Les auteurs sont reconnaissants à K. Kissa pour des discussions utiles et pour fournir lipo-clodronate et L. Ramakrishnan pour le don généreux de pTEC27 et pTEC15 qui permettent l&#39;expression de tdTomato et Wasabi, respectivement. Ce travail fait partie des projets de l&#39;Agence Nationale de la Recherche française (ZebraFlam ANR-10-MIDI-009 et DIMYVIR ANR-13-BSV3-007-01) et septième programme-cadre de la Communauté européenne (FP7-PEOPLE-2011-ITN) en vertu de convention de subvention aucune. PITN-GA-2011-289209 pour le Marie-Curie de formation initiale Réseau FishForPharma. Nous tenons également à remercier l&#39;Association Gregory Lemarchal et Vaincre La Mucoviscidose (RF20130500835) pour le financement CM Dupont.

The authors have nothing to disclose.

Le poisson zèbre a récemment émergé comme un excellent système de modèle vertébré pour étudier la dynamique de l&#39;infection bactérienne utilisant large champ et imagerie confocale en temps réel 36. La combinaison de suspensions mycobactériennes dispersées (protocole 2.2) ainsi que les méthodes de micro-injection (protocole 4) permet infections reproductibles systémiques, et le suivi ultérieur et la visualisation de la progression de l&#39;infection avec un accent particulier sur les interac...

Mycobacterium abscessus est un pathogène émergent qui provoque une large gamme de syndromes cliniques chez l&#39;homme. Ceux-ci comprennent les infections cutanées ainsi que des infections pulmonaires chroniques sévères, principalement rencontrées dans immunodéprimés et chez les patients atteints de fibrose kystique 1,2,3,4. M. abscessus est également considéré comme l&#39;un des principaux espèces de mycobactéries à croissance rapide responsables des infections nosocomiales et iatrogènes chez les humains. En outre, plusieurs rapports récents ont mis en évidence la possibilité que M. abscessus pourrait traverser la barrière hémato-encéphalique et induire des lésions importantes dans le système nerveux central (SNC) 5,6. En dépit d&#39;être un producteur rapide, M. expositions abscessus aussi plusieurs fonctionnalités pathogènes qui sont liés à ceux de Mycobacterium tuberculosis, y compris la capacité de garder le silence pendant des années au sein des structures granulomateuses et de générer des lésions dans les poumons caséeuses 7. Plus inquiétante est le faible sensibilité de M. abscessus aux antibiotiques, ce qui rend ces infections extrêmement difficile à traiter conduisant à un taux d&#39;échec thérapeutique significatif 8,9. La menace importante de cette espèce est principalement sa résistance intrinsèque à des antibiotiques, ce qui est une préoccupation majeure dans les établissements 10 de santé publique et d&#39;une contre-indication à la transplantation pulmonaire 11. M. de les écrans lisses (S) ou rugueuses morphotypes (R) de la colonie qui mènent à différents résultats cliniques. A la différence de la souche S, R bactéries ont tendance à croître de bout en bout, ce qui conduit à une corde ou un cordon structure semblable à 12,13. Plusieurs études indépendantes basées sur des modèles cellulaires ou animaux soit révélé le phénotype hyper-virulence de la R morphotype 14,15. Des études épidémiologiques, les cas les plus graves de M. infections pulmonaires abscessus semblent être associés avec des variantes R 16 qui sont la seule variantea vu persister pendant des années dans un hôte infecté 3. La différence de morphotype repose sur la présence (en S) ou perte (en R) de glycopeptidolipides de surface associée (GPL) 12. Toutefois, en raison des limites inhérentes aux modèles cellulaires / animales actuellement disponibles utilisés pour étudier M. infection abscessus, nos connaissances concernant les événements physiopathologiques des variantes de R ou S reste obscure. L&#39;infection des souris immuno-compétentes par voie intraveineuse ou en aérosol conduit à la colonisation transitoire, d&#39;empêcher l&#39;utilisation de souris pour étudier les infections persistantes et pour vivo tests de sensibilité dans la drogue 17. Par conséquent, le développement de modèles animaux qui se prêtent à la manipulation de la réponse de l&#39;hôte est un défi majeur. Dans ce contexte, les modèles non-mammifères d&#39;infection ont été récemment mis au point, y compris Drosophila melanogaster 18 qui offre plusieurs avantages tels que le coût, la rapidité et l&#39;acceptabilité éthique oVer le modèle de la souris. Le modèle de poisson zèbre (Danio rerio) de l&#39;infection a également été explorée de visualiser, par imagerie non invasive, la progression et la chronologie de M. abscessus infection chez un animal en direct 19. Surtout, une preuve de concept a également été établi pour démontrer son aptitude pour les évaluations antibiotiques in vivo contre M. abscessus 17,20. Le poisson zèbre ont été largement utilisés au cours des deux dernières décennies pour étudier les interactions entre les différents agents pathogènes et le système immunitaire de l&#39;hôte 21. Le succès croissant de ce modèle vertébré alternatif repose sur les opportunités majeurs et uniques qui ont motivé et validés son utilisation pour une meilleure compréhension de nombreuses infections virales et bactériennes 19,22,23,24,25,26,27,28,29. Contrairement à la plupart des autres modèles animaux, embryons de poisson zèbre sont optiquement transparent, ce qui permet l&#39;imagerie de fluorescence non invasive 30. Cette has conduit à étudier M. abscessus infecté embryons de poisson zèbre avec des détails sans précédent, culminant avec la description de Cording extracellulaire, qui représentent un exemple de plasticité morphologique bactérienne. Cording représente un nouveau mécanisme de subversion du système immunitaire et un mécanisme essentiel dans la promotion pathogenèse de M. aiguë infection abscessus 19. Ce rapport décrit les nouveaux outils et les méthodes utilisant l&#39;embryon de poisson zèbre à déchiffrer les traits physiopathologiques de M. abscessus infection et d&#39;étudier les interactions intimes entre le bacille et le système immunitaire inné. Tout d&#39;abord, la micro-injection d&#39;un protocole détaillé qui comprend le traitement de l&#39;inoculum bactérien, la préparation de l&#39;embryon, et l&#39;infection en soi, est présentée. Méthodes spécifiquement adaptés pour évaluer M. virulence abscessus par la mesure de différents paramètres, tels que la survie de l&#39;hôte et de la charge bactérienne, sont présentés. Une attention particulière est donnée sur la façonà surveiller, à un niveau spatio-temporel, et le sort progression de l&#39;infection et la réponse immunitaire de l&#39;hôte à M. abscessus par microscopie vidéo. En outre, pour enquêter sur la contribution et le rôle des macrophages lors de M. abscessus infection, les méthodes pour générer des macrophages-appauvri embryons (en utilisant des approches soit génétiquement ou chimiquement base-) sont décrites. Enfin, les protocoles de visualiser les interactions spécifiques avec les macrophages ou les neutrophiles en utilisant soit des embryons fixes ou vivant sont documentés. Le but de ce rapport est de stimuler de nouvelles études pour jeter une lumière nouvelle sur M. les mécanismes de virulence abscessus et notamment le rôle de Cording dans la mise en place d&#39;un processus d&#39;infection aiguë et incontrôlée.

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			<td>Borosilicate glass capillaries&#160;</td>
			<td>Sutter instrument Inc</td>
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			<td>Micropipette puller device&#160;</td>
			<td>Sutter Instrument Inc</td>
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			<td>Microinjector</td>
			<td>Tritech Research&#160;</td>
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			<td>Tweezers</td>
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			<td>Microloader Tips</td>
			<td>Eppendorf</td>
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deciphering and imaging pathogenesis and cording of mycobacterium abscessus in zebrafish embryos

Zebrafish (Danio rerio) embryos are increasingly used as an infection model to study the function of the vertebrate innate immune system in host-pathogen interactions.&#160;The ease of obtaining large numbers of embryos, their accessibility due to external development, their optical transparency as well as the availability of a wide panoply of genetic/immunological tools and transgenic reporter line collections, contribute to the versatility of this model.&#160;In this respect, the present manuscript describes the use of zebrafish as an&#160;in vivo&#160;model system to investigate the chronology of Mycobacterium abscessus infection. This human pathogen can exist either as smooth (S) or rough (R) variants, depending on cell wall composition, and their respective virulence can be imaged and compared in zebrafish embryos and larvae. Micro-injection of either S or R fluorescent variants directly in the blood circulation via the caudal vein, leads to chronic or acute/lethal infections, respectively. This biological system allows high resolution visualization and analysis of the role of mycobacterial cording in promoting abscess formation. In addition, the use of fluorescent bacteria along with transgenic zebrafish lines harbouring fluorescent macrophages produces a unique opportunity for multi-color imaging of the host-pathogen interactions. This article describes detailed protocols for the preparation of homogenous M. abscessus inoculum and for intravenous injection of zebrafish embryos for subsequent fluorescence imaging of the interaction with macrophages. These techniques open the avenue to future investigations involving mutants defective in cord formation and are dedicated to understand how this impacts on M. abscessus pathogenicity in a whole vertebrate.

Bien que différents sites anatomiques peuvent être injectés 32, les injections de veine caudale sont souvent utilisés pour générer une infection systémique pour les analyses ultérieures, y compris les expériences de survie, la détermination de la charge bactérienne, une activité de phagocytose ou la formation du cordon. Les injections dans les muscles de la queue sont utilisés pour évaluer le recrutement des macrophages au site d&#39;injection (figure 3A). Pour étudier et de co...

Watch this Scientific Journal Video about Deciphering and Imaging Pathogenesis and Cording of Mycobacterium abscessus in Zebrafish Embryos at JoVE.com

Deciphering and Imaging Pathogenesis and Cording of Mycobacterium abscessus in Zebrafish Embryos

Optically transparent zebrafish embryos are widely used to study and visualize in real time the interactions between pathogenic microorganisms and the innate immune cells. Micro-injection of Mycobacterium abscessus, combined with fluorescence imaging, is used to scrutinize essential pathogenic features such as cord formation in zebrafish embryos.

Décrypter et de l&#39;imagerie et la pathogenèse de Cording<em&gt; Mycobacterium abscessus</em&gt; Dans embryons de poissons zèbres

Zebrafish (Danio rerio) embryos are increasingly used as an infection model to study the function of the vertebrate innate immune system in host-pathogen ...

deciphering-imaging-pathogenesis-cording-mycobacterium-abscessus

Research

JoVE Journal

Immunology and Infection

Deciphering and Imaging Pathogenesis and Cording of Mycobacterium abscessus in Zebrafish Embryos

10.1K vues.  Université Montpellier. Optically transparent zebrafish embryos are widely used to study and visualize in real time the interactions between pathogenic microorganisms and the innate immune cells. Micro-injection of Mycobacterium abscessus, combined with fluorescence imaging, is used to scrutinize essential pathogenic features such as cord formation in zebrafish embryos. 

Vidéo: Deciphering and Imaging Pathogenesis and Cording of Mycobacterium abscessus in Zebrafish Embryos

Imaging of HIV-1 Envelope-induced Virological Synapse and Signaling on Synthetic Lipid Bilayers

Human immunodeficiency virus type 1 (HIV-1) infection occurs most efficiently via cell to cell transmission2,10,11. This cell to cell transfer between CD4+ T cells involves the formation of a virological synapse (VS), which is an F-actin-dependent cell-cell junction formed upon the engagement of HIV-1 envelope gp120 on the infected cell with CD4 and the chemokine receptor (CKR) CCR5 or CXCR4 on the target cell 8. In addition to gp120 and its receptors, other membrane proteins, particularly the adhesion molecule LFA-1 and its ligands, the ICAM family, play a major role in VS formation and virus transmission as they are present on the surface of virus-infected donor cells and target cells, as well as on the envelope of HIV-1 virions1,4,5,6,7,13. VS formation is also accompanied by intracellular signaling events that are transduced as a result of gp120-engagement of its receptors. Indeed, we have recently showed that CD4+ T cell interaction with gp120 induces recruitment and phosphorylation of signaling molecules associated with the TCR signalosome including Lck, CD3&zeta;, ZAP70, LAT, SLP-76, Itk, and PLC&gamma;15.
In this article, we present a method to visualize supramolecular arrangement and membrane-proximal signaling events taking place during VS formation. We take advantage of the glass-supported planar bi-layer system as a reductionist model to represent the surface of HIV-infected cells bearing the viral envelope gp120 and the cellular adhesion molecule ICAM-1. The protocol describes general procedures for monitoring HIV-1 gp120-induced VS assembly and signal activation events that include i) bi-layer preparation and assembly in a flow cell, ii) injection of cells and immunofluorescence staining to detect intracellular signaling molecules on cells interacting with HIV-1 gp120 and ICAM-1 on bi-layers, iii) image acquisition by TIRF microscopy, and iv) data analysis. This system generates high-resolution images of VS interface beyond that achieved with the conventional cell-cell system as it allows detection of distinct clusters of individual molecular components of VS along with specific signaling molecules recruited to these sub-domains.

This article describes a method to visualize formation of an HIV-1 envelope-induced virological synapse on glass supported planar bilayers by total internal reflection fluorescence (TIRF) microscopy. The method can also be combined with immunofluorescence staining to detect activation and redistribution of signaling molecules that occur during HIV-1 envelope-induced virological synapse formation.

Imagerie de VIH-1 Enveloppe induite Synapse virologique et de signalisation sur bicouches lipidiques synthétiques

Human immunodeficiency virus type 1 (HIV-1) infection occurs most efficiently via cell to cell transmission2,10,11. This cell to cell transfer between ...

Recherche

Immunologie et infection

Infection of Zebrafish Embryos with Intracellular Bacterial Pathogens

Zebrafish (Danio rerio) embryos are increasingly used as a model for studying the function of the vertebrate innate immune system in host-pathogen interactions 1. The major cell types of the innate immune system, macrophages and neutrophils, develop during the first days of embryogenesis prior to the maturation of lymphocytes that are required for adaptive immune responses. The ease of obtaining large numbers of embryos, their accessibility due to external development, the optical transparency of embryonic and larval stages, a wide range of genetic tools, extensive mutant resources and collections of transgenic reporter lines, all add to the versatility of the zebrafish model. Salmonella enterica serovar Typhimurium (S. typhimurium) and Mycobacterium marinum can reside intracellularly in macrophages and are frequently used to study host-pathogen interactions in zebrafish embryos. The infection processes of these two bacterial pathogens are interesting to compare because S. typhimurium infection is acute and lethal within one day, whereas M. marinum infection is chronic and can be imaged up to the larval stage 2, 3. The site of micro-injection of bacteria into the embryo (Figure 1) determines whether the infection will rapidly become systemic or will initially remain localized. A rapid systemic infection can be established by micro-injecting bacteria directly into the blood circulation via the caudal vein at the posterior blood island or via the Duct of Cuvier, a wide circulation channel on the yolk sac connecting the heart to the trunk vasculature. At 1 dpf, when embryos at this stage have phagocytically active macrophages but neutrophils have not yet matured, injecting into the blood island is preferred. For injections at 2-3 dpf, when embryos also have developed functional (myeloperoxidase-producing) neutrophils, the Duct of Cuvier is preferred as the injection site. To study directed migration of myeloid cells towards local infections, bacteria can be injected into the tail muscle, otic vesicle, or hindbrain ventricle 4-6. In addition, the notochord, a structure that appears to be normally inaccessible to myeloid cells, is highly susceptible to local infection 7. A useful alternative for high-throughput applications is the injection of bacteria into the yolk of embryos within the first hours after fertilization 8. Combining fluorescent bacteria and transgenic zebrafish lines with fluorescent macrophages or neutrophils creates ideal circumstances for multi-color imaging of host-pathogen interactions. This video article will describe detailed protocols for intravenous and local infection of zebrafish embryos with S. typhimurium or M. marinum bacteria and for subsequent fluorescence imaging of the interaction with cells of the innate immune system.

Transparent zebrafish embryos have proved useful model hosts to visualize and functionally study interactions between innate immune cells and intracellular bacterial pathogens, such as Salmonella typhimurium and Mycobacterium marinum. Micro-injection of bacteria and multi-color fluorescence imaging are essential techniques involved in the application of zebrafish embryo infection models.

L&#39;infection des embryons de poisson zèbre avec bactéries pathogènes intracellulaires

Zebrafish (Danio rerio) embryos are increasingly used as a model for studying the function of the vertebrate innate immune system in host-pathogen ...

Growth of Mycobacterium tuberculosis Biofilms

Mycobacterium tuberculosis, the etiologic agent of human tuberculosis, has an extraordinary ability to survive against environmental stresses including antibiotics. Although stress tolerance of M. tuberculosis is one of the likely contributors to the 6-month long chemotherapy of tuberculosis 1, the molecular mechanisms underlying this characteristic phenotype of the pathogen remain unclear. Many microbial species have evolved to survive in stressful environments by self-assembling in highly organized, surface attached, and matrix encapsulated structures called biofilms 2-4. Growth in communities appears to be a preferred survival strategy of microbes, and is achieved through genetic components that regulate surface attachment, intercellular communications, and synthesis of extracellular polymeric substances (EPS) 5,6. The tolerance to environmental stress is likely facilitated by EPS, and perhaps by the physiological adaptation of individual bacilli to heterogeneous microenvironments within the complex architecture of biofilms 7.
In a series of recent papers we established that M. tuberculosis and Mycobacterium smegmatis have a strong propensity to grow in organized multicellular structures, called biofilms, which can tolerate more than 50 times the minimal inhibitory concentrations of the anti-tuberculosis drugs isoniazid and rifampicin 8-10. M. tuberculosis, however, intriguingly requires specific conditions to form mature biofilms, in particular 9:1 ratio of headspace: media as well as limited exchange of air with the atmosphere 9. Requirements of specialized environmental conditions could possibly be linked to the fact that M. tuberculosis is an obligate human pathogen and thus has adapted to tissue environments. In this publication we demonstrate methods for culturing M. tuberculosis biofilms in a bottle and a 12-well plate format, which is convenient for bacteriological as well as genetic studies. We have described the protocol for an attenuated strain of M. tuberculosis, mc27000, with deletion in the two loci, panCD and RD1, that are critical for in vivo growth of the pathogen 9. This strain can be safely used in a BSL-2 containment for understanding the basic biology of the tuberculosis pathogen thus avoiding the requirement of an expensive BSL-3 facility. The method can be extended, with appropriate modification in media, to grow biofilm of other culturable mycobacterial species.
Overall, a uniform protocol of culturing mycobacterial biofilms will help the investigators interested in studying the basic resilient characteristics of mycobacteria. In addition, a clear and concise method of growing mycobacterial biofilms will also help the clinical and pharmaceutical investigators to test the efficacy of a potential drug.

Growth of Mycobacterium tuberculosis Biofilms

Mycobacterium tuberculosis forms drug tolerant biofilms when cultured in certain conditions. Here we describe methods for culturing M. tuberculosis biofilms and determining the frequency of drug tolerant persisters. These protocols will be useful for further studies into the mechanisms of drug tolerance in M. tuberculosis.

La croissance de la Mycobacterium tuberculosis Les biofilms

Mycobacterium tuberculosis, the etiologic agent of human tuberculosis, has an extraordinary ability to survive against environmental stresses including ...

Non-invasive Imaging of Disseminated Candidiasis in Zebrafish Larvae

Disseminated candidiasis caused by the pathogen Candida albicans is a clinically important problem in hospitalized individuals and is associated with a 30 to 40% attributable mortality6. Systemic candidiasis is normally controlled by innate immunity, and individuals with genetic defects in innate immune cell components such as phagocyte NADPH oxidase are more susceptible to candidemia7-9. Very little is known about the dynamics of C. albicans interaction with innate immune cells in vivo. Extensive in vitro studies have established that outside of the host C. albicans germinates inside of macrophages, and is quickly destroyed by neutrophils10-14. In vitro studies, though useful, cannot recapitulate the complex in vivo environment, which includes time-dependent dynamics of cytokine levels, extracellular matrix attachments, and intercellular contacts10, 15-18. To probe the contribution of these factors in host-pathogen interaction, it is critical to find a model organism to visualize these aspects of infection non-invasively in a live intact host. 
The zebrafish larva offers a unique and versatile vertebrate host for the study of infection. For the first 30 days of development zebrafish larvae have only innate immune defenses2, 19-21, simplifying the study of diseases such as disseminated candidiasis that are highly dependent on innate immunity. The small size and transparency of zebrafish larvae enable imaging of infection dynamics at the cellular level for both host and pathogen. Transgenic larvae with fluorescing innate immune cells can be used to identify specific cells types involved in infection22-24. Modified anti-sense oligonucleotides (Morpholinos) can be used to knock down various immune components such as phagocyte NADPH oxidase and study the changes in response to fungal infection5. In addition to the ethical and practical advantages of using a small lower vertebrate, the zebrafish larvae offers the unique possibility to image the pitched battle between pathogen and host both intravitally and in color. 
The zebrafish has been used to model infection for a number of human pathogenic bacteria, and has been instrumental in major advances in our understanding of mycobacterial infection3, 25. However, only recently have much larger pathogens such as fungi been used to infect larva5, 23, 26, and to date there has not been a detailed visual description of the infection methodology. Here we present our techniques for hindbrain ventricle microinjection of prim25 zebrafish, including our modifications to previous protocols. Our findings using the larval zebrafish model for fungal infection diverge from in vitro studies and reinforce the need to examine the host-pathogen interaction in the complex environment of the host rather than the simplified system of the Petri dish5.

The rapid development, small size and transparency of zebrafish are tremendous advantages for the study of innate immune control of infection1-4. Here we demonstrate techniques for infecting zebrafish larvae using the fungal pathogen Candida albicans by microinjection, methodology recently used to implicate phagocyte NADPH oxidase activity in control of fungal dimorphism5.

L&#39;imagerie non invasive de la candidose disséminée chez les larves poisson zèbre

Disseminated candidiasis caused by the pathogen Candida albicans is a clinically important problem in hospitalized individuals and is associated with a 30 ...

Imaging Mycobacterium tuberculosis in Mice with Reporter Enzyme Fluorescence

Reporter enzyme fluorescence (REF) utilizes substrates that are specific for enzymes present in target organisms of interest for imaging or detection by fluorescence or bioluminescence. We utilize BlaC, an enzyme expressed constitutively by all M. tuberculosis strains. REF allows rapid quantification of bacteria in lungs of infected mice. The same group of mice can be imaged at many time points, greatly reducing costs, enumerating bacteria more quickly, allowing novel observations in host-pathogen interactions, and increasing statistical power, since more animals per group are readily maintained. REF is extremely sensitive due to the catalytic nature of the BlaC enzymatic reporter and specific due to the custom flourescence resonance energy transfer (FRET) or fluorogenic substrates used. REF does not require recombinant strains, ensuring normal host-pathogen interactions. We describe the imaging of M. tuberculosis infection using a FRET substrate with maximal emission at 800 nm. The wavelength of the substrate allows sensitive deep tissue imaging in mammals. We will outline aerosol infection of mice with M. tuberculosis, anesthesia of mice, administration of the REF substrate, and optical imaging. This method has been successfully applied to evaluating host-pathogen interactions and efficacy of antibiotics targeting M. tuberculosis.

Imaging Mycobacterium tuberculosis in Mice with Reporter Enzyme Fluorescence

We describe the optical imaging of mice infected with Mycobacterium tuberculosis (M. tuberculosis) using reporter enzyme fluorescence (REF). This protocol facilitates the sensitive and specific detection of M. tuberculosis in pre-clinical animal models for pathogenesis, therapeutics and vaccine research.

Imagerie de Mycobacterium tuberculosis chez la souris avec la journaliste Enzyme Fluorescence

Reporter enzyme fluorescence (REF) utilizes substrates that are specific for enzymes present in target organisms of interest for imaging or detection by ...

Identification of Virulence Markers of Mycobacterium abscessus for Intracellular Replication in Phagocytes

What differentiates Mycobacterium abscessus from other saprophytic mycobacteria is the ability to resist phagocytosis by human macrophages and the ability to multiply inside such cells. These virulence traits render M. abscessus pathogenic, especially in vulnerable hosts with underlying structural lung disease, such as cystic fibrosis, bronchiectasis or tuberculosis. How patients become infected with M. abscessus remains unclear. Unlike many mycobacteria, M. abscessus is not found in the environment but might reside inside amoebae, environmental phagocytes that represent a potential reservoir for M. abscessus. Indeed, M. abscessus is resistant to amoebal phagocytosis and the intra-amoeba life seems to increase M. abscessus virulence in an experimental model of infection. However, little is known about M. abscessus virulence in itself. To decipher the genes conferring an advantage to M. abscessus intracellular life, a screening of a M. abscessus transposon mutant library was developed. In parallel, a method of RNA extraction from intracellular Mycobacteria after co-culture with amoebae was developed. This method was validated and allowed the sequencing of whole M. abscessus transcriptomes inside the cells; providing, for the first time, a global view on M. abscessus adaptation to intracellular life. Both approaches give us an insight into M. abscessus virulence factors that enable M. abscessus to colonize the airways in humans.

Identification of Virulence Markers of Mycobacterium abscessus for Intracellular Replication in Phagocytes

Here, we present two protocols to study Phagocyte-Mycobacterium abscessus interactions: the screening of a transposon mutant library for bacterial intracellular deficiency and the determination of bacterial intracellular transcriptome from RNA sequencing. Both approaches provide insight into the genomic advantages and transcriptomic adaptations enhancing intracellular bacteria fitness.

Identification de marqueurs de Virulence de Mycobacterium abscessus de réplication intracellulaire dans les Phagocytes

What differentiates Mycobacterium abscessus from other saprophytic mycobacteria is the ability to resist phagocytosis by human macrophages and the ability ...

Modeling Tuberculosis in Mycobacterium marinum Infected Adult Zebrafish

Mycobacterium tuberculosis is currently the deadliest human pathogen causing 1.7 million deaths and 10.4 million infections every year. Exposure to this bacterium causes a wide disease spectrum in humans ranging from a sterilized infection to an actively progressing deadly disease. The most common form is the latent tuberculosis, which is asymptomatic, but has the potential to reactivate into a fulminant disease. Adult zebrafish and its natural pathogen Mycobacterium marinum have recently proven to be an applicable model to study the wide disease spectrum of tuberculosis. Importantly, spontaneous latency and reactivation as well as adaptive immune responses in the context of mycobacterial infection can be studied in this model. In this article, we describe methods for the experimental infection of adult zebrafish, the collection of internal organs for the extraction of nucleic acids for the measurement of mycobacterial loads and host immune responses by quantitative PCR. The in-house-developed, M. marinum-specific qPCR assay is more sensitive than the traditional plating methods as it also detects DNA from non-dividing, dormant or recently dead mycobacteria. As both DNA and RNA are extracted from the same individual, it is possible to study the relationships between the diseased state, and the host and pathogen gene-expression. The adult zebrafish model for tuberculosis thus presents itself as a highly applicable, non-mammalian in vivo system to study host-pathogen interactions.

Modeling Tuberculosis in Mycobacterium marinum Infected Adult Zebrafish

Here, we present a protocol to model human tuberculosis in an adult zebrafish using its natural pathogen Mycobacterium marinum. Extracted DNA and RNA from the internal organs of infected zebrafish can be used to reveal the total mycobacterial loads in the fish and the host&#39;s immune responses with qPCR.

Modélisation de la tuberculose chez Mycobacterium marinum adultes infectés poisson zèbre

Mycobacterium tuberculosis is currently the deadliest human pathogen causing 1.7 million deaths and 10.4 million infections every year. Exposure to this ...

Adoptive Immunotherapy of iNKT Cells in Glucose-6-Phosphate Isomerase (G6PI)-Induced RA Mice

Rheumatoid arthritis (RA) is a complex chronic inflammatory autoimmune disease. The pathogenesis of the disease is related to invariant natural killer T (iNKT) cells. Patients with active RA present fewer iNKT cells, defective cell function, and excessive polarization of Th1. In this study, an RA animal model was established using a mixture of hGPI325-339 and hGPI469-483 peptides. The iNKT cells were obtained by in vivo induction and in vitro purification, followed by infusion into RA mice for adoptive immunotherapy. The in vivo imaging system (IVIS) tracking revealed that iNKT cells were mainly distributed in the spleen and liver. On day 12 after cell therapy, the disease progression slowed down significantly, the clinical symptoms were alleviated, the abundance of iNKT cells in the thymus increased, the proportion of iNKT1 in the thymus decreased, and the levels of TNF-&#945;, IFN-&#947;, and IL-6 in the serum decreased. Adoptive immunotherapy of iNKT cells restored the balance of immune cells and corrected the excessive inflammation of the body.

Adoptive Immunotherapy of iNKT Cells in Glucose-6-Phosphate Isomerase G6PI-Induced RA Mice

This protocol uses G6PI mixed peptides to construct rheumatoid arthritis models that are closer to that of human rheumatoid arthritis in CD4+ T cells and cytokines. High purity invariant natural killer T cells (mainly iNKT2) with specific phenotypes and functions were obtained by in vivo induction and in vitro purification for adoptive immunotherapy.

Immunothérapie adoptive des cellules iNKT dans les souris de RA induites par l'isomérase de glucose-6-Phosphate (G6PI)

Rheumatoid arthritis (RA) is a complex chronic inflammatory autoimmune disease. The pathogenesis of the disease is related to invariant natural killer T ...

Visualization of Macrophage Lytic Cell Death During Mycobacterial Infection in Zebrafish Embryos via Intravital Microscopy

Zebrafish is an excellent model organism for studying innate immune cell behavior due to its transparent nature and reliance solely on its innate immune system during early development. The Zebrafish Mycobacterium marinum (M. marinum) infection model has been well-established in studying host immune response against mycobacterial infection. It has been suggested that different macrophage cell death types will lead to the diverse outcomes of mycobacterial infection. Here we describe a protocol using intravital microscopy to observe macrophage cell death in zebrafish embryos following M. marinum infection. Zebrafish transgenic lines that specifically label macrophages and neutrophils are infected via intramuscular microinjection of fluorescently labeled M. marinum in either the midbrain or the trunk. Infected zebrafish embryos are subsequently mounted on low melting agarose and observed by confocal microscopy in X-Y-Z-T dimensions. Because long-term live imaging requires using low laser power to avoid photobleaching and phototoxicity, a strongly expressing transgenic is highly recommended. This protocol facilitates the visualization of the dynamic processes in vivo, including immune cell migration, host pathogen interaction, and cell death.

This protocol describes a technique for visualizing macrophage behavior and death in embryonic zebrafish during Mycobacterium marinum infection. Steps for the preparation of bacteria, infection of the embryos, and intravital microscopy are included. This technique may be applied to the observation of cellular behavior and death in similar scenarios involving infection or sterile inflammation.

Visualisation de la mort des cellules lytiques de Macrophage pendant l'infection mycobactérienne dans les embryons de poisson zèbre par l'intermédiaire de la microscopie intravitale

Zebrafish is an excellent model organism for studying innate immune cell behavior due to its transparent nature and reliance solely on its innate immune ...

Phage Therapy Application to Counteract Pseudomonas aeruginosa Infection in Cystic Fibrosis Zebrafish Embryos

Antimicrobial resistance, a major consequence of diagnostic uncertainty and antimicrobial overprescription, is an increasingly recognized cause of severe infections, complications, and mortality worldwide with a huge impact on our society and on the health system. In particular, patients with compromised immune systems or pre-existing and chronic pathologies, such as cystic fibrosis (CF), are subjected to frequent antibiotic treatments to control the infections with the appearance and diffusion of multidrug resistant isolates. Therefore, there is an urgent need to address alternative therapies to counteract bacterial infections. Use of bacteriophages, the natural enemies of bacteria, can be a possible solution. The protocol detailed in this work describes the application of phage therapy against Pseudomonas aeruginosa infection in CF zebrafish embryos. Zebrafish embryos were infected with P. aeruginosa to demonstrate that phage therapy is effective against P. aeruginosa infections as it reduces lethality, bacterial burden and pro-inflammatory immune response in CF embryos.

Phage Therapy Application to Counteract Pseudomonas aeruginosa Infection in Cystic Fibrosis Zebrafish Embryos

Presented here is a protocol for Pseudomonas aeruginosa infection and phage therapy application in cystic fibrosis (CF) zebrafish embryos.

Application de thérapie de phage pour contrecarrer l’infection de Pseudomonas aeruginosa dans les embryons de poisson zèbre de fibrose kystique

Antimicrobial resistance, a major consequence of diagnostic uncertainty and antimicrobial overprescription, is an increasingly recognized cause of severe ...