Thèses sur le sujet « Cellules bactériennes »
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Pichavant, Muriel. « Mécanismes de sensibilisation par voie aérienne : interactions entre cellules épithéliales bronchiques et cellules dendritiques ». Lille 2, 2004. http://www.theses.fr/2004LIL2S018.
Texte intégralMucosal immune response depends on the surveillance network established by dendritic cells (DC), located within airway epithelium. DC are professionnal antigen presenting cells, which play a key role in the development and the polarization of immune responses. Exposure to microbial products or allergens increases the number of DC within bronchial epithelium. Moreover, airway sensitization to allergens depends on the presence of pathogen-associated molecular patterns, involving probably bronchial epithelial cell (BEC) activation. To test this hypothesis, we analyzed the crosstalk between BEC and DC in response to a potent vaccinal agent: KpOmpA and to an aeroallergen: Der p1. KpOmpA, an outer membrane protein from Klebsiella pneumoniae, activates macrophages and DC, and has immunomodulatory properties. Our results show that KpOmpA-activated BEC take part to innate immune response through the recruitment of neutrophils. Moreover, BEC trigger the migration of myeloid DC precursors and favor their differentiation/maturation. This study demonstrates the role of BEC in the development of innate and adaptive immune responses after PAMP exposure. Since Der p1, a cystein protease allergen from Dermatophagoïdes pteronyssinus, is able to induce airway sensitization of atopic patients, we evaluated interactions between BEC from non atopic (NA) and allergic asthmatic (AA) donors and DC. Der p1 triggers CCL2, CCL5 and CXCL10 production in both groups, whereas CCL20 is only induced with AA BEC. Langerhans cell precursors are recruited by AA BEC, in addition to monocyte-derived DC precursors which are recruited in both groups. This mechanism of airway sensitization to Der p1 probably implicate the selective recruitment of a DC sub-population. These data show that BEC participate to the development of the immune response through their capacity to regulate the homeostasis of airway DC, and their differentiation/maturation. Thus, bronchial epithelium targeting and activation could be important in vaccination process via airway mucosa
Bernard, Sandra. « Adhérence de Neisseria meningitidis aux cellules endothéliales humaines : rôle du récepteur cellulaire CD147 ». Paris 7, 2012. http://www.theses.fr/2012PA077242.
Texte intégralN. Meningitidis, also referred to as meningococcus, is a commensal bacterium of the human nasopharynx, responsible for septicemia and meningitis. The interaction between N. Meningitidis and endothelial cells has a major role in meningococcal pathogenesis. The type IV pili, filamentous appendices distributed on the bacterial surface, are the major adhesins allowing the initial adhesion of the virulent capsulated strains of meningocci to human cells. However, the cell receptor involved in such interaction, as well as the specific adhesin component/s, were still elusive. Previous experiments in our laboratory identified CD 147 as the potential cell receptor for N. Meningitidis type IV pili. My thesis project shows that CD 147 expression is required for the initial type IV pili-mediated adhesion of N. Meningitidis on brain and peripheral endothelial cells. Meningococcal pili can directly interact with the proximal immunoglobulin domain of CD 147 and this interaction engages specifically the major pilin pilE and the minor pilin pilV within the pilus structure. Finally, the role of CD 147 and these meningococcal pilins was confirmed during infection ex vivo of human brain slices, which were validated as infection model for N. Meningitidis. Altogether, the results obtained shed light on the initial process of meningococcal adhesion on human cells, first step of an infectious disease that still represents a severe public health issue Worldwide
Grimault, Valérie. « Etude des mécanismes de résistance de la tomate au flétrissement bactérien causé par pseudomonas solanacearum E. F. Smith ». Paris 11, 1993. http://www.theses.fr/1993PA112368.
Texte intégralKrapf, Marie-Ève. « Agrégation de cellules bactériennes par des polymères cationiques (polyéthylèneimine) : influence de la masse moléculaire du polymère et de la présence/absence de surstructures exopolymériques bactériennes sur la déshydratation des boues biologiques ». Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0089/document.
Texte intégralAfter dewatering, a biological sludge still contains an average water content of 70%, thus causing huge environmental problems. To achieve a better understanding of the mechanisms underlying physicochemical interactions inducing water retention in the sludge, the bacterial sludge was modeled by a pure strain producing or not surface appendages, depending on the growth temperature. These bacterial suspensions were flocculated by polyethyleneimine of various molecular weights. Measurements of optical density, electrophoretic mobility, conductivity, pH, absorbance, particle size, as well as AFM and TEM observations were performed. This allowed to characterize aggregates structures and to estimate the influence of molecular weight and concentration of polymer and presence/absence of surface appendages. Measurements of elasticity, spring constant and turgor pressure were carried out by force spectroscopy allowing to characterize nanomechanical properties of aggregates. In a second step, a dewatering of these flocculated suspensions was performed by centrifugation, process used in some wastewater treatment plants. Measurements of elasticity and viscosity were carried out by rheology. Correlations with dryness measurements allowed to conclude that the presence/absence of surface appendages, and also the molecular weight and concentration of the polymer have a significant impact on biological sludge dewatering
Fan, Ying. « Role of the Axis Th-17/Th-22 in the regulation of the pulmonary immune response in allergic asthma ». Thesis, Lille 2, 2013. http://www.theses.fr/2013LIL2S010.
Texte intégralAllergic asthma is characterized by a predominant Th2 response, but additional profiles such as Th17 and Th22 are observed in more severe asthma. Components of the air pollution such as polycyclic aromatic hydrocarbons (PAH) contained in diesel exhausts particles (DEP) contributes to increased prevalence of asthma and play an adjuvant role in the development and exacerbation of allergic inflammation through the skewing of the immune response towards a Th2 profile. In the first part of the thesis, we evaluated the effects of PAH on the Th17/Th22 polarization of PBMCs from healthy and allergic asthmatic subjects, PBMCs from athmatic patients exhibited an increased Th17/Th22 profile compared with non-allergic subjects. DEP-PAH and Benzo[a]Pyrene (B[a]P) stimulation further increased IL-22 but surprisingly decreased IL-17A production in both groups. Th17 transcription factors RORA and RORC were down regulated, whereas AhR target gene CYP1A1 was up-regulated in both groups. Notch was decreased only in asthmatic patients. PAH-induced IL-22 production originated mainly from Th22 cells. The AhR antagonist reversed almost completely the effects of DEP-PAH, but only partially the effects of B[a]P, on IL-22/IL-17 reciprocal regulation. The kinases PI3K, JNK and ERK participated to the enhancing effect of B[a]P on IL-22 production, whereas p38 MAP kinase had an inhibitory effect.The second part of the thesis evaluated the co-stimulatory effect of combined PRR- and allergen-activated DCs on Th17/Th22 polarization in healthy and asthmatic subjects. Dog allergen stimulated DCs induced a small production of IL-22 in T cells. Additional activation by TLR3, TLR9 and NOD2 ligands led to increased production of pro-Th2 chemokines by DCs only from asthmatic patients allergic to dogs. In contrast, an adjuvant role was observed on the maturation and pro-Th17/Th22 cytokines production by DCs from both asthmatic and non-allergic subjects. In T cells co-cultured with DCs stimulated by dog allergen and PRR ligands, we found a mixed Th2/Th17/Th22 profile in asthmatic patients and a Th1/Th22 profile in non-allergic subjects. IL-22 producing cells were mainly Th22 in both groups with more Th22 cells were observed in asthmatic subjects. IL-17 and IL-22 production was9differently regulated between asthmatic subjects and non-allergic subjects, TGF-β having a pro-Th17 role while IL-23 having a pro-Th22 role.In vivo, a model of chronic dog-induced asthma was developed leading increased airway resistance, Th2 chemokine and Th2/Th17/Th22 cytokine production as well as neutrophil but little eosinophil recruitment in the lung. Gene expression of IL-22 was observed at early time points whereas IL-22 protein appeared later on. NOD2 ligand further increased airway resistance, protein production and gene expression induced by dog allergen challenge but inhibited the small eosinophil recruitment in the lung.These results show that in humans, IL-17 and IL-22 productions are regulated differently between allergic asthmatic and non-allergic subjects. Altogether, pollution and some bacterial or viral infections may contribute in asthmatic patients to the severity of the disease and to progression of airway remodeling. The developed in vivo model will allow dissecting the mechanisms participating to the severity of asthma
Fouchet, Pierre. « Caractérisation de l'hétérogénéité de populations bactériennes par cytométrie en flux : études de paramètres physiologiques et structuraux ». Compiègne, 1994. http://www.theses.fr/1994COMPD696.
Texte intégralNourikyan, Julien. « Études biochimiques et cellulaires de tyrosine-kinases bactériennes ». Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10307/document.
Texte intégralBacteria possess a particular family of tyrosine-autokinases named BY-kinases. These enzymes are involved in the regulation of numerous cellular functions including the synthesis and export of extracellular polysaccharides that play a critical role in the virulence of different bacterial pathogens. However, the mechanisms of these processes remain unknown. The aim of my thesis was to characterize the role of these BY-kinases by structural and functional approaches. For that, I have realized three independent studies in three bacterial models. In Escherichia coli, I have characterized the interaction surface between the BY-kinase Wzc and its cognate phosphatase Wzb to understand how Wzb dephosphorylates Wzc. In Staphylococcus aureus, I have studied structurally the pseudo-BY-kinase CapB1. By comparison with the structure of its active homologue CapB2, my studies have allowed to suggest the existence of a mechanism controlling capsular polysaccharides synthesis involving both CapB1 and CapB2. Last, in Streptococcus pneumoniae, I have showed that while the autophosphorylation of the BY-kinase CpsD is necessary for proper synthesis of capsular polysaccharides, it is also involved in cell division. Thus, my work shows that a mechanism coordinating capsule production and cellular cycle exists in the pneumococcus. These works constitute a preliminary and promising step toward the development of new molecules, targeting specifically BY-kinases and aim to combat the virulence of bacterial pathogens
Pivetal, Jérémy. « Développement et premières applications d'une méthode de tri de cellules bactériennes par marquage de l'ADN avec des nanoparticules magnétiques pour l'étude de la diversité bactérienne environnementale et des transferts horizontaux de gènes in situ ». Thesis, Ecully, Ecole centrale de Lyon, 2013. http://www.theses.fr/2013ECDL0010/document.
Texte intégralDespite their importance, bacterial communities in the environment remain poorly characterized. On the one hand, it is difficult to gain knowledge of the community as a whole because over 99% of bacteria are recalcitrant to in vitro culture, rendering classic microbiological approaches imposible to carry out. On the other hand, metagenomics, which can be used to circumvent culture-based approaches by extracting all the genomes from a given environment, is also problematic given the associated technical limitations (biases related to DNA extraction, cloning, PCR, genome sequencing and assembling etc.), and conceptual difficulties related to the complexity and the homogeneity of the environments. In order to overcome some of the limitations of these approaches, bacterial cell selection methods have been developed and can be used to improve our understanding of microbial diversity. Based on taxonomic and/or functional selection and the direct isolation of bacterial cells from an environmental sample, bacterial cell selection can be used to reduce microbial community complexity by targeting specific populations, or even an isolated cell. A variety of classic approaches such as cultivation or DNA/RNA extraction can then be carried out. This cycle can theoretically be repeated until all members of the community are characterized. The aim of this doctoral thesis was to design a novel cell selection tool based on the permanent integration of micro-magnets into a microfluidic canal. In conjunction with a new miniaturized magnetic selection system that provides several advantages over larger systems (portable, low cost, requiring smaller reaction volumes and can be potentially integrated on “laboratory on a chip” systems), a method for selective bacterial cell isolation using magnetic labeling was developed. The bacterial cells were targeted based on taxonomic criteria; biotin-labeled probes were developed for a specific region of the 23S rRNA gene. Following in situ hybridization with the probes, baceterial cells were labeled with streptavidin-functionalized magnetic nanoparticles. First results showed that the tool was specific and sensitive enough to trap labeled and diluted (0,04%) cells from a suspension at levels that are comparible to populations of interest found in complex environmental communities. This tool has also been adapted to study in situ horizontal gene transfer as well. The application of a cellular selection tool that labels targets with magnetic nanoparticles coupled to fluidic microsystems with integrated nano-magnets looks very promising for future studiesin environmental microbiology
Maisnier-Patin, Karine. « Analyse des propriétés immunologiques de la protéine OmpX de Escherichia coli : conséquences sur les stratégies vaccinales anti-tumorales ». Lyon 1, 2002. http://www.theses.fr/2002LYO10209.
Texte intégralParadis-Bleau, Catherine. « Génomique fonctionnelle des protéines de division cellulaire et du peptidoglycane : développement de nouveaux agents antibactériens ». Thesis, Université Laval, 2007. http://www.theses.ulaval.ca/2007/24377/24377.pdf.
Texte intégralThis thesis first presents the critical outcome of antibiotic resistance among emerging and re-emerging bacterial pathogens worldwide. The incessant increase and spread of antibiotic resistance mechanisms compromise the efficiency of available antibacterial therapies and increase the impact of bacterial infections on human mortality and morbidity. This thesis focuses efforts to identify new antibacterial targets in order to develop novel classes of antibacterial agents using the opportunistic pathogen Pseudomonas aeruginosa as a research model. The first chapter of this thesis reports the exploitation of the cell division proteins FtsZ and FtsA as antibacterial targets. A detailed scientific review is presented along with two articles reporting the synthesis and selection of inhibitors against FtsZ and FtsA. These inhibitors represent potent candidates to develop new classes of antibacterial agents targeting the bacterial cell division process. The second chapter describes the use of the essential bacterial cell wall biosynthesis enzymes MurC, MurD, MurE and MurF as antibacterial targets. A scientific review first summarises the biology of these amide ligase enzymes and three scientific articles report the selection of peptide inhibitors against MurD, MurE and MurF by phage display. The novel mode of action of these inhibitors against the unexploited Mur enzymes can be the basis for future development of antibacterial agents targeting the cell wall biosynthesis pathway by peptidomimetism. The last chapter exposes the antibacterial potential of the phage-encoded endolysin enzymes. A review describes the mode of action and the biology of endolysins as efficient antibacterial agents targeting the integrity of the bacterial cell wall layer. Finally, an article presents the peptidoglycan hydrolytic activity of the P. aeruginosa phage ΦKZ gp144 lytic transglycosylase. This endolysin is able to pass through the bacterial membranes and thus represents a strong candidate for developing new antibacterial therapies against Gram-negative bacteria. In conclusion, this thesis provides various attractive ways to develop new antibacterial strategies and face the problem of antibiotic resistance.
Inscrite au Tableau d'honneur de la Faculté des études supérieures
El, Meouche Imane. « Etude du régulateur transcriptionnel SigmaD chez Clostridium difficile ». Rouen, 2014. http://www.theses.fr/2014ROUES008.
Texte intégralThe main part of this work focuses on the characterization of the C. Difficile SigD factor and its role in the regulation of autolysis, motility and production of the two major virulence factors, toxins A and B. After the inactivation of sigD, we show that SigD factor positively controls C. Difficile motility whereas its contribution to the autolysis, if any, is modest. The global regulon of SigD was then determined by transcriptonic analysis using microarrays. Among the down-regulated genes in the sigD mutant strain, we find the late flagellar genes, the genes encoding toxins A and B and the gene encoding their regulator TcdR. We could identify SigD-dependent promoters upstream many genes including those encoding the flagellin FliC, the anti-SigD FlgM, and TcdR. In addition, we proved that SigD binds with RNA polymerase to initiate the transcription of tcdR. Furthermore, we identified a specific SigD-dependent consensus sequence in C. Difficile. Finally, we determined the antagonistic role of FlgM, the anti-SigD, in the repression of SigD-dependent genes. We prove that SigD is a positive and direct regulator of motility and toxin synthesis in C. Difficile. Another part of the work focuses on the autolysins Cwp19 and Acd of C. Difficile. Single mutants for acd and cwp19 genes showed that only Cwp-19 is involved in the long-term lysis of C. Difficile. A double-mutant acd-cwp19 seems to have the same autolytic profile as cwp19 single mutant. The glucosaminidase Acd does not seem to have a major involvement in autolysis of C. Difficile. Additional analyzes are in progress to determine the enzymatic activity of the Cwp19 autolysin
Corelli, Barbara. « Investigation of Klebsiella virulence : the role of capsule in Klebsiella rhinoscleromatis pathogenesis and characterization of a Klebsiella pneumoniae capsule mutant unable to produce colibactin toxin ». Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC265/document.
Texte intégralThe recent emergence and global expansion of hypervirulent and multidrug-resistant clones of K. pneumoniae have increased general interest in Klebsiella. However, knowledge of Klebsiella pathogenesis at the molecular and cellular level is still scant. We pursued two lines of research focused on Klebsiella pathogenesis. The first aimed to characterize a K. pneumoniae capsule mutant unable to produce a functional colibactin. Colibactin is a genotoxic secondary metabolite produced mainly by commensals and extraintestinal pathogenic E. coli strains, but also by some K. pneumoniae strains. It induces double-strand DNA breaks leading to tumor formation in colorectal cancer and contributes to increased virulence. However, its structure, biosynthesis, secretion and mode of action have yet to be fully defined. Previous work from our laboratory showed that a K. pneumoniae capsule mutant was unable to produce a functional colibactin, suggesting a role for capsule in this process. We report herein that capsule does not in fact have a role in the colibactin effect and that the inability of the capsule mutant to induce DNA damage is due to a strong dominant negative mutation in ClbD, an essential enzyme of the colibactin biosynthetic pathway. We are currently characterizing this mutation to understand how it deeply affects ClbD structure and function. The second project explored the role of capsule (CPS) in K. rhinoscleromatis pathogenesis. K. rhinoscleromatis is a K. pneumoniae subspecies responsible for rhinoscleroma, a human specific chronic granulomatous disease of the upper airways characterized by the formation of atypical foamy macrophages called Mikulicz cells. However, little is known about the pathophysiological mechanisms underlying this disease. Using our mouse model, we report that a K. rhinoscleromatis CPS mutant is attenuated in vivo but also that Mikulicz cells are observed upon infection with higher doses of K. rhinoscleromatis CPS mutant. Altogether, our data indicate that 1) CPS is a virulence factor of K. rhinoscleromatis, which is not involved in the specific appearance of Mikulicz cells and that 2) the K. rhinoscleromatis specific factors controlling the appearance of Mikulicz cells remain to be identified. The new insights brought to Klebsiella pathogenicity by this work represent a significant contribution to the understanding of rhinoscleroma pathogenesis and of the role of an enzyme implicated in colibactin biosynthesis. This opens new lines of research on K. pneumoniae and K. rhinoscleromatis pathogenesis
Roy, Monica. « MÉCANISME DE RECRUTEMENT DES LEUCOCYTES DANS LE CERVEAU ». Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/28952/28952.pdf.
Texte intégralBrosson, Damien. « Analyse protéomique et caractérisation de nouvelles protéines de paroi chez Encephalitozoon cuniculi ». Phd thesis, Clermont-Ferrand 2, 2006. http://tel.archives-ouvertes.fr/docs/00/68/86/92/PDF/2006CLF21636.pdf.
Texte intégralTawk, Mira. « Action et contrôle des leucotoxines de Staphylococcus aureus sur les cellules cibles ». Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAJ111/document.
Texte intégralThe γ-hemolysin HlgC/HlgB and the Panton and Valentine leukocidin (PVL) are two pore-forming toxins of the family of bicomponent leukotoxins secreted by S. aureus that directly target human neutrophils (hPNNs) and increase the pathogenicity of the bacteria. These leukotoxins also are capable of targeting other cell types such as rat cerebellar granular neurons and DRG. First, the compound of the class S binds to a membrane receptor, C5aR. Alanine-scanning mutagenesis allowed the characterization of a cluster of amino acids localized on two loops of the “Rim” domain essential for LukS-PV binding to C5aR. Then, after the class F subunit binding, HlgC/HlgB and PVL appear to be internalized, allowing an increase in [Ca2+]i. Despite the similarities between these two subunits, the class F component allows each leukotoxin to activate different pathways. Derivatives of para-sulfonato-calix[4]arene have an inhibitory effect on these toxins and may offer a potential to be used as auxiliary to antibiotherapy
Liu, Yang Patricia. « Etude de propriétés biophysiques de cellule bactérienne par la réfractométrie optofluidique ». Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1050/document.
Texte intégralRefractive index is one of the most important physical parameters in governing the light-reaction behaviors of cells and other microorganisms. Its significance lies in the fact that it can be used to determine or correlate with other important biophysical parameters such as dry mass, wet mass, elasticity and used to study dynamic cell activities. The main objective of this research is to study and measure refractive indices of single bacterium and cell as well as cell’s response to microenvironment stimulations.The experimental study includes two approaches. One approach is the development of an integrated microfluidic immersion refractometer platform to measure the biophysical parameters (the size, shape and refractive index) of three bacteria species, namely Echerichia coli, Shigella flexneri and Vibrio cholera. These parameters could provide biophysical signatures of the targeted bacteria. The significance of this research work lies in establishing a rapid, label-free and low-cost system for detection of minute amount of harmful waterborne bacteria in drinking water.The other experimental approach is to obtain the refractive index distribution of a single cell with the focus on studying the intracellular lipid droplets and their response towards microenvironmental stimulation using an optical diffraction tomographic system integrated with fluorescence imaging. The investigation of the refractive index of cellular lipid droplets initiates a novel approach for deeper understanding of the lipid droplets and their critical roles in metabolism
Barthélémy, Adeline. « Rôle des cellules T natural killer invariants (iNKT) dans la surinfection bactérienne post-grippale ». Thesis, Lille 2, 2016. http://www.theses.fr/2016LIL2S002/document.
Texte intégralXDurant l’infection par le virus Influenza A (IAV), les changements physiques et immunologiques du poumon prédisposent l’hôte aux surinfections bactériennes. Les cellules T Natural Killer invariantes (iNKT) sont des lymphocytes T innés pouvant avoir des rôles bénéfiques ou délétères durant l’infection. Nos objectifs ont visé à (i) étudier le rôle naturel des cellules iNKT et (ii) à rechercher l’effet d’une activation exogène des cellules iNKT dans la surinfection bactérienne post-influenza.Lors de mon arrivée, le laboratoire venait de décrire, pour la première fois en contexte infectieux, que les cellules iNKT étaient capables de produire de l’IL-22 au cours de l’infection grippale. Cette cytokine joue un rôle majeur dans les processus de maintien et de réparation des épithéliums. L’une desDuring the infection by the virus Influenza A ( IAV), the physical and immunological changes of the lung predispose the host to the bacterial secondary infections. The invariant cells(units) T Natural Killer iNKT ) are lymphocytes T innate being able to have beneficial or noxious roles during the infection. Our objectives aimed at i) to study the natural role of cells(units) iNKT and ii) to look for the effect of an exogenous activation of cells(units) iNKT in the bacterial secondary infection post-influenza. During my arrival, the laboratory had just described, for the first time in infectious context, that cells(units) iNKT were capable of producing of IL-22 during the flu-like infection. This cytokine plays a major role in the processes of preservation and repair of epitheliums [...]
Jourda, de Vaux de Foletier Albane. « Etude de la cellulolyse bactérienne dans le caecum des équidés : variations de la population bactérienne liées à l’âge et à l'alimentation : caractérisation de l'espèce bactérienne cellulolytique dominante : interactions avec une espèce non cellulolytique caécale ». Dijon, 1997. http://www.theses.fr/1997DIJOS060.
Texte intégralPierro, Annalisa. « Protein structural dynamics in bacteria via nitroxide-based SDSL-EPR spectroscopy : from method improvements to in-cell studies ». Electronic Thesis or Diss., Aix-Marseille, 2021. http://theses.univ-amu.fr.lama.univ-amu.fr/211116_PIERRO_290xrxu60ryzjfl293g970fjmdnl_TH%20(1).pdf.
Texte intégralThe study of biomolecules in their native environment has been one of the main goals of structural biology in the last decade. As a result, we are assisting to a remarkable increase of new "in-cell" approaches, like Cryo-ET, FRET and NMR. Among these approaches, Site-Directed Spin Labeling (SDSL) coupled to Electron Paramagnetic Resonance (EPR) spectroscopy shows competitive and advantageous features to capture protein dynamics inside cells. In particular, nitroxide-based SDSL-EPR combines the advantages of high sensitivity and the lack of size constraints on the biomolecule of interest with the ability to capture protein structural transitions and interactions at physiological temperature. Despite the methodological advancements of the technique that have allowed the community to obtain increasingly relevant results, progresses still need to be done.In this work, the main limitation of nitroxide-based SDSL-EPR has been addressed. In the first time, we focused on the development of delivery methods to introduce the labeled protein in bacterial cells. Next, the stability of nitroxide labels in reducing environments and in-cell has been assessed, monitoring in parallel the viability of the cells during the EPR measurements. Thanks to the results achieved in this methodological part, we were able to study the structural dynamics of two flexible chaperone proteins directly in bacterial cells: NarJ from Escherichia coli and UreG from Sporosarcina pasteurii. Finally, to go further in understanding the impact of the cellular environment on the protein dynamics, the data obtained in cellular context were compared with those obtained in vitro or in a cell-mimicking environment
Angely, Christelle. « Propriétés mécaniques et fonctionnelles des cellules épithéliales respiratoires exposées à une toxine bactérienne : l’adénylate cyclase ». Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC0058/document.
Texte intégralThe increase in respiratory infections involving virulent factors of bacterial origin has become a major public health issue. A better knowledge of the cell respiratory response in the course of the initial cell invasion by bacterial toxins is important from the pathophysiological and therapeutical point of views.The purpose of this work is to decipher the cellular and molecular mechanisms involved in the exposition of respiratory epithelial cells to the adenylate cyclase toxin (CyaA) produced by Bordetella pertussis which is the whooping cough agent. We have chosen this toxin for its multiple capacities of penetrating a wide range of eukaryotic cells. Indeed, this toxin enables direct translocation of its catalytic domain across the plasma membrane of target cells using the endogen calmoduline to increase the cAMP rate at supraphysiological levels. However, the effects of these changes on mechano-chemical signaling (mechanotransduction) pathways remain largely unknown while it affects cellular functions and cell integrity. So, we perform an evaluation of cellular functions as well as mechanical and adhesion properties of respiratory epithelial cells exposed to CyaA toxin in order to detect some critical modifications in the mechanotransduction processes.In a preliminary study aiming at defining physiopathological concentrations of CyaA toxin used in our experiments, we determined the cell viability degree for 3 concentrations of CyaA toxin (0.5; 5 and 10 nM). We found that the smallest concentration (0.5 nM) did not affect cell viability whereas inducing supraphysiological cAMP levels in less than one hour.Then, we assessed the effects of CyaA toxin on cell migration and repair phenomenon, on ciliary beating and on cell permeability of epithelial cells representative of the different levels of the respiratory tract. The toxin induces a decrease in cell migration and repair, an increase in cell permeability suggesting a weakening of lateral cell-cell junctions.Immunostaining was performed on intracellular and interfacial structures of alveolar epithelial cells exposed to the 3 concentrations of CyaA toxin. Results show that CyaA toxin is able to induce cytoskeleton remodeling and a decrease in the number of focal adhesions. Finally, a refined analysis of mechanical properties and adhesion parameters was performed on the same cells by 2 techniques of micro/nanomanipulation modified to permit at the same time, an evaluation of cell adhesion and cell rigidity (Atomic Force Microscopy with indentation and force spectroscopy to characterize the number of bond during adhesion reinforcement and multiscale Magnetic Twisting Cytometry). To evaluate the role of cAMP on cellular and molecular changes, we tested the enzymatically inactive form of CyaA toxin called CyaAE5 which could not permit to increase the intracellular cAMP rate.The AFM experiments have revealed that the main effect of CyaA toxin is to decrease the number of associated integrin-ligand bounds (meaning an alteration of clustering) while, at the smallest concentration of CyaA toxin, we observe an increase in cell rigidity with an individual bound reinforcement, a result consistent with MTC results. Nevertheless, CyaE5 does not exhibit such cellular effects. On the whole, these results suggest that CyaA toxin affects the mechanotransduction pathways of cells exposed to the toxin, a result which is in agreement with the expected effects of cAMP increase (notably cytoskeleton remodeling, lateral junction alteration and inhibition of Rac1 expression) what brings a new vision of the cytotoxicity induced by the adenylate cyclase toxin
Tozatto, Maio Karina. « Immunogenetics in sickle cell disease ». Thesis, Sorbonne Paris Cité, 2019. http://www.theses.fr/2019USPCC093.
Texte intégralSickle cell disease (SCD) is the most common inherited hemoglobinopathy, caused by a single nucleotide polymorphism (SNP) in the beta-globin (HBB) gene. This SNP determines the synthesis of S haemoglobin (HbS), which polymerizes under stress conditions, sickling the red blood cell (RBC). Sickle RBC are less deformable, more adherent to the endothelium, and more susceptible to haemolysis. SCD complications are explained by the interaction between haemolysis, vaso-occlusion and inflammatory activation, determined by the RBC sickling. Patients with SCD may present several complications, affecting all organs. Clinical presentation is very heterogeneous, ranging from patients who have mild symptoms to patients who die from disease complications. Because inflammation plays a major role in SCD, polymorphisms in inflammatory genes are potential targets to explain this heterogeneity. Haematopoietic stem cell transplantation (HSCT) is the only curative therapy currently available for SCD, with good results shown after human leukocyte antigen (HLA) identical sibling HSCT. However, most patients will not have a matched sibling donor. Patients with SCD are mostly from African origin, the less represented ethnic group in stem cell donor registries. To date, few studies using local registries were performed to find the probability of having a potential unrelated donor in SCD settings. This study aimed to assess the role of inflammatory genes encoding Toll-like receptors (TLR) in the occurrence of bacterial infections in patients with SCD, because infection is a leading cause of mortality in SCD, and TLR recognize a wide range of bacteria. Patients included had DNA samples and clinical data available. SNPs were genotyped by real-time polymerase chain reaction (RT-PCR). Four hundred thirty patients, mostly from Brazilian and Sub-Saharan African origin, were divided in two groups: infected (n=235, patients who presented at least one episode of bacterial infection), and non-infected (n=195, patients who never presented bacterial infections). The T/A genotype of SNP rs4696480 in TLR2 was less frequent in infected patients (50% versus 67%, OR=0.50, 95% CI 0.34-0.75, p<0.001). In addition, the T/T genotype of this SNP was more frequent among infected patients (15% versus 5%, OR=0.50, 95% CI 0.34-0.75, p<0.001). Previous reports in other settings showed that A/A carriers had higher secretion of inflammatory markers, while T allele was associated with less occurrence and severity of inflammatory diseases. Hence, T/A genotype might express the ideal inflammatory response to defeat bacteria, while the weaker inflammatory response determined by the T/T genotype increases susceptibility to bacterial infections in SCD settings
A doença falciforme (DF) é a hemoglobinopatia hereditária mais frequente, causada por um polimorfismo de nucleotídeo único (SNP) no gene da betaglobina (HBB). A ocorrência desse SNP determina a síntese de hemoglobina S, que polimeriza sob condições de stress, alterando a conformação das hemácias, que adquirem forma de drepanócitos. Os drepanócitos são menos deformáveis, mais aderentes ao endotélio e mais suscetíveis à hemolise. As complicações clínicas da DF podem ser explicadas pela interação entre a vasoclusão, hemólise e ativação inflamatória resultantes da presença dos drepanócitos na circulação. Os pacientes com DF podem apresentar numerosas complicações, que afetam todos os órgãos. A apresentação clínica da DF é muito heterogênea, variando de pacientes pouco sintomáticos a pacientes que falecem por complicações da doença. Visto que a inflamação tem um papel importante na fisiopatologia da DF, polimorfismos em genes inflamatórios poderiam explicar essa heterogeneidade.O transplante de células tronco hematopoiéticas (TCPH) é a única terapia curativa disponível atualmente para a DF, com bons resultados demonstrados em TCPH de doador aparentado antígeno leucocitário humano (HLA) idêntico. Não obstante, a maioria dos pacientes não dispõe de doador aparentado HLA idêntico. A DF ocorre em pacientes normalmente de origem africana, o grupo étnico menos representado em registro de doadores de células tronco. Nos dias de hoje, poucos estudos, utilizando registros locais, avaliaram a probabilidade de encontrar potenciais doadores não aparentados para pacientes com DF. Este estudo teve por objetivo avaliar o papel de genes inflamaórios que codificam receptores Toll-like (TLR) na ocorrência de infecções bacterianas em pacientes com DF, visto que infecção é uma das principais causas de mortalidade em DF, e os TLR reconhecem diversos tipos de bactérias. Os pacientes incluídos no estudo tinham amostras de DNA e dados clínicos disponiveis. Os SNPs foram genotipados por reação em cadeia de polimerase em tempo real (RT-PCR). Quatrocentos e trinta pacientes, a maioria de orgem brasileira ou africana subsaariana, foram divididos em dois grupos, infectados (n=235, pacientes que apresentaram ao menos um episodio de infecção bacteriana), e não infectados (n=195, pacientes que nunca tiveram tais infecções). O genótipo T/A do SNP rs4696480 foi menos frequente em pacientes infectados (50% versus 67%, OR=0.50, 95% CI 0.34-0.75, p<0.001). Além disso, o genótipo T/T do mesmo SNP foi mais frequente em pacientes infectados (15% versus 5%, OR=0.50, 95% CI 0.34-0.75, p<0.001). Estudos prévios mostraram que indivíduos com genótipo A/A apresentavam mais secreção de marcadores inflamatórios, enquanto o alelo T foi associado a menor ocorrência e menor gravidade de doenças inflamatórias
Coutanceau, Emmanuelle. « Fonctions immunomodulatrices de la mycolactone, principal facteur de virulence de Mycobacterium ulcerans ». Paris 7, 2006. http://www.theses.fr/2006PA077214.
Texte intégralMycobacterium ulcerans (Mu) is the causative agent of Buruli ulcer, a skin disease destroying both cutaneous and sub-cutaneous tissues. The pathology is linked to bacterial production of mycolactone, a lipophilic toxin. During my PhD thesis, the immune responses developed by host during infection by Mu, and the mycolactone contribution to these processes were studied. Firstly, the humoral and cellular responses developed in a mouse model of infection by Mu were characterized. These studies revealed Hsp65 immunogenicity and we tested the efficiency of a DNA vaccine encoding this antigen. Phagocytic cells internalized Mu during the primary stages of infection. This was a surprising result because Mu bas always been described as strictly extracellular. In addition, macrophages infected by Mu had a different expression profile for cytokines and chemokines compared to cells infected with a mycolactone deficient mutant. These observations led us to suggest that endogenous production of mycolactone may modulate the host immune response. Then, mycolactone impact on immune cells was characterized. Mycolactone blocked TNF-α production by macrophages in vitro. Furthermore, its immunosuppressive effect was also observed in dendritic cells, in which it causes cytotoxic effects, inhibition of maturation and inhibition of lymphocyte priming. In vivo, our preliminary pharmacological study shows that mycolactone is transported to lymphoid organs, where it acts by blocking lymphocyte proliferation. In conclusion, these results demonstrate that mycolactone is a novel immunosuppressive molecule, with a mode of action distinct from other well-known immunosuppressors such asFK506
Lina, Gérard. « Diversité des composants bactériens initiateurs de l'activation monocytaire ». Lyon 1, 1996. http://www.theses.fr/1996LYO1T155.
Texte intégralPerrin, Jackie. « Virulence bactérienne et défenses de l’hôte : contribution des cellules phagocytaires dans l’immunité innée chez la drosophile ». Université Joseph Fourier (Grenoble ; 1971-2015), 2009. http://www.theses.fr/2009GRE10098.
Texte intégralIn eukaryotes, phagocytic cells are involved in the defense against pathogens by insuring the recognition of foreign bodies, their internalization and elimination. We developed the use of the fly Drosophila melanogaster for the prospective study of the phagocytes contribution in the innate immunity and their role in host-pathogen interactions. In phagocytes, the GTPases of the family Rho have an essential role in the actin cytoskeleton dynamics that take place during cellular adhesion and pathogen internalisation. We proved that the RhoGTPase Rac2 is specifically involved in drosophila cellular immune response and contributes to the resistance in infections by the pathogenic bacteria Pseudomonas aeruginosa. This bacteria raises major public health problems, in particular at the patients affected by cystic fibrosis. I focused in the toxin ExoS of P. Aeruginosa which is injected in host cells targeting RhoGTPases. In particular, Rac2 is inhibited by this toxin resulting in reduced phagocytosis and resistance to infection. In parallel, I participated in the identification of new virulence factors of P. Aeruginosa in association with Pr P. Cosson (Centre Médical Universitaire, Geneva). My work also concerned the research for new players of the cellular immune response. I looked into an evolutionary conserved family of proteins, the nonaspanins also called TM9SF proteins, who’s function in the phagocytosis had been previously shown in amoeba. We proved that TM9SF4 plays an important role in drosophila infection resistance via its implication in phagocytosis and cellular adhesion
Henry, Thomas. « Physiologie de S. Typhimurium dans l'environnement intracellulaire : la division bactérienne et la modulation des moteurs moléculaires eucaryotes sur la vacuole contenant Salmonella ». Aix-Marseille 2, 2005. http://theses.univ-amu.fr.lama.univ-amu.fr/2005AIX22030.pdf.
Texte intégralVianney, Anne. « Analyse génétique et biochimique du système Tol impliqué dans l'importation de macromolécules et le maintien de l'intégrité de l'enveloppe chez Escherichia coli K-12 ». Lyon 1, 1994. http://www.theses.fr/1994LYO10167.
Texte intégralDedieu, Luc. « Régulation de l'expression des porines chez Campylobacter jejuni ». Aix-Marseille 2, 2005. http://www.theses.fr/2005AIX20676.
Texte intégralLe, Guern Florent. « Inhibition de souches bactériennes par de nouveaux composés photosensibles conjugués à la Polymyxine B ». Thesis, Limoges, 2017. http://www.theses.fr/2017LIMO0075/document.
Texte intégralDespite advances achieved over the last decade, infections caused by multi-drug resistant bacterial strains are increasingly important societal issues that need to be addressed. New approaches have already been developed in order to overcome this problem. Photodynamic antimicrobial chemotherapy (PACT) could provide an alternative to fight infectious bacteria. Interesting results have been obtained against Gram-positive bacteria, but it also appeared that Gram-negative strains were less sensitive to PACT. Enhanced efficacy against Gram-negative bacteria had been previously obtained following three differents strategies, which are respectively the use of cationic photosensitizers, photosensitizers bound to antimicrobial peptides, or a membrane disrupting agent. Polymyxin B is an antimicrobial peptide, known as the “last-line” treatment against Gram-negative resistant strains, which has already been used as a disrupting agent in order to improve PACT. In addition of this enhancement, this peptide is known for its strong interaction for Gram-negative bacteria. Thus, in this work, we designed differents coumpounds, consisting of a photosensitizer covalently attached to derivatives of polymyxin B, through a spacer or a chemical platform. These combinations have led to the creation of novel compounds which have shown highly photobactericidal activities against a wide spectrum of bacteria. Moreover, these compounds present enhanced affinity for bacteria, which should significantly reduce side effects on mammalian cells. This study confirmed the importance of using antimicrobial in order to target bacterial strains. Thus, such results may allow the creation of novels PACT-based dermatological treatments efficient against a wide spectrum of bacterial strains
Maurice, Corinne. « Étude des cycles de vie des bactériophages dans les écosystèmes aquatiques par analyse de cellules individuelles : importance de la physiologie, de la diversité de l'hôte et de la variabilité de l'écosystème ». Montpellier 2, 2009. http://www.theses.fr/2009MON20235.
Texte intégralWithin aquatic ecosystems, bacteriophages are the most abundant entities even exceeding bacterial numbers by an order of magnitude. Viral production takes place via two major replication cycles: the lytic and the lysogenic cycles. The prevalence and the regulation factors of both cycles have been extensively studied using phage/host systems in controlled conditions, and the in situ environmental and bacterial parameters involved remain unclear. The main objective of this PhD is to study the regulation mechanisms underlying the prevalence of both viral replication cycles within natural ecosystems, from the single-cell level of analysis to the level of the ecosystem. At the single-cell level, we show the importance of bacterial physiology and activity on the prevalence of one cycle over the other. More specifically, we demonstrate a dual role of the bacterial physiology, acting first as a signal for a lysogenic interaction, then as an inducing signal of the lytic cycle, leading to the ‘abandon the sinking ship' concept. In addition to the significant impact of bacterial physiology, we further establish that certain bacterial phylogenetic groups could be more susceptible to lysogenic infections than others. At the ecosystem level, lysogeny seems to occur more frequently in freshwater systems than in coastal lagoons. Furthermore, natural variability of the environmental conditions influences the dynamics of both cycles, as their highest frequencies occurred under intermediate variability conditions. Finally, an inter-ecosystem analysis reveals a replacement dynamic between these two cycles, whereas within the same ecosystem, both cycles can co-exist and even co-vary. This work shows in situ the influence of the environment on both viral replication cycles, directly through the variability of environmental conditions, and indirectly through changes of bacterial physiology and activity
Zampatti, Olivier. « Modèle in vitro de simulation de la cavité buccale : étude de la plaque bactérienne dentaire et évaluation d'agents antiplaque ». Toulouse, INPT, 1994. http://www.theses.fr/1994INPT030A.
Texte intégralJulliand, Véronique. « Etude de l'écosystème caecal des équidés : aptitude à dégrader les polyosides pariétaux, caractérisation quantitative et qualitative des flores cellulolytiques bactériennes et fongiques dominantes ». Dijon, 1996. http://www.theses.fr/1996DIJOS066.
Texte intégralBachy, Emmanuel. « Stimulation bactérienne chronique et développement de lymphomes de type Natural Killer T-Cell (NKT) chez la souris ». Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10261.
Texte intégralPas de résumé en anglais
Brest, Patrick. « Interaction entre les Escherichia coli pathogènes et la muqueuse intestinale : mécanismes cellulaires et moléculaires de la réponse immunitaire innée induite par les facteurs de virulence bactériens ». Nice, 2003. http://www.theses.fr/2003NICE4038.
Texte intégralBajolet-Laudinat, Odile. « Lectines de "Pseudomonas aeruginosa" : rôles dans les fonctions de barrière et de transport des cellules épithéliales respiratoires et dans l'adhérence bactérienne ». Paris 11, 1994. http://www.theses.fr/1994PA114841.
Texte intégralRanava, David. « Etude d'un consortium microbien producteur d'hydrogène : de l'interaction inter-bactérienne au bioréacteur ». Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4700.
Texte intégralIn nature microorganisms live in communities, in which the complementarity of their metabolism allows them to colonize less favourable ecological niches. Biodegradation of organic matter requires tight metabolic coupling between the different microorganisms involved, and constitutes an ideal model for studying the interactions between them, which are still not well established and require further characterization. Furthermore, deciphering the metabolic couplings established between the partners would allow optimization of this process for production of compounds of biotechnological interest, such as hydrogen. During the course of this work we have studied an artificial consortium constituted by Desulfovibris vulgaris Hildenborough sulphate-reducing bacterium, and Clostridium acetobutylicum a fermentative bacterium; both of them are found in natural consortia involved in biomass degradation. Microbiological, metabolic and microscopic approaches allowed us to show the existence of a physical interaction, with exchange of cytoplasmic molecules, between the two bacteria. This is associated with reorientation of the carbon flux in Clostridium acetobutylicum, resulting in increased hydrogen production. This behaviour is linked with the nutritional stress of D. vulgaris. Moreover, AI-2 type signal molecules produced in these conditions are crucial for the physical interaction between the two bacterial partners. An inhibitor produced by D. vulgaris in certain conditions has been discovered. This work has allowed us to acquire new knowledge about metabolic relations and physical interactions between bacteria involved in biomass degradation in a consortium
Torre, Cédric. « Résistance des planaires à l'infection bactérienne : caractérisation de la mémoire immunitaire innée ». Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0528.
Texte intégralMy Thesis work has focused on the description of the planarian antibacterial immunity, and more precisely the innate immune memory.The innate immune memory forms a host defense line to the reinfection which only involves components from innate immunity. Present in vertebrates and invertebrates, invertebrates are a model of choice because devoid of acquired immunity. The planarian has an innate immune memory against S. aureus, which, after a reinfection, displays an exacerbated elimination. The depletion of stem cells from planarians and tissue graft highlighted stem cells as the main actors of this immune response. An RNAi screening combined with a transcriptomic profiling brought out genes and classified them within a signaling pathway involving a peptido-glycan receptor (pgrp-2), a histone methyltransferase (setd8.1), and an effector mechanism of the bacterial elimination (p38 and morn2). Setd8.1, histone methyltransferase, would be the core of the process putting epigenetic marks on DNA loci, ensuring the increased expression of effector genes after reinfection. This mechanism, described in humans, has neither involved stem cells, nor this type of histone methyltransferase as actors in the innate immune memory.Collectively, the investigation of the planarian immune system allowed the discovery of new antibacterial defense mechanisms, and transferring it to humans could complete the actual approach of the infectious disease treatment
Haichar, Feth-el-Zahar. « Impact des exsudats racinaires dans la sélection des taxa et fonctions bactériens dans la rhizosphère ». Aix-Marseille 2, 2008. http://theses.univ-amu.fr.lama.univ-amu.fr/2008AIX22049.pdf.
Texte intégral[. . . ] We first of all, performed DNA-SIP using a 13C labelled macromolecule, the cellulose in order to identify bacterial community involved in cellulose degradation in soil over time. We also examined the ability of different plant species to select different taxa and functions from the same reservoir. We determined which carbon source was used and by which bacterial group in the rhizosphere of four plant species using stable isotope probing technique. To do this, we growth wheat, maize, rape and Medicago truncatula, separately in the same soil under 13CO2 (99% of atom 13C). This study revealed that root compartment was the most selective habitat as the bacterial community inhabiting the roots of wheat, rape, maize and Medicago truncatula were specific for each plant compared to the rhizosphere soil, where bacterial community were not very different between plants. We also demonstrated that plant exert a high impact on soil organic matter turnover in the rhizosphere. The last study was devoted to the analysis of the structure and the dynamic of bacterial community using DNA- and RNA-SIP in the rhizosphere of Arabidopsis thaliana and to set up mRNA-SIP technic to analyse bacterial gene expression in the rhizosphere. The combination of rDNA- and rRNA-SIP in the rhizosphere of A. Thaliana over time revealed an evolution of bacterial populations especially in the rhizosphere soil probably in relation to plant stage development leading to a modification of root exudates nature, whereas root colonizing bacteria seemed well established and were not delocalized by new colonizers. The development of mRNA-SIP allowed us to analyze the expression of certain genes in the rhizosphere of A. Thaliana. [. . . ]
Alberge, Francois-Baptiste. « La localisation dynamique d'un complexe respiratoire module la respiration bactérienne ». Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4031.
Texte intégralBy providing the energy for the cellular metabolism, oxidative phosphorylation (OXPHOS) is an essential process for most living organisms. In order to thrive, the efficiency of membrane respiratory chains which constitute the OXPHOS must be optimized. Thus it is important to address mechanisms by which the efficiency of the OXPHOS is regulated in response to varying metabolic needs.The question addressed during this PhD is the following: does it exist a specific organization of the OXPHOS components in prokaryotic membranes and does it contribute to the regulation of the OXPHOS process?I have investigated the spatio-temporal organization of a respiratory complex, the nitrate reductase NarGHI of the E. coli bacterium. After creating the tools needed to visualize submicrometrically this complex in the unique cell, I have shown the existence of a polar microcompartimentation during anaerobic respiration using fluorescence microscopy. I have demonstrated the dynamic subcellular organization of NarGHI in response to metabolic conditions. Anaerobiosis and a sufficient ∆pH are cues required to promote such cellular organization. Finally, I have demonstrated that polar microcompartimentation of the complex increases the electron flux and the efficiency of the associated respiratory chains.Overall, these results provide a novel view on OXPHOS in bacterial cells by demonstrating that spatio-temporal organization of a respiratory complex tunes the overall efficiency of the process in response to environmental cues
Ben, Amara Amira. « Cellules placentaires et infection par coxiella burnetii ». Thesis, Aix-Marseille 2, 2011. http://www.theses.fr/2011AIX20687/document.
Texte intégralIn pregnant women Q fever presents obstetrical complications. The principal way of human contamination by Coxiella burnetii, the agent of Q fever, is due to aerosols from placentas of infected animals. The nature of placenta cells that are targeted by C. burnetii remains unknown. I showed that C. burnetii infects BeWo and JEG trophoblastic cells and that organisms intensively replicated in BeWo cells and survived in JEG cells. A microarray analysis showed that C. burnetii induced a specific inflammatory response in BeWo cells. These results suggest that trophoblasts may serve as a reservoir for C. burnetii. Placenta macrophages placentaires may also targeted by C. burnetii. I showed that placenta CD14+ macrophages were characterized by phenotypic, transcriptional and functional properties different from those of circulating monocytes and monocyte-derived macrophages. In addition, placenta CD14+ macrophages differentiate into multinucleated giant cells that may regulate the cytolytic activity of macrophages in the placenta context since placenta CD14+ macrophages were not polarized in M1 or M2 macrophages. While M1/M2 polarization of macrophages is well established, that of monocytes remains an important question. We activated monocytes with canonical agonists of M1 and M2 profiles in macrophages using microarrays. The early response, 6 hours, of monocytes corresponded to a type M1/M2 response but the delayed response, 18 hours, did not correspond to the M1/M2 dichotomy, demonstrating a new level of heterogeneity of myeloid cells
Kuttler, Celine. « Modélisation de l'expression génétique bactérienne dans un pi-calcul stochastique à objets concurrents ». Phd thesis, Université des Sciences et Technologie de Lille - Lille I, 2007. http://tel.archives-ouvertes.fr/tel-00111653.
Texte intégralAkoum, Ali. « Mise en évidence d'une nouvelle substance anticoagulante d’origne bactérienne sécrétée par « Myxococcus xanthus » : la myxaline : caractérisation et études in vitro de ses propriétés biologiques ». Compiègne, 1987. http://www.theses.fr/1987COMPD053.
Texte intégralMyxococcus xanthus, the best known of myxobacteria, is a gram negative bacterium that produces numerous interesting molecules in its growth medium. Very few glycopeptides and glycoproteins are known to be produced by bacteria. However, we demonstrate here, that it is able to excrete a glycol peptide with blood anticoagulant activity that we call Myxaline. This molecule has been purified, characterized and tested in vitro for its effect on clotting factors. In addition, we have evaluated the in vitro biocompatibility of some myxaline extracst dotted with cell growth properties, which might improve the reendothelialisation of vascular prostheses
Liu, Lexuan. « Interaction de la transcription et de la traduction dans l'adaptation bactérienne à des concentrations sous-létales d'un inhibiteur de la traduction ». Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS390.
Texte intégralBacteria often encounter sublethal levels of antibiotics produced by other microorganisms in the environment. In clinical settings, sublethal levels of antibiotics may result from incomplete management of prescribed amounts or concentration gradients present in heterogeneous environments. The adaptation of bacteria to inhibitors of the fundamental cellular processes targeted by these molecules depends on a stress response mechanism that allows cells to alter their metabolism to avoid cell death. However, the mechanistic details of this kind of response generally remain to be described. As a result of the presence of sublethal concentrations of antibiotics targeting translation, such as chloramphenicol, bacteria reduce their growth rates, but their cell size and DNA content are not affected (Basan et al. 2015). Our laboratory has recently shown that during this adaptation, transcriptional capacity decreases while translational rates increase due to the presence of a ppGpp-dependent feedback loop that regulates ribosomal activity and expression (Zhang et al. 2020). The decrease in growth rate in these conditions is a result in a limitation of the cell’s capacity for gene transcription, rather than translation. This study was done at the population level. In order to measure the change in GFP expression, cell size and growth rate at the single cell level and as a function of time, I carried out time-lapse microscopy experiments. I used GFP reporter constructs with a ribosomal promoter or two constitutive promoters, P5 and PLtet, used to measure transcription capacity. I used microfluidics to control the condition in time by shifting the growth medium from one without antibiotic to one with antibiotic. In my results, we show that the change in expression of GFP after addition of antibiotic depends on whether the promoter is regulated by ppGpp and on the affinity of the promoter for RNA polymerase. Under translation inhibition, expression of the ribosomes increases, this is followed by an increase in the translation capacity and a decrease in the transcription capacity and thus in the growth rate. Cell size is maintained via an unexpected transient increase in added size
Canonne, Joanne. « Régulation d'AtMYB30, un facteur de transcription d'arabidopsis thaliana impliqué dans la défence : de la cellule végétale aux effecteurs bactériens ». Toulouse 3, 2011. http://www.theses.fr/2011TOU30332.
Texte intégralThe activation of plant defence mechanisms is a costly process for the plant that needs to be tightly regulated. In this context, a precise control of transcriptional regulation appears to be essential during pathogen attack. AtMYB30, an Arabidopsis thaliana MYB transcription factor, acts as a positive regulator of hypersensitive cell death, a form of resistance set up by the plant in response to pathogens. Our results show that AtMYB30 activity is subject to many regulatory processes coming from both the plant cell and the extracellular environment, through microbial effectors. Particularly, our data showed that a secreted phospholipase A2, AtsPLA2-a, is relocalized to the plant cell nucleus where it interacts with AtMYB30. AtsPLA2-a exerts a spatio-temporal control on AtMYB30 activity, thus limiting the extent of cell death. MIP1, an Arabidopsis putative ubiquitin ligase, is a negative regulator of AtMYB30 activity. MIP1 is thought to ubiquitinate AtMYB30, leading to its degradation. Finally, XopD, a type III effector from the phytopathogenic bacterium Xanthomonas campestris, directly targets AtMYB30 to inhibit its activity. These results illustrate an original strategy developed by Xanthomonas to modulate the host transcriptome through direct suppression of the activity of a transcription factor essential for plant defence. Together, our data highlight the fine tuning of AtMYB30 activity for a necessary attenuation of plant cell death responses associated with resistance, a feature that may be exploited by pathogenic microorganisms. The future characterization of other AtMYB30 partners, both plant and microbial, should uncover additional mechanisms for AtMYB30 regulation. The results obtained during my PhD provide a first step for the future identification of molecular and biochemical mechanisms enabling plants to control microbial invasion and cell death responses leading to resistance
Zuttion, Francesca. « Effet inhibiteur des glycoclusters dans l'adhésion bactérienne des Pseudomonas aeruginosa caractérisé par microscopie à force atomique : de la molécule à la cellule ». Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEC031/document.
Texte intégralPseudomonas aeruginosa (PA) is a human opportunistic pathogen responsible for 20% -30% of nosocomial infections in French hospitals. For healthy people, it presents no real danger, but for people with cystic fibrosis disease and immune-compromised patients, it is the leading cause of mortality and lung infections. PA has developed antibiotic multi-resistant strains and new and more effective therapeutic approaches are needed. It binds to the surface of the host cells by an interaction between proteins (lectins) present on the membrane and sugars of the host-cell membrane. The lectin-sugar interaction plays an important role in adherence of the bacteria and in the manufacture of a pathogenic biofilm.A new therapeutic approach is to create synthetic molecules (glycoclusters) of greater affinity than the natural sugars present on the cells. To this aim, more than 150 glycoclusters have been synthetized and screened to find the best candidate to inhibit the bacteria infection process. Some of them have been selected and studied by Atomic Force Microscopy (AFM). In particular, this thesis is devoted to study the lectin-glycocluster and cell-bacteria interactions by AFM. The combination of AFM imaging with molecular dynamic simulations let understanding the role of the geometry of the glycoclusters on the complex formation, while AFM spectroscopy accesses the lectin-glycocluster interaction forces at the molecular and cellular levels. The reduction of bacterial adhesion has been observed upon the addition of the glycocluster. This confirms the anti-adhesive properties of the glycocluster and validates the procedure. The ultimate goal is the identification of the best glycoclusters in order to develop new drugs
Athman, Rafika. « Etude des conséquences physiopathologiques de l'invalidation du gène de la villine chez la souris et dans des modèles cellulaires en culture ». Paris 7, 2002. http://www.theses.fr/2002PA077010.
Texte intégralNarni-Mancinelli, Émilie. « Étude des mécanismes effecteurs des lymphocytes T CD8+ mémoires nécessaires à l'élimination de la bactérie intracellulaire Listeria monocytogènes chez la souris ». Nice, 2008. http://www.theses.fr/2008NICE4029.
Texte intégralMemory CD8 T cells (TMCD8) represent the major effector arm of the adaptive immunity by providing protective immunity against intracellular pathogens. Upon antigen-driven reactivation, TMCD8 differentiate into cytolytic, IFN-/TNF- secreting effector cells allowing for the control of the growth and the clearance of intracellular pathogens. Mice infected with a sublethal dose of the intracellular bacterium Listeria monocytogenes (Lm) develop TMCD8 which mediate protective responses against reinfection with a lethal dose of bacteria. However, neither expression of cytolytic nor IFN-/TNF--secreting activities is absolutely required for Lm clearance during a secondary infection. As an in vivo original approach, we analyzed the TMCD8 response in mice immunized with Lm mutants that do not induce protection. Using this system, we showed that CCL3 derived from reactivated TMCD8 is required for efficient killing of Lm. CCL3 induces a rapid TNF- secretion by inflammatory mononuclear phagocytics cells (MPC), which further promotes the generation of an oxidative burst by both themselves and neutrophils Oxidative burst is the final bactericidal mechanism involved in Lm clearance. These results uncover two levels of regulation of the protective response: (i) an antigen-dependent phase in which TMCD8 are reactivated and activate the innate immunity, and (ii) an antigen-independent phase in which the MPCs coordinate innate immunity and promote bactericidal effector activities. In this context, CCL3-secreting TMCD8 are able to mediate bystander killing of an unrelated pathogen upon antigen-specific reactivation, a mechanism that may be important for the design of therapeutic vaccines
Roche, Béatrice. « Etude du rôle de la frataxine bactérienne CyaY chez Escherichia coli ». Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4083.
Texte intégralFe-S cluster containing proteins are involved in many cellular processes such as respiration, DNA repair or gene regulation. In vivo, Fe-S cluster biogenesis is catalysed by specific protein machineries, ISC and SUF, conserved in both eukaryotes and prokaryotes. Frataxin (FXN) is a small protein found in humans, plants, yeast and Gram negative bacteria. In eukaryotes, a defect in FXN leads to drastic phenotypes such as mitochondrial iron accumulation, drastic decrease of Fe-S cluster protein activity, sensitivity to oxidants. In humans, FXN deficiency is responsible for the neurodegenerative disease, Friedreich’s ataxia. In prokaryotes like E. coli, a defect in CyaY, the bacterial FXN homolog, does not lead to significant phenotypes compared to the wild-type strain. During my thesis, I investigated the role of the bacterial FXN CyaY in E. coli. I showed that, in vivo, CyaY assisted the ISC-catalyzed Fe-S cluster biogenesis. A genetic link was also observed between cyaY and iscX, demonstrating that these proteins participate in Fe-S cluster biogenesis. In a second part, I investigated the differences between the impact of the eukaryotic versus prokaryotic FXN. I showed that the IscU 108th residue is crucial for the CyaY-dependency. Finally, I used a transcriptomic approach to test whether CyaY has a global role in E. coli
Gueniche, Farida. « Effets de dérivés d'exopolysaccharides bactériens sur le comportement de fibroblastes et de cellules mésenchymateuses d'origine médullaire dans des tissus reconstruits à des fins d'ingénierie tissulaire ». Paris 13, 2006. http://www.theses.fr/2006PA132037.
Texte intégralExopolysaccharides (EPS) extracted from deep sea bacteria (IFREMER) are a new generation of polysaccharides heparan-mimetic. In this work, we are investigated the potential effects of native EPS and derived EPS, namely: GY785 OSDR, GY785 DROS on the performance of mesenchymal cells in 2D and 3D cultures. We demonstrated that derived EPS, GY785 DROS were able to stimulate the proliferation of human dermal fibroblasts as well as human medullary stromal cells in 2D and 3D cultures, the 3D cultures being considered as reconstructed conjonctive tissue. In our hands, with EPS GY785 DROS, medullary stromal cells were shown to adopt a mesenchymal cell phenotype. Furthermore we evidenced that derived EPS GY785 DROS was able to interact with growth factor particularly fibroblast growth factor 2 (FGF-2) and that this interaction promoted the pro-proliferative effect of this later. Our results raise the possibility to use EPS for tissue engineering in order to favour tissue regeneration and also to improve graftings in man for example with severely burnst patients and or with patients suffering from epidermolysis bullosa for whom dermal covering is vital
Grac, Edith. « Stochasticité dans la réponse d'individus bactériens à une perturbation : étude dynamique ». Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00728293.
Texte intégralLe, Gall-David Sandrine. « Isolement, caractérisation génétique d'une souche de Salmonella hypermutatrice, et étude de son adaptabilité à un stress acide ». Rennes 1, 2009. http://www.theses.fr/2009REN1B077.
Texte intégralAmong a Salmonella enterica strain collection, Salmonella enterica serovar Heidelberg (Hm) was described with a hypermutator phenotype (Hm). Its sequencing and a construction of a mutant (ΔmutS) have demonstrated that the emergence of the hypermutation phenotype was due to a deletion of 12 bp. The objective of this study was to investigate the influence of the hypermutator phenotype on Salmonella Heidelberg survivor and virulence. S. Heidelberg strains Hm and ΔmutS showed higher resistance to an acid stress of pH 3. 3. Bidimensional electrophresis analysis of extracellular proteins of this strains allowed the identification of seven proteins associated with better survival in acid stress conditions. S. Heilderberg strains Hm and ΔmutS also showed better adhesion to epithelial cells. In conclusion, our results reveales that the hypermutation phenotype allows a better adaptation of strains to hostile conditions and may increase their pathogenicity