Interactions cytokiniques dans le microenvironnement inflammatoire (Analyse à large échelle de la réponse aux Interférons de Type I lors la de polarisation des Lymphocytes T auxiliaires)

Les interférons de Type I (IFN) sont des cytokines produites par les cellules en réponse à une infection virale. Les IFNs ont des effets pleïotropiques et parfois paradoxaux, protecteur ou néfaste pour l immunité Innée ou adaptative. Certains facteurs intrinsèques (type cellulaire) peuvent expliquer une partie ces discordances. Mon travail de thèse s est intéressé à l effet du microenvironnement cytokinique sur la réponse IFN. En utilisant des analyses à large échelle, nous avons étudié la réponse IFN dans 4 contextes de polarisation des lymphocytes T auxiliaires (Th). Nous avons identifié 1/ un programme de transcription conservé et 2/ une réponse IFN flexible, modulant spécifiquement les principales fonctions des Th (cytokines, chemokines) en fonction du contexte polarisant. La réponse antivirale apparait aussi flexible avec une moins bonne protection des Th2 et Th17 contre l infection par HIV-1et HIV-2. Nos résultats suggèrent que l environnement cytokinique contrôle en partie la réponse IFN et peut ainsi moduler cette dernière dans différents contextes physiopathologiques.Type I IFN (IFN) are innate cytokines produced by host cells during viral infection. Ithas pleiotropic and sometimes opposing, protective or detrimental effects, on both innateand adaptive immunity that remain poorly understood. Parts of IFN response may be explain by intrinsic effect (cell- specificity). My thesis was focused on the effect of the microenvironment, as present during T Helper cell differentiation, on IFN response. Using a systems level approach, we studied IFN responses during Four Human T Helper cell differentiation. We identified 1/ a conserved IFN- induced transcriptional program comprising mostly antiviral genes 2/ a flexible IFN response, leading to a different pattern of chemokine and cytokine induction by IFN in distinct Th environments. Antiviral response was also flexible with a lesser protection to HIV-1 and HIV-2 infection in Th2 and Th17 contexts. Our in vitro results suggested that environmental control might shape the effects of IFN in different physiopathological contexts.PARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF

Model Checking to Assess T-Helper Cell Plasticity

Computational modeling constitutes a crucial step toward the functional understanding of complex cellular networks. In particular, logical modeling has proven suitable for the dynamical analysis of large signaling and transcriptional regulatory networks. In this context, signaling input components are generally meant to convey external stimuli, or environmental cues. In response to such external signals, cells acquire specific gene expression patterns modeled in terms of attractors (e.g., stable states). The capacity for cells to alter or reprogram their differentiated states upon changes in environmental conditions is referred to as cell plasticity. In this article, we present a multivalued logical framework along with computational methods recently developed to efficiently analyze large models. We mainly focus on a symbolic model checking approach to investigate switches between attractors subsequent to changes of input conditions. As a case study, we consider the cellular network regulating the differentiation of T-helper (Th) cells, which orchestrate many physiological and pathological immune responses. To account for novel cellular subtypes, we present an extended version of a published model of Th cell differentiation. We then use symbolic model checking to analyze reachability properties between Th subtypes upon changes of environmental cues. This allows for the construction of a synthetic view of Th cell plasticity in terms of a graph connecting subtypes with arcs labeled by input conditions. Finally, we explore novel strategies enabling specific Th cell polarizing or reprograming events.LabEx MemoLife, Ecole Normale Supérieure, FCT grants: (PEst-OE/EEI/LA0021/2013, IF/01333/2013), Ph.D.program of the Agence National de Recherche sur Le Sida (ANRS), European Research Council consolidator grant

Human Dendritic Cells Activated by TSLP and CD40L Induce Proallergic Cytotoxic T Cells

Human thymic stromal lymphopoietin (TSLP) is a novel epithelial cell–derived cytokine, which induces dendritic cell (DC)-mediated CD4+ T cell responses with a proallergic phenotype. Although the participation of CD8+ T cells in allergic inflammation is well documented, their functional properties as well as the pathways leading to their generation remain poorly understood. Here, we show that TSLP-activated CD11c+ DCs potently activate and expand naive CD8+ T cells, and induce their differentiation into interleukin (IL)-5 and IL-13–producing effectors exhibiting poor cytolytic activity. Additional CD40L triggering of TSLP-activated DCs induced CD8+ T cells with potent cytolytic activity, producing large amounts of interferon (IFN)-γ, while retaining their capacity to produce IL-5 and IL-13. These data further support the role of TSLP as initial trigger of allergic T cell responses and suggest that CD40L-expressing cells may act in combination with TSLP to amplify and sustain pro-allergic responses and cause tissue damage by promoting the generation of IFN-γ–producing cytotoxic effectors

Distinct Cytokine Profiles of Neonatal Natural Killer T Cells after Expansion with Subsets of Dendritic Cells

Natural killer T (NKT) cells are a highly conserved subset of T cells that have been shown to play a critical role in suppressing T helper cell type 1–mediated autoimmune diseases and graft versus host disease in an interleukin (IL)-4–dependent manner. Thus, it is important to understand how the development of IL-4– versus interferon (IFN)-γ–producing NKT cells is regulated. Here, we show that NKT cells from adult blood and those from cord blood undergo massive expansion in cell numbers (500–70,000-fold) during a 4-wk culture with IL-2, IL-7, phytohemagglutinin, anti-CD3, and anti-CD28 mAbs. Unlike adult NKT cells that preferentially produce both IL-4 and IFN-γ, neonatal NKT cells preferentially produce IL-4 after polyclonal activation. Addition of type 2 dendritic cells (DC2) enhances the development of neonatal NKT cells into IL-4+IFN-γ− NKT2 cells, whereas addition of type 1 dendritic cells (DC1) induces polarization towards IL-4−IFN-γ+ NKT1 cells. Adult NKT cells display limited plasticity for polarization induced by DC1 or DC2. Thus, newly generated NKT cells may possess the potent ability to develop into IL-4+IFN-γ− NKT2 cells in response to appropriate stimuli and may thereafter acquire the tendency to produce both IL-4 and IFN-γ

PI3K is critical for the nuclear translocation of IRF-7 and type I IFN production by human plasmacytoid predendritic cells in response to TLR activation

Plasmacytoid predendritic cells (pDCs) are the main producers of type I interferon (IFN) in response to Toll-like receptor (TLR) stimulation. Phosphatidylinositol-3 kinase (PI3K) has been shown to be activated by TLR triggering in multiple cell types; however, its role in pDC function is not known. We show that PI3K is activated by TLR stimulation in primary human pDCs and demonstrate, using specific inhibitors, that PI3K is required for type I IFN production by pDCs, both at the transcriptional and protein levels. Importantly, PI3K was not involved in other proinflammatory responses of pDCs, including tumor necrosis factor α and interleukin 6 production and DC differentiation. pDCs preferentially expressed the PI3K δ subunit, which was specifically involved in the control of type I IFN production. Although uptake and endosomal trafficking of TLR ligands were not affected in the presence of PI3K inhibitors, there was a dramatic defect in the nuclear translocation of IFN regulatory factor (IRF) 7, whereas nuclear factor κB activation was preserved. Thus, PI3K selectively controls type I IFN production by regulating IRF-7 nuclear translocation in human pDCs and could serve as a novel target to inhibit pathogenic type I IFN in autoimmune diseases

Aberrant fucosylation enables breast cancer clusterin to interact with dendritic cell-specific ICAM-grabbing non-integrin (DC-SIGN)

Clusterin is a glycoprotein able to mediate different physiological functions such as control of complement activation, promotion of unfolded protein clearance and modulation of cell survival. Clusterin is overexpressed in many types of cancers and a large body of evidence suggests that it promotes carcinogenesis and tumor progression. We have previously described a novel clusterin glycoform present in human semen, but not in serum, highly enriched in terminal fucose motifs. Here we show that human luminal breast cancer (LBC) clusterin also bears terminal fucosylated glycans, conferring clusterin the ability to interact with DC-SIGN, a C-type lectin receptor expressed by myeloid cells. This clusterin glycosylation pattern was absent or diminished in non-involved juxtatumoral tissue, suggesting that fucosylated clusterin might represent a cancer associated glycoform. We also found that DC-SIGN is expressed by luminal breast cancer intratumoral macrophages. Moreover, experiments performed in vitro using semen fucosylated clusterin and monocyte derived macrophages showed that the interaction of semen clusterin with DC-SIGN promoted a proangiogenic profile, characterized by a high production of VEGF, IL-8 and TNF-α. Our results reveal an unexpected complexity on the structure and function of secretory clusterin produced by tumors and suggest that fucosylated clusterin produced by luminal breast cancer cells might play a role in tumor progression by promoting the release of pro-angiogenic factors by intratumoral macrophages.Fil: Merlotti Ippólito, Antonela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; Argentina. Institute Curie; FranciaFil: López Malizia, Álvaro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Michea, Paula. Institute Curie; FranciaFil: Bonte, Pierre Emmanuel. Institute Curie; FranciaFil: Goudot, Christel. Immunite Et Cancer; FranciaFil: Carregal, María Sol. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Nuñez, Nicolás. Immunite Et Cancer; FranciaFil: Sedlik, Christine. Institute Curie; FranciaFil: Ceballos, Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Soumelis, Vassili. Institute Curie; FranciaFil: Amigorena, Sebastián. Institute Curie; FranciaFil: Geffner, Jorge Raúl. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Piaggio, Eliane. Institute Curie; FranciaFil: Sabatte, Juan Atilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; Argentin

TSLP-activated dendritic cells induce human T follicular helper cell differentiation through OX40-ligand.

T follicular helper cells (Tfh) are important regulators of humoral responses. Human Tfh polarization pathways have been thus far associated with Th1 and Th17 polarization pathways. How human Tfh cells differentiate in Th2-skewed environments is unknown. We show that thymic stromal lymphopoietin (TSLP)-activated dendritic cells (DCs) promote human Tfh differentiation from naive CD4 T cells. We identified a novel population, distinct from Th2 cells, expressing IL-21 and TNF, suggestive of inflammatory cells. TSLP-induced T cells expressed CXCR5, CXCL13, ICOS, PD1, BCL6, BTLA, and SAP, among other Tfh markers. Functionally, TSLP-DC-polarized T cells induced IgE secretion by memory B cells, and this depended on IL-4Rα. TSLP-activated DCs stimulated circulating memory Tfh cells to produce IL-21 and CXCL13. Mechanistically, TSLP-induced Tfh differentiation depended on OX40-ligand, but not on ICOS-ligand. Our results delineate a pathway of human Tfh differentiation in Th2 environments