Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Transcription profiling by array of mouse dendritic cells which were pulsed with apoptotic bodies from NIT-1 cells

ABSTRACT: We have been interested whether peripheral tolerance can be restored by vaccination with antigen-presenting cells (APCs) loaded with apoptotic bodies. Dendritic cells (DCs) are powerful APCs that have a critical role in the initiation and progression of autoimmunity. We previously demonstrated that DCs loaded with apoptotic islet cells prevents experimental type 1 diabetes (T1D), an autoimmune disease caused by beta-cell destruction. The goal of this study is to characterize the molecular changes on gene expression -transcriptome- occurring in these DCs pulsed with apoptotic bodies. Cells from four different genetically identical NOD (Non-Obese Diabetic) mice were used to obtain DCs. DCs were loaded with apoptotic bodies from NIT-1 cell line (insulinoma from NOD mice). Unloaded DCs were used as control in four paired experiments. Moreover, transcriptome from NIT-1 apoptotic bodies was determined. Mouse Gene 1.0 ST Arrays from Affymetrix (28,853 genes) were hybridized and genes with a p-value <= 0.002, adjusted p-value <= 0.08 and fold change (FC) >= 1.38 were considered upregulated, and genes with FC <= -1.37 were considered downregulated. Results demonstrate that apoptotic cells engulfment promotes molecular changes in DCs towards tolerogenic features. Gene expression profile of DCs from NOD mice that captured NIT-1 apoptotic bodies showed a downregulation of genes involved in antigen presentation and differential expression of cytokine, chemokine, natural immunity and immunoregulation genes together with the presence of specific transcripts for islet autoantigens. Molecular changes of DCs caused by the uptake of apoptotic bodies are key factors to induce antigen-specific peripheral tolerance.

ORGANISM(S): Mus musculus

DISEASE(S): no disease

SUBMITTER: Irma Pujol Autonell

PROVIDER: E-MEXP-3374 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Apoptosis plays a pivotal role in embryogenesis and postnatal cell homeostasis, involving DNA or subcellular fragmentation, and shedding of small membranous microvesicles termed apoptotic bodies (AB). Following DNA damage, hypoxia, or vascular injury, the chemokine CXCL12 has been implicated in the recruitment of progenitor cells for tissue regeneration through its receptor CXCR4 and in mechanisms counteracting apoptosis. Whether AB deliver alarm signals for regenerative responses to neighbouring cells beyond recruitment or eat-me signals for phagocytes and relevance to diseases with abundant apoptosis, eg atherosclerosis, remains unknown. Here we show that endothelial cell-derived AB are generated during diet-induced atherosclerosis and can be transferred to recipient endothelial or smooth muscle cells to induce functional expression of CXCL12. This is mediated through miRNA-126 enriched in AB, which acts by silencing RGS16 translation and unlocking CXCR4 to unleash an auto-regulatory feedback loop inducing CXCL12. Injection of AB promoted mobilization and incorporation of progenitor cells, reducing diet-induced atherosclerosis in apolipoprotein E-deficient mice, and local transfer of microRNA-126 inhibited collar-induced arterial plaque formation. This was associated with increased smooth muscle content but decreased macrophage and apoptotic cell content, all features of plaque stability. Our data identify a new mechanism, by which AB confer microRNA-126 as a paracrine alarm messenger to enhance CXCR4 signals and CXCL12 expression, thereby limiting or repairing vascular damage. This adds to the important functions of microRNAs in health and disease and may extend to progenitor cell recruitment during other forms of tissue repair or homeostasis. AB were isolated from supernatants of apoptotic, serum-starved human umbilical vein endothelial cells (HUVECs) by sequential centrifugation steps. Total RNA was isolated from AB or HUVECs and microRNA was purified using the mirVanaTM miRNA Isolation Kit (Ambion). microRNA obtained from 10 µg of total RNA was labeled using the mirVanaTM miRNA Labeling Kit (Ambion) and fluorescent Cy3 (Molecular Probes), and hybridized to the Ambion mirVanaTM miRNA Bioarray (1566 v.1). Hybridized mirVana miRNA Bioarrays were scanned and quantified by using ImaGene 5.5.4 (Bio Discovery). Resulted signal intensities were background corrected and then normalized using variance stabilization normalization. (Huber, 2002).

Project description:Abstract Two major dendritic cell (DC) subsets have been described in the islets of mice: The immunogenic CD8Î±-CD11b+ DCs and the tolerogenic CD8Î±+CD103+ DCs. We have recently reported on reduced numbers of the minor population of tolerogenic CD8Î±+CD103+ DCs in the pancreas of 5 week old pre-diabetic non-obese diabetic (NOD) mice. Aim: To analyze also the larger subset of CD11c+CD8Î±- DCs isolated from the pancreas of pre-diabetic NOD mice 1) for maturation and tolerance inducing molecules found abnormally expressed on CD8Î±+CD103+ DCs, and 2) for genome-wide gene expression to further elucidate abnormalities in underlying gene expression networks. Methods: CD11c+CD8Î±- DCs were isolated from 5 week old C57BL/6 and NOD pancreas. Expression of cell surface markers including CD86, CCR5, CD11b, CD103, Clec9a, CD24 and CD200R3 were measured by FACS. Genome-wide gene expression by microarray was assessed during the steady state and after in vitro LPS stimulation. Results: The steady state pancreatic CD11c+ CD8Î±- DCs during the pre-diabetic stage showed: 1) A reduced expression of several gene networks important for the prime functions of the cell, such as for cell renewal, immune stimulation and immune tolerance induction, for migration and for the provision of growth factors for beta cell regeneration. This general deficiency state was corroborated by a reduced in vivo proliferation (BrdU incorporation) of the cells and the reduced expression in FACS analysis of CD86, CCR5, CD103, Clec9a, CD24 and CD200R3 on the cells. 2) A hyper reactivity of these cells to LPS correlated with an enhanced pro-inflammatory state characterized by altered expression of a number of classical pro-inflammatory factors and cytokines. Conclusion: The NOD CD11c+CD8Î±- DCs seem to be Janus-faced depending on the conditions: Deficient in steady state with reduced immune stimulation capabilities also for tolerance induction; over-inflammatory with a molecular profile suggesting a preferential stimulatory capacity for Th1 cells when encountering a Pathogen-Associated Molecular Pattern (PAMP) in the form of LPS. We used microarray gene expression analysis to explain the abnormal expression of several cell surface markers involved in tolerace, migration and maturation in the steady-state and to measure the effect of a PAMP such as LPS We isolated RNA from FACS sorted CD11c+CD8Î±- DCs in 10 pooled pancreases from pre-diabetic NOD and non-diabetic C57BL/6 mice at 5 weeks. In addition, we treated in another experiment the isolated pancreas DCs with LPS (and PBS), incubated for 18h and measured gene expression. We compared gene expression between strains NOD vs C57BL/6 under steady-state and after in-vitro LPS/PBS stimulation.

Project description:Dendritic cells (DCs) are a special class of leukocytes able to activate both innate and adaptive immune responses. They interact with microbes through germline-encoded pattern-recognition receptors (PRRs), which recognize molecular patterns expressed by various microorganisms. Upon antigen binding, PRRs instruct DCs for the appropriate priming of natural killer cells, followed by specific T-cell responses. Once completed the effector phase, DCs reach the terminal differentiation stage and eventually die by apoptosis. We have observed that following lipopolysaccharide (LPS)-stimulation the initiation of the apoptotic pathway in DCs is due the activation of NFAT proteins. Indeed, LPS induces Src-family kinase and phospholipase C (PLC)Î³2 activation, influx of extracellular Ca2+ and calcineurin-dependent nuclear NFAT translocation. The initiation of this pathway is independent of TLR4 engagement, and dependent exclusively on CD14. According with this observation CD14-deficient DCs do not die following LPS stimulation. Nevertheless, CD14-deficient DC death following LPS activation can be restored by co-stimulating DCs with LPS and thapsigargin. Thapsigargin empties the intracellular calcium stores by blocking calcium pumping into the sarcoplasmic and endoplasmic reticulum and thereby activates plasma membrane calcium channels. This, in turn, allows an influx of calcium into the cytosol and NFAT activation. To identify the NFAT controlled apoptosis genes in LPS activated DCs we have performed a kinetic microarray analysis (0, 48 and 60 h) in conditions allowing or inhibiting NFAT activation. Four genes have been selected: Nur77, Gadd45g, Ddit3/Gadd153/Chop-10 and Tia1. To identify apoptosis genes selectively modulated by NFAT, a comparative kinetic (time points 0, 48 and 60 h) microarray analysis was performed in the following conditions: 1) wild type bone marrow derived DCs (wtBMDCs) stimulated with LPS; 2) CD14-deficient BMDCs stimulated with LPS; 3) wtBMDCs stimulated with LPS in presence of thapsigargin; 4) CD14-deficient BMDCs stimulated with LPS in presence of thapsigargin.

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Transcription profiling by array of mouse dendritic cells which were pulsed with apoptotic bodies from NIT-1 cells

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