A role for dendritic cells in bleomycin-induced pulmonary fibrosis in mice?

RATIONALE: Lung dendritic cells (DCs) have been shown to accumulate in human fibrotic lung disease, but little is known concerning a role for DCs in the pathogenesis of fibrotic lung. OBJECTIVES: To characterize lung DCs in an in vivo model of bleomycin-induced pulmonary fibrosis in mice. METHODS: We characterized the kinetics and activation of pulmonary DCs during the course of bleomycin-induced lung injury by flow cytometry on lung single-cell suspensions. We also characterized the lymphocytes accumulating in bleomycin lung and the chemokines susceptible to favor the recruitment of immune cells. MEASUREMENTS AND MAIN RESULTS: We show, for the first time, that increased numbers of CD11c(+)/major histocompatibility complex class II(+) DCs, including CD11b(hi) monocyte-derived inflammatory DCs, infiltrate the lung of treated animals during the fibrotic phase of the response to bleomycin. These DCs are mature DCs expressing CD40, CD86, and CD83. They are associated with increased numbers of recently activated memory T cells expressing CD44, CD40L, and CD28, suggesting that fully mature DCs and Ag-experienced T cells can drive an efficient effector immune response within bleomycin lung. Most importantly, when DCs are inactivated with VAG539, a recently described new immunomodulator, VAG539 treatment attenuates the hallmarks of bleomycin lung injury. CONCLUSIONS: These findings identify lung DCs as key proinflammatory cells potentially able to sustain pulmonary inflammation and fibrosis in the bleomycin model

Non-Invasive Molecular Imaging of Fibrosis Using a Collagen-Targeted Peptidomimetic of the Platelet Collagen Receptor Glycoprotein VI

Background: Fibrosis, which is characterized by the pathological accumulation of collagen, is recognized as an important feature of many chronic diseases, and as such, constitutes an enormous health burden. We need non-invasive specific methods for the early diagnosis and follow-up of fibrosis in various disorders. Collagen targeting molecules are therefore of interest for potential in vivo imaging of fibrosis. In this study, we developed a collagen-specific probe using a new approach that takes advantage of the inherent specificity of Glycoprotein VI (GPVI), the main platelet receptor for collagens I and III. Methodology/Principal: Findings An anti-GPVI antibody that neutralizes collagen-binding was used to screen a bacterial random peptide library. A cyclic motif was identified, and the corresponding peptide (designated collagelin) was synthesized. Solid-phase binding assays and histochemical analysis showed that collagelin specifically bound to collagen (Kd 10−7 M) in vitro, and labelled collagen fibers ex vivo on sections of rat aorta and rat tail. Collagelin is therefore a new specific probe for collagen. The suitability of collagelin as an in vivo probe was tested in a rat model of healed myocardial infarctions (MI). Injecting Tc-99m-labelled collagelin and scintigraphic imaging showed that uptake of the probe occurred in the cardiac area of rats with MI, but not in controls. Post mortem autoradiography and histological analysis of heart sections showed that the labeled areas coincided with fibrosis. Scintigraphic molecular imaging with collagelin provides high resolution, and good contrast between the fibrotic scars and healthy tissues. The capacity of collagelin to image fibrosis in vivo was confirmed in a mouse model of lung fibrosis. Conclusion/Significance: Collagelin is a new collagen-targeting agent which may be useful for non-invasive detection of fibrosis in a broad spectrum of diseases.Psycholog

The diversity of myeloid immune cells shaping wound repair and fibrosis in the lung

In healthy circumstances the immune system coordinates tissue repair responses in a tight balance that entails efficient inflammation for removal of potential threats, proper wound closure, and regeneration to regain tissue function. Pathological conditions, continuous exposure to noxious agents, and even ageing can dysregulate immune responses after injury. This dysregulation can lead to a chronic repair mechanism known as fibrosis. Alterations in wound healing can occur in many organs, but our focus lies with the lung as it requires highly regulated immune and repair responses with its continuous exposure to airborne threats. Dysregulated repair responses can lead to pulmonary fibrosis but the exact reason for its development is often not known. Here, we review the diversity of innate immune cells of myeloid origin that are involved in tissue repair and we illustrate how these cell types can contribute to the development of pulmonary fibrosis. Moreover, we briefly discuss the effect of age on innate immune responses and therefore on wound healing and we conclude with the implications of current knowledge on the avenues for future research

Dendritic cells and pulmonary fibrosis : study on an animal model of bleomycin-induced fibrosis in mice

Les cellules dendritiques, puissantes cellules présentatrices d'antigène, jouent un rôle-clé dans l'initiation et la régulation des réponses immunitaires et inflammatoires (Lipscomb et al., 2002). Elles sont présentes à l'état de cellules immatures dans la plupart des muqueuses, disséminées dans le tissu interstitiel et les épithéliums. Elles sont chargées de capter les antigènes exogènes, de les apprêter et de migrer vers les organes lymphoïdes pour les présenter aux lymphocytes T spécifiques. Au cours de cette migration, elles acquièrent les caractéristiques des cellules dendritiques matures présentes dans les organes lymphoïdes (expression forte des molécules HLA de classe II et des molécules de costimulation CD40, CD80, CD83, CD86). Les cellules dendritiques sont présentes dans le poumon normal (Vermaelen et al., 2005). Elles sont impliquées dans la physiopathologie de différentes maladies pulmonaires et jouent un rôle pathogénique essentiel dans certaines d'entre elles comme l'histiocytose langerhansienne ou l'asthme (Tazi et al ., 2000; Lambrecht et Hammad, 2003). Leur rôle au cours des processus fibrosants n'a cependant jamais été évalué. En effet, contrairement à d'autres cellules présentatrices d'antigènes que sont les macrophages, dont le rôle dans la réaction fibrosante est clairement établi (Agostini et al ., 1997), le rôle des cellules dendritiques au cours des processus de réparation alvéolaire n'a pas été étudié. Notre travail visait à étudier in vivo le rôle des cellules dendritiques au cours de la fibrose pulmonaire sur un modèle animal par induction d’une fibrose à la bléomycine chez la souris. Les premières étapes du projet ont consisté à caratériser par cytométrie en flux la présence de cellules dendritiques dans le poumon des animaux 3, 7 et 14 jours après instillation intratrachéale de bléomycine. L'étude s'est poursuivie par une caractérisation du phénotype de surface des cellules dendritiques en cherchant à préciser leur état d’activation et de maturation. L'étape suivante a consisté à rechercher par RT-QPCR les principales chimiokines responsables du recrutement des cellules dendritiques. Les résultats montrent une augmentation du nombre des cellules dendritiques CD11c+ / CMH II+ infiltrant le poumon dès J7, avec une sous-population de cellules activées exprimant fortement les molécules CMH II. Ces résultats sont corroborés par une augmentation de la population cellulaire totale du broyat de poumon dès J3, ainsi que par une augmentation de la cellularité totale et du nombre de cellules inflammatoires dans les lavages bronchoalvéolaires (LBA) à J7 et J14. L'étude a été complétée par une caractérisation plus approfondie du phénotype de surface des cellules dendritiques en cherchant à préciser leur état d’activation/maturation. [...]Dendritic cells (DCs), potent antigen-presenting cells, play a key role in the initiation and regulation of immune and inflammatory responses (Lipscomb et al., 2002). Immature DCs are present in the most of mucous membranes, disseminated in the interstitial tissue and the epithelia. They are able to deal with exogenous antigens, to process them and to migrate to lymphoid organs and to present them to T lymphocytes. During their migration, they have the characteristics of mature DCs in lymphoid organs (higher expression of MHC class-II molecules and costimulation-molecules (CD40, CD80, CD83, CD86). Dendritic cells are present in the normal lung (Vermarlen et al., 2005). They are implicated in the pathophysiology of different pulmonary diseases and play a crucial pathogenic role in some of them like Langerhan’s cell Histiocytosis or asthma (Tazi et al., 2000; Lambrecht et Hammad, 2003). However, their role in the fibrosing process has never been studied. In fact, the role of macrophages (other antigen presenting cells (APCs)) in fibrosing reaction has been clearly established (Agostini et al., 1997), but DCs function during the alveolar healing process has not been studied. The purpose of this thesis is to study the in vivo role of DCs in bleomycin-induced pulmonary fibrosis in mice. The first step of this project is to demonstrate by flow cytometry the presence of DCs in the lung of these animals 3, 7 and 14 days after intratracheal bleomycin instillation. We continued our research with the surface phenotypic characterization of DCs identifying their activation state and maturation. The next step consists to search the main chemokines which are responsive for dendritic cells recruitment by RT-qPCR. Our results show an increase of CD11c+ / MHC class II+ DCs number infiltrating the lung after D7, with an activated cell subpopulation which strongly express MHC class II molecules. The results are corroborated by an increase of the total cell population in the lung homogenate after D3 and by an increase of the total cellularity and inflammatory cells number in broncho-alveolar lavages (BAL) at D7 and at D14. This study was completed by the surface phenotypic characterization of DCs identifying their activation state and maturation. [...

Facteurs de susceptibilité génétique associés à la progression des cancers de la prostate

Le cancer de la prostate est devenu le cancer le plus fréquent chez l homme dans la grande majorité des pays occidentaux. En France, pour l année 2005, le nombre de nouveaux cas de cancer de la prostate a été estimé à plus de 62 000. Certains facteurs de risque ont été identifiés (l âge, l histoire familiale, l origine ethnique) mais la composante génétique est mal évaluée. Il reste encore aujourd hui de nombreux gènes à identifier avant de connaître les causes moléculaires du cancer de la prostate.Dans ce contexte, le but de cette thèse était la de couverte de nouveaux facteurs de risque génétiques gènes du cancer de la prostate au sein d'une population caucasienne. Récemment une étude à démontré que des interactions à la surface cellulaire entre KAI1 sur les cellules tumorales et DARC le récepteur leurre à cytokine sur les cellules vasculaires adjacentes déclenchent la sénescence dans les cellules tumorales et suppriment les métastases. Dans le présent travail, nous nous sommes proposé de déterminer si le gène DARC est impliqué dans la susceptibilité du cancer de la prostate en utilisant une étude cas-témoins. Pour cela, nous avons testé l association entre le polymorphisme D42G et le cancer de la prostate métastatique. Mais nos résultats n ont pas plaidé en faveur d'un rôle de ce polymorphisme dans la progression du cancer de la prostate et chez les patients ayant des variants de susceptibilité du cancer de la prostate en 8q24.Dans une seconde étape, nous avons analysé des interactions synergiques entre des polymorphismes de gènes intervenant dans la voie des androgènes et oestrogènes (SRD5A2 (V89L), CYP19 (répétition TTTA), AR (répétition CAG)) avec des variations génétiques en 8q24 (rs1447295 et rs6983267). Cette étude a montré que les marqueurs en 8q24 et le polymorphisme d un gène du métabolisme œstrogène travaillent ensemble dans la susceptibilité du cancer de la prostate. De manière intéressante, nous avons démontré que le polymorphisme de CYP19 augmente le risque d agressivité chez les porteurs de variants en 8q24 (p< 0,0001).PARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Alimentation d'une population adulte active à Brazzaville (Congo)

Une évaluation nutritionnelle a été réalisée sur une population adulte en activité professionnelle dont l’âge est compris entre 30 et 40 ans à Brazzaville (Congo). La méthode utilisée à été l’interview, type questionnaire alimentaire quantitatif. La majorité des sujets présentaient une insuffisance en poids et en apports énergétiques, ainsi qu'un risque de carences en protéines, magnésium, calcium et en fer. En conclusion, il s’avère nécessaire de corriger l’alimentation de cette population sur la base de l’utilisation de produits locaux et de l’élaboration des programmes de Santé-Nutrition-Éducatio

Analysis of poorly stratified lateritic terrains overlying a granitic bedrock in West Africa, using 2-D electrical resistivity tomography

Two-dimensional electrical resistivity tomography has been employed to investigate the subsurface structure of a thick lateritic weathering mantle overlying a granitic bedrock in southeastern Senegal. The resistivities were measured along two kilometric profiles insuring continuous coverage. Exploration pits exposed the different weathering layers, i.e., a saprolite, a mottle zone, a soft ferricrete and a ferricrete, whose respective thicknesses were used to constrain the measured apparent resistivity, despite their spatial variations. Colour-modulated pseudo-sections of apparent resistivity versus pseudo-depth including the groundsurface topography clearly show spatial variations in electrical properties of the weathering layers since their apparent resistivity changes faster than their respective thickness. The data from a cross-borehole survey along with estimates of resistivity for aquifers and granite were integrated into the pseudo-sections to provide more useful results about the real resistivity ranges of the weathering layers. The resulting geo-electrical images document the geometric topographies. The spatial relationships between the granitic bedrock and groundsurface topographies suggest that a large surface was mainly shaped by weathering processes while the hillslope geomorphic patterns result from erosion processes or lateritic weathering of reworked materials leading to ferricrete development according to the different landforms observed. It is suggested that climatic changes were implied in the landscape evolution of our study area. (Résumé d'auteur

Chondrocalcin is internalized by chondrocytes and triggers cartilage destruction via an interleukin-1β-dependent pathway

International audienceChondrocalcin is among the most highly synthesized polypeptides in cartilage. This protein is released from its parent molecule, type II pro-collagen, after secretion by chondrocytes. A participation of extracellular, isolated chondrocalcin in mineralization was proposed more than 25 years ago, but never demonstrated. Here, exogenous chondrocalcin was found to trigger MMP13 secretion and cartilage destruction ex vivo in human cartilage explants and did so by modulating the expression of interleukin-1 beta in primary chondrocyte cultures in vitro. Chondrocalcin was found internalized by chondrocytes. Uptake was found mediated by a single 18-mer peptide of chondrocalcin, which does not exhibit homology to any known cell-penetrating peptide. The isolated peptide, when artificially linked as a tetramer, inhibited gene expression regulation by chondrocalcin, suggesting a functional link between uptake and gene expression regulation. At the same time, the tetrameric peptide potentiated chondrocalcin uptake by chondrocytes, suggesting a cooperative mechanism of entry. The corresponding peptide from type I pro-collagen supported identical cell-penetration, suggesting that this property may be conserved among C-propeptides of fibrillar pro-collagens. Structural modeling localized this peptide to the tips of procollagen C-propeptide trimers. Our findings shed light on unexpected function and mechanism of action of these highly expressed proteins from vertebrates