The initiation of the mucosal immune response in Peyers patch (PP) relies on the sampling, processing and efficient presentation of foreign antigens by dendritic cells (DC). PP DC encompass five subsets, among which CD11b+ conventional DC (cDC) and LysoDC have distinct progenitors and functions but share many cell surface markers. This has previously led to confusion between these two subsets. In addition, another PP DC subset, termed double-negative (DN), remains poorly characterized. Here, we have studied the genetic relatedness of the different subsets of PP cDC at steady state and under TLR7 ligand stimulation. We also provide the transcriptional profiles of subepithelial TIM-4- and interfollicular TIM-4+ macrophages.
Distribution, location, and transcriptional profile of Peyer's patch conventional DC subsets at steady state and under TLR7 ligand stimulation.
Sex, Age, Specimen part, Treatment
View SamplesDendritic cells (DCs) are the sentinels of the mammalian immune system and they undergo a complex maturation process mediated by activation upon pathogen detection. Recent studies described the analysis of activated DCs by transcriptional profiling, but translation regulation was never taken in account. Therefore, the nature of the mRNAs being translated at various stages of DC activation was determined with the help of translational profiling, which is the sucrose gradient fractionation of polysomal-bound mRNAs combined to microarrays analysis. Total and polysomal-bound mRNA populations were compared in immature (0h) and LPS-stimulated (4h and 16h) human monocyte-derived DCs with the help of Affymetrix microarrays. Biostatistical analysis indicated that 296 mRNA molecules are translationally regulated during DC-activation. The most abundant biological process among the regulated mRNAs was protein biosynthesis, indicating the existence of a negative feedback loop regulating translation. Interestingly, a cluster of 17 ribosomal proteins were part of the regulated mRNAs, indicating that translation may be fine-tuned by particular components of the translational machinery. Our observations highlight the importance of translation regulation during the immune response, and may favour the identification of novel gene clusters or protein networks relevant for immunity. Our study also provides information on the possible absence of correlation between gene expression and real protein production in DCs.
Ribosomal protein mRNAs are translationally-regulated during human dendritic cells activation by LPS.
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View SamplesGuanabenz is an FDA approved drug for hypertension. It has been shown also to be an inhibitor of GADD34, the stress-inducible cofactor of PP1. GADD34 has been shown to play a key role in controlling cytokine production in MEFs and dendritic cells.
No associated publication
Sex, Age, Specimen part
View SamplesIn response to inflammatory stimulation, dendritic cells (DCs) have a remarkable pattern of differentiation that exhibits specific mechanisms to control the immune response. Here we show that in response to polyriboinosinic:polyribocytidylic acid (poly I:C), DCs mount a specific transcription program during which the growth arrest and DNA damage-inducible protein 34 (GADD34/MyD116), a phosphatase 1 (PP1) cofactor, is expressed. Together with its constitutively active counterpart CReP, GADD34 promotes an extensive dephosphorylation of the translation initiation factor eIF2-alfa in activated DCs. In turn, dephosphorylation of eIF2-alfa prevents the translation inhibition normally associated with cellular stress or detection of cytoplasmic double-stranded RNA. These observations have important implications in linking pathogen detection with the integrated stress responses molecular machinery. The importance of this regulation for DC function is exemplified by the alteration of IFN-beta production or the induction of caspase-3 cleavage upon inhibition of PP1 activity.
No associated publication
Specimen part
View SamplesIn response to inflammatory stimulation, dendritic cells (DCs) have a remarkable pattern of differentiation (maturation) that exhibits specific mechanisms to control immunity. Here, we show that in response to Lipopolysaccharides (LPS), several microRNAs (miRNAs) are regulated in human monocyte-derived dendritic cells. Among these miRNAs, miR-155 is highly up-regulated during maturation. Using LNA silencing combined to microarray technology, we have identified the Toll-like receptor / interleukin-1 (TLR/IL-1) inflammatory pathway as a general target of miR-155. We further demonstrate that miR-155 directly controls the level of important signal transduction molecules. Our observations suggest, therefore, that in mature human DCs, miR-155 is part of a negative feedback loop, which down-modulates inflammatory cytokine production in response to microbial stimuli.
MicroRNA-155 modulates the interleukin-1 signaling pathway in activated human monocyte-derived dendritic cells.
No sample metadata fields
View SamplesMouse embryonic stem (ES) cells remain pluripotent in vitro when grown in presence of Leukaemia Inhibitory Factor (LIF). LIF starvation leads to apoptosis of some of the ES-derived differentiated cells, together with p38a MAP kinase activation. Apoptosis, but not morphological cell differentiation, is blocked by a p38 inhibitor, PD 169316. To further understand the mechanism of action of this compound, we have identified its specific targets by microarray studies. We report on the global expression profiles of genes expressed at three days upon LIF withdrawal (d3) compared to pluripotent cells and of genes whose expression is modulated at d3 under anti-apoptotic conditions. We showed that at d3 without LIF cells express, earlier than anticipated, specialized cell markers and that when the apoptotic process was impaired, expression of differentiation markers was altered. In addition, functional tests revealed properties of anti-apoptotic proteins not to alter cell pluripotency and a novel role for metallothionein 1 gene which prevents apoptosis of early differentiated cells.
Apoptosis and differentiation commitment: novel insights revealed by gene profiling studies in mouse embryonic stem cells.
No sample metadata fields
View SamplesFunctional characterization of human dendritic cell subsets is limited due to the very low frequency of these cells in vivo. We developed an in vitro culture system for the simultaneous generation of XCR1+ DCs and MoDCs from cord blood CD34+ cells. Their global gene expression profiles at steady state and under activation, phenotypes, morphologies and responses to different TLR ligands where characterized and compared with those of their in vivo counterparts. The study demonstrated that the XCR1+ DCs generated in vitro from cord blood CD34+ cells are equivalent to blood XCR1+ DCs and also allowed a rigorous comparison of this DC subset with MoDC which are often considered as the reference model for DCs. Altogether, our results showed that in vitro generated XCR1+ DCs are a better model for the study of blood DC than the conventionally used MoDCs.
Human XCR1+ dendritic cells derived in vitro from CD34+ progenitors closely resemble blood dendritic cells, including their adjuvant responsiveness, contrary to monocyte-derived dendritic cells.
Specimen part, Treatment
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Broad and Largely Concordant Molecular Changes Characterize Tolerogenic and Immunogenic Dendritic Cell Maturation in Thymus and Periphery.
Specimen part, Treatment
View SamplesPsoriasis is a chronic inflammatory skin disease of unknown etiology. Although macrophages and dendritic cells (DCs) have been proposed to drive the psoriatic cascade, their largely overlapping phenotype hampered studying their respective role. Topical application of Imiquimod, a Toll-like receptor 7 agonist, induces psoriasis in patients and psoriasiform inflammation in mice. We showed that daily application of Imiquimod for 14 days recapitulated both the initiation and the maintenance phase of psoriasis. Based on our ability to discriminate Langerhans cells (LCs), conventional DCs, monocytes, monocyte-derived DCs and macrophages in the skin, we characterized their dynamics during both phases of psoriasis. During the initiation phase, neutrophils infiltrated the epidermis whereas monocytes and monocyte-derived DCs were predominant in the dermis. During the maintenance phase, LCs and macrophage numbers increased in the epidermis and dermis, respectively. LC expansion resulted from local proliferation, a conclusion supported by transcriptional analysis. Continuous depletion of LCs during the course of Imiquimod treatment aggravated chronic psoriatic symptoms as documented by an increased influx of neutrophils and a stronger inflammation. Therefore, by developing a mouse model that mimics the human disease more accurately, we established that LCs play a negative regulatory role during the maintenance phase of psoriasis.
Dynamics and Transcriptomics of Skin Dendritic Cells and Macrophages in an Imiquimod-Induced, Biphasic Mouse Model of Psoriasis.
Specimen part, Treatment
View SamplesPlasmacytoid dendritic cells (pDC) are the major source of type I interferons (IFN-I) during viral infections, in response to triggering of endosomal Toll Like Receptors (TLR) 7 or 9 by viral single-stranded RNA or unmethylated CpG DNA, respectively. IFN-I production in pDC occurs in specialized endosomes encompassing preformed signaling complexes of TLR7 or 9 with their adaptor molecule MyD88 and the transcription factor interferon regulatory factor 7 (IRF7). The triggering of TLR leads to IRF7 phosphorylation, nuclear translocation and binding to the promoters of the genes encoding IFN-I to initiate their transcription. pDC express uniquely high levels of IRF7 at steady state and this expression is further enhanced by positive IFN-I feedback signaling during viral infections. However, the specific cell-intrinsic roles of MyD88 versus IFN-I signaling in pDC responses to a viral infection have not been rigorously dissected. To achieve this aim, we generated mixed bone marrow chimera mice (MBMC) allowing to rigorously compare the gene expression profiles of WT versus Ifnar1-KO or MyD88-KO pDC isolated from the same animals at steady state or after infection with the mouse cytomegalovirus (MCMV). Our results indicate that, in vivo during MCMV infection, pDC undergo a major transcriptional reprogramming, under combined instruction of IFN-I, IFN- and direct TLR triggering. However, these different stimuli drive specific, largely distinct, gene expression programs. We rigorously determined which gene modules require cell-intrinsic IFN-I signaling for their induction in pDC during a physiological viral infection in vivo. We delineated non-redundant versus shared versus antagonistic responses with IFN-. We demonstrated that cell-intrinsic IFN-I responsiveness is dispensable for induction of the expression of all IFN-I/III genes and many cytokines or chemokines in pDC during MCMV infection, contrary to MyD88 signaling.
Molecular dissection of plasmacytoid dendritic cell activation <i>in vivo</i> during a viral infection.
Specimen part, Treatment
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