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

Mécanismes de génération des macrophages immunorégulateurs humains : rôle de l’axe IL-27 / Adénosine / PGE2

The purpose of the present thesis is to study the molecular mechanisms associated with the polarization of human macrophages towards an immunoregulatory phenotype, similar to that of tumor associated macrophages (TAM). Laboratory data have shown the role of IL-27 in this process, mostly by its capacity to modulate CD39 expression, which controls, at least in part, the acquisition of an immunoregulatory phenotype by human macrophages.The purpose of this work was to specify the molecular mechanisms involved in the acquisition of the regulatory phenotype, downstream IL-27. The results confirm the central role of adenosine, and therefore of the ectonucleotidase CD39, and identify the molecule PGE2 in the functional polarization of immunoregulatory macrophages. These data confirm the importance of IL-27 in the generation of human immunoregulatory macrophages and specify the involved molecular mechanisms. Over the long term, these results will allow to evaluate new strategies in the treatment of solid tumors, whose local immunosuppression is associated with a strong infiltrate of CD39-expressing macrophages.Ce projet de thèse s’inscrit dans l’étude des mécanismes moléculaires associés à la polarisation des macrophages humains vers un phénotype immunorégulateur similaire à celui des macrophages tumoraux (TAM). Des données du laboratoire avaient montré le rôle de l'IL-27 dans ce processus, notamment au travers de sa capacité à moduler l'expression de CD39 qui contrôle, au moins en partie, l’acquisition d’un phénotype immunorégulateur par les macrophages humains. L’objectif de ce travail a été de préciser les mécanismes moléculaires impliqués dans l’acquisition du phénotype régulateur, en aval de l’IL-27. Les résultats confirment le rôle central de l’adénosine, et donc de l’ectonucléotidase CD39, et identifient la molécule PGE2 dans la polarisation fonctionnelle des macrophages immunorégulateurs. Ces données confirment l'importance de l'IL-27 dans la génération des macrophages immunorégulateurs humains et précisent les mécanismes moléculaires impliqués. A plus long terme, ces résultats permettront d’évaluer de nouvelles stratégies dans le traitement de tumeurs solides dont l’immunosuppression locale est associée à un fort infiltrat de macrophages exprimant CD39

Mechanisms of generation of human immunoregulatory macrophages : role of the IL-27 / Adenosine / PGE2 axis

Ce projet de thèse s’inscrit dans l’étude des mécanismes moléculaires associés à la polarisation des macrophages humains vers un phénotype immunorégulateur similaire à celui des macrophages tumoraux (TAM). Des données du laboratoire avaient montré le rôle de l'IL-27 dans ce processus, notamment au travers de sa capacité à moduler l'expression de CD39 qui contrôle, au moins en partie, l’acquisition d’un phénotype immunorégulateur par les macrophages humains. L’objectif de ce travail a été de préciser les mécanismes moléculaires impliqués dans l’acquisition du phénotype régulateur, en aval de l’IL-27. Les résultats confirment le rôle central de l’adénosine, et donc de l’ectonucléotidase CD39, et identifient la molécule PGE2 dans la polarisation fonctionnelle des macrophages immunorégulateurs. Ces données confirment l'importance de l'IL-27 dans la génération des macrophages immunorégulateurs humains et précisent les mécanismes moléculaires impliqués. A plus long terme, ces résultats permettront d’évaluer de nouvelles stratégies dans le traitement de tumeurs solides dont l’immunosuppression locale est associée à un fort infiltrat de macrophages exprimant CD39.The purpose of the present thesis is to study the molecular mechanisms associated with the polarization of human macrophages towards an immunoregulatory phenotype, similar to that of tumor associated macrophages (TAM). Laboratory data have shown the role of IL-27 in this process, mostly by its capacity to modulate CD39 expression, which controls, at least in part, the acquisition of an immunoregulatory phenotype by human macrophages.The purpose of this work was to specify the molecular mechanisms involved in the acquisition of the regulatory phenotype, downstream IL-27. The results confirm the central role of adenosine, and therefore of the ectonucleotidase CD39, and identify the molecule PGE2 in the functional polarization of immunoregulatory macrophages. These data confirm the importance of IL-27 in the generation of human immunoregulatory macrophages and specify the involved molecular mechanisms. Over the long term, these results will allow to evaluate new strategies in the treatment of solid tumors, whose local immunosuppression is associated with a strong infiltrate of CD39-expressing macrophages

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

International audienceThe 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

The ecto-ATPDase CD39 is involved in the acquisition of the immunoregulatory phenotype by M-CSF-macrophages and ovarian cancer tumor-associated macrophages: Regulatory role of IL-27

International audienceTumor-associated macrophages (TAM) are immunosuppressive cells that can massively accumulate in the tumor microenvironment. In patients with ovarian cancer, their density is correlated with poor prognosis. Targeting mediators that control the generation or the differentiation of immunoregulatory macrophages represents a therapeutic challenge to overcome tumor-associated immunosuppression. The ectonucleotidase CD39 hydrolyzes ATP into extracellular adenosine that exhibits potent immunosuppressive properties when signaling through the A2A adenosine receptor. We report here that CD14 C CD163 C TAM isolated from ovarian cancer patients and macrophages generated in vitro with M-CSF, express high levels of the membrane ectonucleotidase CD39 compared to classically activated macrophages. The CD39 inhibitor POM-1 and adenosine deaminase (ADA) diminished some of the immunosuppressive functions of CD14 high CD163 high CD39 high macrophages, such as IL-10 secretion. We identified the cytokine IL-27, secreted by tumor-infiltrating neutrophils, located close to infiltrating CD163 C macrophages, as a major rheostat of CD39 expression and consequently, on the acquisition of immunoregulatory properties by macrophages. Accordingly, the depletion of IL-27 downregulated CD39 and PD-L1 expression as well as IL-10 secretion by M-CSF-macrophages. Collectively, these data suggest that CD39, drived by IL-27 and CD115 ligands in ovarian cancer, maintains the immunosuppressive phenotype of TAM. This work brings new information on the acquisition of immunosuppressive properties by tumor-infiltrating macrophages

Mucosal and systemic immune correlates of viral control after SARS-CoV-2 infection challenge in seronegative adults.

Human infection challenge permits in-depth, early, and pre-symptomatic characterization of the immune response, enabling the identification of factors that are important for viral clearance. Here, we performed intranasal inoculation of 34 young adult, seronegative volunteers with a pre-Alpha severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strain. Of these participants, 18 (53%) became infected and showed an interferon-dominated mediator response with divergent kinetics between nasal and systemic sites. Peripheral CD4+ and CD8+ T cell activation and proliferation were early and robust but showed distinct kinetic and phenotypic profiles; antigen-specific T cells were largely CD38+Ki67+ and displayed central and effector memory phenotypes. Both mucosal and systemic antibodies became detectable around day 10, but nasal antibodies plateaued after day 14 while circulating antibodies continued to rise. Intensively granular measurements in nasal mucosa and blood allowed modeling of immune responses to primary SARS-CoV-2 infection that revealed CD8+ T cell responses and early mucosal IgA responses strongly associated with viral control, indicating that these mechanisms should be targeted for transmission-reducing intervention