the gradient of a neutrophil chemoattractant. To induce neutrophil recruitment, a small piece of agarose gel (~1-mm3 size) containing neutrophil chemoattractant MIP-2 (CXCL2, a CXC chemokine) or WKYMVm (Trp-Lys-Tyr-Val-D-Met, a synthetic analog of bacterial peptide) is placed on the muscle tissue adjacent to the observed postcapillary venule. With time-lapsed video photography and computer software ImageJ, neutrophil intraluminal crawling on endothelium, neutrophil transendothelial migration and the migration and chemotaxis in tissue are visualized and tracked. This protocol allows reliable and quantitative analysis of many neutrophil recruitment parameters such as intraluminal crawling velocity, transmigration time, detachment time, migration velocity, chemotaxis velocity and chemotaxis index in tissue. We demonstrate that using this protocol, these neutrophil recruitment parameters can be stably determined and the single cell locomotion conveniently tracked in vivo.

We describe a protocol of brightfield intravital microscopy for measuring dynamic neutrophil-endothelial cell interactions during neutrophil recruitment in response to the source of a neutrophil chemoattractant in vivo. Neutrophil intraluminal crawling, transendothelial migration and chemotaxis in mouse cremaster muscle tissue are visualized with time-lapsed video photography and tracked with ImageJ.

Suivi des rampants neutrophiles intraluminale, migration trans et le chimiotactisme dans les tissus par microscopie intravitale Vidéo

The recruitment of circulating leukocytes from blood stream to the inflamed tissue is a crucial and complex process of inflammation1,2. In the ...

Quantitative In vitro Assay to Measure Neutrophil Adhesion to Activated Primary Human Microvascular Endothelial Cells under Static Conditions

The vascular endothelium plays an integral part in the inflammatory response. During the acute phase of inflammation, endothelial cells (ECs) are activated by host mediators or directly by conserved microbial components or host-derived danger molecules. Activated ECs express cytokines, chemokines and adhesion molecules that mobilize, activate and retain leukocytes at the site of infection or injury. Neutrophils are the first leukocytes to arrive, and adhere to the endothelium through a variety of adhesion molecules present on the surfaces of both cells. The main functions of neutrophils are to directly eliminate microbial threats, promote the recruitment of other leukocytes through the release of additional factors, and initiate wound repair. Therefore, their recruitment and attachment to the endothelium is a critical step in the initiation of the inflammatory response. In this report, we describe an in vitro neutrophil adhesion assay using calcein AM-labeled primary human neutrophils to quantitate the extent of microvascular endothelial cell activation under static conditions. This method has the additional advantage that the same samples quantitated by fluorescence spectrophotometry can also be visualized directly using fluorescence microscopy for a more qualitative assessment of neutrophil binding.

Quantitative In vitro Assay to Measure Neutrophil Adhesion to Activated Primary Human Microvascular Endothelial Cells under Static Conditions

Neutrophil adherence to the activated endothelium at sites of infection is an integral component of the host's inflammatory response. Described in this report is a neutrophil binding assay that allows for the in vitro quantitation of primary human neutrophil binding to endothelial cells activated by inflammatory mediators under static conditions.

Quantitative<em&gt; In vitro</em&gt; Test pour mesurer l&#39;adhésion des neutrophiles à Activé cellules endothéliales microvasculaires humaines primaires dans des conditions statiques

The vascular  endothelium plays an integral part in the inflammatory response. During the  acute phase of inflammation, endothelial cells (ECs) are ...

Quantitative Assessment of Human Neutrophil Migration Across a Cultured Bladder Epithelium

The recruitment of immune cells from the periphery to the site of inflammation is an essential step in the innate immune response at any mucosal surface. During infection of the urinary bladder, polymorphonuclear leukocytes (PMN; neutrophils) migrate from the bloodstream and traverse the bladder epithelium. Failure to resolve infection in the absence of a neutrophilic response demonstrates the importance of PMN in bladder defense. To facilitate colonization of the bladder epithelium, uropathogenic Escherichia coli (UPEC), the causative agent of the majority of urinary tract infections (UTIs), dampen the acute inflammatory response using a variety of partially defined mechanisms. To further investigate the interplay between host and bacterial pathogen, we developed an in vitro model of this aspect of the innate immune response to UPEC. In the transuroepithelial neutrophil migration assay, a variation on the Boyden chamber, cultured bladder epithelial cells are grown to confluence on the underside of a permeable support. PMN are isolated from human venous blood and are applied to the basolateral side of the bladder epithelial cell layers. PMN migration representing the physiologically relevant basolateral-to-apical direction in response to bacterial infection or chemoattractant molecules is enumerated using a hemocytometer. This model can be used to investigate interactions between UPEC and eukaryotic cells as well as to interrogate the molecular requirements for the traversal of bladder epithelia by PMN. The transuroepithelial neutrophil migration model will further our understanding of the initial inflammatory response to UPEC in the bladder.

We developed an in vitro model that mimics an important component of the acute inflammatory response during infection of the bladder with uropathogenic Escherichia coli. The transuroepithelial neutrophil migration assay enables quantitative assessment of human neutrophil migration across bladder epithelia, cultured on permeable supports, in response to bacterial infection or chemoattractant substances.

Évaluation quantitative des neutrophiles migrations humaines à travers une culture d&#39;épithélium de la vessie

The recruitment of immune cells from the periphery to the site of inflammation is an essential step in the innate immune response at any mucosal surface. ...

Human Neutrophil Flow Chamber Adhesion Assay

Neutrophil firm adhesion to endothelial cells plays a critical role in inflammation in both health and disease. The process of neutrophil firm adhesion involves many different adhesion molecules including members of the &beta;2 integrin family and their counter-receptors of the ICAM family. Recently, naturally occurring genetic variants in both &beta;2 integrins and ICAMs are reported to be associated with autoimmune disease. Thus, the quantitative adhesive capacity of neutrophils from individuals with varying allelic forms of these adhesion molecules is important to study in relation to mechanisms underlying development of autoimmunity. Adhesion studies in flow chamber systems can create an environment with fluid shear stress similar to that observed in the blood vessel environment in vivo. Here, we present a method using a flow chamber assay system to study the quantitative adhesive properties of human peripheral blood neutrophils to human umbilical vein endothelial cell (HUVEC) and to purified ligand substrates. With this method, the neutrophil adhesive capacities from donors with different allelic variants in adhesion receptors can be assessed and compared. This method can also be modified to assess adhesion of other primary cell types or cell lines.

A method of quantitating neutrophil adhesion is reported. This method creates a dynamic flow environment similar to that encountered in a blood vessel. It allows the investigation of neutrophil adhesion to either purified adhesion molecules (ligand) or endothelial cell substrate (HUVEC) in a context similar to the in vivo environment with sheer stress.

Human neutrophiles Chambre flux Essai d&#39;adhésion

Neutrophil firm adhesion to endothelial cells plays a critical role in inflammation in both health and disease. The process of neutrophil firm adhesion ...

Neutrophil Isolation and Analysis to Determine their Role in Lymphoma Cell Sensitivity to Therapeutic Agents

Neutrophils are the most abundant (40% to 75%) type of white blood cells and among the first inflammatory cells to migrate towards the site of inflammation. They are key players in the innate immune system and play major roles in cancer biology. Neutrophils have been proposed as key mediators of malignant transformation, tumor progression, angiogenesis and in the modulation of the antitumor immunity; through their release of soluble factors or their interaction with tumor cells. To characterize the specific functions of neutrophils, a fast and reliable method is coveted for in vitro isolation of neutrophils from human blood. Here, a density gradient separation method is demonstrated to isolate neutrophils as well as mononuclear cells from the blood. The procedure consists of layering the density gradient solution such as Ficoll carefully above the diluted blood obtained from patients diagnosed with chronic lymphocytic leukemia (CLL), followed by centrifugation, isolation of mononuclear layer, separation of neutrophils from RBCsby dextran then lysis of residual erythrocytes. This method has been shown to isolate neutrophils &#8805; 90 % pure. To mimic the tumor microenvironment, 3-dimensional (3D) experiments were performed using basement membrane matrix such as Matrigel. Given the short half-life of neutrophils in vitro, 3D experiments with fresh human neutrophils cannot be performed. For this reason promyelocytic HL60 cells are differentiated along the granulocytic pathway using the differentiation inducers dimethyl sulfoxide (DMSO) and retinoic acid (RA). The aim of our experiments is to study the role of neutrophils on the sensitivity of lymphoma cells to anti-lymphoma agents. However these methods can be generalized to study the interactions of neutrophils or neutrophil-like cells with a large range of cell types in different situations.

Neutrophils are the most abundant type of white blood cells. The isolation of neutrophils from human blood by density gradient separation method and the differentiation of human promyelocytic (HL60) cells along the granulocytic pathway are described here; to test their role on sensitivity of lymphoma cells to anti-lymphoma agents.

Neutrophiles Isolement et analyse pour déterminer leur rôle dans le lymphome cellulaire Sensibilité aux agents thérapeutiques

Neutrophils are the most abundant (40% to 75%) type of white blood cells and among the first inflammatory cells to migrate towards the site of ...

A Novel In Vitro Wound Healing Assay to Evaluate Cell Migration

The aim of this work is to show a novel method to evaluate the ability of some immunomodulatory molecules, such as antimicrobial peptides (AMPs), to stimulate cell migration. Importantly, cell migration is a rate-limiting event during the wound-healing process to re-establish the integrity and normal function of tissue layers after injury. The advantage of this method over the classical assay, which is based on a manually made scratch in a cell monolayer, is the usage of special silicone culture inserts providing two compartments to create a cell-free pseudo-wound field with a well-defined width (500 &#956;m). In addition, due to an automated image analysis platform, it is possible to rapidly obtain quantitative data on the speed of wound closure and cell migration. More precisely, the effect of two frog-skin AMPs on the migration of bronchial epithelial cells will be shown. Furthermore, pretreatment of these cells with specific inhibitors will provide information on the molecular mechanisms underlying such events.

A Novel In Vitro Wound Healing Assay to Evaluate Cell Migration

Here, we present a protocol to evaluate the effect of peptides on the migration of bronchial epithelial cells. This method allows for the rapid and highly reproducible obtainment of quantitative data on the speed of cell migration and wound closure.

Un roman In Vitro de la plaie guérison test afin d’évaluer la Migration cellulaire

The aim of this work is to show a novel method to evaluate the ability of some immunomodulatory molecules, such as antimicrobial peptides (AMPs), to ...

Analysis of Shear Flow-induced Migration of Murine Marginal Zone B Cells In Vitro

Marginal zone B cells (MZBs) are a population of B cells that reside in the mouse splenic marginal zones that envelop follicles. To reach the follicles, MZBs must migrate up the shear force of blood flow. We present here a method for analyzing this flow-induced MZB migration in vitro. First, MZBs are isolated from the mouse spleen. Second, MZBs are settled on integrin ligands in flow chamber slides, exposed to shear flow, and imaged under a microscope while migrating. Third, images of the migrating MZBs are processed using the MTrack2 automatic cell tracking plugin for ImageJ, and the resulting cell tracks are quantified using the Ibidi chemotaxis tool. The migration data reveal how fast the cells move, how often they change direction, whether the shear flow vector affects their migration direction, and which integrin ligands are involved. Although we use MZBs, the method can easily be adapted for analyzing migration of any leukocyte that responds to the force of shear flow.

Marginal zone B cells (MZBs) respond to the force of shear flow by re-orienting their migration path up the flow. This protocol shows how to record and analyze the migration using a fluidics unit, pump, microscope imaging system, and free software.

Analyse de cisaillement induite par le flux de Migration des cellules B Zone marginale murin In Vitro

Marginal zone B cells (MZBs) are a population of B cells that reside in the mouse splenic marginal zones that envelop follicles. To reach the follicles, ...

A High-throughput Assay to Assess and Quantify Neutrophil Extracellular Trap Formation

Neutrophil extracellular traps (NETs) are immunogenic extracellular DNA structures that can be released by neutrophils upon a wide variety of triggers. NETs have been demonstrated to serve as an important host defense mechanism that traps and kills microorganisms. On the other hand, they have been implicated in diverse systemic autoimmune diseases. NETs are immunogenic and toxic structures that contain a pool of relevant autoantigens including anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) and systemic lupus erythematosus (SLE). Different forms of NETs can be induced depending on the stimulus. The amount of NETs can be quantified using different techniques including measuring DNA release in supernatants, measuring DNA-complexed with NET-molecules like myeloperoxidase (MPO) or neutrophil elastase (NE), measuring the presence of citrullinated histones by fluorescence microscopy, or flow cytometric detection of NET-components which all have different features regarding their specificity, sensitivity, objectivity, and quantity. Here is a protocol to quantify ex vivo NET formation in a highly-sensitive, high-throughput manner by using three-dimensional immunofluorescence confocal microscopy. This protocol can be applied to address various research questions about NET formation and degradation in health and disease.

This protocol describes a highly sensitive and high throughput neutrophil extracellular trap (NET) assay for the semi-automated quantification of ex vivo NET formation by immunofluorescence three-dimensional confocal microscopy. This protocol can be used to evaluate NET formation and degradation after different stimuli and can be used to study potential NET-targeted therapies.

Un test haut débit pour évaluer et quantifier les neutrophiles piège extracellulaire Formation

Neutrophil extracellular traps (NETs) are immunogenic extracellular DNA structures that can be released by neutrophils upon a wide variety of triggers. ...