Immunité anti-aspergillaire (modulations de la fonction phagocytaire du macrophage par le cytomégalovirus ; rôle de la cellule dendritique)

Aspergillus fumigatus est responsable d'une infection opportuniste grave l'aspergillose invasive. La défense contre les conidies d'Aspergillus fumigatus s'organise sur le site d'infection autour de deux principales cellules : le macrophage et la cellule dendritique. Cette étude a porté sur l'interaction des conidies aspergillaires avec ces deux types cellulaires. Des études cliniques ont montré que le cytomegalovirus est un facteur favorisant l'aspergillose invasive. Nous avons montré par un modèle de coinfection, in vitro, que le cytomégalovirus diminue les récepteurs au complément sur les macrophages et l'adhérence des conidies aspergillaires. Les cellules dendritiques jouent un rôle essentiel à l'interface de l'immunité innée et spécifique. Nous avons démontré que l'internalisation des conidies d'A.fumigatus dans les cellules dendritiques humaines induit leur maturation et la sécrétion de cytokines et de chimiokines. Cette sécrétion est caractéristique d'un profil inflammatoire et pourrait influencer la polarisation de la réponse spécifique vers un profil Th1 protecteur.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Production et enregistrement des vaccins : cas de la grippe pandémique porcine

REIMS-BU Santé (514542104) / SudocSudocFranceF

Expression of Proinflammatory and Regulatory Cytokines via NF-κB and MAPK-Dependent and IFN Regulatory Factor-3-Independent Mechanisms in Human Primary Monocytes Infected by Mycobacterium tuberculosis

Knowledge of the molecular events regulating the innate response to Mycobacterium tuberculosis (Mtb) is critical for understanding immunological pathogenesis and protection from tuberculosis. To this aim, the regulation and the expression of regulatory and proinflammatory cytokines were investigated in human primary monocytes upon Mtb infection. We found that Mtb-infected monocytes preferentially express a proinflammatory cytokine profile, including IL-6, TNF-α, and IL-1β. Conversely, among the regulatory cytokines, Mtb elicited IL-10 and IL-23 release while no expression of IL-12p70, IL-27, and IFN-β was observed. The analysis of the signalling pathways leading to this selective cytokine expression showed that in monocytes Mtb activates MAPK and NF-κB but is unable to stimulate IRF-3 phosphorylation, a transcription factor required for IL-12p35 and IFN-β gene expression. Thus, by inducing a specific cytokine profile, Mtb can influence the immunoregulatory properties of monocytes, which represent important target of novel vaccinal strategies against Mtb infection

Characterization of Immunostimulatory CpG-Rich Sequences from Different Bifidobacterium Species ▿

The beneficial effects of Bifidobacterium are partly due to its immunostimulatory properties. These immunostimulatory properties may be linked to the presence of unmethylated CpG motifs specific to bacterial DNA, which may induce a TH1 response by activating Toll-like receptors (TLR). Using in silico analyses, PCR amplification, and dot blotting, we characterized the CpG content of various bifidobacterial strains and evaluated the immunostimulatory properties and genomic heterogeneity of these motifs in the genus. Our in silico study, based on entire genome sequences from five bifidobacterial strains, showed that Bifidobacterium genomes contain numerous CpG motifs, including 5′-purine-purine-CG-pyrimidine-pyrimidine-3′ and 5′-purine-TCG-pyrimidine-pyrimidine-3′ motifs, and biologically active sequences previously identified in lactic acid bacteria. We identified four CpG-rich sequences with Bifidobacterium longum NCC2705. Two sequences with a percent G+C of about 68% included 14 and 16 CpG motifs. Two sequences with a percent G+C of about 60% included 16 and 6 CpG motifs. These sequences induce the production of monocyte chemoattractant protein 1 (MCP-1) and tumor necrosis factor alpha (TNF-α) through a pattern of TLR9 stimulation on RAW 264.7 macrophages. No link could be established between their immunostimulatory properties, the number of CpG motifs, and percent G+C. We investigated inter- and intraspecies heterogeneity in 71 strains of various origins. These sequences were highly conserved in the genus. No link was found between the presence of the CpG-rich sequence and the origin of the strains (healthy, allergic, or preterm infants). The high frequency of CpG motifs in the DNA of Bifidobacterium may play an important role in the immunostimulatory properties of commensal or probiotic bifidobacterial strains

Plasmacytoid dendritic cells in multiple sclerosis: intracerebral recruitment and impaired maturation in response to interferon-beta.

The roles of plasmacytoid dendritic cells (pDCs) and their response to interferon (IFN)-beta therapy in multiple sclerosis (MS) patients are poorly understood. We identified pDC accumulation in white matter lesions and leptomeninges of MS brains and abundant expression of the Type I IFN-induced protein MxA, mainly in perivascular CD3+ lymphocytes in lesions, indicating Type I IFN production by activated pDCs. The pDC chemoattractant chemerin was detected in intralesional cerebrovascular endothelial cells, and the chemerin receptor was expressed on infiltrating leukocytes, including pDCs. The effect of IFN-beta on pDC phenotype and function was evaluated in MS patients before and during IFN-beta treatment. Although IFN-beta did not modify the frequency and immature phenotype of circulating pDC, they showed lower expression of major histocompatibility complex Class II and blood-dendritic cell antigen 2 molecules and upregulation of CD38 and B7H1 costimulatory molecules. On exposure to CpG (a site where cytosine [C] lies next to guanine [G] in the DNA sequence [the p indicates that C and G are connected by a phosphodiester bond]) oligodeoxynucleotides in vitro, pDCs from IFN-beta-treated MS patients showed reduced expression of the pDC maturation markers CD83 and CD86 molecules; in vitro IFN-beta treatment of pDCs from healthy donors resulted in lower secretion of proinflammatory cytokines, including IFN-alpha, and a decreased ability to stimulate allogeneic T cells in response to maturative stimuli. These data indicate that IFN-beta modulates the immunologic functions of pDC, thus identifying pDCs as a novel target of IFN-beta therapy in MS patients.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe

Human Dendritic Cells following Aspergillus fumigatus Infection Express the CCR7 Receptor and a Differential Pattern of Interleukin-12 (IL-12), IL-23, and IL-27 Cytokines, Which Lead to a Th1 Response

Aspergillus fumigatus is the most prevalent airborne fungal pathogen and causes fatal invasive aspergillosis in immunocompromised patients. Given the essential role of dendritic cells (DC) in initiating and regulating immune responses, we investigated the impact of A. fumigatus conidial infection on human DC. A. fumigatus conidia were rapidly internalized and induced the release of tumor necrosis factor alpha within the first 8 h. After A. fumigatus infection, the majority of DC underwent full maturation, although CCR7 expression was observed only in DC that had internalized the conidia. Additionally, the analysis of regulatory cytokines showed that infected DC simultaneously produced interleukin-12p70 (IL-12p70) and significant amounts of IL-10. IL-10 neutralization was not able to further increase IL-12p70 production from infected DC. Whereas the central role of IL-12 in the generation of Th1 cells has long been appreciated, recently two other members of the IL-12 family, IL-23 and IL-27, were reported to play important roles in the regulation of gamma interferon (IFN-γ) production from naïve and memory T cells. A. fumigatus-infected DC were also able to express high levels of IL-23p19 and low levels of IL-27p28 at later stages of infection. According to this expression pattern, A. fumigatus-infected DC were able to prime IFN-γ production of naïve T cells. Thus, this study on the expression of the new IL-12 family members controlling the Th1 response sheds light on a novel aspect of the contribution of DC to anti-Aspergillus immunity

IFN-β improves BCG immunogenicity by acting on DC maturation

Given the variable protective efficacy provided by Mycobacterium bovis bacillus Calmette-Guérin (BCG), there is an urgent need to develop new vaccines against tuberculosis. As dendritic cells (DC) play a critical role in initiating and regulating a protective T cell response against the pathogens, the comprehension of mycobacterium-induced modulation of DC functions is critical to pinpoint new, immunological strategies. To this end, a comparative analysis of the effect induced by BCG and Mycobacterium tuberculosis (Mtb) infection on the DC immunophenotype indicated that BCG is less efficient in inducing DC maturation than Mtb. In addition, BCG-infected DC poorly expressed IFN-β and displayed a reduced production of IL-12 as compared with Mtb-stimulated cells. The impaired expression of IL-12p35 and IFN-β is likely a result of the inability of BCG to induce the activation of the IFN regulatory factor-3. Taking into account these data, we sought to investigate whether the exogenous addition of IFN-β, a cytokine that exerts important effects on the immune system, could enhance the Th1-polarizing capacity of BCG-infected DC. Interestingly, when DC infected by BCG were pretreated in vitro with IFN-β, they displayed a fully mature phenotype and released a significant amount of bioactive IL-12p70, which resulted in an enhanced Th1 response. This study demonstrates that IFN-β potentiates DC immunological functions following BCG infection, thus suggesting IFN-β as a possible candidate as vaccine adjuvant

Deux ensembles funéraires d'époque romaine. Avenue Jean-Jaures à Nimes (Gard)

International audienceCet ouvrage tente de caractériser un quartier funéraire périurbain du Haut-Empire à Nîmes à travers l'étude conjointe de deux ensembles mis au jour dans le cadre d'opérations d'archéologie préventive en 1996 et en 2003. Ces espaces funéraires sont implantés le long d'une voie menant à la porte dite "du Cadereau", au sud-est de l'agglomération antique. L'analyse topographique met en évidence un développement original sous forme d'un lotissement en grandes parcelles allongées, subdivisées en concessions au recrutement familial et desservies par des chemins secondaires. Les deux ensembles, principalement datés entre le milieu du Ier s. et la fin du IIe s., présentent d'évidentes similitudes dans la gestion de l'espace, la place accordée aux tombes de très jeunes enfants, les modes de sépultures ou les pratiques de dépôts de mobilier. Ces caractéristiques communes ne s'observent pas toujours dans les autres nécropoles nîmoises, ce qui fait penser qu'on a affaire à une population homogène, peut-être issue de quartiers urbains situés à proximité. Les données disponibles témoignent de l'adoption avancée des pratiques funéraires romaines et de l'appartenance des défunts à un niveau intermédiaire de la société nîmoise. Enfin, l'étude détaillée et pluridisciplinaire des cinquante-sept structures funéraires mises au jour et des dépôts qui y sont associés, constitue un nouveau jalon pour la connaissance des pratiques funéraires en Gaule narbonnaise

ESX-1 dependent impairment of autophagic flux by Mycobacterium tuberculosis in human dendritic cells

Emerging evidence points to an important role of autophagy in the immune response mediated by dendritic cells (DC) against Mycobacterium tuberculosis (Mtb). Since current vaccination based on Bacillus Calmette-Guerin (BCG) is unable to stop the tuberculosis epidemic, a deeper comprehension of the alterations induced by Mtb in DC is essential for setting new vaccine strategies. Here, we compared the capacity of virulent (H37Rv) and avirulent (H37Ra) Mtb strains as well as BCG to modulate autophagy in human primary DC. We found that Mtb H37Rv impairs autophagy at the step of autophagosome-lysosome fusion. In contrast, neither Mtb H37Ra nor BCG strains were able to hamper autophagosome maturation. Both these attenuated strains have a functional inhibition of the 6kD early secreted antigenic target ESAT-6, an effector protein of the ESAT-6 Secretion System-1(ESX-1)/type VII secretion system. Notably, the ability to inhibit autophagy was fully restored in recombinant BCG and Mtb H37Ra strains in which ESAT-6 secretion was re-established by genetic complementation using either the ESX-1 region from Mtb (BCG::ESX-1) or the PhoP gene (Mtb H37Ra::PhoP), a regulator of ESAT-6 secretion. Importantly, the autophagic block induced by Mtb was overcome by rapamycin treatment leading to an increased interleukin-12 expression and, in turn, to an enhanced capacity to expand a Th1-oriented response. Collectively, our study demonstrated that Mtb alters the autophagic machinery through the ESX-1 system, and thereby opens new exciting perspectives to better understand the relationship between Mtb virulence and its ability to escape the DC-mediated immune response