αvβ3-dependent cross-presentation of matrix metalloproteinase–2 by melanoma cells gives rise to a new tumor antigen

A large array of antigens that are recognized by tumor-specific T cells has been identified and shown to be generated through various processes. We describe a new mechanism underlying T cell recognition of melanoma cells, which involves the generation of a major histocompatibility complex class I–restricted epitope after tumor-mediated uptake and processing of an extracellular protein—a process referred to as cross-presentation—which is believed to be restricted to immune cells. We show that melanoma cells cross-present, in an αvβ3-dependent manner, an antigen derived from secreted matrix metalloproteinase–2 (MMP-2) to human leukocyte antigen A*0201-restricted T cells. Because MMP-2 activity is critical for melanoma progression, the MMP-2 peptide should be cross-presented by most progressing melanomas and represents a unique antigen for vaccine therapy of these tumors

Faecalibacterium prausnitzii Skews Human DC to Prime IL10-Producing T Cells Through TLR2/6/JNK Signaling and IL-10, IL-27, CD39, and IDO-1 Induction

The human colonic mucosa contains regulatory type 1-like (Tr1-like, i.e., IL-10-secreting and Foxp3-negative) T cells specific for the gut Clostridium Faecalibacterium prausnitzii (F. prausnitzii), which are both decreased in Crohn's disease patients. These data, together with the demonstration, in mice, that colonic regulatory T cells (Treg) induced by Clostridium bacteria are key players in colon homeostasis, support a similar role for F. prausnitzii-specific Treg in the human colon. Here we assessed the mechanisms whereby F. prausnitzii induces human colonic Treg. We demonstrated that F. prausnitzii, but not related Clostridia, skewed human dendritic cells to prime IL-10-secreting T cells. Accordingly, F. prausnitzii induced dendritic cells to express a unique array of potent Tr1/Treg polarizing molecules: IL-10, IL-27, CD39, IDO-1, and PDL-1 and, following TLR4 stimulation, inhibited their up-regulation of costimulation molecules as well as their production of pro-inflammatory cytokines IL-12 (p35 and p40) and TNFα. We further showed that these potent tolerogenic effects relied on F. prausnitzii-induced TLR2/6 triggering, JNK signaling and CD39 ectonucleotidase activity, which was induced by IDO-1 and IL-27. These data, together with the presence of F. prausnitzii-specific Tr1-like Treg in the human colon, point out to dendritic cells polarization by F. prausnitzii as the first described cellular mechanism whereby the microbiota composition may affect human colon homeostasis. Identification of F. prausnitzii-induced mediators involved in Tr1-like Treg induction by dendritic cells opens therapeutic avenues for the treatment of inflammatory bowel diseases

Folding of Matrix Metalloproteinase-2 Prevents Endogenous Generation of MHC Class-I Restricted Epitope

BACKGROUND: We previously demonstrated that the matrix metalloproteinase-2 (MMP-2) contained an antigenic peptide recognized by a CD8 T cell clone in the HLA-A*0201 context. The presentation of this peptide on class I molecules by human melanoma cells required a cross-presentation mechanism. Surprisingly, the classical endogenous processing pathway did not process this MMP-2 epitope. METHODOLOGY/PRINCIPAL FINDINGS: By PCR directed mutagenesis we showed that disruption of a single disulfide bond induced MMP-2 epitope presentation. By Pulse-Chase experiment, we demonstrated that disulfide bonds stabilized MMP-2 and impeded its degradation. Finally, using drugs, we documented that mutated MMP-2 epitope presentation used the proteasome and retrotranslocation complex. CONCLUSIONS/SIGNIFICANCE: These data appear crucial to us since they established the existence of a new inhibitory mechanism for the generation of a T cell epitope. In spite of MMP-2 classified as a self-antigen, the fact that cross-presentation is the only way to present this MMP-2 epitope underlines the importance to target this type of antigen in immunotherapy protocols

La présentation croisée de la métalloprotéase matricielle-2 par les cellules de mélanome génère un épitope T spécifique de ce cancer

La plupart des tumeurs expriment des antigènes susceptibles d'être reconnus par des lymphocytes T CD8 cytotoxiques. Néanmoins, les essais d'immunothérapies réalisés chez l'homme, ciblant différents antigènes reconnus par des lymphocytes T, ont montré une efficacité limitée. L'une des voies possibles pour améliorer ces traitements consiste à identifier de nouveaux antigènes tumoraux. Dans ce but, nous avons étudié la spécificité de lymphocytes T ayant infiltré les mélanomes de 22 patients. Ce criblage a permis d'identifier un nouvel antigène de tumeur reconnu par un clone T CD8 dans le contexte HLA-A*0201 : la métalloprotéase matricielle-2 (MMP-2). Nous avons également montré que l'épitope MMP-2560-568 n'était pas présenté par la voie endogène classique, mais par présentation croisée. L'apprêtement original de MMP-2, utilisé exclusivement par les cellules de mélanome, et ses fonctions pro-tumorales en font un candidat idéal à cibler en immunothérapie anti-mélanome.Most tumor cells express antigens that can be recognized by cytotoxic T CD8 lymphocytes. Nevertheless, immunotherapeutic trials, targeting various human tumor cell antigens recognized by T lymphocytes, have shown limited efficacy. To improve these treatments, it is necessary to identify new tumor antigens. With this aim, we studied the specificity of melanoma infiltrating lymphocytes from 22 patients. This screening allowed us to identify a new tumor antigen recognized by a CD8 T cell clone in the HLA-A*0201 context : the matrix metalloproteinase-2 (MMP-2). We also showed that the MMP-2560-568 epitope is not processed by the classical endogenous pathway, but by cross-presentation. The original processing of the MMP-2 epitope, only used by melanoma cells, and the pro-tumoral functions of MMP-2 make of this new antigen an ideal target for immunotherapy, and opens the way to new innovative therapeutic strategies to treat HLA-A*0201 melanoma patients.NANTES-BU Sciences (441092104) / SudocSudocFranceF

Pymac: Quelle stratégie adopter pour une TPE (très petite entreprise ) digitale ?

Pymac est une agence web installée à Aix-en-Provence depuis 1998. L’arrivée des « systèmes de gestion de contenus » a bouleversé les acteurs traditionnels du marché. En effet, en proposant des modèles de sites avec un univers graphique et des cases préétablies, ces programmes informatiques ont facilité l’émergence de nouveaux entrants avec un coût moins élevé. Pymac s’est alors orientée vers la maintenance de sites afin de diversifier son offre et tirer parti de ses connaissances techniques.Pymac est ainsi reconnue pour sa technicité. Pourtant, tant le fondateur que la directrice actuelle ne sont pas informaticiens. Le fondateur vient de la distribution et sa fille, directrice actuelle, a également fait une formation en commerce. Ils se sont, certes, entourés d’informaticiens très compétents, mais la force de Pymac est sûrement de construire des sites comme des magasins en cherchant à susciter l’envie de rester aux utilisateurs. Ceci permet de mettre en évidence l’importance de la réflexion stratégique, marketing et commerciale

rhétorique et palabre: Réalités et représentations de la violence en postcolonie

info:eu-repo/semantics/publishe

Human gut microbiota-reactive DP8α regulatory T cells, signature and related emerging functions

International audienceIn mice, microbiota-induced Tregs both maintain intestinal homeostasis and provide resistance to immuno-pathologies in the adult. Identifying their human functional counterpart therefore represents an important goal. We discovered, in the human colonic lamina propria and blood, a FoxP3-negative IL-10-secreting Treg subset, which co-expresses CD4 and CD8α (hence named DP8α) and displays a TCR-reactivity against Faecalibacterium prausnitzii , indicating a role for this symbiotic bacterium in their induction. Moreover, supporting their role in intestinal homeostasis, we previously reported both their drastic decrease in IBD patients and their protective role in vivo against intestinal inflammation, in mice. Here, we aimed at identifying the genomic, phenotypic and functional signatures of these microbiota-induced Tregs, towards delineating their physiological role(s) and clinical potential. Human F. prausnitzii -reactive DP8α Treg clones were derived from both the colonic lamina propria and blood. RNA-sequencing, flow cytometry and functional assays were performed to characterize their response upon activation and compare them to donor- and tissue-matched FoxP3 + Treg clones. DP8α Tregs exhibited a unique mixed Tr1-like/cytotoxic CD4 + T cell-profile and shared the RORγt and MAF master genes with mouse gut microbiota-induced FoxP3 + Tregs. We revealed their potent cytotoxic, chemotactic and IgA-promoting abilities, which were confirmed using in vitro assays. Therefore, besides their induction by a Clostridium bacterium, DP8α Tregs also partake master genes with mouse microbiota-induced Tregs. The present identification of their complete signature and novel functional properties, should be key in delineating the in vivo roles and therapeutic applications of these unique human microbiota-induced Tregs through their study in pathological contexts, particularly in inflammatory bowel diseases