Humanized Mouse Model to Study Bacterial Infections Targeting the Microvasculature

Neisseria meningitidis causes a severe, frequently fatal sepsis when it enters the human blood stream. Infection leads to extensive damage of the blood ...

Paris Cardiovascular Research Centre

Université Paris Descartes

By combining intravital multiphoton microscopy and bacterial genetics we have developed a technique enabling real-time imaging of bacterial proliferation and tissue responses in a live animal. Spatial and temporal control of the infection process was achieved by microinjecting GFP(+)-expressing uropathogenic Escherichia coli (UPEC) into tubules of exteriorized kidneys in live rats. GFP(+) was introduced in the clinical UPEC strain CFT073 as a single-copy chromosomal gene fusion. Within hours, bacterial colonization was accompanied by marked ischaemic effects, perivascular leakage, loss of tubular integrity and localized recruitment of immune cells. The pathophysiology was altered in response to an isogenic bacterial strain lacking the exotoxin haemolysin, revealing the subtle and temporal roles of bacterial virulence factors in vivo. Microdissection and RNA extraction of the injected nephron allowed molecular analysis of prokaryotic and eukaryotic gene expression. The techniques described here can be applied to study the integrated cell communication evoked by a variety of bacterial pathogens, assisting in the design of strategies to combat bacterial infections.

Real-time studies of the progression of bacterial infections and immediate tissue responses in live animals.

En combinant la microscopie intravitale multiphoton et g&eacute;n&eacute;tique bact&eacute;rienne, nous avons d&eacute;velopp&eacute; une technique qui permet une imagerie en temps r&eacute;el des r&eacute;ponses de tissus et la prolif&eacute;ration bact&eacute;riennes dans un animal vivant. Contr&ocirc;le spatial et temporel du processus d&#39;infection a &eacute;t&eacute; r&eacute;alis&eacute; par GFP microinjecting (+)-exprimant des uropathog&egrave;nes Escherichia coli (UPEC) dans les tubules d&#39;ext&eacute;rioris&eacute;s reins chez les rats vivants. GFP(+) a &eacute;t&eacute; introduit dans la souche UPEC clinique CFT073 comme une fusion de g&egrave;nes chromosomiques exemplaire unique. Dans les heures, la colonisation bact&eacute;rienne &eacute;tait accompagn&eacute;e d&#39;effets marqu&eacute;s par isch&eacute;mie, p&eacute;rivasculaires fuite, perte d&#39;int&eacute;grit&eacute; tubulaire et recrutement localis&eacute;e des cellules immunitaires. La physiopathologie a &eacute;t&eacute; chang&eacute;e en r&eacute;ponse &agrave; une souche bact&eacute;rienne isog&eacute;nique, sans l&#39;exotoxine h&eacute;molysine, r&eacute;v&eacute;lant les r&ocirc;les subtils et temporelles des facteurs de virulence bact&eacute;rienne in vivo. Microdissection et extraction de l&#39;ARN du n&eacute;phron inject&eacute;e a permis l&#39;analyse mol&eacute;culaire de l&#39;expression des g&egrave;nes procaryotes et eucaryotes. Les techniques d&eacute;crites ici peuvent &ecirc;tre appliqu&eacute;es &agrave; l&#39;&eacute;tude de la communication de cellule int&eacute;gr&eacute;e &eacute;voqu&eacute;e par une vari&eacute;t&eacute; de bact&eacute;ries pathog&egrave;nes, aider &agrave; la conception de strat&eacute;gies de lutte contre les infections bact&eacute;riennes.

&Eacute;tudes en temps r&eacute;el de la progression des infections bact&eacute;riennes et les r&eacute;actions des tissus imm&eacute;diate dans les animaux vivants.

Combinando la microscopia multifotonica intravital e genetica batterica abbiamo sviluppato una tecnica che consente l&#39;acquisizione in tempo reale delle risposte tessuto e proliferazione batteriche in un animale vivo. Controllo spaziale e temporale del processo di infezione &egrave; stato raggiunto da microinjecting GFP (+)-esprimendo uropathogenic Escherichia coli (UPEC) in tubuli di reni exteriorized in ratti dal vivo. GFP(+) &egrave; stato introdotto nel ceppo clinico UPEC CFT073 come una fusione singola copia cromosomica gene. In poche ore, colonizzazione batterica era accompagnata da effetti contrassegnato ischemico, perivascolare perdite, perdita di integrit&agrave; tubolare e localizzata reclutamento di cellule del sistema immunitario. La fisiopatologia &egrave; stata alterata in risposta a un ceppo batterico isogeni manca l&#39;esotossina haemolysin, rivelando i ruoli sottili e temporali dei fattori di virulenza batterica in vivo. Microdissection ed estrazione del RNA del nefrone iniettato ha permesso l&#39;analisi molecolare dell&#39;espressione genica in procarioti ed eucarioti. Le tecniche descritte qui possono essere applicate per studiare la comunicazione integrata cella evocata da una variet&agrave; di agenti patogeni batterici, assistenza nella progettazione di strategie per combattere le infezioni batteriche.

Studi in tempo reale della progressione delle infezioni batteriche e risposte immediate dei tessuti animali vivi.

Mediante la combinaci&oacute;n de microscopia intravital de multifot&oacute;n y gen&eacute;tica bacteriana hemos desarrollado una t&eacute;cnica que permite la proyecci&oacute;n de imagen en tiempo real de respuestas de tejido y proliferaci&oacute;n bacterianas en un animal vivo. Control espacial y temporal del proceso de infecci&oacute;n fue alcanzado por microinjecting GFP (+)-expresando uropat&oacute;genos Escherichia coli (UPEC) en los t&uacute;bulos de los ri&ntilde;ones exteriorizados en ratas vivos. GFP(+) se introdujo en la cepa cl&iacute;nica de la UPEC CFT073 como una fusi&oacute;n de genes cromos&oacute;micos solo copia. Dentro de las horas, colonizaci&oacute;n bacteriana fue acompa&ntilde;ada por efectos marcados isqu&eacute;mico, perivascular fugas, p&eacute;rdida de integridad tubular y reclutamiento localizada de c&eacute;lulas inmunes. La patofisiolog&iacute;a fue alterada en respuesta a una cepa bacteriana isog&eacute;nicas carecer la hemolisina exotoxina, revelando las funciones sutiles y temporales de los factores de virulencia bacteriana in vivo. Microdisecci&oacute;n y extracci&oacute;n de RNA de la nefrona inyectada permitieron el an&aacute;lisis molecular de la expresi&oacute;n g&eacute;nica de procariotas y eucariotas. Las t&eacute;cnicas descritas aqu&iacute; pueden aplicarse para estudiar la comunicaci&oacute;n celular integrado por una variedad de pat&oacute;genos bacterianos, asistir en el dise&ntilde;o de estrategias para combatir las infecciones bacterianas.

Estudios en tiempo real de la progresi&oacute;n de infecciones bacterianas y las respuestas inmediata del tejido en animales vivos.

The holy grail of infection biology is to study a pathogen within its natural infectious environment, the living host. Advances in in vivo imaging techniques have begun to introduce the possibility to visualize, in real time, infection progression within a living model. In this review we detail the current advancements and knowledge in multiphoton microscopy and how it can be related to the field of microbial infections. This technology is a new and very valuable tool for in vivo imaging, and using this technique it is possible to begin to study various microbes within their natural infectious environment - the living host.

Progression of bacterial infections studied in real time--novel perspectives provided by multiphoton microscopy.

Le Saint-Graal de la biologie de l&#39;infection est d&#39;&eacute;tudier un pathog&egrave;ne dans son environnement naturel d&#39;infectieuse, l&#39;h&ocirc;te de la vie. Progr&egrave;s dans les techniques d&#39;imagerie in vivo ont commenc&eacute; &agrave; introduire la possibilit&eacute; de visualiser, en temps r&eacute;el, la progression de l&#39;infection au sein d&#39;un mod&egrave;le vivant. Dans cette revue, nous d&eacute;taillons les avanc&eacute;es actuelles et les connaissances dans la microscopie multiphoton et comment elle peut &ecirc;tre li&eacute;e au champ des infections microbiennes. Cette technologie est un outil nouveau et tr&egrave;s pr&eacute;cieux pour l&#39;imagerie in vivo, et en utilisant cette technique, il est possible de commencer &agrave; &eacute;tudier divers microbes dans leur nature infectieuse - l&#39;h&ocirc;te vivant.

Progression des infections bact&eacute;riennes &eacute;tudi&eacute;es en temps r&eacute;el--perspectives nouvelles fournies par la microscopie multiphoton.

Il Santo Graal della biologia di infezione &egrave; lo studio di un agente patogeno nel suo ambiente naturale infettive, l&#39;host vivente. Progressi nelle tecniche di imaging in vivo hanno cominciato ad introdurre la possibilit&agrave; di visualizzare, in tempo reale, la progressione di infezioni all&#39;interno di un modello di vita. In questa recensione abbiamo dettaglio le attuali progressi e le conoscenze in microscopia multifotonica e come pu&ograve; essere collegato al campo di infezioni microbiche. Questa tecnologia &egrave; uno strumento nuovo e molto prezioso per imaging in vivo, e usando questa tecnica &egrave; possibile iniziare a studiare vari microbi con il loro ambiente naturale infettive - host vivente.

Progressione di infezioni batteriche studiato in tempo reale - romanzo prospettive fornite da microscopia multifotonica.

El Santo Grial de la biolog&iacute;a de la infecci&oacute;n es estudiar un pat&oacute;geno dentro de su naturaleza infecciosa, el anfitri&oacute;n de la vida. Avances en las t&eacute;cnicas de imagen in vivo han empezado a introducir la posibilidad de visualizar en tiempo real, la progresi&oacute;n de la infecci&oacute;n dentro de un modelo de vida. En esta revisi&oacute;n detallan los avances actuales y conocimiento en microscop&iacute;a multifot&oacute;n y c&oacute;mo puede relacionar el campo de las infecciones microbianas. Esta tecnolog&iacute;a es una herramienta nueva y muy valiosa para la proyecci&oacute;n de imagen in vivo, y con esta t&eacute;cnica es posible comenzar a estudiar varios microbios dentro de su naturaleza infecciosa - el anfitri&oacute;n de la vida.

Progresi&oacute;n de infecciones bacterianas estudiadas en tiempo real--novela perspectivas proporcionados por microscop&iacute;a multifot&oacute;n.

Ascending urinary tract infections can cause extensive damage to kidney structure and function. We have used a number of advanced techniques including multiphoton microscopy to investigate the crucial early phases of uropathogenic Escherichia coli induced pyelonephritis within a living animal. Our results reveal a previously undescribed innate vascular response to mucosal infection, allowing isolation and eradication of the pathogen. The extremely rapid host response to mucosal infection was highlighted by the triggering of a cascade of events within 3-4 h. Epithelial signalling produced an increase in cellular O(2) consumption and affected microvascular flow by clotting, causing localized ischaemia. Subsequent ischaemic damage affected pathophysiology with actin re-arrangement and epithelial sloughing leading to paracellular bacterial movement. A denuded tubular basement membrane is shown to hinder immediate dissemination of bacteria, giving the host time to isolate the infection by clotting. Suppression of clotting by heparin treatment caused fatal urosepsis. Clinically these findings may be relevant in antibiotics delivery in pyelonephritis patients and to the use of anticoagulants in sepsis.

Bacterial infection-mediated mucosal signalling induces local renal ischaemia as a defence against sepsis.

Croissant des infections urinaires peut causer des dommages consid&eacute;rables &agrave; la structure du rein et la fonction. Nous avons utilis&eacute; un certain nombre de techniques avanc&eacute;es, y compris la microscopie multiphoton pour enqu&ecirc;ter sur les premi&egrave;res phases cruciales des uropathog&egrave;nes Escherichia coli induit py&eacute;lon&eacute;phrite au sein d&#39;un animal vivant. Nos r&eacute;sultats r&eacute;v&egrave;lent une non d&eacute;crite r&eacute;ponse vasculaire inn&eacute;e &agrave; l&#39;infection muqueuse, permettant l&#39;isolement et l&#39;&eacute;radication de l&#39;agent pathog&egrave;ne. La r&eacute;ponse de l&#39;h&ocirc;te extr&ecirc;mement rapide &agrave; l&#39;infection muqueuse a &eacute;t&eacute; soulign&eacute;e par le d&eacute;clenchement d&#39;une cascade d&#39;&eacute;v&eacute;nements au sein de 3-4 h. &eacute;pith&eacute;liales signalisation produit une augmentation de la consommation cellulaire d&#39;o (2) et affect&eacute; flux microvasculaire par coagulation, provoquant l&#39;isch&eacute;mie localis&eacute;. Dommages isch&eacute;miques subs&eacute;quentes affect&eacute;es physiopathologie avec le r&eacute;am&eacute;nagement de l&#39;actine et la desquamation &eacute;pith&eacute;liale, entra&icirc;nant un mouvement bact&eacute;rienne paracellulaire. Une membrane de sous-sol tubulaire d&eacute;nud&eacute;e est montr&eacute;e pour entraver la diffusion imm&eacute;diate des bact&eacute;ries, donnant le temps de l&#39;h&ocirc;te pour isoler l&#39;infection par coagulation. Suppression de la coagulation par traitement h&eacute;parine caus&eacute; orbitaire fatale. Sur le plan clinique, ces conclusions pourraient &ecirc;tre pertinentes dans la livraison des antibiotiques chez les patients de py&eacute;lon&eacute;phrite et &agrave; l&#39;utilisation des anticoagulants en septic&eacute;mie.

Induite par l&#39;infection bact&eacute;rienne signalisation muqueuse induit une isch&eacute;mie r&eacute;nale locale comme moyen de d&eacute;fense contre l&#39;infection.

Crescente di infezioni del tratto urinario pu&ograve; causare gravi danni alla struttura del rene e funzione. Abbiamo utilizzato una serie di tecniche avanzate tra cui microscopia multifotonica per indagare le prime fasi cruciali di uropathogenic Escherichia coli indotta da pielonefrite all&#39;interno di un animale vivente. I nostri risultati rivelano una nuovo precedentemente risposta vascolare innata all&#39;infezione della mucosa, consentendo l&#39;isolamento e l&#39;eradicazione del patogeno. La risposta estremamente rapida ospite all&#39;infezione della mucosa &egrave; stata evidenziata con l&#39;innesco di una cascata di eventi all&#39;interno di 3-4 h. epiteliali segnalazione prodotto un aumento nel consumo di apparato cellulare e colpite il flusso microvascolare di coagulazione, causando ischemia localizzata. Danno ischemico successiva colpite Fisiopatologia con rielaborazione di actina e desquamazione epiteliale che conduce al movimento batterica paracellular. Una membrana tubolare denudata &egrave; mostrata ad ostacolare immediata diffusione di batteri, dando il tempo di host per isolare l&#39;infezione di coagulazione. Soppressione della coagulazione mediante trattamento eparina causato urosepsis fatale. Clinicamente questi risultati possono essere rilevanti in consegna gli antibiotici in pazienti pielonefrite e all&#39;uso di anticoagulanti nella sepsi.

Mediata da infezione batterica segnalazione della mucosa induce ischemia renale locale come una difesa contro la sepsi.

Ascendente de infecciones del tracto urinario puede causar grandes da&ntilde;os en la estructura del ri&ntilde;&oacute;n y la funci&oacute;n. Hemos utilizado una serie de t&eacute;cnicas avanzadas incluyendo microscop&iacute;a multifot&oacute;n para investigar las primeras fases cruciales de uropat&oacute;genos Escherichia coli inducida por pielonefritis dentro de un animal vivo. Nuestros resultados revelan una respuesta vascular innata Sines infecci&oacute;n mucosa, lo que permite el aislamiento y la erradicaci&oacute;n del pat&oacute;geno. La respuesta del hu&eacute;sped extremadamente r&aacute;pida a la infecci&oacute;n mucosa se destac&oacute; por la activaci&oacute;n de una cascada de eventos dentro de 3-4 h. epitelial se&ntilde;alizaci&oacute;n producido un aumento en el consumo de O(2) celular y afectado flujo microvascular por coagulaci&oacute;n, provocando isquemia localizada. Da&ntilde;o isqu&eacute;mico posterior afectado Fisiopatolog&iacute;a con entrega en forma actina y descamaci&oacute;n epitelial hacia paracelular movimiento bacteriano. Una membrana tubular denudada del s&oacute;tano se muestra a obstaculizar la difusi&oacute;n inmediata de las bacterias, dando el tiempo de host para aislar la infecci&oacute;n por coagulaci&oacute;n. Supresi&oacute;n de coagulaci&oacute;n por tratamiento con heparina hab&iacute;a causado urosepsis fatal. Cl&iacute;nicamente, estos resultados pueden ser relevantes en la entrega de antibi&oacute;ticos en pacientes de pielonefritis y el uso de anticoagulantes en la sepsis.

Mediada por la infecci&oacute;n bacteriana de se&ntilde;alizaci&oacute;n mucosa induce isquemia renal local como una defensa contra la sepsis.

In vitro studies have been essential to describe the molecular details of bacteria-host cell interactions in general and the functions of bacterial effector proteins in particular. Recent advancements in in vivo imaging techniques are facilitating the next logical step to visualize the dynamic infection process as it happens within the living host while analyzing the role of bacterial effector proteins in vivo. Data obtained from this emerging field of 'tissue microbiology', combined with the massive knowledge base generated from research in 'cellular microbiology' will eventually provide a complete picture of the complex infection process.

Real-time live imaging to study bacterial infections in vivo.

Studying the events that occur when a pathogen comes into contact with its host is the basis of the field of infection biology. Over the years, work in this area has revealed many facets of the infection process, including attachment, invasion and colonization by the pathogen, and of the host responses, such as the triggering of the immune system. Recent advancements in imaging technologies, such as multiphoton microscopy (MPM), mean that the field is in the process of taking another big leap forward. MPM allows for cellular-level visualization of the real-time dynamics of infection within the living host. The use of live animal models means that all the interplaying factors of an infection, such as the influences of the immune, lymphatic and vascular systems, can be accounted for. This review outlines the developing field of MPM in pathogen-host interactions, highlighting a number of new insights that have been 'brought to light' using this technique.

Multiphoton imaging of host-pathogen interactions.

A bacterial infection is accompanied by dynamic alterations in tissue homeostasis within the infected organ. What starts as a local bacterium-host cell interaction at the site of infection changes over time to include distant signaling and the engagement of multiple cell types in an effort to eradicate the bacteria. Recent advancements in imaging technologies, such as multiphoton microscopy, provide new tools to visualize the realtime dynamics of infection within the living host. The use of live animal models means that all of the interplaying factors, such as the immune, lymphatic, nervous, and vascular systems, are present and can be accounted for. This review describes novel insights of innate immune defense mechanisms obtained using real-time visualization of the infected tissue in a live animal model. This emerging field of "tissue microbiology" will provide data that, when combined with the massive knowledge base generated from research in "cellular microbiology," will provide a more complete picture of the complex infection process.

Novel innate immune functions revealed by dynamic, real-time live imaging of bacterial infections.

The progression of a natural bacterial infection is a dynamic process influenced by the physiological characteristics of the target organ. Recent developments in live animal imaging allow for the study of the dynamic microbe-host interplay in real-time as the infection progresses within an organ of a live host. Here we used multiphoton microscopy-based live animal imaging, combined with advanced surgical procedures, to investigate the role of uropathogenic Escherichia coli (UPEC) attachment organelles P and Type 1 fimbriae in renal bacterial infection. A GFP+ expressing variant of UPEC strain CFT073 and genetically well-defined isogenic mutants were microinfused into rat glomerulus or proximal tubules. Within 2 h bacteria colonized along the flat squamous epithelium of the Bowman's capsule despite being exposed to the primary filtrate. When facing the challenge of the filtrate flow in the proximal tubule, the P and Type 1 fimbriae appeared to act in synergy to promote colonization. P fimbriae enhanced early colonization of the tubular epithelium, while Type 1 fimbriae mediated colonization of the center of the tubule via a mechanism believed to involve inter-bacterial binding and biofilm formation. The heterogeneous bacterial community within the tubule subsequently affected renal filtration leading to total obstruction of the nephron within 8 h. Our results reveal the importance of physiological factors such as filtration in determining bacterial colonization patterns, and demonstrate that the spatial resolution of an infectious niche can be as small as the center, or periphery, of a tubule lumen. Furthermore, our data show how secondary physiological injuries such as obstruction contribute to the full pathophysiology of pyelonephritis.

Uropathogenic Escherichia coli P and Type 1 fimbriae act in synergy in a living host to facilitate renal colonization leading to nephron obstruction.

La progression d&#39;une infection bact&eacute;rienne naturelle est un processus dynamique influenc&eacute; par les caract&eacute;ristiques physiologiques de l&#39;organe cible. R&eacute;cents d&eacute;veloppements en imagerie animaux vivant permettant l&#39;&eacute;tude de l&#39;interaction dynamique microbe-h&ocirc;te en temps r&eacute;el en cours de l&#39;infection au sein d&#39;un organe d&#39;un h&ocirc;te vivant. Ici, nous avons utilis&eacute; multiphoton animal vivant ax&eacute;e sur la microscopie imagerie, combin&eacute; avec des interventions chirurgicales avanc&eacute;es, pour enqu&ecirc;ter sur le r&ocirc;le des uropathog&egrave;nes Escherichia coli (UPEC) pi&egrave;ce jointe organites P et les fimbriae de Type 1 dans l&#39;infection bact&eacute;rienne r&eacute;nale. Un GFP + exprimant la variante de la souche CFT073 UPEC et mutants isog&eacute;niques g&eacute;n&eacute;tiquement bien d&eacute;finies ont &eacute;t&eacute; microinfused en glom&eacute;rule de rat ou de tubules proximaux. Dans 2 h les bact&eacute;ries ont colonis&eacute; le long de l&#39;&eacute;pith&eacute;lium pavimenteux plate de la capsule de Bowman en d&eacute;pit d&#39;&ecirc;tre expos&eacute;s au filtrat primaire. Quand le d&eacute;fi de l&#39;&eacute;coulement de filtrat dans le tubule proximal, les fimbriae de P et de Type 1 est apparu &agrave; agir en synergie pour favoriser la colonisation. Fimbriae P renforc&eacute;e d&eacute;but de la colonisation de l&#39;&eacute;pith&eacute;lium tubulaire, tandis que les fimbriae de Type 1, v&eacute;hicul&eacute;e par la colonisation du centre du tubule par un m&eacute;canisme cens&eacute; impliquer liaison horizontal et la formation de biofilm. La communaut&eacute; bact&eacute;rienne h&eacute;t&eacute;rog&egrave;ne dans le tubule touch&eacute;s par la suite la filtration r&eacute;nale conduisant &agrave; une obstruction totale du n&eacute;phron dans les 8 h. Nos r&eacute;sultats r&eacute;v&egrave;lent l&#39;importance de facteurs physiologiques, tels que la filtration dans la d&eacute;termination la colonisation bact&eacute;rienne et d&eacute;montrent que la r&eacute;solution spatiale d&#39;un cr&eacute;neau infectieuse peut &ecirc;tre aussi petite que le centre ou p&eacute;riph&eacute;rie, d&#39;une lumi&egrave;re du tubule. En outre, nos r&eacute;sultats montrent comment secondaires blessures physiologiques tels qu&#39;obstruction contribuent &agrave; la pleine physiopathologie de la py&eacute;lon&eacute;phrite.

Uropathogenic Escherichia coli P et les fimbriae de Type 1 agissent en synergie dans un h&ocirc;te vivant pour faciliter la colonisation r&eacute;nale conduisant &agrave; l&#39;obstruction du n&eacute;phron.

La progressione di un&#39;infezione batterica naturale &egrave; un processo dinamico influenzato dalle caratteristiche fisiologiche dell&#39;organo bersaglio. Recenti sviluppi in vivo imaging animale consentono per lo studio dell&#39;interazione dinamica microbo-host in tempo reale con il progredire dell&#39;infezione all&#39;interno di un organo di un ospite dal vivo. Qui abbiamo usato multifotonica basati su microscopia animale vivo imaging, combinato con le procedure chirurgiche avanzate, per indagare il ruolo di uropathogenic Escherichia coli (UPEC) attaccamento organelli P e fimbriae di tipo 1 in infezione batterica renale. Un GFP + esprimendo la variante del ceppo UPEC CFT073 e mutanti isogeni geneticamente ben definiti sono stati microinfused nel glomerulo ratto o tubuli prossimali. Entro 2 h batteri colonizzati lungo l&#39;epitelio squamoso piatta della capsula di Bowman pur essendo esposto al filtrato primario. Quando di fronte alla sfida del flusso filtrato nel tubulo prossimale, i fimbriae di P e di tipo 1 &egrave; apparso ad agire in sinergia per promuovere la colonizzazione. Fimbriae P enhanced precoce colonizzazione dell&#39;epitelio tubulare, mentre fimbriae di tipo 1 mediate la colonizzazione del centro del tubulo tramite un meccanismo crede che coinvolgono l&#39;associazione inter-bacterial e formazione di biofilm. La comunit&agrave; batterica eterogenea all&#39;interno del tubulo colpite successivamente renale filtrazione che porta all&#39;ostruzione totale del nefrone entro 8 h. I nostri risultati dimostrano che la risoluzione spaziale di una nicchia infettiva pu&ograve; essere piccola come il centro o periferia, di un lume del tubulo e rivelano l&#39;importanza dei fattori fisiologici come la filtrazione nella determinazione modelli di colonizzazione batterica. Inoltre, i nostri dati mostrano lesioni fisiologiche come secondari come ostruzione contribuiscono alla Fisiopatologia piena di pielonefrite.

Uropathogenic Escherichia coli P e 1 tipo fimbriae agiscono in sinergia in un&#39;ospite vivente per facilitare la colonizzazione renale che conduce all&#39;ostruzione del nefrone.

La progresi&oacute;n de una infecci&oacute;n bacteriana natural es un proceso din&aacute;mico, influenciado por las caracter&iacute;sticas fisiol&oacute;gicas de los &oacute;rganos de destino. Novedades en proyecci&oacute;n de imagen de animal vivo permiten el estudio de la interacci&oacute;n din&aacute;mica de hosts de microbio en tiempo real mientras que progresa la infecci&oacute;n dentro de un &oacute;rgano de un host directo. Aqu&iacute; utilizamos multifot&oacute;n basadas en microscopia animal vivo imaging, combinado con procedimientos quir&uacute;rgicos avanzados, para investigar el papel de uropat&oacute;genos Escherichia coli (UPEC) accesorio org&aacute;nulos P y fimbrias tipo 1 en infecci&oacute;n bacteriana renal. GFP + expresando la variante de la cepa de la UPEC CFT073 y gen&eacute;ticamente definidos isog&eacute;nicas mutantes fueron microinfused en el glom&eacute;rulo de rata o t&uacute;bulos proximales. Dentro de 2 h bacterias colonizadas por el epitelio escamoso plano de la c&aacute;psula de Bowman de a pesar de estar expuesto al filtrado primario. Cuando enfrenta el reto del flujo de filtrado en el t&uacute;bulo proximal, las fimbrias P y tipo 1 parecen actuar en sinergia para promover la colonizaci&oacute;n. Las fimbrias P mejorado colonizaci&oacute;n temprana del epitelio tubular, mientras que las fimbrias tipo 1 mediada por colonizaci&oacute;n del centro del t&uacute;bulo mediante un mecanismo que se cree que involucra el enlace inter-bacterial y formaci&oacute;n de biopel&iacute;culas. La heterog&eacute;nea comunidad bacteriana dentro de los t&uacute;bulos afectados posteriormente filtraci&oacute;n renal lleva a la obstrucci&oacute;n total de la nefrona dentro de 8 h. Nuestros resultados revelan la importancia de factores fisiol&oacute;gicos como filtraci&oacute;n en determinar los patrones de colonizaci&oacute;n bacteriana y demuestran que la resoluci&oacute;n espacial de un nicho infecciosa puede ser tan peque&ntilde;a como el centro o la periferia de un lumen del t&uacute;bulo. Adem&aacute;s, nuestros datos muestran lesiones fisiol&oacute;gicas como secundarias tales como obstrucci&oacute;n de contribuir a la fisiopatolog&iacute;a completa de pielonefritis.

Uropathogenic Escherichia coli P y fimbrias tipo 1 act&uacute;an en sinergia en un host de vida para facilitar la colonizaci&oacute;n renal lleva a la obstrucci&oacute;n de la nefrona.

Bacterial infection of human vasculature can lead to unregulated systemic activation of coagulation and innate immunity and rapidly becomes life threatening. Neisseria meningitidis is a vascular pathogen that causes fatal sepsis and meningitis. Post-mortem histological analysis of tissues from individuals infected with N. meningitidis show large bacterial aggregates in close association with the vascular wall of small vessels. The ability of this bacterium to colonize blood vessel endothelium is likely to impact its capacity to both multiply in the blood stream and reach the brain. This process will be referred to as vascular colonization. Recent work has described a number of early steps in N. meningitidis vascular colonization, from attachment to proliferation and dissemination, focusing on the bacterial-host interaction.

Vascular colonization by Neisseria meningitidis.

Septic shock caused by Neisseria meningitidis is typically rapidly evolving and often fatal despite antibiotic therapy. Further understanding of the mechanisms underlying the disease is necessary to reduce fatality rates. Postmortem samples from the characteristic purpuric rashes of the infection show bacterial aggregates in close association with microvessel endothelium but the species specificity of N. meningitidis has previously hindered the development of an in vivo model to study the role of adhesion on disease progression. Here we introduced human dermal microvessels into SCID/Beige mice by xenografting human skin. Bacteria injected intravenously exclusively associated with the human vessel endothelium in the skin graft. Infection was accompanied by a potent inflammatory response with the secretion of human inflammatory cytokines and recruitment of inflammatory cells. Importantly, infection also led to local vascular damage with hemostasis, thrombosis, vascular leakage and finally purpura in the grafted skin, replicating the clinical presentation for the first time in an animal model. The adhesive properties of the type IV pili of N. meningitidis were found to be the main mediator of association with the dermal microvessels in vivo. Bacterial mutants with altered type IV pili function also did not trigger inflammation or lead to vascular damage. This work demonstrates that local type IV pili mediated adhesion of N. meningitidis to the vascular wall, as opposed to circulating bacteria, determines vascular dysfunction in meningococcemia.

Adhesion of Neisseria meningitidis to dermal vessels leads to local vascular damage and purpura in a humanized mouse model.

A humanized model of microvascular infection.

Purpura fulminans in adults is a rare but devastating disease. Its pathophysiology is not well known.

Keira Melican

INSERM U970

Paris Cardiovascular Research Centre

Humanized Mouse Model to Study Bacterial Infections Targeting the Microvasculature

Keira Melican

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Paris Cardiovascular Research Centre

Humanized Mouse Model to Study Bacterial Infections Targeting the Microvasculature

INSERM U970