High expression of antioxidant proteins in dendritic cells: possible implications in atherosclerosis

Dendritic cells (DCs) display the unique ability to activate naive T cells and to initiate primary T cell responses revealed in DC-T cell alloreactions. DCs frequently operate under stress conditions. Oxidative stress enhances the production of inflammatory cytokines by DCs. We performed a proteomic analysis to see which major changes occur, at the protein expression level, during DC differentiation and maturation. Comparative two-dimensional gel analysis of the monocyte, immature DC, and mature DC stages was performed. Manganese superoxide dismutase (Mn-SOD) reached 0.7% of the gel-displayed proteins at the mature DC stage. This important amount of Mn-SOD is a primary antioxidant defense system against superoxide radicals, but its product, H(2)O(2), is also deleterious for cells. Peroxiredoxin (Prx) enzymes play an important role in eliminating such peroxide. Prx1 expression level continuously increased during DC differentiation and maturation, whereas Prx6 continuously decreased, and Prx2 peaked at the immature DC stage. As a consequence, DCs were more resistant than monocytes to apoptosis induced by high amounts of oxidized low density lipoproteins containing toxic organic peroxides and hydrogen peroxide. Furthermore DC-stimulated T cells produced high levels of receptor activator of nuclear factor kappaB ligand, a chemotactic and survival factor for monocytes and DCs. This study provides insights into the original ability of DCs to express very high levels of antioxidant enzymes such as Mn-SOD and Prx1, to detoxify oxidized low density lipoproteins, and to induce high levels of receptor activator of nuclear factor kappaB ligand by the T cells they activate and further emphasizes the role that DCs might play in atherosclerosis, a pathology recognized as a chronic inflammatory disorder.Comment: cpyright: American Society of Biochemistry and Molecular Biolog

Flt3(+) macrophage precursors commit sequentially to osteoclasts, dendritic cells and microglia

BACKGROUND: Macrophages, osteoclasts, dendritic cells, and microglia are highly specialized cells that belong to the mononuclear phagocyte system. Functional and phenotypic heterogeneity within the mononuclear phagocyte system may reveal differentiation plasticity of a common progenitor, but developmental pathways leading to such diversity are still unclear. RESULTS: Mouse bone marrow cells were expanded in vitro in the presence of Flt3-ligand (FL), yielding high numbers of non-adherent cells exhibiting immature monocyte characteristics. Cells expanded for 6 days, 8 days, or 11 days (day 6-FL, day 8-FL, and day 11-FL cells, respectively) exhibited constitutive potential towards macrophage differentiation. In contrast, they showed time-dependent potential towards osteoclast, dendritic, and microglia differentiation that was detected in day 6-, day 8-, and day 11-FL cells, in response to M-CSF and receptor activator of NFκB ligand (RANKL), granulocyte-macrophage colony stimulating-factor (GM-CSF) and tumor necrosis factor-α (TNFα), and glial cell-conditioned medium (GCCM), respectively. Analysis of cell proliferation using the vital dye CFSE revealed homogenous growth in FL-stimulated cultures of bone marrow cells, demonstrating that changes in differential potential did not result from sequential outgrowth of specific precursors. CONCLUSIONS: We propose that macrophages, osteoclasts, dendritic cells, and microglia may arise from expansion of common progenitors undergoing sequential differentiation commitment. This study also emphasizes differentiation plasticity within the mononuclear phagocyte system. Furthermore, selective massive cell production, as shown here, would greatly facilitate investigation of the clinical potential of dendritic cells and microglia

Class III myosins shape the auditory hair bundles by limiting microvilli and stereocilia growth.

International audienceThe precise architecture of hair bundles, the arrays of mechanosensitive microvilli-like stereocilia crowning the auditory hair cells, is essential to hearing. Myosin IIIa, defective in the late-onset deafness form DFNB30, has been proposed to transport espin-1 to the tips of stereocilia, thereby promoting their elongation. We show that Myo3a(-/-)Myo3b(-/-) mice lacking myosin IIIa and myosin IIIb are profoundly deaf, whereas Myo3a-cKO Myo3b(-/-) mice lacking myosin IIIb and losing myosin IIIa postnatally have normal hearing. Myo3a(-/-)Myo3b(-/-) cochlear hair bundles display robust mechanoelectrical transduction currents with normal kinetics but show severe embryonic abnormalities whose features rapidly change. These include abnormally tall and numerous microvilli or stereocilia, ungraded stereocilia bundles, and bundle rounding and closure. Surprisingly, espin-1 is properly targeted to Myo3a(-/-)Myo3b(-/-) stereocilia tips. Our results uncover the critical role that class III myosins play redundantly in hair-bundle morphogenesis; they unexpectedly limit the elongation of stereocilia and of subsequently regressing microvilli, thus contributing to the early hair bundle shaping

HIV/SIV Infection Primes Monocytes and Dendritic Cells for Apoptosis

Subversion or exacerbation of antigen-presenting cells (APC) death modulates host/pathogen equilibrium. We demonstrated during in vitro differentiation of monocyte-derived macrophages and monocyte-derived dendritic cells (DCs) that HIV sensitizes the cells to undergo apoptosis in response to TRAIL and FasL, respectively. In addition, we found that HIV-1 increased the levels of pro-apoptotic Bax and Bak molecules and decreased the levels of anti-apoptotic Mcl-1 and FLIP proteins. To assess the relevance of these observations in the context of an experimental model of HIV infection, we investigated the death of APC during pathogenic SIV-infection in rhesus macaques (RMs). We demonstrated increased apoptosis, during the acute phase, of both peripheral blood DCs and monocytes (CD14+) from SIV+RMs, associated with a dysregulation in the balance of pro- and anti-apoptotic molecules. Caspase-inhibitor and death receptors antagonists prevented apoptosis of APCs from SIV+RMs. Furthermore, increased levels of FasL in the sera of pathogenic SIV+RMs were detected, compared to non-pathogenic SIV infection of African green monkey. We suggest that inappropriate apoptosis of antigen-presenting cells may contribute to dysregulation of cellular immunity early in the process of HIV/SIV infection

Les cellules géantes formées en présence de l interleukine-17Adans les granulomes de tuberculose (mécanismes de formation, de survie et fonctions)

Dans la tuberculose, Mycobacterium tuberculosis forme des granulomes dans les poumons avec, au centre, des cellules myéloïdes mono et multi-nucléées et autour, des lymphocytes. Nous avons étudié la biologie des cellules géantes dans ces granulomes tuberculeux: formation, mécanismes de survie et fonctions. Notre groupe a publié que l IL-17A déclenche la fusion des cellules dendritiques (DC). Notre travail démontre que cette cytokine induit BCL2A1/BFL1, qui régule la survie des DC et les chémokines CCL2 et CCL20 qui dirigent le regroupement nécessaire à leur fusion. In situ, l'IL-17A est exprimée par les lymphocytes T de la couronne du granulome tuberculeux. BCL2A1, CCL2 et CCL20 sont exprimés par les cellules myéloïdes mono-et multi-nucléées. Ensuite, nous avons caractérisé le phénotype, les fonctions immunitaires et l'activité microbicide des DC traitées par l'IL-17A. Nous avons trouvé qu elles co-expriment des marqueurs de DC et de macrophages, conservent les fonctions classiques des DC, synthétisent un profil spécifique d enzymes destructrices et exercent une microbicidie variable suivant les souches de Mycobactéries. Nous avons nommé GMIC (Giant Myeloid Inflammatory Cell), ces cellules géantes induites par l'IL-17A. Nous proposons qu'elles constituent un nouvel effecteur myéloïde qui contrôle les mycobactéries. Ainsi, l'IL-17A participerait au maintien du cœur myéloïde du granulome tuberculeux en favorisant la formation des cellules géantes possédant des fonctions destructrices et microbicides. Les mécanismes moléculaires que nous avons documentés devraient permettre le développement de nouvelles stratégies thérapeutiques et vaccinales contre la tuberculose.Tuberculosis, caused by Mycobacterium tuberculosis infection, results in the development of granulomas in affected tissues. These structures are formed by a myeloid cell core including multinucleated giant cells and surrounded by T lymphocytes. We studied mechanisms of survival, formation and functions of giant cells in Mycobacterium granulomas. Previously, our group showed that the cytokine IL-17A induces the fusion of dendritic cells (DC). Here, we identified molecules induced by the IL-17A genetic program in myeloid cells: BFL1 regulated DC survival, while the chemokines CCL2 and CCL20 directed clustering required for DC fusion. In situ, in human TB granulomas, we found that IL-17A was expressed by T lymphocytes while BFL1, CCL2 and CCL20 were expressed by the mono- and multi-nucleated myeloid cells. Then we characterized phenotype, immune functions and microbicidal activity of IL-17A-treated DC and their derived giant cells. They expressed a mixed DC-macrophage phenotype, retained classical DC functions, synthesized several destructive enzymes and had increased and differential microbicidal activities against Mycobacterium species. We named GMIC (giant myeloid inflammatory cells) these IL-17A-dependent giant cells, and propose that they constitute a new inflammatory myeloid effector with potent microbicidal activities. Altogether, our results show that IL-17A may participate in the maintenance of the myeloid core of human tuberculosis granuloma by promoting the formation of GMIC with potent destructive and microbicidal functions. The molecular mechanisms we have documented should help the development of new tuberculosis therapeutic and vaccination strategies.LYON-ENS Sciences (693872304) / SudocSudocFranceF

Clonage Gateway R@ de la région précoce pour étudier les interactions système immunitaire humain -MCPyV dans le carcinome de Merkel

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Conditions logistiques et évolution de la qualité de la clémentine de Corse

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Conditions logistiques et évolution de la qualité de la clémentine de Corse

*INRA Corse, Unité Régionale de Documentation, 20230 San Giuliano Diffusion du document : INRA Corse, Unité Régionale de Documentation, 20230 San GiulianoNational audienc

Quelle démarche de recherche sur la qualité pour une production locale ? La clémentine de Corse

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