Rôle des hospicells dans la progression et la dissémination tumorale ovarienne : implication particulière des macrophages

Le cancer ovarien constitue la première cause de mortalité des cancers gynécologiques. Il se caractérise à stade avancé par une dissémination péritonéale, la formation de liquide d'ascite et un haut taux de mortalité. Malgré un traitement associant chirurgie et chimiothérapie (sels de platine et taxanes), la plupart des patientes récidivent. Cette récidive est dans 50 % des cas combinée à l'acquisition d'une chimiorésistance dont l'origine pourrait provenir, entres autres, du microenvironnement tumoral. Rafii et al. ont isolé des cellules originales du microenvironnement tumoral ovarien, les Hospicells, à partir de liquide d'ascite de patientes atteintes d'un cancer ovarien de stade III. Bien que leur origine soit inconnue, ces cellules présentent des homologies avec les cellules souches mésenchymateuses (MSCs) ou les fibroblastes associés au cancer (CAFs). Les Hospicells sont capables de favoriser la chimiorésistance des cellules tumorales ovariennes par un échange membranaire de protéines d'efflux de molécules chimiothérapeutiques. De plus, les Hospicells présentent des propriétés immunosuppressives, notamment en inhibant la prolifération et la production de cytokines de certains lymphocytes T. Les travaux réalisés au laboratoire ont mis en évidence que les Hospicells permettent également une augmentation de la croissance tumorale par une activation de l'angiogenèse. Mes travaux de thèse ont consisté à déterminer la nature des interactions entre les Hospicells et les cellules tumorales ovariennes ou d'autres cellules du microenvironnement, responsables des effets pro-tumoraux décrits précédemment. J'ai pu mettre en évidence in vitro et in vivo (modèles de xénogreffes intrapéritonéales de cellules tumorales ovariennes dans des souris immunodéprimées) que les Hospicells sont capables, par un facteur sécrété, d'induire la production d'IL-6, d'IL-8 et de VEGF (cytokines pro-angiogéniques) par les cellules tumorales ovariennes. Cependant, alors que les Hospicells favorisent systématiquement la croissance tumorale in vivo, les résultats obtenus in vitro sont lignée tumorale ovarienne spécifique. Des données complémentaires obtenues au laboratoire ont montré que les interactions établies entre les cellules tumorales et les Hospicells in vitro ne permettent pas d'expliquer l'activation de l'angiogenèse mise en évidence in vivo. Nous avons donc cherché d'autres partenaires potentiels des Hospicells au sein du microenvironnement tumoral permettant d'expliquer les effets pro-tumoraux observés in vivo. J'ai ainsi montré que les Hospicells sont capables d'entraîner le recrutement de macrophages au sein des tumeurs ovariennes. Les Hospicells peuvent, par un facteur sécrété, polariser les monocytes/macrophages en un phénotype pro-tumoral de macrophages associés aux tumeurs (TAMs) et entraîner la sécrétion par ces cellules d'IL-6, IL-8, VEGF, GM-CSF, IL-1 (alpha et beta), MCP-1, etc... Je me suis également intéressé aux voies de signalisation cellulaires potentiellement impliquées dans la sécrétion d'IL-6, IL-8 et VEGF par les cellules tumorales ou les macrophages, induite par les Hospicells. Bien que ces voies restent en cours d'études, j'ai mis en évidence que le TNF-alpha, l'IL-1alpha, les œstrogènes, Fas Ligand, la S1P, le LPA et le NO ne sont pas impliqués dans cette sécrétion de cytokines. J'ai cependant montré une implication de la voie COX-2 dans la synthèse de VEGF par les macrophages induite par les Hospicells. Nous établissons ainsi l'hypothèse que les Hospicells sont capables d'établir des interactions avec les cellules tumorales ovariennes et les macrophages présents au sein de la tumeur, entraînant une sécrétion de cytokines pro-tumorales. Les Hospicells permettent l'activation et la polarisation des monocytes/macrophages en un phénotype pro-tumoral entraînant ainsi le recrutement de nouveaux macrophages vers le site tumoral. Ces interactions permettent une croissance tumorale et une angiogenèse augmentée, et peuvent favoriser les processus métastatiques et la chimiorésistance. Ces résultats soulignent l'intérêt de cibler le microenvironnement, et notamment les Hospicells, dans le but d'améliorer la prise en charge de patientes atteintes d'un cancer ovarien.Ovarian cancer is the leading cause of death from gynaecological cancer in the world and is characterized by peritoneal dissemination, ascite development and a high rate of mortality. Advanced epithelial ovarian cancer is treated by a cytoreductive surgery and chemotherapy but most of patients experience a recurrence with the apparition of a chemoresistance. The microenvironment could be implied in this recurrence and the resistance to chemotherapies. Rafii et al. isolated original cells, called Hospicells, from ascitic fluid of patients with a grade III ovarian cancer. Although their origin is unknown, these cells share homologies with mesenchymal stem cells (MSCs) or carcinoma associated fibroblasts (CAFs). Hospicells are able to enhance the chemoresistance of ovarian cancer cells via a membrane exchange of chemotherapeutic drugs efflux proteins. Moreover, Hospicells present immunosuppressive properties as the inhibition of proliferation and cytokine production of T lymphocytes. The research carried out in the laboratory showed that Hospicells can also enhance tumour growth by activating the angiogenesis. My PhD focused on the description of interactions between Hospicells and ovarian cancer cells or other stromal cells, responsible for the pro-tumoral effects described previously. I highlighted in vitro and in vivo (intraperitoneal xenograft of ovarian cancer cells in immunosuppressed mice) that Hospicells are able, by a secreted factor, to induce the production of IL-6, IL-8 and VEGF (pro-angiogenic cytokines) in ovarian cancer cells. However, while Hospicells always enhance tumor growth in vivo, the results obtained in vitro are ovarian cancer cell line specific. Complementary data obtained in the laboratory showed that the interactions between ovarian cancer cells and Hospicells in vitro are not sufficient to explain the activation of angiogenesis highlighted in vivo. Therefore, we looked for another potential cellular partner for Hospicells in the tumor microenvironment that could explain the pro-tumoral effects observed in vivo. I showed that Hospicells can activate the recruitment of macrophages toward ovarian tumors. Hospicells can, by a secreted factor, polarize monocytes/macrophages into a pro-tumoral phenotype of tumor associated macrophages (TAMs) and trigger the secretion by these cells of IL-6, IL-8, VEGF, GM-CSF, IL-1, MCP-1, etc... I also studied the cellular pathways potentially implied in the secretion of IL-6, IL-8 and VEGF by ovarian cancer cells or macrophages, induced by Hospicells. Although these pathways are still under study, I highlighted that the TNF-alpha, the IL-1alpha, estrogens, Fas Ligand, the S1P, the LPA and the NO are not implied in this secretion of cytokines. However, I showed an implication of the COX-2 pathway in the VEGF synthesis induced by Hospicells in macrophages. We thus make the hypothesis that Hospicells are able to establish interactions with ovarian cancer cells and tumor macrophages, resulting in a secretion of pro-tumoral cytokines. Hospicells allow the activation and polarization of monocytes/macrophages into a pro-tumoral phenotype enhancing the recruitment of new macrophages toward the tumor site. These interactions allow an enhanced tumor growth and angiogenesis, and can activate metastatic process and the acquisition of a chemoresistance. These results underline the importance of targeting the microenvironment, especially the Hospicells, in order to improve the management of patients with ovarian cancer

La fabrique d'un habiter péri urbain : le transport et la centralité

National audiencePériVia est une recherche menée par l'une des équipes de l'UMR CITERES, en collaboration avec des chercheurs de l'UMR LADYSS et de l'IPTH. Elle vise à mieux comprendre la mobilité quotidienne et hebdomadaire de personnes qui résident dans une commune périurbaine et mènent une activité professionnelle dans une autre commune et pour la plupart, au sein du pôle urbain voisin. Elle interroge également des individus habitant le pôle urbain et qui ont une activité professionnelle en dehors de ce pôle. Toutes les personnes enquêtées résident en Indre et Loire, un département polarisé par une agglomération française moyenne et qui regroupe plus de la moitié de la population de ce départemen

La construction de l'habiter à l'échelle de la vie : diversité des figures identitaires de l'habitat et culture de l'habiter

Nous proposons à travers cette contribution de traiter de " l'habiter des individus ", et de formuler ainsi quelques pistes en vue de la définition et de la compréhension de ce que pourrait être une " culture de l'habiter " . Notre démarche part d'un constat d'insatisfaction : parlant d'habiter l'on constate que l'on a tendance à entendre trop facilement - habitat, et de fait à réduire la notion d'habiter à cette seule dimension. Aussi, les recherches dont nous nous proposons de faire ici l'écho, ont toutes en commun de considérer qu'habiter ne renvoie pas uniquement au fait de " résider " ou de " se loger ", mais bien plus au rapport des individus à l'espace en général, considéré comme environnement construit qui fait sens pour les individus. L'intérêt de l'approche par l'habiter est donc de renverser le questionnement sur l'habitat et, ce faisant, d'interroger le désir identitaire et son exploitation tant marchande que réglementaire (Le Couédic, 2003) sous l'angle spécifique de la signification que ces enjeux prennent au regard de la construction identitaire d'un habitant à travers son cheminement biographique

Urban Form Optimization for the Energy Performance of Buildings Using Citysim

The energy efficiency of the urban texture relies notably on the buildings’ form, which characterizes its capability to take profit of the solar potential as well as its loss of energy through the envelope. Therefore, the general layout at the district scale has a significant impact on the global energy balance in a dense built environment, where the relative position of the adjacent buildings generate shadowing and inter-reflection on a large part of the incoming solar radiation. In the current work, an urban energy simulator named CitySim is used together with a hybrid evolutionary algorithm. The physical model within CitySim features the computation of shortwave radiation including reflections, longwave radiation and a nodal thermal model for the building energy flows. The complete simulation leads to a rather precise evaluation of the annual heating needs, defined as the objective function to be minimized at the district scale. An existing district in Paris is taken as case study: the Bercy park front. Its buildings are disposed in several blocks surrounding courtyards with openings on the park’s side (southwest). This district is recent (1994-2005) and located in a dense area of seven stories buildings. In its original design, the access to sunlight was taken into account by the planner, thus the initial intuition of the architect is compared with optimized configurations. The paper describes a case of urban form optimization, with the formal description of the variables, constraints and objectives of the problem and the definition of the geometrical case for Bercy Front Park. The optimization variables focus on geometrical properties such as the height of the buildings and glazing ratios. The thermal properties of the building (insulation, glazing type) are set in accordance with the French standards of the thermal regulation (RT2005). The urban layouts resulting of the optimization process are analyzed and discussed

Bio accessibility of tire-associated organic chemicals in fish gut (Oncorhynchus mykiss): insights from an in vitro digestion model

Tire and Road Wear Particles (TRWP) account for an important part of the anthropogenic particles released into the environment. There are scientific knowledge gaps as to the potential bio accessibility of chemicals associated with TRWP to aquatic organisms. This study aimed to investigate the solubilization of five tire-associated chemicals into fish gut using an in vitro digestion model (Oncorhynchus mykiss). Our results show that the targeted compounds were partly and rapidly solubilized into simulated fluids (SF) present in the gastrointestinal tract within a typical gut transit time for fish (3h in SFGASTRIC and 24h in SFINTESTINAL). The effects of food co-ingestion on the solubilization of tire-associated chemicals was compound-specific and either lowered or stimulated their solubilization into the gut fluids. Therefore, the uptake of the tire associated chemicals by the epithelial cells and related toxicity to fish need to be investigated

O-Glycosylation of the N-terminal region of the serine-rich adhesin Srr1 of Streptococcus agalactiae explored by mass spectrometry.

International audienceSerine-rich (Srr) proteins exposed at the surface of Gram-positive bacteria are a family of adhesins that contribute to the virulence of pathogenic staphylococci and streptococci. Lectin-binding experiments have previously shown that Srr proteins are heavily glycosylated. We report here the first mass-spectrometry analysis of the glycosylation of Streptococcus agalactiae Srr1. After Srr1 enrichment and trypsin digestion, potential glycopeptides were identified in collision induced dissociation spectra using X! Tandem. The approach was then refined using higher energy collisional dissociation fragmentation which led to the simultaneous loss of sugar residues, production of diagnostic oxonium ions and backbone fragmentation for glycopeptides. This feature was exploited in a new open source software tool (SpectrumFinder) developed for this work. By combining these approaches, 27 glycopeptides corresponding to six different segments of the N-terminal region of Srr1 [93-639] were identified. Our data unambiguously indicate that the same protein residue can be modified with different glycan combinations including N-acetylhexosamine, hexose, and a novel modification that was identified as O-acetylated-N-acetylhexosamine. Lectin binding and monosaccharide composition analysis strongly suggested that HexNAc and Hex correspond to N-acetylglucosamine and glucose, respectively. The same protein segment can be modified with a variety of glycans generating a wide structural diversity of Srr1. Electron transfer dissociation was used to assign glycosylation sites leading to the unambiguous identification of six serines and one threonine residues. Analysis of purified Srr1 produced in mutant strains lacking accessory glycosyltransferase encoding genes demonstrates that O-GlcNAcylation is an initial step in Srr1 glycosylation that is likely required for subsequent decoration with Hex. In summary, our data obtained by a combination of fragmentation mass spectrometry techniques associated to a new software tool, demonstrate glycosylation heterogeneity of Srr1, characterize a new protein modification, and identify six glycosylation sites located in the N-terminal region of the protein

Experimental and numerical investigation of the response of a swirled flame to flow modulations in a non-adiabatic combustor

Turbulent combustion models for Large Eddy Simulation (LES) aims at predicting the flame dynamics. So far, they have been proven to predict correctly the mean flow and flame properties in a wide range of configurations. A way to challenge these models in unsteady situations is to test their ability to recover turbulent flames submitted to harmonic flow modulations. In this study, the Flame Transfer Function (FTF) of a CH4/H2/air premixed swirled-stabilized flame submitted to harmonic flowrate modulations in a non-adiabatic combustor is compared to the response computed using the Filtered TAbulated Chemistry for LES (F-TACLES) formalism. Phase averaged analysis of the perturbed flow field and flame response reveal that the velocity field determined with Particle Image Velocimetry measurements, the heat release distribution inferred from OH* images and the probability of presence of burnt gases deduced from OH-Planar Laser Induced Fluorescence measure- ments are qualitatively well reproduced by the simulations. However, noticeable differences between experiments and simulations are also observed in a narrow frequency range. A detailed close-up view of the flow field highlight differences in experimental OH* and numerical volumetric heat release rate distributions which are at the origin of the differences observed between the numerical and experimental FTF. These differences mainly originate from the outer shear layer of the swirling jet where a residual reaction layer takes place in the simulations which is absent in the experiments. Consequences for turbulent combustion modeling are suggested by examining the evolution of the perturbed flame brush envelope along the downstream distance of the perturbed flames. It is shown that changing the grid resolution and the flame subgrid scale wrinkling factor in these regions does not alter the numerical results. It is finally concluded that the combined effects of strain rate and enthalpy defect due to heat losses are the main factors leading to small but sizable differences of the flame response to coherent structures synchronized by the acoustic forcing in the outer shear layer of the swirling flow. These small differences in flame response lead in turn to a misprediction of the FTF at specific forcing frequencies

Complex Labelling and Similarity Prediction in Legal Texts: Automatic Analysis of France's Court of Cassation Rulings

International audienceDetecting divergences in the applications of the law (where the same legal text is applied differently by two rulings) is an important task. It is the mission of the French Cour de Cassation. The first step in the detection of divergences is to detect similar cases, which is currently done manually by experts. They rely on summarised versions of the rulings (syntheses and keyword sequences), which are currently produced manually and are not available for all rulings. There is also a high degree of variability in the keyword choices and the level of granularity used. In this article, we therefore aim to provide automatic tools to facilitate the search for similar rulings. We do this by (i) providing automatic keyword sequence generation models, which can be used to improve the coverage of the analysis, and (ii) providing measures of similarity based on the available texts and augmented with predicted keyword sequences. Our experiments show that the predictions improve correlations of automatically obtained similarities against our specially colelcted human judgments of similarity

Redirecting splicing with bifunctional oligonucleotides

Abstract: Ectopic modulators of alternative splicing are important tools to study the function of splice variants and for correcting mis-splicing events that cause human diseases. Such modulators can be bifunctional oligonucleotides made of an antisense portion that determines target specificity, and a nonhybridizing tail that recruits proteins or RNA/protein complexes that affect splice site selection (TOSS and TOES, respectively, for targeted oligonucleotide silencer of splicing and targeted oligonucleotide enhancer of splicing). The use of TOSS and TOES has been restricted to a handful of targets. To generalize the applicability and demonstrate the robustness of TOSS, we have tested this approach on more than 50 alternative splicing events. Moreover, we have developed an algorithm that can design active TOSS with a success rate of 80%. To produce bifunctional oligonucleotides capable of stimulating splicing, we built on the observation that binding sites for TDP-43 can stimulate splicing and improve U1 snRNP binding when inserted downstream from 50 splice sites. A TOES designed to recruit TDP-43 improved exon 7 inclusion in SMN2. Overall, our study shows that bifunctional oligonucleotides can redirect splicing on a variety of genes, justifying their inclusion in the molecular arsenal that aims to alter the production of splice variants